The study, published in Frontiers in Carbon, was led by Carolina F. de Matos and Mayara B. Leão of the Federal University of Pampa and the Federal University of Santa Maria, together with colleagues at the Franciscan University and the Pontifical Catholic University of Rio Grande do Sul. Their central question was deceptively basic: when a paracetamol molecule meets a graphene-based adsorbent, what kind of bond holds it there? The answer matters because adsorption is one of the cheapest water-treatment technologies available, yet most studies in the field report only how much contaminant a material removes, not why. Without a mechanistic understanding, researchers are essentially tuning materials blind.

The materials at the heart of the work are three-dimensional networks of reduced graphene oxide, or 3D-rGO. Flat graphene sheets have an enormous surface area, but they suffer from a fatal flaw in water: the sheets stack back together through strong π-π and van der Waals interactions, collapsing into clumps with little accessible surface. They are also hydrophobic and easily leach into waterways as hard-to-recover fragments. The three-dimensional version solves both problems. By assembling reduced graphene oxide sheets into an interconnected porous scaffold — a monolithic hydrogel — the researchers created a material with high porosity, good mechanical properties, and a structure that resists restacking. Similar materials have already shown promise for removing dyes, oils, pesticides, metals, and drugs such as ibuprofen, diclofenac, and naproxen.

To probe how chemistry and structure jointly govern performance, the team synthesized four adsorbents from the same graphene oxide precursor. Three were three-dimensional hydrogels reduced with different concentrations of ascorbic acid — a mild, food-safe reducing agent — at 0, 5, and 25 millimoles per liter, yielding materials labeled 3D-rGO0, 3D-rGO5, and 3D-rGO25. The fourth was a two-dimensional reduced graphene oxide, 2D-rGO. The logic was elegant: more reducing agent strips away more oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups, while also compacting the porous structure. Scanning electron microscopy revealed the expected trend — the more ascorbic acid used, the denser and less cavernous the scaffold. Potentiometric titration quantified the chemistry: 3D-rGO0 carried 10.62 millimoles of carboxyl groups per gram, while 3D-rGO5 and 3D-rGO25 carried only 3.08 and 2.52 respectively. Surface areas ranged from 62.8 square meters per gram for the most compact material up to 172.3 for the loosest.

The adsorption experiments told a story with two distinct chapters. In the kinetic tests, where 8 milligrams of each material were suspended in 5 milliliters of a 50 milligram-per-liter paracetamol solution, speed favored the most oxidized and most porous material. 3D-rGO0 reached equilibrium in roughly five hours, with half of the adsorbable drug captured in just 15.9 minutes, while 2D-rGO needed about a day and nearly 193 minutes to reach the halfway point. But when the researchers measured total capacity — how much drug each material could hold at saturation — the ranking inverted. 3D-rGO5, the material with an intermediate reduction level, absorbed a striking 235.7 milligrams of paracetamol per gram, the highest of the four. The heavily reduced 3D-rGO25 and the flat 2D-rGO came next at 176.8 and 175.1 milligrams per gram, and the fast-acting 3D-rGO0 trailed at 157.6.

The explanation lies in a trade-off between morphology and chemistry. 3D-rGO0’s loose, granular structure gives drug molecules rapid access to its abundant oxygenated sites, so it adsorbs quickly — but its low surface area limits total capacity. 3D-rGO5 occupies a sweet spot: a cohesive three-dimensional network with large cavities, moderate compaction, and enough residual oxygen groups to bind the drug strongly. Isotherm fitting added another clue. All three 3D materials followed the Langmuir model, consistent with monolayer adsorption on a finite set of sites, while the 2D material fit the Sips model, which blends Freundlich behavior at low concentrations with Langmuir saturation at high ones. Dimensionality, it seems, shapes not just how much drug is captured but the very character of the process.

To understand what happens at the molecular scale, the team turned to density functional theory calculations using the SIESTA code. They built simplified graphene models decorated with one or two copies of three representative oxygen groups — epoxy, hydroxyl, and carboxyl — and simulated paracetamol docking onto each. The local density approximation was chosen deliberately because it handles weak, π-stacking interactions on sp2 carbon systems better than gradient-corrected functionals. Binding energies were corrected for basis set superposition error, and Mulliken population analysis quantified how much electronic charge shifted between drug and surface.

The simulations delivered a clear verdict: every configuration, without exception, was physisorption. Even the most energetically favorable cases — 1.28 electron-volts for graphene bearing two hydroxyl groups and 1.48 electron-volts for two carboxyl groups — showed binding distances and charge transfers incompatible with true chemical bonding. Total charge density isosurface analysis confirmed the point visually: no shared electron density bridges appeared between the drug and the graphene, ruling out chemisorption. Instead, the interaction is dominated by hydrogen bonding between the drug and the surface’s oxygen groups, with the strength climbing steadily as functional groups multiply. The HOMO-LUMO gap analysis reinforced the picture — the electronic structure of the combined system barely differed from that of its isolated components, exactly what one expects when molecules sit on a surface rather than react with it.

The convergence of theory and experiment is what makes this study significant. The simulations predicted that more oxygen groups mean stronger binding; the experiments showed that more oxygen groups and more accessible pores mean higher capacity. The team even observed that adding functional groups slightly deforms the graphene sheet, and that the graphene acts as an amphoteric charge donor depending on how the drug orients itself — details that only quantum calculations could reveal. Together, the two lines of evidence establish a design principle: the ideal paracetamol adsorbent is a three-dimensional graphene scaffold that is porous enough to let the drug reach its interior, yet retains a threshold density of oxygenated functional groups. Reduce too little and the structure stays loose but chemistry-starved; reduce too much and the pores collapse and the binding sites vanish.

For a world increasingly worried about pharmaceuticals in its drinking water, the implications are practical. The synthesis takes about two hours, uses ascorbic acid rather than harsh reagents, and produces a monolithic hydrogel that is easy to handle and recover — addressing the leaching problem that plagues two-dimensional nanomaterials. The researchers suggest their findings provide a solid foundation for developing more efficient and advanced water-treatment technologies, and the same experimental-theoretical framework could be extended to other emerging contaminants, from antibiotics to endocrine disruptors. The humble painkiller in the medicine cabinet may soon meet its match in a sponge made of atom-thin carbon.

Subject of Research: Paracetamol adsorption mechanisms on three-dimensional reduced graphene oxide materials for water treatment

Article Title: Unlocking the paracetamol adsorption mechanism in graphene tridimensional-based materials: an experimental-theoretical approach

Article References: de Matos, C. F., Leão, M. B., Vendrame, L. F. O., Jauris, I. M., Zanella, I., & Fagan, S. B. (2024). Unlocking the paracetamol adsorption mechanism in graphene tridimensional-based materials: an experimental-theoretical approach. Frontiers in Carbon, 3, Article 1305183. https://doi.org/10.3389/frcrb.2024.1305183

Image Credits: AI Generated

DOI: 10.3389/frcrb.2024.1305183

Keywords: graphene, paracetamol, adsorption, water treatment, reduced graphene oxide, density functional theory, physisorption, functional groups, emerging contaminants, 3D-rGO, pharmaceutical pollution, hydrogel

The mixed-suspension mixed-product-removal crystallizer has long served as the conceptual and practical workhorse of continuous crystallization. In an MSMPR vessel, the slurry is assumed to be well mixed, so that crystals of every size experience the same supersaturation environment, and the product stream withdrawn from the vessel has the same composition as the well-mixed contents. This idealization yields a particularly elegant theoretical consequence: the steady-state crystal population density distribution, when plotted on a logarithmic scale against particle size, becomes a straight line whose slope is directly related to the ratio of growth rate to residence time. This relationship has allowed generations of crystallization researchers to extract nucleation and growth kinetics directly from steady-state particle-size measurements, and it underpins the population-balance modeling framework used in the present study. At the same time, the well-mixed assumption introduces the very limitation that staging seeks to address, because a broad residence-time distribution means some crystals spend far longer in the vessel than others, and back-mixing can carry fine particles into environments where they continue to compete for supersaturation.

The tension at the heart of single-stage operation deserves elaboration. Supersaturation, the thermodynamic driving force for crystallization, must be generated somewhere in the process, whether by cooling, antisolvent addition, or evaporation. In a single vessel, that driving force is spent on competing processes: nucleation of new crystals, growth of existing ones, and, in polymorphic systems, the selection and maintenance of the desired solid form. High supersaturation favors nucleation, which multiplies the crystal population and divides the available solute among more particles, yielding smaller crystals with wider distributions. Low supersaturation favors growth on existing crystal surfaces, which produces larger and more uniform particles but leaves more solute unconverted and reduces the productivity of the equipment. These are not merely engineering inconveniences; they reflect the fundamental kinetics of how crystals are born and how they grow, and no single set of operating conditions can optimize both simultaneously in one vessel.

Staging resolves this conflict by temporal separation rather than by compromise. In a two-stage configuration, the first vessel can operate at conditions that favor controlled nucleation and early growth, while the second vessel operates at lower supersaturation, where the crystal population that survived the first stage can grow to its target size without the disruptive generation of new nuclei. The comparison reported for paracetamol and carbamazepine is methodologically significant precisely because it holds total active volume and overall residence time constant between the single-stage and two-stage configurations. Without this constraint, any improvement observed in a staged system could simply be attributed to the additional equipment volume or longer processing time. By matching these variables, the study isolates the effect of how supersaturation is distributed in time and space, and the results make a clear argument: the benefit of staging lies in the controlled distribution of the driving force, not in added capacity.

The choice of model compounds strengthens the generality of these findings. Paracetamol crystallizing as Form I represents a relatively well-behaved cooling crystallization system, one that has become a standard benchmark in crystallization research because its solubility behavior, metastable-zone width, and growth kinetics have been extensively characterized. Carbamazepine crystallizing as Form III presents a more demanding challenge, because carbamazepine is notorious among pharmaceutical polymorphs for the complexity of its solid-form landscape, with multiple anhydrous and solvated forms that can interconvert depending on temperature, solvent composition, and mechanical history. Antisolvent-assisted cooling crystallization of carbamazepine must therefore manage not only particle size but also the risk of nucleating or transforming into an undesired polymorph. That the two-stage configuration improved polymorphic selectivity in both systems, despite their contrasting crystallization behavior, suggests that the underlying mechanism, namely the suppression of secondary nucleation through staged desupersaturation, operates across chemically distinct APIs.

The experimental design employed here reflects the maturing methodology of quality-by-design in pharmaceutical development. The Box-Behnken design is a response-surface approach that efficiently samples a four-factor experimental space with fewer runs than a full factorial design while avoiding the extreme corner combinations that might push the process into inoperable regimes. By applying independent designs to each compound, the study acknowledges that paracetamol and carbamazepine respond differently to the same process levers, and that a compound-specific operating space is more informative than a generic one. The four factors chosen, residence time, relative supersaturation, seed loading, and power input per unit volume, span the principal degrees of freedom available to a crystallization engineer. Seed loading deserves particular attention, because continuous crystallization differs fundamentally from batch operation in how seeding is implemented: rather than charging a single dose of seed crystals at the start, continuous operation requires a continuous stream of seed material, which raises practical questions about seed preparation, seed quality, and the long-term consistency of the seed supply.

The population-balance modeling component illustrates both the power and the requirements of mechanistic crystallization modeling. A population-balance equation describes how the number of crystals in each size class evolves over time under the combined influences of nucleation, growth, breakage, agglomeration, and removal. When calibrated against experimental data and, critically, validated against data not used in the fitting process, such models can interpolate within the experimental domain and support scenario analysis for operating conditions that were not directly tested. The reported coefficients of determination between 0.894 and 0.943, with normalized root-mean-square errors between 1.8 and 8.8 percent, indicate that the models captured the dominant behavior of both systems with useful quantitative fidelity. The emphasis on external validation is important, because crystallization models calibrated on one dataset can appear deceptively accurate while failing to generalize, particularly when kinetic parameters are correlated or when the model structure omits relevant phenomena such as breakage or size-dependent growth.

The multimodal process analytical technology deployed in the study reflects a broader trend toward real-time monitoring in continuous pharmaceutical manufacturing. Attenuated total reflection Fourier-transform infrared spectroscopy and Raman spectroscopy probe the liquid and solid phases respectively, allowing dissolved concentration and polymorphic content to be estimated without withdrawing samples. Focused-beam reflectance measurement provides chord-length distributions, which are related to but not identical with true particle-size distributions, since the measured chords depend on particle shape, orientation, and the concentration of the suspension. The careful validation of these online measurements against independent offline references, such as laser diffraction and microscopy, is what transforms them from trend indicators into quantitative process monitors. This validation work, though less glamorous than the optimization results themselves, is essential for regulatory acceptance of real-time release testing and for the closed-loop control strategies that continuous crystallization ultimately promises.

The attention paid to fouling and downstream processability distinguishes this work from much of the continuous-crystallization literature, which has historically prioritized yield and particle size. Fouling, the accumulation of crystal deposits on vessel walls, impellers, and heat-transfer surfaces, is a persistent operational challenge in continuous crystallizers. It degrades heat transfer, alters the effective working volume, disturbs mixing and residence-time distribution, can blind optical PAT probes, and eventually forces shutdown for cleaning, undermining the very continuity that justifies continuous operation. The finding that two-stage operation reduced fouling by roughly 42 to 46 percent for the two compounds is therefore operationally meaningful, and the mechanism is plausible: by lowering the supersaturation experienced in each individual vessel, staging reduces the thermodynamic driving force for heterogeneous nucleation on surfaces, which is a principal pathway for fouling formation.

The downstream consequences of particle attributes are equally concrete. Filtration time declined by 26.3 percent for paracetamol and 34.4 percent for carbamazepine when the two-stage configuration was used, a direct consequence of the larger median particle sizes and narrower distributions. The relationship between particle size and filtration follows from classical cake-filtration theory, in which the specific cake resistance varies inversely with particle size, so that modest increases in median size can produce disproportionate reductions in filtration time. Narrower distributions further improve washing efficiency and reduce mother-liquor retention, which affects both drying time and final product purity. Elongated or needle-like crystals, which often result from high-supersaturation conditions, pack poorly in filter cakes and create high resistance; the reported improvements in morphology under staged operation therefore compound the benefits of size alone.

The trade-off between product quality and space-time yield deserves honest acknowledgment. Longer residence times improved particle size, distribution width, and polymorphic content, but reduced space-time yield, meaning that a given equipment volume produced less material per unit time. This is not a flaw in the study but a genuine feature of crystallization physics: crystal growth takes time, and time spent growing is time during which the vessel is not processing new feed. The practical resolution of this trade-off depends on which constraints dominate a given manufacturing scenario, whether the bottleneck is downstream filtration capacity, equipment volume, or product quality specifications. The value of the response-surface models developed here is precisely that they allow such trade-offs to be quantified and navigated rather than discovered by trial and error.

The preservation of chemical purity and mass-balance closure across all configurations provides an important baseline assurance. Mass-balance closure, the accounting identity that solute entering the system must equal solute leaving in product and mother liquor, is a stringent test of experimental rigor in continuous operation, because it requires accurate measurement of flows, concentrations, and solids contents over extended steady-state periods. That closure was maintained while fouling was present in the single-stage configuration suggests careful experimental technique, and it lends credibility to the comparative conclusions. Similarly, the extended polymorphic stability testing addresses a concern specific to continuous operation: because continuous crystallizers operate at steady state for long periods, any slow polymorphic transformation that would be invisible in a batch process could accumulate over time and compromise the solid form of the product.

Looking beyond the two compounds studied, the findings suggest a design principle for continuous pharmaceutical crystallization that is likely to generalize: the distribution of supersaturation across stages is a primary design variable, comparable in importance to residence time or temperature profile. The authors are appropriately measured in their claims, presenting the work as a reproducible demonstration for two APIs with contrasting behavior rather than a universal framework. Extending the approach to compounds with different solubility temperature-dependence, different growth kinetics, or different polymorphic landscapes would test the boundaries of the principle, as would configurations with more than two stages or with interstage seeding or fines dissolution. The combination of structured experimentation, externally validated mechanistic modeling, multimodal PAT, and operational metrics such as fouling and filtration time offers a template for how continuous crystallization research can connect molecular-level phenomena to manufacturing-relevant outcomes, and it is this end-to-end perspective that gives the study its practical significance for the pharmaceutical industry’s ongoing transition toward continuous manufacturing.

Subject of Research: Continuous crystallization of pharmaceutical compounds in mixed suspension mixed product removal systems

Article Title: Continuous crystallization of pharmaceutical compounds in mixed suspension mixed product removal systems

Article References: Tan, F. (2026). Continuous crystallization of pharmaceutical compounds in mixed suspension mixed product removal systems. Frontiers in Chemistry, 14, Article 1947756. https://doi.org/10.3389/fchem.2026.1947756

Image Credits: AI Generated

DOI: 10.3389/fchem.2026.1947756

Keywords: continuous crystallization, MSMPR, pharmaceutical manufacturing, paracetamol, carbamazepine, polymorphism, population-balance modeling, process analytical technology, particle-size distribution, fouling, filtration, quality by design

The study focused on two amphipod species from the family Gammaridae: the native Gammarus pulex, a widespread European freshwater shrimp long used as a sentinel of water quality, and Gammarus tigrinus, an invasive North American species that has colonized many degraded European waterways. Specimens of the native species were collected from a calcium-rich spring complex in southern Poland, while the invasive animals came from the Kłodnica River, a heavily industrialized tributary of the Oder that has been altered by more than a century of coal mining and receives substantial domestic and industrial wastewater. Water chemistry at the two sites differed dramatically: conductivity in the river was nearly ten times higher than at the spring, and salinity, ammonium and phosphate levels were all markedly elevated, reflecting the intense anthropogenic pressure on that catchment.

In the laboratory, animals were acclimated in water from their own collection sites and then exposed to five concentrations of each drug, ranging from 0.5 to 5,000 milligrams per liter, alongside drug-free controls. Survival and mobility were assessed at 24, 48, 72 and 96 hours, with animals failing to respond to a gentle touch of a laboratory needle counted as dead. The researchers also calculated standard acute toxicity benchmarks, the LC50, the concentration lethal to half the test population, and the EC50, the concentration that immobilizes half the animals, using probit analysis.

The results defied simple expectations. Paracetamol emerged as the most dangerous of the compounds tested: at the highest concentration, every animal of both species died within 24 hours, and by the end of the 96-hour experiment, the drug had killed 100 percent of individuals at all tested concentrations, while control animals survived. Mortality followed a striking temporal pattern across all treatments, with two distinct peaks, one after 24 hours, likely reflecting acute shock from sudden pollutant exposure, and another after 96 hours, suggesting cumulative or delayed toxic effects. Ibuprofen and ketoprofen also killed all animals rapidly at the highest doses, but at intermediate concentrations their effects were more variable and clearly species-dependent, with the native G. pulex generally succumbing earlier than its invasive relative.

Perhaps the most surprising result concerns the invasive species itself. The researchers had hypothesized that G. tigrinus, which thrives in the polluted Kłodnica River and is known for broad ecological tolerance, would consistently outperform the native species under pharmaceutical stress. That prediction was only partially borne out. The invasive amphipod did show delayed mortality and greater survival at some intermediate concentrations, particularly under ibuprofen exposure and in the drug mixture, but this advantage eroded with time. Prolonged exposure and higher concentrations erased most differences between the species, indicating that invasive status alone does not confer general resistance to pharmaceutical contaminants.

The drug mixture produced equally instructive results. Rather than showing a simple additive toxicity, the 1:1 combination of ibuprofen and ketoprofen generated complex, species-specific and time-dependent responses, with the invasive species surviving better than the native one at a few intermediate concentrations. This nonlinearity echoes earlier findings on other drug cocktails: mixtures of nonsteroidal anti-inflammatory drugs have been shown to be far more toxic to the water flea Daphnia magna than any single component, and combinations of antidepressants and anti-inflammatories have increased mortality in fish. Because pharmaceuticals almost never occur alone in natural waters, the authors argue that single-compound risk assessments may substantially underestimate real-world hazards.

Immobilization data added another layer of complexity. Paralysis appeared mainly after 48 hours of exposure and did not reliably precede death; many immobilized animals either recovered temporarily or were later classified as dead. This suggests that immobilization is a transient stress response rather than a stable predictor of lethality, complicating the interpretation of standard ecotoxicological endpoints. The calculated LC50 and EC50 values themselves showed wide confidence intervals and inconsistent trends, and in several cases toxicity thresholds could not be reliably determined at all, underscoring the difficulty of characterizing pharmaceutical toxicity with conventional acute-testing frameworks.

The study also highlights a regulatory gap. Under the European Union’s Water Framework Directive, only a limited number of pharmaceuticals are routinely monitored in surface waters, and the European Commission has acknowledged that monitoring focuses narrowly on hot spots such as hospital discharges. Yet the environmental ubiquity of these compounds is well documented: surveys across 20 countries detected ibuprofen in more than 90 percent of analyzed samples, and concentrations of ibuprofen and ketoprofen in rivers near Madrid have reached several micrograms per liter, levels at which sublethal effects on gammarids have previously been recorded. Because many drugs are chemically stable, a large fraction of the active ingredient can be excreted unchanged, and their polarity and lipophilicity allow them to travel widely in water, accumulate in tissues and biomagnify through food chains, potentially reaching human consumers of fish and other aquatic organisms.

The authors caution that their experimental design, which used water from each species’ natural habitat, may have introduced site-specific differences in water chemistry as a confounding factor, and they recommend that future work employ fully standardized conditions to disentangle species-specific sensitivity from environmental effects. Still, they note that G. tigrinus is well adapted to the conditions of the Kłodnica River, where it occurs at high densities, so the observed habitat differences are unlikely to have imposed significant additional stress on that species.

The broader message is stark. Even at low doses, pharmaceuticals can cause serious ecological disturbances and ripple through aquatic trophic chains, and the ready availability of over-the-counter analgesics, combined with the absence of systematic monitoring, leaves freshwater ecosystems exposed to a threat that is heterogeneous, cumulative and poorly captured by current risk assessment. The researchers call for multi-species toxicity testing and realistic exposure scenarios that reflect the mixtures actually found in the environment, arguing that only such approaches can adequately gauge the environmental risks posed by the drugs society consumes so freely.

Subject of Research: Acute toxicity of non-opioid analgesics to native and invasive Gammarus crustaceans

Article Title: Evaluation of non-opioid analgesic toxicity and their effects on native and invasive species of crustaceans ( Gammaridae , Gammarus )

Article References: Cieplok, A., Orpych, B., Chrobak, K., Rusinek, K., Czerniawski, R., & Spyra, A. (2026). Evaluation of non-opioid analgesic toxicity and their effects on native and invasive species of crustaceans (Gammaridae, Gammarus). BioRisk, 24, 85-102. https://doi.org/10.3897/biorisk.24.176556

Image Credits: AI Generated

DOI: 10.3897/biorisk.24.176556

Keywords: pharmaceutical pollution, ecotoxicology, Gammarus, freshwater ecosystems, invasive species, paracetamol, ibuprofen, ketoprofen, water quality, Evaluation, non-opioid, analgesic

The technique at the heart of the work is reverse-phase high-performance liquid chromatography, or RP-HPLC, a workhorse of pharmaceutical quality control. In essence, the method pushes a dissolved sample through a narrow column packed with microscopic silica beads coated in a nonpolar layer. The drug molecules interact with this stationary phase while being carried along by a liquid mobile phase, and because different compounds interact with different strengths, they separate and emerge at distinct times. A detector then registers each compound as a peak, and the size of the paracetamol peak reveals how much of the drug is present. The sensitivity, precision, and reproducibility of RP-HPLC have made it the default choice for verifying the content of pharmaceutical formulations, including the ubiquitous paracetamol tablet.

What makes the new study notable is not the mere existence of another paracetamol assay, as the authors themselves acknowledge, but the systematic way the method was constructed. Conventional method development typically proceeds one variable at a time: adjust the solvent mixture, run the sample, adjust the pH, run it again. This trial-and-error process is slow, and worse, it can miss interactions between variables, situations where changing two parameters together produces effects that neither produces alone. Analytical Quality by Design, or AQbD, flips the script. It begins with an Analytical Target Profile, a formal statement of what the method must achieve, and then uses risk assessment and designed experiments to map out how every critical parameter influences performance. The result is not just a working method but a deep, quantitative understanding of why it works.

The researchers, led by Kranti Satpute of Dayanand College of Pharmacy in Latur, Maharashtra, began by defining the attributes their method needed: adequate retention of the paracetamol peak, good peak symmetry, high chromatographic efficiency, a reproducible signal, and clean separation from any tablet excipients or impurities. They then ranked potential method variables by risk, classifying each as low, medium, or high priority. This triage focused their experimental effort on the parameters most likely to disrupt the analysis, a philosophy borrowed directly from quality risk management frameworks used across the pharmaceutical industry. Variables deemed low risk, such as those unlikely to affect retention or peak shape, were set aside, while high-risk candidates were earmarked for systematic investigation.

For the optimization itself, the team turned to a Central Composite Design, a form of Response Surface Methodology that examines multiple factors simultaneously across five levels each. Three chromatographic parameters were varied: the concentration of organic modifier in the mobile phase, the pH of that phase, and the flow rate of the pump. The ranges, spanning 5 to 25 percent organic modifier, pH 6.3 to 6.7, and flow rates of 0.8 to 1.2 milliliters per minute, were grounded in preliminary experiments. The design tracked three responses: retention time, peak area, and theoretical plate count, the last being a measure of column efficiency. Analysis of variance then revealed which factors and interactions were statistically significant, something a one-factor-at-a-time approach could never expose.

The statistics delivered a clear verdict. Retention time was strongly influenced by organic modifier concentration, with a p-value of 0.0001, and by flow rate, at p equal to 0.0004, while pH turned out to be statistically irrelevant to retention, with a p-value of 0.9917. Flow rate also significantly affected peak area and theoretical plate count. Three-dimensional response surface plots visualized these relationships, showing retention time falling as organic modifier increased while peak area and plate counts remained comparatively stable across the studied ranges. This kind of visual and statistical map of method behavior is precisely the knowledge that conventional approaches leave on the table, and it gave the team a rational basis for deciding which parameters must be tightly controlled during routine use.

The final method settled on a mobile phase of water, acetonitrile, and methanol in an 80:15:5 ratio, adjusted to pH 6.5 with triethylamine, flowing at 1.0 milliliter per minute through an Agilent TC-C18 column, with ultraviolet detection at 254 nanometers, the wavelength where paracetamol absorbs most strongly. Under these conditions, paracetamol eluted as a sharp, symmetrical peak at roughly 5.4 minutes, within a total run time of just seven minutes. Crucially, the design of experiments also defined a Method Operable Design Region, a design space within which the method is guaranteed to perform acceptably even if conditions drift slightly. Instead of a single fragile set of settings, quality control laboratories gain a flexible operating window with assured performance, a concept regulators increasingly favor under ICH Q14.

Validation followed the latest ICH Q2(R2) guidelines, and the numbers were impressive. Linearity held across concentrations from 18 to 42 micrograms per milliliter with a correlation coefficient of 0.9995, about as close to a perfect straight line as analytical chemistry allows. Repeatability produced a relative standard deviation of just 0.66 percent, and intermediate precision, tested across different days, analysts, and instruments, came in at 1.75 percent. Accuracy experiments at 80, 100, and 120 percent of the target concentration yielded recoveries between 100.03 and 102.85 percent, with an overall mean recovery of 101.58 percent and a relative standard deviation of 0.70 percent, comfortably within the accepted 97 to 103 percent window. Specificity testing confirmed that blank, placebo, and impurity-spiked samples produced no interfering peaks at the paracetamol retention time, and photodiode array assessment supported peak purity.

Robustness testing added a final layer of confidence, showing that the method tolerated small deliberate variations in conditions within the established design space, though the authors caution that flow rate and organic modifier concentration deserve strict control given their outsized influence on retention. An updated risk assessment confirmed that controls such as instrument calibration and proper material handling had reduced residual risks to a minimum. The practical upshot is a method that is simple, fast, accurate, and, perhaps most importantly, self-documenting: a laboratory adopting it inherits not just a recipe but a scientifically justified understanding of which knobs matter and how much they can be turned. For a drug taken by hundreds of millions of people daily, that transparency is more than academic elegance.

The broader significance of the study lies in its demonstration of a lifecycle mindset for analytical procedures. Rather than treating method development as a one-off exercise capped by a validation report, the AQbD framework embeds risk management, multivariate statistics, and control strategies into the very fabric of the method, aligning with the quality-by-design principles now sweeping through pharmaceutical manufacturing. As regulators worldwide push for analytical flexibility backed by scientific justification, studies like this one, applying Central Composite Design to an everyday drug, show how even the most routine quality control test can be rebuilt as a model of modern, data-driven science. The humble paracetamol tablet, it turns out, is a fitting stage for that quiet revolution.

Subject of Research: Development and validation of an AQbD-based RP-HPLC method for quantifying paracetamol in pharmaceutical tablets

Article Title: Analytical quality by design driven RP HPLC method development and validation for quantification of paracetamol in pharmaceutical tablets

Article References: Satpute, K., Avhad, A., Syed, S. M., Sonwane, S., Yelmate, A., Shetkar, B., Birajdar, M., & Lohiya, G. (2026). Analytical quality by design driven RP HPLC method development and validation for quantification of paracetamol in pharmaceutical tablets. Discover Chemistry, 3(1), Article 565. https://doi.org/10.1007/s44371-026-01007-7

Image Credits: AI Generated

DOI: 10.1007/s44371-026-01007-7

Keywords: paracetamol, RP-HPLC, Analytical Quality by Design, Central Composite Design, method validation, pharmaceutical analysis, liquid chromatography, ICH Q2(R2), design space, quality control, response surface methodology, tablets

The research team, led by Khadega A. Al-Maqdi of UAE University together with colleagues at Khalifa University, the University of Arkansas at Little Rock, and collaborators, chose horseradish peroxidase (HRP) for good reason. Peroxidases are oxidoreductase enzymes that use hydrogen peroxide to oxidize a broad range of substrates, and HRP in particular has long attracted attention for water remediation because of its high catalytic efficiency and selectivity. The catch is operational: free enzymes in solution are fragile, difficult to recover, and quickly lose activity under the temperature swings, pH extremes, and oxidative conditions of real treatment scenarios. Poor reusability drives up cost and has largely confined enzyme-based remediation to the laboratory. Immobilization on a solid support is the standard remedy, and the nature of that support can make or break the technology.

The support selected here was UiO-66-NH2, a zirconium-based metal–organic framework (MOF) built from zirconium chloride and 2-aminoterephthalic acid. MOFs are crystalline, highly porous materials in which metal ions or clusters are coordinated to organic linkers, producing enormous internal surface areas and tunable pore architectures. UiO-66-NH2 brings additional advantages: the strong zirconium–oxygen coordination bonds confer exceptional structural and aqueous stability, while pendant amino groups on the linkers promote hydrogen bonding and electrostatic interactions at the enzyme–MOF interface, helping the protein adhere and remain stable. Immobilization was deliberately simple and gentle. Five milligrams of the MOF were dispersed in solutions of HRP at concentrations ranging from 0.5 to 4 milligrams per milliliter, shaken for four hours, and then collected by centrifugation and washed to remove unbound enzyme. This physical adsorption approach preserves the enzyme’s native structure better than covalent coupling or crosslinking, at the cost of a need to verify that the protein does not leach away.

Optimization experiments showed that relative activity rose as the HRP loading concentration increased from 0.5 to 1 milligram per milliliter but plateaued beyond that point, indicating that the MOF had reached its maximum uptake capacity at 1 milligram per milliliter, which was used for all subsequent work. Leaching tests addressed the Achilles heel of physical immobilization: after the first wash, minimal enzyme was detected in the wash solution, and after the second wash no unbound HRP appeared in the supernatant at all, confirming that the enzyme was effectively anchored. The composite was then subjected to a battery of characterization techniques. Scanning electron microscopy revealed that the MOF crystallized as ball-shaped particles whose morphology was unchanged by enzyme loading, while energy-dispersive X-ray spectroscopy detected increases in the carbon, nitrogen, and oxygen signals after immobilization, consistent with protein incorporation. Powder X-ray diffraction showed that the characteristic diffraction peaks of the framework survived intact, and thermogravimetric analysis revealed an additional low-temperature weight loss in the composite attributable to protein decomposition, further evidence of successful binding.

Brunauer–Emmett–Teller surface area measurements added a telling detail. The bare MOF had a surface area of 256.27 square meters per gram, which dropped to 207.33 square meters per gram after enzyme loading, with pore volume falling from 0.17 to 0.14 cubic centimeters per gram. Both materials displayed Type I nitrogen adsorption isotherms, indicating predominantly microporous character. The reduction suggests that HRP molecules partially blocked the framework’s pores, a pattern seen repeatedly in other enzyme–MOF systems such as laccase on MIL-53(Al) and beta-lactamase on ZIF-8. Fourier-transform infrared spectroscopy told a complementary story: the amide I and amide II bands characteristic of the protein’s peptide bonds overlapped with the framework’s own absorptions in the 1500 to 1700 per centimeter region, producing broadened signals without shifts or signs of framework degradation. Together the data confirmed that immobilization neither destroyed the MOF’s crystallinity nor its thermal stability, which persisted up to roughly 350 to 400 degrees Celsius.

Functional testing revealed that immobilization did more than just fix the enzyme in place; it changed its operating envelope. Both free and immobilized HRP performed best at pH 4, with a narrow operational window from pH 3 to 5, but the immobilized enzyme showed roughly 30 percent higher activity than the free enzyme at pH 3, hinting at improved stability or substrate accessibility under acidic conditions. More striking was the temperature shift: free HRP peaked at 30 degrees Celsius, while HRP@UiO-66-NH2 reached maximum activity at 40 degrees and outperformed the free enzyme by around 10 percent or more at 50 and 70 degrees. The peroxide story was equally significant. Free HRP achieved maximum activity at about 0.72 millimolar hydrogen peroxide and then declined sharply, because excess peroxide drives the enzyme’s heme into irreversibly inactive species. The immobilized enzyme peaked at 1.08 millimolar and retained substantial activity at 1.62 and 2.43 millimolar, indicating that the framework shields the protein from oxidative damage and restricts the conformational changes that lead to heme destruction.

Reusability, the economic linchpin of any immobilized enzyme, proved robust. Over four consecutive reaction cycles, HRP@UiO-66-NH2 retained approximately 95 percent of its initial activity, with a decline to around 60 percent only in the fifth cycle, likely from leaching or denaturation. The authors are careful to note, however, that post-use characterization was not performed, so retained catalytic activity demonstrates functional reusability but does not directly prove that the framework’s crystallinity and morphology survived the cycles; future work combining post-cycle diffraction, spectroscopy, microscopy, and leaching measurements is needed to distinguish enzyme deactivation, mass-transfer limitations, and possible structural changes in the MOF.

The real test came with pollutants. The team challenged the biocatalyst with a mixture of nine structurally diverse emerging pollutants detected in water sources across China, the United Arab Emirates, Poland, and Brazil: 2-mercaptobenzothiazole (a rubber-industry chemical), paracetamol, the antibiotic sulfamethoxazole, the preservative methylparaben, salicylic acid, the antibiotic lincomycin hydrochloride, the beta-blocker atenolol, the fungicide thiabendazole, and the insect repellent DEET. Degradation was quantified by liquid chromatography–tandem mass spectrometry in multiple-reaction-monitoring mode, a sensitive approach that tracks the disappearance of each compound’s characteristic molecular transitions. Within 30 minutes, HRP@UiO-66-NH2 degraded 99.7 percent of 2-mercaptobenzothiazole and 97.4 percent of paracetamol, while the remaining pollutants were removed far less efficiently, a pattern consistent with earlier reports that certain peroxidases struggle with specific substrates, possibly because of competition or inhibition within the mixture rather than inherent inability.

That gap is where redox mediators enter the picture. The team added 1-hydroxybenzotriazole (HOBT), a small molecule that HRP oxidizes to a reactive species capable of transferring oxidative equivalents to pollutants that interact poorly with the enzyme’s active site. The effect was dramatic and pollutant-dependent. Degradation of sulfamethoxazole rose from 23.3 to 53.1 percent, methylparaben from 14.5 to 57.6 percent, and salicylic acid from 12.4 to 54.3 percent, while MBT and paracetamol, already nearly eliminated, showed no further change, and thiabendazole, lincomycin, and atenolol remained largely untouched. Comparisons with free HRP added nuance: free enzyme plus HOBT pushed sulfamethoxazole degradation to 80.2 percent, roughly 30 percentage points higher than the immobilized version, possibly because minor conformational changes imposed by the support alter substrate selectivity. Yet the immobilized enzyme outperformed free HRP on DEET by more than 10 percent, encouraging for a notoriously recalcitrant compound. Unlike MOF-based adsorption, which merely accumulates pollutants on finite surface sites and requires regeneration, the enzyme–MOF composite catalytically transforms susceptible molecules through repeated oxidation cycles powered by hydrogen peroxide.

The authors are candid about limitations. The experiments were conducted in a controlled buffered model-water system, so performance may differ in real wastewater laden with organic matter, dissolved ions, and competing contaminants. Removal of a parent compound does not confirm complete mineralization or reduced toxicity, and transformation products were not identified, meaning the proposed mediator-assisted mechanisms remain plausible rather than proven pathways. Still, the study demonstrates that a zirconium MOF can simultaneously protect a fragile enzyme, extend its thermal and peroxide tolerance, enable four-cycle reuse, and, with a selectively applied redox mediator, broaden its reach across chemically diverse micropollutants. The researchers propose evaluating HRP@UiO-66-NH2 as a targeted polishing treatment for emerging pollutants, with mediators deployed according to pollutant-specific effects, and call for follow-up work on transformation products, toxicity before and after treatment, real-matrix performance, and scalability. If those hurdles are cleared, enzyme–MOF composites of this kind could move from the laboratory bench toward a genuine role in safeguarding drinking water.

Subject of Research: Immobilization of horseradish peroxidase on the metal–organic framework UiO-66-NH2 for enzymatic degradation of emerging water pollutants

Article Title: Efficient enzyme-mediated degradation of various emerging pollutants, including 2-mercaptobenzothiazole, paracetamol, and sulfamethoxazole, using HRP@UiO-66-NH2

Article References: Al-Maqdi, K. A., Alneyadi, S., Elmerhi, N., Siddig, L. A., Alzamly, A., Shah, I., & Ashraf, S. S. (2026). Efficient enzyme-mediated degradation of various emerging pollutants, including 2-mercaptobenzothiazole, paracetamol, and sulfamethoxazole, using HRP@UiO-66-NH2. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38269-8

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38269-8

Keywords: horseradish peroxidase, UiO-66-NH2, metal–organic framework, enzyme immobilization, emerging pollutants, water remediation, bioremediation, redox mediator, HOBT, sulfamethoxazole, paracetamol, LC–MS/MS

The molecule at the center of the study, 5-[(Z)-1,3-thiazol-2-yldiazenyl]quinolin-8-ol, abbreviated TDQ, belongs to the azo dye family, compounds defined by their signature nitrogen-nitrogen double bond, the azo group, which gives them their intense colors. Azo dyes have historically dominated textiles, leather, paints, and printing, but researchers have increasingly explored them in solar cells, optical systems, and even pharmacology, where azo-bearing heterocycles show antibacterial, antiviral, and antifungal activity. Quinoline, the second structural element of TDQ, brings its own electrochemical pedigree: the redox behavior of quinoline derivatives has attracted sustained research interest, making the pairing of a quinoline scaffold with a thiazole-linked azo bridge a logical candidate for electrode modification.

Synthesis of the dye followed a classic diazotization-coupling route performed under carefully controlled cold conditions. The team dissolved 2-aminothiazole in concentrated hydrochloric acid and rapidly chilled the mixture in an ice-salt bath to roughly 0 to 5 degrees Celsius before adding nitrosylsulfuric acid to generate the diazonium salt. After two hours of stirring at the same low temperature, the diazonium solution was combined with an alkaline solution of 8-hydroxyquinoline, with the pH held between 5 and 6 throughout the coupling step. Thin-layer chromatography tracked the reaction to completion, and the resulting dark red solid was filtered, washed, dried, and recrystallized from ethanol, delivering a 70 percent yield with a melting point of 95 to 96 degrees Celsius.

Structural confirmation relied on a battery of spectroscopic techniques. Infrared spectroscopy revealed the hydroxyl stretch of the quinoline group at 3382 inverse centimeters, aromatic carbon-hydrogen stretches at 2929, carbon-nitrogen and carbon-sulfur vibrations at 1602 and 778, and, critically, the azo linkage at 1454 inverse centimeters. Proton nuclear magnetic resonance in DMSO-d6 showed the expected hydroxyl singlet near 9.0 ppm alongside aromatic signals between 6.82 and 7.37 ppm. Ultraviolet-visible spectra recorded in DMSO, DMF, ethanol, and acetone displayed sharp absorptions at 414, 396, 386, and 409 nanometers respectively, with DMSO giving the strongest response, while mass spectrometry produced a molecular ion peak at m/z 257.3, consistent with the formula C12H8N4OS.

To build the sensor, the researchers ground one milligram of TDQ with graphite powder and silicon oil in a 70:30 ratio for half an hour, then packed the paste into a 3-millimeter electrode cavity. Electrochemical benchmarking against a bare carbon paste electrode used the standard potassium ferrocyanide redox probe in 1 M potassium chloride. The bare electrode showed weak redox peaks and large peak separations, hallmarks of slow electron transfer and a limited active surface. The TDQ-modified version, by contrast, delivered markedly higher peak currents at reduced overpotential, and calculations based on the Randles-Sevcik equation put the electroactive surface area at 0.04526 square centimeters, well above the 0.0267 square centimeters of the unmodified paste.

Impedance spectroscopy reinforced that story. Nyquist plots showed a semicircle at high frequencies whose diameter reflects charge transfer resistance: the bare electrode registered 234.82 ohms, while the TDQ-modified electrode dropped to 177.47 ohms, indicating faster interfacial electron transport and more efficient ion pathways. Bode plots added a capacitive dimension, with the modified electrode displaying more negative phase angles at low frequencies, a sign of stronger charge retention and better energy storage behavior. The authors note that this combination of lower resistance and enhanced capacitance makes the dye-modified surface attractive not only for sensing but potentially for energy storage applications as well.

With the platform validated, the team turned to the three target analytes in 0.2 M phosphate buffer. pH optimization across the range 5.8 to 7.4 showed peak currents rising to a maximum at pH 7.0, the physiological value, which was adopted for all subsequent experiments. Scan rate studies then probed the underlying mechanism: for dopamine, a log-log slope of 1.012 indicated an adsorption-controlled process, while uric acid’s slope of 0.370 pointed to diffusion control, and paracetamol’s slope of 0.474 likewise suggested diffusion-dominated behavior. Concentration studies from 10 to 100 micromolar produced calibration curves with correlation coefficients of 0.9979 for dopamine, 0.9982 for uric acid, and 0.98 for paracetamol.

The detection limits, calculated as three times the standard deviation divided by the calibration slope, came out at 6.86 micromolar for dopamine, 10.28 micromolar for uric acid, and 15.93 micromolar for paracetamol, with corresponding quantification limits of 21.15, 34.29, and 42.58 micromolar. The most striking result, however, came from simultaneous detection. In cyclic voltammetry, the modified electrode resolved three distinct oxidation peaks at 0.265 volts for dopamine, 0.554 volts for uric acid, and 0.875 volts for paracetamol, giving peak-to-peak separations of 0.289 and 0.321 volts. Differential pulse voltammetry sharpened the discrimination further, with separations of 0.227 and 0.362 volts, allowing all three compounds to be identified and quantified in a single run.

Practical durability and real-world performance rounded out the evaluation. Across five identically prepared electrodes, the relative standard deviation was just 0.85 percent, and the sensor retained 94 percent of its original dopamine response after twenty days of laboratory storage. When the team applied the standard addition method to a commercially available dopamine hydrochloride injection diluted into buffer, recoveries of spiked samples ranged from 97 to 102 percent, demonstrating that the sensor can deliver accurate measurements in a genuine pharmaceutical matrix rather than only in idealized solutions.

The broader significance lies in the simplicity and economy of the approach. Carbon paste electrodes are cheap, easy to prepare, and easy to refresh, and a milligram-scale dye modifier transforms their otherwise mediocre electrochemistry into a selective, stable sensing platform. Because dopamine imbalances are linked to Parkinson’s disease, Alzheimer’s disease, schizophrenia, and Huntington’s disease, uric acid levels flag kidney failure, pneumonia, and metabolic disorders, and paracetamol monitoring underpins safe use of one of the world’s most common analgesics, a single low-cost electrode that reads all three simultaneously could find a home in clinical labs, pharmaceutical quality control, and point-of-care diagnostics. The Davangere team’s work adds a quinoline-azo dye to the growing toolbox of molecular modifiers, showing that sometimes the fastest route to better biosensing runs through the chemistry of color.

Subject of Research: Electrochemical detection of dopamine, uric acid, and paracetamol using a quinoline-azo dye modified carbon paste electrode

Article Title: Electrochemical sensing of dopamine, uric acid, and paracetamol using a quinoline-azo dye modified carbon paste electrode

Article References: Paalaplara, K. H., Chinnagiri, K. T., Chinnagiri, R. T., & Thippandegowdru, R. M. (2026). Electrochemical sensing of dopamine, uric acid, and paracetamol using a quinoline-azo dye modified carbon paste electrode. Discover Electrochemistry, 3(1), Article 42. https://doi.org/10.1007/s44373-026-00127-0

Image Credits: AI Generated

DOI: 10.1007/s44373-026-00127-0

Keywords: electrochemical sensor, azo dye, quinoline, carbon paste electrode, dopamine, uric acid, paracetamol, cyclic voltammetry, differential pulse voltammetry, electrocatalysis, detection limit, pharmaceutical analysis

The trigger for the exchange is a secondary analysis of the BeNeDuctus trial, conducted by Hoornenborg and colleagues, which examined extremely preterm infants who received paracetamol for pain relief. According to the letter, that analysis found a significantly increased risk of moderate-to-severe bronchopulmonary dysplasia, a chronic lung condition of prematurity, as well as longer requirements for respiratory support among infants exposed to the drug. Because the sample originated from a randomized controlled trial, the finding carries more weight than the observational studies that have fueled suspicion of paracetamol for the past two decades. The letter’s authors commend the trial team while pressing the point that even these researchers continue to call for yet more studies rather than recommending a change in practice.

Bronchopulmonary dysplasia remains one of the most consequential outcomes in neonatology. It arises when the lungs of infants born extremely early fail to develop normally, often after weeks of mechanical ventilation and oxygen therapy, and it predicts years of respiratory illness, rehospitalization and impaired growth. Any drug that measurably raises the risk of moderate-to-severe disease would represent a serious threat to a vulnerable population, which is precisely why the letter frames the question in such stark terms. The authors ask, in effect, how much evidence is enough before the burden of proof shifts from those who suspect harm to those who assume safety.

The biological plausibility of a paracetamol-lung link rests on the drug’s metabolism. Paracetamol is processed primarily in the liver, but a fraction is converted by cytochrome enzymes into a reactive metabolite, N-acetyl-p-benzoquinone imine, which depletes glutathione, the cell’s principal antioxidant defense. The developing lung expresses xenobiotic-metabolizing enzymes, meaning that pulmonary tissue can locally generate toxic metabolites from circulating paracetamol. In a preterm infant, whose antioxidant systems are immature and whose lungs are already under oxidative assault from oxygen therapy and ventilation, additional glutathione depletion could plausibly tip the balance toward arrested alveolar development. Pharmacokinetic studies in very preterm infants have documented measurable exposure not only to the parent compound but to all of its metabolites at standard intravenous doses, underscoring that these tiny patients handle the drug differently from adults.

This mechanistic concern is not merely theoretical. Preclinical work summarized in the pulmonary physiology literature has explicitly called for animal models to understand why the perinatal lung appears uniquely susceptible to acetaminophen, the American name for the same molecule. Meanwhile, a cohort study of extremely preterm infants detected acetaminophen and its xenobiotic metabolites in human milk and reported associations with both bronchopulmonary dysplasia and retinopathy of prematurity, another disease of oxidative stress. There have even been reports of paracetamol overdose in newborns and infants proving life-threatening, a reminder that the therapeutic window in this population is narrower than commonly assumed. Together, these strands sketch a coherent biological story in which a drug once considered benign for the lung may interfere with redox-sensitive developmental processes at exactly the wrong moment.

The broader epidemiological record adds a second, parallel line of concern. Systematic reviews and meta-analyses stretching back more than a decade have consistently reported associations between paracetamol use in pregnancy and wheezing illness or asthma in offspring, and more recent syntheses of prenatal exposure studies have reached similar conclusions. Research in high-risk birth cohorts has also examined early-life acetaminophen exposure in combination with genetic variation in glutathione S-transferase enzymes, finding evidence that the drug’s oxidative burden may interact with inherited detoxification capacity to shape asthma risk into adolescence. Population studies of childhood asthma prevalence continue to list early paracetamol exposure among the modifiable risk factors under scrutiny, and even lactation, long considered a safe channel, has been questioned in the pediatric literature.

What makes the new trial-based analysis so important is the hierarchy of evidence it occupies. Observational studies of drug exposure are notoriously vulnerable to confounding by indication: children who receive more paracetamol tend to be sicker, and sicker infants develop more lung disease regardless of which painkiller they receive. A secondary analysis nested within a randomized controlled trial does not eliminate that problem entirely, since randomization in the parent BeNeDuctus trial was not designed to allocate paracetamol, but it does allow investigators to control for illness severity far more rigorously than most registry or cohort studies can. The fact that a signal for moderate-to-severe bronchopulmonary dysplasia and prolonged respiratory support survived that scrutiny is what lends the letter its urgency.

Yet the letter’s authors are careful not to overclaim causation, and the trial investigators themselves stopped short of a practice change, calling instead for further research into paracetamol’s respiratory effects in preterm infants. That restraint reflects genuine clinical dilemmas. Preterm infants undergo painful procedures, from cannulation to surgery for patent ductus arteriosus, and untreated pain carries its own documented harms, including stress responses that destabilize cerebral blood flow. Paracetamol has become attractive precisely because it avoids the renal, gastrointestinal and platelet side effects of nonsteroidal anti-inflammatory drugs. An overview of systematic reviews on paracetamol’s efficacy and safety concluded that while the drug offers modest analgesic benefit, its safety profile in vulnerable groups deserves continued attention, a conclusion that now reads differently in light of the neonatal data.

The dilemma is sharpened by trends in neonatal care. A recent analysis of fifteen years of respiratory and hemodynamic management in very premature infants documented evolving approaches to bronchopulmonary dysplasia, and observational multicenter registries have compared conservative and medical strategies for managing the ductus arteriosus, a condition for which paracetamol has itself been trialed as a closing agent. In other words, paracetamol is not merely an incidental exposure in the neonatal unit; it is increasingly embedded in treatment protocols. If the drug independently worsens lung outcomes, the implications extend from analgesia guidelines to the very protocols designed to protect the preterm lung, and clinicians would need to weigh analgesic benefit against a respiratory cost that previous risk-benefit calculations never included.

For now, the letter functions as both a summary and a challenge. It gathers the mechanistic, pharmacokinetic, preclinical and epidemiological threads into a single argument that the evidence base has grown substantial enough to demand action beyond another round of observational studies. The authors, who report no competing interests and no external funding, frame their appeal around the families and clinicians they serve, and their central question, how much evidence is enough, is one that guideline committees, regulators and neonatologists will now have to answer explicitly. Whether the answer comes from adequately powered randomized trials of analgesic strategy in extremely preterm infants or from a precautionary shift in prescribing habits, the era in which paracetamol was assumed to be harmless to the developing lung is drawing to a close.

Subject of Research: The association between paracetamol exposure and bronchopulmonary dysplasia in extremely preterm infants

Article Title: Paracetamol and the developing lung: how much evidence is enough?

Article References: Verd, S., Boo, S., & Costa-Orvay, J.-A. (2026). Paracetamol and the developing lung: how much evidence is enough?. Pediatric Research. https://doi.org/10.1038/s41390-026-05532-0

Image Credits: AI Generated

DOI: 10.1038/s41390-026-05532-0

Keywords: paracetamol, acetaminophen, bronchopulmonary dysplasia, preterm infants, neonatology, respiratory support, glutathione, oxidative stress, asthma risk, BeNeDuctus trial, Pediatric Research, drug safety

The study, led by first author Hoda Tayebi Hillali, DDS, MSc, of the University of Santiago de Compostela in Spain, belongs to a class of research often described as the apex of the evidence hierarchy. Rather than adding one more cohort to an already crowded literature, an umbrella review systematically aggregates and evaluates the results of previous meta-analyses, the studies that themselves pool data from many individual investigations. In this case, the researchers identified seven meta-analyses covering an extraordinary body of data: more than three million participants drawn from cohorts across multiple countries and continents. That scale matters. Neurodevelopmental outcomes such as autism and ADHD arise from complex interactions of genetics, prenatal environment, and postnatal factors, and no single study of a few thousand participants can hope to isolate the contribution of one common medication with confidence. By synthesizing the totality of pooled evidence, the team sought to answer whether the pattern of associations across the literature holds up when the quality of the underlying research is taken into account.

The headline result is a tale of two analyses, and the contrast between them is where the scientific substance lies. When the reviewers performed unrestricted assessments, taking the results of all included meta-analyses at face value, they did find small positive associations between prenatal paracetamol exposure and both autism and ADHD. In other words, taken naively, the literature appears to say that exposure is linked with a modestly higher risk of these conditions. But when the team restricted their assessments to the higher-quality meta-analyses and the higher-quality individual studies nested within them, something revealing happened: the effect estimates were substantially attenuated, shrinking toward the null, which in epidemiological terms means shrinking toward no effect at all. No robust epidemiological evidence, the reviewers concluded, supported a causal association. The association, in effect, was strongest exactly where the science was weakest.

Why would better-designed studies show weaker effects? The answer lies in a cluster of well-understood biases that plague observational research on medications in pregnancy, and understanding them is essential to interpreting the entire debate. Paracetamol is not taken at random. It is taken by people who are experiencing pain or fever, and both of those conditions themselves have been associated in some studies with altered neurodevelopmental outcomes. Fever during pregnancy, for example, is an independent exposure of interest in its own right, and separating the effect of the drug from the effect of the illness it treats is genuinely difficult. Families who seek and take medication may also differ systematically from those who do not, in health status, socioeconomic circumstances, access to care, and health-seeking behavior, all of which correlate with child development through entirely different pathways. Without randomized assignment, which would of course be ethically impossible here, observational studies can only adjust for measured confounders, and the measured confounders are never complete.

There is also the problem of exposure measurement. Most studies in this literature rely on maternal self-report, sometimes months or years after the pregnancy, asking women to recall how often and how much paracetamol they took. Recall is imperfect and misclassification is likely, and misclassification that is linked to outcome awareness can bias results in either direction. Mothers of children diagnosed with autism or ADHD may probe their memories differently from mothers of children without diagnoses, a phenomenon related to recall bias. Some studies have attempted to mitigate this with pharmacy dispensing records or biomarker data, and it is precisely the meta-analyses weighting such higher-quality designs where the associations thin out. The umbrella review’s finding that effect estimates approach null as methodological quality improves is the statistical fingerprint of bias operating in the weaker studies, rather than a signal of a genuine biological effect being masked.

The authors themselves framed the finding as a call for evidence over alarm. In a statement accompanying the publication, Hillali said: A widely debated question deserves more than headlines, it deserves robust evidence. Our findings show that the apparent association between prenatal paracetamol exposure and autism or ADHD weakens as methodological quality improves, challenging the interpretation of a causal link and supporting evidence-based decisions during pregnancy. That formulation captures the central epistemological point: an association observed across many small, imperfect studies is not the same as a demonstrated cause, and the difference between the two has real consequences for how clinicians counsel patients and how regulators craft guidance.

The stakes of this debate extend well beyond academic argument. Paracetamol occupies a unique position in the pharmacology of pregnancy. Untreated fever in pregnancy has itself been linked in various studies to adverse outcomes, and alternative analgesics such as nonsteroidal anti-inflammatory drugs carry their own concerns, particularly in later gestation, where they pose recognized fetal risks. If pregnant people and their clinicians were to abandon paracetamol based on the weaker observational evidence, they might be pushed toward options with better-documented harms or toward untreated pain and fever, swapping a hypothetical and increasingly doubtful risk for a concrete one. This risk-benefit calculus is why professional bodies have generally maintained, amid the accumulating controversy, that paracetamol remains the preferred analgesic and antipyretic in pregnancy when clinically indicated, at the lowest effective dose for the shortest necessary duration.

Umbrella reviews occupy a distinctive and sometimes uncomfortable position in scientific publishing. Because they sit atop a mountain of prior syntheses, they are vulnerable to a form of garbage-in aggregation if they simply average everything below them. The strength of this analysis lies in its stratified approach: rather than pooling all seven meta-analyses into a single summary, the team compared what the evidence looks like when quality criteria are enforced against what it looks like when they are not. The progressive attenuation of effect estimates across that quality gradient is, in effect, a diagnostic test for bias applied to an entire literature. It does not prove that paracetamol is entirely free of any developmental influence, a claim no observational evidence base could ever establish with certainty, but it shifts the burden. What remains after the highest-quality evidence is isolated is an association so small and so unstable that it cannot be distinguished from residual confounding, measurement error, and chance.

For the broader public, the review is also a case study in how health science news should be consumed. Headlines announcing that a common painkiller is linked with autism are, by the mechanics of epidemiology, almost always reporting relative associations from observational data, not demonstrated causal effects on individual children. The distinction matters because autism and ADHD are highly heritable conditions shaped by thousands of genetic variants and a web of environmental factors, and any single prenatal exposure, if it contributes at all, would contribute only a tiny fraction of that variance. Absolute risk changes implied by the attenuated estimates in the highest-quality analyses are vanishingly small compared with the risks of leaving significant pain or fever untreated. The researchers’ synthesis, drawing on data from more than three million people, suggests that pregnant people who need paracetamol can discuss its use with their clinicians on the basis of reassurance rather than fear, and that the loudest claims in this debate were, in the end, built on the shakiest foundations.

What comes next is likely to be continued refinement rather than resolution. Future work may draw on sibling-control designs, which compare siblings discordant for exposure and thereby control for stable family-level confounders, and on large biobank-linked cohorts with objective prescription data. The umbrella review’s conclusion does not close the file on prenatal paracetamol, but it does reframe the question: the burden of proof now rests squarely on those who would assert a causal link, and the current evidence, examined at the highest level of rigor available, does not meet it. For a field in which headlines have too often outrun the data, that recalibration is itself a significant scientific result.

Subject of Research: Prenatal paracetamol exposure and the risk of neurodevelopmental disorders in children

Article Title: Does paracetamol/acetaminophen use in pregnancy increase the risk of neurodevelopmental disorders in children?

Article References: Does paracetamol/acetaminophen use in pregnancy increase the risk of neurodevelopmental disorders in children?. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: paracetamol, acetaminophen, pregnancy, autism, ADHD, neurodevelopmental disorders, umbrella review, meta-analysis, epidemiology, observational bias, prenatal exposure, Developmental Medicine & Child Neurology

The story began on 31 May 2023, when the girl’s grandmother brought her to a local health center with cough, runny nose, and fever. She was discharged with amoxicillin dispersible tablets, cetirizine syrup, and paracetamol tablets. What followed was a cascade of miscommunication. The prescription itself was barely legible and omitted critical details — the patient’s name, her age, and even the prescriber’s identity — making it impossible to tell whether the medication was intended for the child or the grandmother. The dispensing envelope the grandmother received simply abbreviated the drug as PCM, and she administered the tablets exactly as she understood the label: 1000 milligrams on the first day, 3000 milligrams on the second, and another 1000 milligrams on the third. The correct total for a child her age would have been roughly 1800 milligrams across the entire period.

Within days, the child’s condition deteriorated dramatically. A private facility diagnosed gastroenteritis and prescribed cotrimoxazole and promethazine, missing the true cause entirely. By 4 June, she arrived at Malindi Sub County Hospital with severe dehydration — sunken eyes, skin pinch lasting more than two seconds, reduced skin turgor — along with pneumonia, evidenced by crepitations and rapid breathing. She received aggressive rehydration with Ringer’s lactate, multiple antibiotics, and zinc supplementation. Then, at 5:30 in the evening, she began to convulse, requiring an intramuscular loading dose of phenobarbital. Even at this point, paracetamol poisoning was not on the diagnostic radar.

The turning point came the next morning, when clinicians took a more detailed history and asked the grandmother to present every medication given before admission. Medication reconciliation — the systematic process of comparing what a patient actually took against what was prescribed — revealed the overdose immediately. Liver function tests confirmed the suspicion with striking clarity: alanine aminotransferase peaked at 1566.2 IU/L, far above the 1000 IU/L threshold conventionally used to define hepatotoxicity, while aspartate aminotransferase reached 302.3 IU/L. Gamma-glutamyl transferase climbed steadily and albumin fell, painting a biochemical picture of an injured liver. The ALT-predominant pattern, with the two transaminases rising in near 1:1 proportion, is characteristic of paracetamol-induced liver injury and helped distinguish it from other causes of hepatic damage.

Then the resource limitations of the setting began to bite. Malindi Sub County Hospital did not stock N-acetylcysteine, the antidote that replenishes glutathione and neutralizes the toxic metabolite NAPQI responsible for paracetamol’s liver damage. Serum paracetamol levels, prothrombin time, and international normalized ratio — the standard laboratory tools for assessing poisoning severity and coagulation status — were simply unavailable. When clinicians attempted to place a nasogastric tube, the child’s nose began to bleed; oozing also appeared at her intravenous cannula site. These clinical signs of coagulopathy, combined with hypoalbuminemia, forced the team to act empirically, administering vitamin K and fresh frozen plasma without laboratory confirmation, a pragmatic departure from guidelines that caution against routine plasma use in pediatric liver failure.

Sourcing the antidote became an ordeal in itself. The nearest supply of N-acetylcysteine was 232 kilometers away in Mombasa, and the pharmacy there would only sell an entire pack of ten ampoules when the child needed just two or three. The family lacked coverage from the National Hospital Insurance Fund, Kenya’s universal health insurance scheme at the time, and the cost was beyond their means. Only when a well-wisher stepped in to pay was the antidote secured. The first infusion began at 9:00 pm on 6 June — roughly 80 hours after the last paracetamol dose, far beyond the traditional window in which the antidote is considered most effective.

What happened next surprised the clinical team. Despite the delay of more than 84 hours from initial exposure, the child’s liver enzymes began to fall rapidly after N-acetylcysteine therapy, with ALT dropping to 431.1 IU/L and AST to 105.6 IU/L within days. Several hours into the third infusion, she regained consciousness, fully oriented, with a Glasgow Coma Scale score of 15/15 and stable vital signs. She received fresh frozen plasma on alternate days to guard against hemorrhagic complications, along with supportive care including dextrose infusions, vitamins, and lactulose. By 14 June 2023, just ten days after the overdose began, she was discharged having made a full recovery.

The case, the authors argue, is less a story of individual negligence than of compounding system failures. Incomplete prescriptions and careless dispensing practices are well-documented drivers of medication errors, particularly when drugs are handed over without patient-specific information. Caregiver misunderstanding and poor communication compound the risk, especially when health literacy is low and the dispensed formulation — adult tablets, in this case — is inherently unsuitable for a toddler. Research has suggested that standardized dosing instruments, metric-unit labeling, and picture-based dosing instructions could substantially reduce these administration errors. The diagnostic delay also reflects a broader pattern: early paracetamol poisoning mimics common childhood illnesses like gastroenteritis, with vomiting and lethargy masking the underlying toxicity until the liver begins to fail.

The authors also emphasize a lesson that may resonate far beyond Kenya: even when N-acetylcysteine is given very late — more than 24 hours after exposure — it can still abrogate severe hepatotoxicity in children. This finding challenges the rigid therapeutic windows that dominate high-resource guidelines and offers hope for clinicians working where delayed presentation is the norm rather than the exception. At the same time, the case exposes uncomfortable truths about access to essential medicines in low- and middle-income countries, where antidote stockouts, bureaucratic procurement barriers, and absent insurance coverage can force families to depend on charity for life-saving treatment. The authors call on prescribers to write complete, legible prescriptions; on pharmacists to communicate clearly with caregivers of all literacy levels; and on hospital administrators to encourage enrollment in government-subsidized health coverage.

As a single-center case report, the account cannot be generalized to every setting, and the authors acknowledge this limitation candidly. Yet its value lies precisely in the detail: a near-legible prescription, a dispensing envelope, a grandmother doing her best with the information she was given, a hospital pharmacy without the antidote, and a 232-kilometer journey that stood between a child and survival. Paracetamol was first synthesized in 1878 and marketed in 1955, and its overdose potential was recognized soon after it reached the market. Half a century of research — from the glutathione-dependent mechanism of toxicity elucidated in the 1970s to the Rumack-Matthew nomogram and the Prescott protocol — has made paracetamol poisoning one of the most treatable toxicological emergencies in medicine. This Kenyan case is a reminder that the science is settled; what remains unfinished is the harder work of ensuring that the systems around the medicine, from the prescription pad to the pharmacy shelf, are built to protect the children who depend on them.

Subject of Research: Pediatric paracetamol poisoning caused by medication error and managed in a resource-limited Kenyan hospital

Article Title: A cautionary tale of pediatric paracetamol poisoning in a low-resource setting in Kenya: a case report and review of the literature

Article References: Mongi, A., Naji, S., Rasheed, Y., Mang’ong’o, D., & Okumu, M. (2026). A cautionary tale of pediatric paracetamol poisoning in a low-resource setting in Kenya: a case report and review of the literature. Discover Toxicology, 3(1), Article 6. https://doi.org/10.1007/s44339-026-00047-z

Image Credits: AI Generated

DOI: 10.1007/s44339-026-00047-z

Keywords: paracetamol, acetaminophen overdose, N-acetylcysteine, hepatotoxicity, pediatric poisoning, medication error, Kenya, resource-limited setting, liver function tests, coagulopathy, medication reconciliation, case report

The research, published in Cleaner Engineering and Technology by a team from the Tecnológico Nacional de México led by Bethsabet Jaramillo-Sierra, tackles a contamination problem that spans the globe. Acetaminophen has been detected in wastewater and surface waters on nearly every continent, at concentrations ranging from tens of nanograms per liter in France and Canada to hundreds of micrograms per liter in Colombia and northern Mexico. Although each individual measurement may seem small, the compound’s sheer consumption volume, its availability over the counter, and its resistance to biological degradation mean it accumulates persistently in rivers, drinking water sources, and even treated effluents.

The concern is not merely the presence of the parent molecule. Acetaminophen is poorly biodegradable, so it passes through conventional treatment largely intact, and it has been linked in laboratory studies to genetic damage, oxidative lipid degradation, and liver injury in living organisms. Worse still, during some tertiary treatment steps the compound can transform into by-products that are more dangerous than the original drug, including 1,4-benzoquinone and N-acetyl-p-benzoquinone imine, a hepatotoxic metabolite capable of causing hepatic failure and necrosis. Any credible remediation strategy must therefore do more than hide the molecule; it must destroy it or convert it into harmless end products.

The Mexican team turned to advanced oxidation processes, or AOPs, a family of water treatment methods that operate at ambient temperature and pressure and rely on the generation of highly reactive chemical species, most notably the hydroxyl radical. This radical carries a higher oxidation potential than chlorine and reacts non-selectively with a broad range of organic pollutants, which makes it attractive for treating trace contaminants of many kinds. AOPs also avoid sludge production, do not require adsorbents that need controlled disposal, and can be driven by easily handled reagents such as ozone and hydrogen peroxide, with ozone generated on site from atmospheric air to reduce storage and transport costs.

The experimental apparatus was deliberately simple: a cylindrical stainless-steel reactor with an 11-watt ultraviolet lamp emitting at 200 to 280 nanometers, housed in a quartz tube, coupled to a 12-watt ozone generator and a recirculating reservoir. Synthetic solutions of acetaminophen at 100 milligrams per liter were treated for 60 minutes in 500-milliliter batches, with hydrogen peroxide added at doses of 5, 10, and 15 milligrams per liter. Degradation was tracked by ultraviolet-visible spectrophotometry, chemical oxygen demand was measured colorimetrically, and oxidation by-products were identified using gas chromatography-mass spectrometry following solid-phase extraction.

The results revealed a clear hierarchy of effectiveness. Ultraviolet light alone managed only about 11 percent degradation in an hour, primarily by photolyzing water molecules into hydroxyl radicals and hydrogen atoms, a process that accelerates around the 254-nanometer wavelength. Hydrogen peroxide alone reached roughly 27 percent at the highest dose. Ozone alone, attacking through both direct molecular oxidation and indirect decomposition into hydroxyl radicals, achieved 73 percent. Pairing ozone with ultraviolet light pushed the figure to 84 percent, because photolysis of dissolved ozone generates additional atomic oxygen, hydroxyl radicals, and even hydrogen peroxide in solution, creating multiple parallel destruction pathways.

The real breakthrough came when all three agents were applied simultaneously. The ozone-hydrogen peroxide combination, known as peroxone, promotes hydroxyl radical formation through the mutual reaction of the two oxidants, and adding ultraviolet irradiation on top of this triggered photolysis of both peroxide and dissolved ozone. Under these conditions, with an initial hydrogen peroxide concentration of just 5 milligrams per liter, the team achieved 99 percent acetaminophen degradation in 60 minutes. Notably, the study found an optimal peroxide dose: higher concentrations of 10 and 15 milligrams per liter actually performed worse over time, because excess peroxide and the hydroperoxyl radical it forms act as scavengers, consuming the very hydroxyl radicals that destroy the pollutant.

Chemical analysis confirmed that the combined treatment went beyond mere transformation. Carbon dioxide production rose steadily across the treatment combinations, peaking at 37 milligrams per liter for the triple system, evidence of genuine mineralization rather than simple conversion to other organics. Chemical oxygen demand removal reached 74 percent in the same configuration, compared with just 9 percent for ultraviolet light alone. Color measurements told a parallel story: untreated solutions stayed clear, ultraviolet treatment alone produced a pale carmine tint at 150 platinum-cobalt units as aromatic ring breakdown products accumulated, while the triple system yielded only a faint yellow at 5 units, indicating that even the colored intermediates were being further oxidized. Gas chromatography-mass spectrometry identified by-products dominated by carboxylic acid, ester, and alcohol structures arising from aromatic ring cleavage and recombination, and crucially, the team did not detect hydroquinone or 1,4-benzoquinone, suggesting these hazardous intermediates were themselves degraded during the process.

Energetically, the triple treatment also proved competitive. The researchers calculated the electrical energy per order, a standard metric describing the kilowatt-hours needed to reduce pollutant concentration by one order of magnitude per cubic meter, and obtained 23.00 kilowatt-hours per cubic meter for the peroxide-ozone-UV system, well below the 537 kilowatt-hours per cubic meter required for ultraviolet treatment alone and below several values reported in comparable literature. The estimated operating cost of the best configuration came to 5.04 US dollars per cubic meter, with ultraviolet irradiation dominating the energy bill, ozone generation second, and hydrogen peroxide contributing least. The degradation kinetics followed a pseudo first-order model, with rate constants rising as processes were combined, consistent with the theory that degradation depends primarily on pollutant concentration while oxidant doses remain effectively constant.

Finally, the team assessed whether the treated water was actually safer, using the germination of lettuce seeds as a biological toxicity screen. Untreated and lightly treated samples showed moderate toxicity, with ozone alone inhibiting germination by 40 percent, a sign that oxidative intermediates can be more harmful than the parent drug. But the full triple treatment reduced inhibition to 15 percent, close to the control level, demonstrating that synergistic oxidation both destroys the pollutant and neutralizes its residual toxic footprint. Taken together, the findings position the combined peroxide-ozone-UV process as an operationally simple, reproducible, and relatively inexpensive route to eliminating one of the world’s most ubiquitous pharmaceutical pollutants, though the authors note that complete mineralization would likely require longer treatment times or more intensified oxidative conditions to drive the remaining low-complexity organic by-products all the way to inorganic carbon.

Subject of Research: Degradation of the pharmaceutical pollutant acetaminophen in water using combined advanced oxidation processes involving ozone, hydrogen peroxide, and ultraviolet radiation.

Article Title: Acetaminophen degradation process applying a combination of oxidizing agents and ultraviolet radiation

Article References: Jaramillo-Sierra, B., Mercado-Cabrera, A., Ibañez-Olvera, M., Peña-Eguíluz, R., Rodríguez-Méndez, B. G., & López-Callejas, R. (2026). Acetaminophen degradation process applying a combination of oxidizing agents and ultraviolet radiation. Cleaner Engineering and Technology, 34, Article 101301. https://doi.org/10.1016/j.clet.2026.101301

Image Credits: AI Generated

DOI: 10.1016/j.clet.2026.101301

Keywords: acetaminophen, paracetamol, advanced oxidation processes, ozone, hydrogen peroxide, ultraviolet radiation, hydroxyl radicals, wastewater treatment, pharmaceutical pollution, water purification, mineralization, chemical oxygen demand