The incident itself reads like a textbook medical emergency on the road. A 59-year-old man was driving alone when, according to the available information, a presumed medical event caused him to mount a traffic island and strike a traffic sign. The vehicle continued onto a service road before hitting a tree, and the driver was taken to hospital. Because of his medical condition, the standard field assessments that police normally use to evaluate drug or alcohol impairment could not be performed. Given his known cardiac history, however, officers suspected that medication might have played a role, and blood samples were drawn for toxicological analysis.

Laboratory screening using liquid chromatography-tandem mass spectrometry, the workhorse technique of modern forensic toxicology, detected four cardiovascular medications in the samples: amlodipine, bisoprolol, torasemide and valsartan. The first three were present at concentrations consistent with ordinary therapeutic use, so no further quantification was pursued. Valsartan, by contrast, produced strikingly strong signals, prompting the team to carry out a full quantitative determination using a standard-addition calibration method, a technique particularly well suited to unusual concentrations because known amounts of the analyte are added directly to the patient’s own sample.

The analytical work was rigorous by any standard. Each of three addition levels was processed in eight replicates, the mass spectrometer monitored two separate ion transitions to confirm the identity of the compound, and blank matrix samples showed no interfering signals. Because the concentration was so high, the sample had to be diluted tenfold before measurement. As an independent plausibility check, an external laboratory determined the concentration separately, arriving at 11.7 micrograms per millilitre against the primary laboratory’s 12.7 micrograms per millilitre, a close agreement that strongly supports the reliability of the reported figure.

What makes that number remarkable is the pharmacological context. Valsartan is an angiotensin II receptor antagonist, one of the widely prescribed sartan drugs, which lowers blood pressure by blocking the AT1 receptor. It is typically taken once daily at doses of 80 to 320 milligrams, and therapeutic plasma concentrations are generally considered to lie between 0.80 and 6.0 micrograms per millilitre. Pharmacokinetic studies have shown that single oral doses of 80, 160 and 320 milligrams produce mean blood concentrations of roughly 1.6, 3.8 and 6.4 micrograms per millilitre respectively, and even peak concentrations in healthy volunteers taking 320 milligrams under fasting conditions have reached only about 10.7 micrograms per millilitre. The driver’s measured value of 12.7 micrograms per millilitre therefore sits well above anything expected from normal therapeutic use.

Herein lies the forensic dilemma the authors set out to illuminate. For illicit drugs and many centrally acting medications, toxicology has robust, effect-related reference ranges: documented impairment can be correlated with measured concentrations, and recognised toxic and even lethal thresholds exist. For cardiovascular drugs, the picture is far murkier. Their primary action is on the circulatory system, and adverse effects such as hypotension, dizziness and light-headedness can occur even at correct doses. Establishing that such a medication caused unfitness to drive is difficult enough when blood concentrations fall within the therapeutic range; interpreting elevated concentrations is harder still, because no toxic concentration range for valsartan has ever been defined in the published literature.

The drug’s general safety profile compounds the interpretive problem. Valsartan is regarded as relatively safe even in massive overdose. The most frequently cited case report describes a woman who ingested an estimated 2,240 milligrams in a suicide attempt, suffering pronounced muscle cramps and marked hypotension, yet she improved within two days under supportive care, and no blood concentration was ever measured. Without documented concentration-effect data from overdose survivors, forensic experts have had essentially nothing to anchor their assessments when a driver tests positive for the drug. The new case provides exactly that anchor: a real-world concentration, verified twice, associated with a presumed medical emergency during active participation in road traffic.

The authors also emphasise a subtlety that single-drug toxicology often overlooks. Cardiac patients are rarely managed with one medication; they take combinations. In this case, the driver was also on amlodipine, a calcium channel blocker, bisoprolol, a beta-blocker of the sympatholytic class, and torasemide, a diuretic. When several blood-pressure-lowering agents act together, the heart’s compensatory capacity, its ability to maintain circulation if hypotension begins to develop, is substantially reduced. Bisoprolol in particular blunts the physiological responses that would normally counteract a sudden drop in blood pressure. The authors therefore argue that interactions with other antihypertensive agents and sympatholytic substances must be taken into account when evaluating valsartan findings in drivers, since the combined effect may produce impairment that no single drug concentration would predict.

On the basis of all available information, the team proposes a practical benchmark: valsartan concentrations exceeding 11 micrograms per millilitre should be regarded as elevated, and within the range observed in this case the potential relevance of valsartan intake during driving must be considered substantial. Given that the probability of significant adverse effects rises with concentration, the authors consider it plausible that valsartan was at least partly contributory to the presumed medical emergency behind the wheel. The prescribing information itself offers no help, since no specific studies have ever investigated the effects of valsartan on driving performance or the ability to operate machinery, even though dizziness and fatigue are recognised adverse effects of treatment.

The significance of the case extends well beyond one driver and one crashed car. Millions of people take sartans daily, and most of them drive, yet forensic guidelines for interpreting these drugs in traffic investigations have been almost entirely absent. By documenting a verified elevated concentration linked to an on-road medical incident, and by describing the analytical approach used to quantify it, the Hannover team has created a reference point that future forensic toxicologists can cite when valsartan appears in a traffic case. The authors suggest the incident may serve as a valuable reference for interpreting future traffic-related cases in which the possible involvement of valsartan is under forensic-toxicological assessment, a small but meaningful step toward closing one of the remaining gaps in the science of road safety.

Subject of Research: Forensic interpretation of elevated valsartan concentrations in a road traffic offender

Article Title: Differentiating therapeutic use and potential impairment in the forensic interpretation of valsartan concentrations in road traffic offenders

Article References: Dziadosz, M., Marquenie, L., Rosenberger, W., Klintschar, M., & Teske, J. (2026). Differentiating therapeutic use and potential impairment in the forensic interpretation of valsartan concentrations in road traffic offenders. International Journal of Legal Medicine. https://doi.org/10.1007/s00414-026-04008-4

Image Credits: AI Generated

DOI: 10.1007/s00414-026-04008-4

Keywords: valsartan, forensic toxicology, road traffic, blood pressure medication, LC-MS/MS, hypotension, driving impairment, pharmacokinetics, drug interactions, bisoprolol, International Journal of Legal Medicine, case report