Muscle cramps affect between 57 and 95 percent of people with ALS, and in some individuals they are the very first sign of the disease, arriving even before weakness becomes apparent. These involuntary, often excruciating contractions disrupt daily activities, degrade quality of life, and appear to contribute to measurable muscle damage, reflected in elevated levels of creatine kinase in the blood. The therapeutic cupboard is nearly bare. Mexiletine, an antiarrhythmic drug, showed significant benefit in clinical trials for ALS-related cramping, but it carries a black box warning from the U.S. Food and Drug Administration because of concerns about fatal cardiac arrhythmias. No well-established, safe, and well-tolerated medication currently exists for this symptom in the ALS population.

That unmet need is what drew a team of researchers to an unlikely candidate: TJ-68, known generically as Shakuyakukanzoto, a Japanese Kampo herbal medicine that has been prescribed widely in Japan for decades to treat muscle cramps and pain associated with a variety of conditions, including dialysis-related cramping. The medicine combines two botanical ingredients—peony root and jujube fruit—in a formulation whose clinical use predates modern pharmacology by centuries. A previous pilot trial led by neurologist Hiroshi Mitsumoto of Columbia University Irving Medical Center, conducted using a novel repeated crossover N-of-1 design, found that TJ-68 was safe and suggested a possible benefit for cramping in ALS patients, though the primary outcome did not reach statistical significance. Now, a new study published in the journal Metabolomics has gone beneath the surface of that clinical signal, using cutting-edge analytical chemistry to ask a fundamental question: what is actually happening in the blood chemistry of ALS patients when they cramp, and what does TJ-68 do to that chemistry?

The answer required some of the most sophisticated laboratory instrumentation available to modern medicine. The research team, which included investigators from Columbia, the Mayo Clinic, and collaborating institutions, obtained blood samples from eleven ALS patients who had participated in the randomized, placebo-controlled, double-blind, multi-period crossover trial. Each participant’s plasma was collected at five separate time points: at baseline, at the end of two placebo phases, and at the end of two TJ-68 treatment phases, with one-week washout intervals separating the periods. This repeated-measures design is a statistical advantage in small trials, because each patient serves as his or her own control, allowing researchers to tease apart treatment effects from individual variability.

The metabolomic analysis itself was a tour de force of mass spectrometry. Amino acids and related metabolites, neuromodulators, carnitine and acylcarnitines, choline-related compounds, creatine, creatinine, and uric acid were quantified using liquid chromatography–mass spectrometry on triple quadrupole instruments, employing stable isotope dilution techniques in which isotopically labeled internal standards were spiked into each plasma sample to ensure precise quantification. Tricarboxylic acid cycle intermediates—the metabolic intermediates of cellular respiration—were measured separately using gas chromatography–mass spectrometry with electron impact ionization. All analyses were performed at the Mayo Clinic Metabolomics Core Facility, with calibration curves generated from authentic standards and quality control samples processed alongside the study samples to guarantee accuracy. Protein precipitation with cold methanol and acetonitrile, careful chromatographic separation on C18, C8, and HILIC columns, and derivatization steps involving reagents such as AccQ.Fluor for amino acids and silylating agents for TCA cycle intermediates all formed part of the exacting analytical pipeline.

To link the metabolite measurements to the clinical experience of cramping, the researchers turned to linear mixed-effects models, a statistical framework that accounts for the fact that repeated measurements from the same individual are correlated. They used three different measures of cramp severity derived from the muscle cramp scale: a total score capturing overall severity, a question-specific score covering cramp frequency, and another question-specific score covering the degree to which cramps interfere with overall daily activity. By modeling changes in metabolite levels against changes in cramp severity while adjusting for treatment and period effects, they could identify which molecules tracked most closely with the patients’ suffering.

The findings were revealing. Higher plasma levels of glutamine relative to glutamate, along with elevated levels of arginine and leucine, were associated with more severe muscle cramps. These are not random molecules. Glutamine and glutamate sit at a critical junction in nitrogen metabolism and neurotransmission, and glutamate is the principal excitatory neurotransmitter of the central nervous system—a system already known to be pathologically overactive in ALS, which is precisely why riluzole, the oldest approved ALS drug, works by damping down glutamatergic signaling. Arginine and leucine, meanwhile, are central to muscle metabolism and the urea cycle, hinting that the metabolic milieu of the dying motor unit may itself be priming muscles to fire involuntarily. The implication is that cramping in ALS is not merely a mechanical nuisance but the visible symptom of a measurable biochemical state.

The treatment data told an equally compelling story. When patients took TJ-68, their plasma levels of tryptophan and aconitate rose, while levels of serotonin and acetylcarnitine fell. Tryptophan is the amino acid precursor of serotonin, and the shift in both tryptophan and serotonin suggests the herbal medicine may be modulating pathways of neuromodulation that influence motor neuron excitability. Aconitate, an intermediate of the TCA cycle, points toward changes in cellular energy metabolism, while the drop in acetylcarnitine—a molecule that shuttles acetyl groups into mitochondria—hints at altered muscle energy handling. Perhaps most striking, the researchers found that long-chain acylcarnitines, a family of fatty acid transport intermediates, were correlated with cramp severity, and their levels tended to decrease with TJ-68 treatment. This raises the provocative possibility that disrupted fatty acid metabolism in muscle may be one of the drivers of ALS-related cramping, and that TJ-68 may partly correct it.

Beyond mechanism, the study delivered something of genuine practical value: predictors of who will respond to the medicine. By testing the interaction between baseline metabolite levels and TJ-68 treatment in their statistical models, the team identified four metabolites measured before treatment that predicted whether a given patient’s cramps would improve: uric acid, beta-aminoisobutyric acid, alpha-aminoadipic acid, and acetylcholine. Of these, uric acid stands out immediately, because it is routinely measured in standard clinical chemistry panels at hospitals around the world. A physician treating an ALS patient could, in principle, check a single routine blood test and gain some indication of whether TJ-68 is likely to help that particular patient’s cramps—a small but meaningful step toward personalized symptomatic therapy in a disease where every quality-of-life gain matters.

The significance of this work extends well beyond one herbal remedy and one symptom. It demonstrates, in a rigorously designed clinical framework, that metabolomic technology can dissect the biology of a symptom that has been largely treated as an afterthought, identify the molecular perturbations associated with it, track the pharmacodynamic footprint of an intervention, and predict treatment response from a baseline blood draw. The authors argue that this approach affirms the value of metabolomics for future pharmacotherapy and clinical studies in ALS. Given that effective symptomatic treatments—such as Botox injections for drooling, dextromethorphan-quinidine for pseudobulbar affect, and modafinil for fatigue—have historically emerged from precisely this kind of patient-centered trial design, the metabolic toolkit adds a powerful new dimension to the effort to improve daily life for people living with a fatal disease.

There is also a cultural dimension worth savoring. A formulation rooted in traditional Japanese medicine, whose cramp-relieving reputation spans generations of clinical use, has now been interrogated with triple quadrupole mass spectrometers and linear mixed-effects models—and has emerged with a plausible, testable mechanism of action. The convergence of ancient botanical pharmacy and twenty-first-century omics science is exactly the kind of synthesis that modern medicine needs more of: neither dismissing traditional remedies for lacking molecular explanations, nor accepting them without demanding the evidence. With its safety established, its metabolic signature mapped, and its responders potentially identifiable through a routine blood test, TJ-68 may soon deserve a place in the conversation about comprehensive ALS care—offering relief, however modest, to patients whose muscles betray them daily while medicine searches for a cure.