A prescription medical food used to treat osteoarthritis may induce reversible liver damage in some users, suggests research published in the Annals of Internal Medicine.
Flavocoxid, a proprietary blend of the plant-derived flavonoids, baicalin, and catechins, was found highly likely to be the cause of acute liver injury in three women, and the possible cause of damage in a fourth, report Naga Chalasani (Indiana University School of Medicine, Indianapolis, USA) and co-authors.
The patients, aged 57-68 years, were among 877 patients enrolled in the Drug-Induced Liver Injury Network Prospective Study to monitor the outcome of liver damage thought to be associated with prescription drugs and herbal supplements.
Liver injury developed 1-3 months after beginning flavocoxid, reflected by significant elevations of alanine aminotransferase (mean peak 1268 U/L), alkaline phosphatase (mean peak 510 U/L), and serum bilirubin (mean peak 160.7 µmol/L).
Within 3-12 weeks of discontinuing flavocoxid, the patients' liver enzyme and bilirubin levels returned to normal levels, and patients showed no further sign of acute liver failure or chronic damage.
Chalasani et al say that their study is unable to determine frequency of liver injury among flavocoxid users, or the role of hypersensitivity to the compounds in the reported cases.
"Given its botanical ingredients, variation in the concentration of substances due to various factors, such as harvesting conditions, seasonal variations, and geographic origin, is possible," the team comments. "Unpredictable or unregulated concentration of such polyphenolic substances as catechins may set the stage for toxicity."
In an accompanying editorial, Stephan Reichenback and Peter Jüni, from the University of Bern in Switzerland, note that food supplements and medicinal food stuffs marketed in the USA are not regulated by the Food and Drug Administration until they are on sale.
"To understand the effectiveness and safety of any health care intervention - drug, medical device, food supplement, or medical food - clinical evidence from well-designed randomized trials and observational studies will always be necessary," they comment.
"Given the widespread use and potential harm of medical food and food supplements, the policy of marketing these products in the absence of clinical evidence may need to be reconsidered."
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