Acute Liver Failure After Administration of the Herbal Tranquilizer Kava-Kava (Piper methysticum)

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Sir: The chemistry and pharmacology of kava-kava (Piper methysticum) is unique among psycholeptic substances. The original kava drink is a suspension of lipid material in cold water used by native people for centuries and has not been linked with reports of liver failure. For commercial use, the lipid fraction is gained by alcoholic or acetonic extraction from the root of the kava plant. The extract is dried and pressed into tablets. The major proportion of the lipid components of the kava pyrone consists of 6 chemically well-defined compounds containing the 4-methoxy-2-pyrone ring system (dihydrokavain, dihydromethysticin, kavain, methysticin, desmethoxyyangonin, and yangonin). The different kava pyrones have partially anxiolytic, neuroleptic, sedative-hypnotic, anticonvulsive, muscle-relaxant, analgetic, and spasmolytic effects. A cumulative action of kava combined with alcohol, barbiturates, psychotropics, and muscle relaxants resulting in coma has been described. The exact knowledge of the psychopharmacology of kava is still incomplete.

J Clin Psychiatry 2003;64(2):216-218 [letter]