Kavalactone
Kavalactones are a class of lactone compounds found in the kava shrub. Kavalactones have a wide variety of effects including amnestic, analgesic, anticonvulsant, anxiolytic, nootropic, and sedative/hypnotic activity caused by numerous interactions with the central nervous system via several mechanisms.
Enzyme inhibition
Kava extract has been shown to potently inhibit a wide range of hepatic enzymes, suggesting a very high potential for interactions with many pharmaceuticals and herbal medications. For this reason, kava should never be consumed without the permission of a primary care physician, psychiatrist, and/or any other doctor who is prescribing medication for a patient. It is also recommended that potential users discuss their kava use with a pharmacist. If undergoing anesthesia, it is recommended to note any use of kava well in advance of any surgery. Patients may be instructed to temporarily discontinue use of kava for a set period of time before and after the surgery.
Toxicity