KAVA

Occurrence

Kava is a shrub found on the South Sea Islands.

Uses

Kava is used as an anxiolytic, antiepileptic, antidepressant, antipsychotic, and for anxiety, attention defi cit-hyperactivity disorder, insomnia, restlessness, and headaches. It is also used as a muscle relaxant and to promote wound healing

Indications

Kava-kava (Piper methysticum) is a South Pacific island shrub the rhizome or root of which was used in the past as a ceremonial beverage and that today is popular as an anxiolytic. Historically, women prepared the kava by pounding and then chewing it. After being allowed to ferment in bowls, the kava was drunk by male islanders to mark a special event.The herb would induce a pleasant euphoric tranquility and contribute to the group’s social cohesion.The active ingredients are thought to be kavapyrones (also known as kavalactones), a family of related synergistically active compounds that include kawain and methysticin.

Mechanism of action

The exact mechanism of action is unclear, but it is thought that kavapyrones may act in the amygdala, producing a tranquilizing and muscle relaxant effect. Despite inducing mild sedation and euphoria, there is usually no cognitive or memory impairment at typical doses. Chewing the root results in a local anesthetic effect with temporary numbness. High doses may cause gait impairment, dilated pupils, and eventually impaired motor performance.

Clinical Use

Kava may be effective for the short-term treatment of anxiety. A number of small trials have shown extracts, standardized to 70% kavapyrones, to be significantly and consistently more effective than placebo. Additional studies suggest that kava acts centrally as a muscle relaxant and likely has neuroprotective and nonopioid analgesic properties.

Side effects

Although kava was considered relatively safe until recently, GI upset, headache, allergic skin reactions, elevated liver function tests, and rare extrapyramidal reactions may occur. It should be avoided in patients with known liver disease. Slowed reflexes and diminished judgment may occur at high doses. Heavy chronic use may produce a psychological (rather than physiological) habituation and a pellagralike skin condition known as kava dermatitis characterized by reddened eyes and dry flaking skin with a yellow discoloration; flavokawains A and B are yellow pigments isolated from kava and are likely causative. Despite the resemblance to pellagra, niacin does not reverse this condition.
Heavy kava users have also been observed to lose weight and have low plasma protein levels and low platelet and lymphocyte counts. Pulmonary hypertension and shortness of breath have rarely occurred. Kava should be avoided in pregnant women and children, since the consequences of use are unknown. A recent cause for concern is an uncommon idiosyncratic liver toxicity associated with kava use; in some cases, this has been severe enough to warrant liver transplantation. It is unclear whether kava alone is to blame, but the safety of this herb is under review. Several European countries, where this problem was first reported, have either suspended sales or are acting to make kava a prescription drug.
Kava should not be used with alcohol, benzodiazepines, barbiturates or other sedatives because of their additive effects. In one case, coma resulted from mixing alprazolam and kava. Patients have complained that kava, while relaxing the body, may be less effective for mental anxiety with obsessive or racing thoughts than are the benzodiazepines.