Kava - Medicinal Uses, Interactions, Side Effects, Dosage

Kava
The kava plant (Piper methysticum) is a member of tho pepper family, and is widely cultivated throughout the Pacific Islands.
Uses and Benefits:
As an herbal product in North America (and as a phytomedicine in Europe), kava extracts are commonly used for anxiety, stress, tension, and insomnia. A mildly psychoactive beverage made from the rhizome of the kava plant has been used for centuries by South Pacific Islanders, both ceremonially and socially, reportedly with relaxing or calming properties.
Pharmacology:
A lipid-soluble extract from the plant rhizome contains the main active constituents, called kava pyrones (or kava lactones). The primary kava pyrones include kawain, dihydro­kawain, methysticum, and dihydromethysticum, which have been extensively studied in vitro and in in vivo animal models. These substances appear to have local anesthetic properties by block­ing voltage-dependent sodium channels, which explains why chewing the kava root causes numbness and tingling of the tongue and mucosa. The kava pyrones also have sedative, muscle relaxant, and anticonvulsant properties in animals.
Clinical Trials:
Six randomized, double-blind, placebo-controlled trials of standardized European kava extract products used for anxiety have been published in Germany. In general, the methodologic quality of these German trials was good, but the sample sizes were small in most studies. Double-blinding and randomization procedures were described in most, but not all, studies.
Four of these trials were chronic, lasting 1-6 months, and in­cluded 40-101 patients each. Two studies included patients with a variety of anxiety disorders, while the other two evaluated women with primarily peri menopausal anxiety complaints.
Adverse Effects:
Side effects of the standardized preparations were infrequent and mild in the controlled trials. There were isolated reports of stomach complaints, restlessness, drowsiness, tremor, and headache. Gastrointestinal discomfort, headache, dizziness, and allergic skin reactions have been reported in <2.3% of patients in open trials. Several studies suggest that therapeutic doses of European kava preparations do not affect intellectual and motor function. (kava is commonly believed to act like alcohol). After one 6-month clinical trial, withdrawal effects were reportedly not observed when therapy was discontinued. A kava dermopathy characterized by yellowing of the skin and a scaly dermatitis is common in chronic heavy kava drinkers in the South Pacific; the effects are reversible after discontinuation of the herb.
Kava may have dopamine antagonist properties. Three patients allegedly developed extrapyramidal-like dystonic reactions, and one developed worsening of Parkinson's disease when using European kava preparations. Severe choreoathetosis developed in an Aboriginal Australian man in association with excessive kava beverage bingeing. Excessive amounts of traditionally prepared beverages also may produce CNS depressant or intoxicating effects. There are two reports of U.S. motorists found weaving between lanes who were arrested for "driving under tho influence" after drinking 8-16 cups of a kava beverage. Lastly, several patients with acute necrotizing hepatitis who were using kava products have been reported; one patient required a liver transplanpo, The relationship of acute necrotizing hepatitis to kava use is unclear, but the disorder may represent a rare, idiosyncratic adverse reaction.
Side Effects and Interactions:
There is limited data on drug interactions with kava. Severe disorientation has been reported in a patient using a U.S. kava product in conjunction with alprazolam, cimetidine, and terazosin; whether his symptoms were actually due to a drug­herb interaction is unclear. Therapeutic doses of a European kava preparation reportedly did not affect safety-related performance when administered with alcohol, but a liquid kava preparation did potentiate the CNS-depressant properties of alcohol in a separate study.
Cautions: The German Commission E recommends that duration of administration not exceed 3 months without medical advice, presumably due to concerns of dependence and/or dermopathy. Patients should be warned that kava may adversely affect driving and/or operating heavy machinery.Concomitant use with alcohol or other CNS depressants may have potentiating effects, especially if either is used in high doses. It is not clear if usual therapeutic doses of kava actually warrant these warnings, but caution seems prudent, especially for kava bever­age products, which are more likely to be ingested in excess. Kava is not recommended for pregnant or nursing women due to lack of data.
Preparations & Doses:
The usual recommended dose of kava is 140-250 mg/day of the kava pyrone constituents, in 2-3 divided doses. In European studies, the most common dose was 70 mg t.i.d. (210 mg/day), but ranged from 60-210 mg/day. In the U.S. clinical trial, 120 mg kava pyrones (Kavatrol, by Natrol) was given b.i.d. One major European formulation (WS 1490, also called Laitan) is standardized to 70% kava pyrones (100-mg tablet of kava = 70 mg kava pyrones). In contrast, kava pyrone content of U.S. brands usually varies between 30% and 55%. Kava extracts are commonly available in capsules, tablets, and liquid forms.

Summary Evaluation
Based on several European randomized controlled trials, kava ars to be beneficial for mild anxiety or stress. The relative kava compared to usual doses of pharmaceutical anxiylic drugs is unknown. Kava appears to be well tolerated at Lommended therapeutic doses, but there is potential for effects with higher than recommended doses and for drug ractions. Rare, serious reactions such as hepatitis may occur, the herb should not be used in patients with liver disease. It be prudent for patients susceptible to extrapyramidal side, such as those with Parkinson's disease or those taking lit such as antipsychotics or metoclopramide, to avoid kava interactions have been more clearly defined. Likewise, kava should not be mixed with CNS depressants such as benzodipines or alcohol.

Peter Thomas is a writer, who writes many great articles on herbal medicines for common ailments and diseases. For more information on herbal remedies and home remedies visit our site on health care

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