Taxonomic Class

Piperaceae

Common Trade Names

Aigin, Antares, Ardeydystin, Cetkava, Kava Kava Liquid, Kava Kava Root, Kavarouse, Kavasedon, Kavasporal, Kava Stress, Kavatino, Kavatrol, laitan, Mosaro, Nervonocton N, Potter’s Antigian Tablets, Super 5HT with Kava, Viocava

Common Forms

Prepared as capsules, a drink from pulverized roots, an extract, or tablets. Source

Kava comes from the dried rhizome and root of Piper methysticum, a member of the black pepper family (Piperaceae). Kava, a large shrub with broad, heart-shaped leaves, is native to many South Pacific islands.

Chemical Components

Pharmacologic activity is attributed to the kavapyrones that occur in the root. Biologically active components are obtained from chemical substitution of the basic pyrone structure. Alpha-pyrone components include yangonin, desmethoxyyangonin, 5,6-dehydromethysticin, ll-methoxyyangonin, and] 1-methoxy-nor-yangonin. Methysticin, kawain, dihydromethysticin, and dihydrokawain are active components from the 5,6-dyhydro-alpha-pyrone structure. Pipermethystine is an alkaloid isolated from the plant leaves of kava.

Actions

More than one mode of action is involved. An unquantified synergism exists among kava components. Components of the root may produce local anesthetic activity similar to that of cocaine but lasting longer than that of benzocaine. Kava induced mephenesin-like muscle relaxation in animals but was found to lack curare-like activity. The limbic system is inhibited by kavapyrones, an effect associated with suppression of emotional excitability and mood enhancement. Kava also inhibited haloperidol-induced catalepsy in rats .

In human studies, kava produced mild euphoria with no effects on thought and memory. The neuropharmacologic effects of kava include analgesia, hyporeflexia, and sedation. Kava can impair gait and cause pupil dilation. Some pyrones show fungistatic properties against several fungi, including some that are pathogenic to humans.

Reported Uses

Kava has been useful in attenuating spinal seizures and has antipsychotic properties. Therapeutic trials have shown a degree of seizure control in epileptic patients, suggesting involvement of gamma-aminobutyric acid receptors.

Kava extract has also been studied for treating anxiety disorders. In one study, 101 patients with anxiety of nonpsychotic origin showed improved scores on the Hamilton Anxiety Scale after being given a lipophilic extract of kava standardized to 70 mg of kavalactones three times a day . Both placebo and kava showed benefit as per the scale after 8 weeks, but kava fared significantly better than placebo at 16 weeks (P<.0001). No improvement was seen as measured on the Clinical Global Impression Scale. A meta-analysis of seven double­blind, randomized, placebo-controlled trials found some superiority of kava over placebo for treating anxiety in all trials but statistically significant superiority in only three trials .

Other claims for kava include treatment of asthma, depression, insomnia, muscle spasms, pain, rheumatism, and sexually transmitted disease and promotion of wound healing.

Dosage

Dosage is usually based on the kavapyrone content, which varies with preparation. Most studies in humans used 70 to 240 mg of kavapyrone P.O. daily. One study used 90 to 110 mg of dried kava extract P.O. t.i.d. for the treatment of anxiety . Doses of freshly prepared kava beverages average 400 to 900 g P.O. weekly.

Adverse Reactions

CNS: changes in motor reflexes and judgment, headache, dizziness.

EENT: vision changes.

Long-term, heavy use

CV: hypertension.

GI: diarrhea.

Hematologic: decreased platelet and lymphocyte counts.

Metabolic: reduced plasma protein, urea, and bilirubin levels; weight loss.

Musculoskeletal: increased patellar reflexes.

Respiratory: shortness of breath.

Skin: hypersensitivity reaction .

Other: dopamine antagonism (potential for galactorrhea and breast engorgement), reddened eyes and dry, flaking, discolored skin.

Interactions

Alcohol: Increased kava toxicity. Avoid administration with kava.

Alprazolam: May cause coma . Avoid administration with kava.

Benzodiazepines, other CNS depressants: Additive sedative effects. Avoid administration with kava.

Levodopa: Increased parkinsonian symptoms. Avoid administration with kava.

Pentobarbital: May have additive effects. Avoid administration with kava.

Contraindications And Precautions

Avoid using kava in pregnant or breast-feeding patients and in children under age 12; effects are unknown. Use cautiously in patients with neutropenia, renal disease, or thrombocytopenia. Avoid administration with psychotropic drugs.

Special Considerations

Inform the patient that significant adverse reactions may occur with long-term use of kava.

Caution the patient to avoid alcohol and other CNS depressants because they enhance kava’s sedative and toxic effects.

Inform the patient that absorption of kava may be enhanced if it is taken with food.

Advise women to avoid taking kava during pregnancy or when breast­feeding.

Points of Interest

Kava, although a depressant, is non fermented, nonalcoholic, nonopioid, and nonhallucinogenic and does not appear to cause physiologic dependence, but the risk of psychological dependence exists.

Kava is commonly used in the South Pacific as a ceremonial beverage.

Commentary

Kava has been used or studied most commonly for the treatment of ahxiety, restlessness, and stress. These uses are supported by limited evidence from a few small clinical trials. In studies of kava as an anxiolytic, adverse reactions were minimal, but significant adverse reactions are re­ported with chronic, heavy use. Other therapeutic claims are poorly documented. Additional trials are needed to establish dosing regimens, drug interactions, therapeutic benefits, and adverse effects.


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