A Case for Kava Kava
Among herbal therapies, kava kava appears to be the most researched for its anxiolytic effect. And, according to a Cochrane review of 11 randomized controlled trials (RCTs) with 645 patients, kava extract is effective at reducing anxiety compared with placebo.
Kava kava is a drink derived from the plant Piper methysticum and is not sedating. Although its mechanism of action are unclear, it is proposed to modulate gamma-aminobutyric acid (GABA) activity via alteration of lipid membrane structure and sodium-channel function; inhibit monoamine oxidase B; and block noradrenaline and dopamine reuptake. Doses of up to 400 mg daily have been reported to be safe. Although the drink remains available over the counter in the United States, Australia, and New Zealand, the US Food and Drug Administration has warned about kava kava's potential liver toxicity, and it is banned in some countries because of this concern.
In a review published in 2010, researchers showed that kava kava may be more tolerable and have fewer side effects than benzodiazepines and antidepressants. In particular, five of the reviewed studies demonstrated the drink's therapeutic potential as a standalone therapy in patients with anxiety disorder, GAD, and those being tapered off benzodiazepines; conversely, four studies showed no efficacy in reducing anxiety compared with placebo.
Another review, which reported efficacy for anxiety in 4 of 6 RCTs, recommended checking liver function tests before initiation of kava kava use. This article also advised that patients avoid alcohol and sedatives while using kava kava. In addition, only traditional water-soluble extracts of the rhizome (root) of appropriate kava cultivars should be used.
The most recent RCT of kava kava supports its use. Using the Hamilton Anxiety Rating Scale (HAM-A) as the primary clinical outcome, researchers found a significant reduction in anxiety in 58 participants with GAD who were taking kava compared with those taking placebo, with a moderate effect size. Depending on patients' responses, the liquid kava kava used in the study contained 120-240 mg/day of the active ingredient, kavalactones. No hepatotoxicity was found among the participants.
Medscape Family Medicine © 2014
Cite this: What Can CAM Do for Anxiety? - Medscape - Dec 03, 2014.