Table 3 Trials testing kava
From: Nutritional and herbal supplements for anxiety and anxiety-related disorders: systematic review
Reference | Study Design | Sample Population | Intervention | Control | Length of Treatment | Outcomes | Direction of Evidence | Reported Adverse Events |
|---|---|---|---|---|---|---|---|---|
Volz (1997) [42] | Randomized; Double-blind; Parallel Group | 101 outpatients with anxiety of non-psychotic origin1 | Kava-kava extract WS 1490 (90- 110 mg dry extract = 70 mg kl per capsule) | Placebo | 24 weeks | Significant reduction in anxiety (HAMA, CGI, SCL-90-R, AMS) in favour of kava-kava treatment. | + | Excellent tolerability, similar to placebo; no clinically relevant changes in laboratory results. Stomach upset. |
Scherer (1998)* [48] | Open-label; Uncontrolled Observational study | 52 outpatients with nonpsychotic anxiety | Kava preparation (no dose reported in abstract) | N/A | Not reported in abstract | 42 patients (80.8%) rated kava treatment as "very good" or "good". | + | Rare |
Malsch (2001) [45] | Randomized; Double-blind; Parallel group | 40 adult outpatients with non-psychotic nervous anxiety, tension and restlessness, impairing work performance, normal social activities and relationships2 | Pre-treatment with benodiazepines (tapered off over two weeks) followed by capsules of 50 mg/day of dry extract standardized to 35 mg kava lactone for three weeks | Pre-treatment with benodiazepines (tapered off over two weeks) followed by placebo for three weeks | 5 weeks | Significant reduction in anxiety (HAMA, Bf-S, EAAS, CGI) in kava-treated group. | + | No serious adverse events |
Watkins (2001) [44] | Randomized; Double-blind; Parallel Group | 13 patients with GAD | Kava 280 mg/day (standardized to 30% kavalactones) | Placebo | 4 weeks | Significant improvement in baroreflex control of heart rate in kava-treated group; respiratory sinus arrhythmia did not respond to kava treatment. | + | Not reported |
Connor (2002) [52] | Randomized; Double-blind; Parallel Group | 38 adults with DSM-IV GAD3 | Kava (standardized to 70 mg kavalactones [kl]). Treatment initiated at 149 mg kl/day and increased to 280 mg kl/day for the next 3 weeks. | Placebo | 4 weeks | No significant difference to placebo4 | - | Well tolerated. No evidence of withdrawal or sexual side effects. |
Boerner (2003) [43] | Randomized; Double-blind; Parallel Group | 129 outpatients diagnosed with GAD (GAD; ICD-10: F41.1) | 400 mg/day Kava extract LI 150 (standardized to 30% kavapyrones, extraction solvent 96% ethanol in water, drug-extract ratio 13-20:1) | (1) 10 mg/day Buspirone or (2) 100 mg/day Opipramol | 8 weeks | Kava was shown to be as effective as reference treatments; 75% of patients responded (50% reduction of HAMA score). | + | 1 treatment-related adverse event. No systematic difference between treatments. No liver toxicity reported5. |
Cagnacci (2003) [46] | Randomized; Open; Parallel Groups (3) | 80 peri-menopausal women | Calcium (1 g/day) plus: (1) Kava-Kava,100 mg/day (55% of kavaina; Natural Bradel, Milano, Italy) (2) Kava-Kava, 200 mg/day | Calcium (1 g/day) | 3 months | Significant reduction in STAI scores in favour of combination treatment. | + | Mild/moderate: Nausea Gastric pain. No liver toxicity. |
Gastpar (2003) [50] | Randomized; Double-blind; Parallel Group | 141 adult outpatients diagnosed with neurotic anxiety6 | 150 mg/day kava special extract WS 1490 (standardized to 35 mg kl) | Placebo | 4 weeks | Pronounced decrease in ASI score for the kava group; however not statistically significant overall; however an exploratory analysis of variance across the differences between treatment end and baseline, with center as a second factor, showed superiority of kava over placebo. | - | Increased tiredness. No liver toxicity |
Jacobs (2005) [53] | Randomized; Double-blind; Parallel Group (3) | 391 healthy volunteers with anxiety7 and insomnia | (1) 100 mg kl/day kava (30% total kavalactones in extract) with valerian placebo (2) 6.4 mg/day valerian (1% valerenic acid in extract) with kava placebo | Double placebo | 28 days | Greater reductions in placebo group, but not statistically significant (STAI-State substest). | - | Similar frequency between treatments and placebo. No reports of liver toxicity |
Sarris (2009) [47] | Randomized; Double-blind; Crossover | 41 adult participants with 1 month or more of elevated generalized anxiety | Kava tablets (250 mg/day kavalactones) | Placebo | 3 weeks | Highly significant reduction in anxiety (HAMA, BAI, MADRS) in kava-treated group. | + | No serious adverse events. Mild dizziness, nausea. No liver toxicity. |
Sarris (2009) [51] | Randomized; Double-blind; Crossover | 28 adults with MDD and co-occurring anxiety | Hypericum perforatum8 (1 × 1.8 g tablet, three times/day); Kava rhizome aqueous extract9 (1 × 2.66 g tablet, 3 times/day) | Placebo | 4 weeks | Combination treatment had no significant effects on anxiety (BDI-II). | - | No serious adverse events. Mild gastrointestinal upset. No liver toxicity |