Effect of kava extract and individual kavapyrones on neurotransmitter levels in the nucleus accumbens of rats

A placebo-controlled study of Kava kava in generalized anxiety disorder

We assessed the efficacy and safety of a botanical anxiolytic, Kava kava (Piper methysticum), in treating generalized anxiety disorder (GAD). Thirty-seven adults with DSM-IV GAD were randomly assigned to 4 weeks of double-blind treatment with kava or a matching placebo. Weekly efficacy assessments [Hamilton Anxiety Scale, Hospital Anxiety and Depression Scale (HADS), Self Assessment of Resilience and Anxiety (SARA)] and safety evaluations were conducted. Improvement was observed with both treatments but no differences were found in the principal analysis. Post-hoc analyses revealed significant differences based on baseline anxiety severity, whereby kava was superior on the SARA in low anxiety and placebo was superior on the HADS and SARA in high anxiety. Both treatments were well tolerated. Although kava was not superior to placebo, it would be premature to rule it out as efficacious in GAD.

Life-threatening parkinsonism induced by kava-kava

We present a 45-year-old female with severe parkinsonism induced by kava-kava. The patient, who had a family history of essential tremor, developed severe and persistent parkinsonism after days of treatment with kava extract for anxiety. The symptoms improved with anticholinergics. Kava derivatives could produce severe parkinsonism in individuals with genetic susceptibility.

Kava pyrones exert effects on neuronal transmission and transmembraneous cation currents similar to established mood stabilizers--a review

1. Antiepileptic drugs that are successful as mood stabilizers, e.g. carbamazepine, valproate and lamotrigine, exhibit a characteristic pattern of action on ion fluxes. As a common target, they all affect Na+- and Ca2+ inward and K+ outward currents. 2. Furthermore, they have a variety of interactions with the metabolism and receptor occupation of biogenic amines and excitatory and inhibitory amino acids, and, by this, also influence long- term potentiation (LTP) to different degrees. 3. The kava pyrones (+/-)-kavain and dihydromethysticin are constituents of Piper methysticum. Anticonvulsant, analgesic and anxiolytic properties have been described in small open trials. 4. In the studies summarized in this article the effects mainly of (+/-)-kavain were tested on neurotransmission and especially on voltage gated ion channels. It is assumed that effects on ion channels may significantly contribute to clinical efficacy. 5. Experimental paradigms included current and voltage clamp recordings from rat hippocampal CA 1 pyramidal cells and dorsal root ganglia as well as field potential recordings in guinea pig hippocampal slices. 6. The findings suggest that (i) kava pyrones have a weak Na+ antagonistic effect that may contribute to their antiepileptic properties (ii) that they have pronounced L- type Ca2+ channel antagonistic properties and act as an positive modulator of the early K+ outward current. These two actions may be of importance for mood stabilization. (iii) Furthermore, kava pyrones have additive effects with the serotonin-1A agonist ipsapirone probably contributing to their anxiolytic and sleep- inducing effects. (iv) Finally, they show a distinct pattern of action on glutamatergic and GABAergic transmission without affecting LTP. The latter, however, seems not to be true for the spissum extract of Kava where suppression of LTP was observed. 7. In summary, kava pyrones exhibit a profile of cellular actions that shows a large overlap with several mood stabilizers, especially lamotrigine.

Adverse-effect profile of kava

The use of alternative therapies has increased substantially over the last decade, particularly for more chronic conditions such as anxiety. Among the most widely used treatments are medicinal herbs, or phytomedicines, such as kava (Piper methysticum), which has demonstrated anxiolytic activity in both animal models and clinical samples. Kava has several advantages over conventional pharmacologic treatments for anxiety--in clinical settings it has been associated with better tolerability and lack of physiologic dependence and withdrawal. However, phytomedicines are not rigorously regulated in the United States and systematically collected safety data are very limited. These issues are a leading concern regarding the safety of medicinal herbs such as kava. In this report, the safety profile for kava is provided, including findings from a study of its use in generalized anxiety disorder. Safety parameters assessed include occurrence of adverse events, withdrawal symptoms, effect on heart rate, blood pressure, laboratory assessments, and sexual function. No differences were found between kava and placebo on any of the parameters evaluated. The data support the safety of kava in treating anxiety at 280 mg kava lactones/day for 4 weeks.

Evaluation of combining kava extract with hormone replacement therapy in the treatment of postmenopausal anxiety

OBJECTIVE

to evaluate the efficacy of combining kava extract with hormone replacement therapy in the treatment of menopausal anxiety.

MATERIALS AND METHODS

HAMA score was evaluated before and after therapy in four groups of women in menopause (duration of menopause ranged from 1 to 12 years). The groups were treated with hormone replacement therapy (with and without progestogens) and kava extract or placebo for 6 months.

RESULTS

A significant reduction in HAMA score was observed in all four groups of women. The reduction was more significant in groups taking kava extract than in groups on hormones only.

DISCUSSION

The combined use of hormone replacement therapy and kava extract seems to be effective against menopausal anxiety. Kava extract accelerates resolution of psychological symptoms while hormone therapy safeguards against osteoporosis and cardiovascular disease.

Neuroprotective effects of (+/-)-kavain in the MPTP mouse model of Parkinson's disease

This is the first study to investigate the potential protective effects of the lipophilic kavapyrone (+/-)-kavain in the experimental MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease (PD). Male C57BL/6 mice were treated with (+/-)-kavain (50, 100, or 200 mg/kg i.p.) or vehicle 60 min before and 60 min after a single administration of MPTP (30 mg/kg s.c.) or saline, respectively. Mice were sacrificed after 7 days and the neostriatum was analyzed for dopamine and its metabolites using HPLC with electrochemical detection. Furthermore, nigral sections were processed for tyrosine hydroxylase (TH) immunocytochemistry. To determine the effects of (+/-)-kavain (200 mg/kg) on MPTP metabolism, HPLC analysis of striatal MPP(+) (1-methyl-4-phenylpyridinium) levels was performed. MPTP treatment alone led to a significant depletion of striatal dopamine levels to 12.61% of saline controls. The lower dosages of (+/-)-kavain (50 and 100 mg/kg) showed only a nonsignificant attenuation of MPTP-induced dopamine depletion, but a high dosage of (+/-)-kavain (200 mg/kg) significantly antagonized the dopamine depletion to 58.93% of saline control values. Remarkably, the MPTP-induced decrease of TH-immunoreactivity as well as the loss of nigral neurons was completely prevented by (+/-)-kavain (200 mg/kg). Striatal MPP(+) levels were not altered by (+/-)-kavain treatment. In conclusion, we found that MPTP metabolism was not influenced by (+/-)-kavain and postulate the antiglutamatergic effects of (+/-)-kavain for its protective effects against MPTP toxicity. (+/-)-Kavain may be a novel candidate for further preclinical studies in animal models of PD and other disorders with glutamatergic overactivity.