Safety review of kava (Piper methysticum) by the Natural Standard Research Collaboration

Complementary and Integrative Medicine for Anxiety in Children, Adolescents, and Young Adults

An integrative approach to treating anxiety in children and adolescents takes a biopsychosocial-spiritual approach. Early life stress may translate into anxiety via epigenetic mechanisms, the adoption of maladaptive coping tendencies (poor eating, sedentary lifestyle, substance use), and dysregulation of central autonomic nervous system function. Each of these mechanisms may increase inflammatory markers. This article will explore the efficacy of CIM interventions that work on these mechanisms through mind-body-medicine, acupuncture, nutrition, and supplements.

Prevalence and Factors Associated With Low Birth Weight in the Solomon Islands: Evidence From the 2015 Solomon Islands Demographic and Health Survey data

Low birth weight (LBW) has contributed to more than 80% of under-5 deaths worldwide, most occurring in low- and middle-income countries. We used the 2015 Solomon Islands Demographic and Health Survey data to identify the prevalence and risks associated with LBW in the Solomon Islands. Low birth weight prevalence estimated was 10%. After adjustment for potential confounders, we found the risk of LBW for women with a history of marijuana and kava use was 2.6 times, adjusted relative risk (aRR) 2.64 at a 95% confidence interval [0.64, 10.95] and 2.5 times [aRR: 2.50 (0.63, 9.88)] than among unexposed women, respectively. Polygamous relationship, no antenatal care, decision-making by another person were 84% [aRR: 1.84 (1.15, 2.93)], 73% [aRR: 1.73 (0.96, 3.13)], and 73% [aRR: 1.73 (0.96, 3.13)] than among unexposed women, respectively. We also found that 10% and 4% of LBW cases in the Solomon Islands were attributable to a household of more than 5 members and tobacco and cigarette use history. We concluded that LBW in the Solomon Islands relied more on behavioral risk factors, including substance use and health and social risk factors. We recommended further study on kava use and its impact on pregnancy and LBW.

Biopharmaceutical evaluation of kavain in Piper methysticum G. Forst dried extract: Equilibrium solubility and intestinal permeability in Caco-2 cell model

ETHNOPHARMACOLOGICAL RELEVANCE

Piper methysticum G. Forst, popularly known as kava, is a traditional medicinal plant native from South Pacific islands and widely used to treat anxiety, depression and stress. The psychoactive properties are related to the kavalactones, mainly kavain.

AIM OF THE STUDY

To evaluate the biopharmaceutical properties of synthetic kavain and when present in kava dried extracts by means of equilibrium solubility and intestinal permeability studies in the Caco-2 cell model.

MATERIALS AND METHODS

The equilibrium solubility of kavain was performed using a shake flask incubator at 37 °C in different media at physiological pH range (1.2-6.8). The intestinal permeability of kavain evaluated in Caco-2 cells in the presence and absence of the P-glycoprotein inhibitor verapamil. Kavain concentrations were determined by reversed phase high performance liquid chromatography (HPLC).

RESULTS

HPLC methods were developed and fully validated for kavain quantitation. Kavain demonstrated low solubility and the pH of the aqueous media did not affect its solubility. Kavain was found to be highly permeable and efflux of kavain mediated by P-glycoprotein was not significant during intestinal permeation.

CONCLUSION

The results of biopharmaceutical studies provided useful information for predicting availability of kavain from the gastrointestinal tract and this compound was ranked as BCS Class II, exhibiting dissolution rate-limited absorption.

An Updated Review on the Psychoactive, Toxic and Anticancer Properties of Kava

Kava (Piper methysticum) has been widely consumed for many years in the South Pacific Islands and displays psychoactive properties, especially soothing and calming effects. This plant has been used in Western countries as a natural anxiolytic in recent decades. Kava has also been used to treat symptoms associated with depression, menopause, insomnia, and convulsions, among others. Along with its putative beneficial health effects, kava has been associated with liver injury and other toxic effects, including skin toxicity in heavy consumers, possibly related to its metabolic profile or interference in the metabolism of other xenobiotics. Kava extracts and kavalactones generally displayed negative results in genetic toxicology assays although there is sufficient evidence for carcinogenicity in experimental animals, most likely through a non-genotoxic mode of action. Nevertheless, the chemotherapeutic/chemopreventive potential of kava against cancer has also been suggested. Both in vitro and in vivo studies have evaluated the effects of flavokavains, kavalactones and/or kava extracts in different cancer models, showing the induction of apoptosis, cell cycle arrest and other antiproliferative effects in several types of cancer, including breast, prostate, bladder, and lung. Overall, in this scoping review, several aspects of kava efficacy and safety are discussed and some pertinent issues related to kava consumption are identified.

Biological Activity, Hepatotoxicity, and Structure-Activity Relationship of Kavalactones and Flavokavins, the Two Main Bioactive Components in Kava (Piper methysticum)

Kava (Piper methysticum Forst) is a popular and favorable edible medicinal herb which was traditionally used to prepare a nonfermented beverage with relaxant beneficial for both social and recreational purposes. Numerous studies conducted on kava have confirmed the presence of kavalactones and flavokawains, two major groups of bioactive ingredients, in this miraculous natural plant. Expectedly, both kavalactone and flavokawain components exhibited potent antianxiety and anticancer activities, and their structure-activity relationships were also revealed. However, dozens of clinical data revealed the hepatotoxicity effect which is indirectly or directly associated with kava consumption, and most of the evidence currently seems to point the compounds of flavokawains in kava were responsible. Therefore, our aim is to conduct a systematic review of kavalactones and flavokawains in kava including their biological activities, structure-activity relationships, and toxicities, and as a result of our systematic investigations, suggestions on kava and its compounds are supplied for future research.

Biotechnological processes to obtain bioactive secondary metabolites from some Mexican medicinal plants

The consumption of medicinal plants has increased in recent decades due to the fact that they biosynthesize compounds with many biological activities; thus, some plant species with biological potential are being utilized as raw material by the industries for preparation of drugs, phytodrugs, or food supplements. This has the consequence of overexploitation and deforestation, which endangers plant species-of-interest. In recent years, alternatives have been sought to eradicate this problem. A solution that was given and is maintained is plant biotechnology, which favors the production of secondary metabolites (SMt) with important biological activity. Plant biotechnology allows us to increase the yield of a compound-of-interest, reduces its production times and costs, and allows constant and controlled production of the raw material, while aiding in the protection of medicinal plants that are found in danger of extinction. In the scientific literature, procuring the SMt by means of biotechnological processes is described, highlighting the study of five species from Mexican traditional medicine (Lopezia racemosa, Galphimia glauca, Cnidoscolus chayamansa, and Buddleja cordata), and the main biological activities are as follows: anti-inflammatory, hepatoprotector, neuroprotector, anxiolytic, antitumoral, antibacterial, and antioxidant, among others. KEY POINTS: • Secondary metabolites produce by biotechnology processes • Active secondary metabolites isolated from Mexican medicinal plants • Recent advances on the production of some bioactive secondary metabolites.

Kava as a Clinical Nutrient: Promises and Challenges

Kava beverages are typically prepared from the root of Piper methysticum. They have been consumed among Pacific Islanders for centuries. Kava extract preparations were once used as herbal drugs to treat anxiety in Europe. Kava is also marketed as a dietary supplement in the U.S. and is gaining popularity as a recreational drink in Western countries. Recent studies suggest that kava and its key phytochemicals have anti-inflammatory and anticancer effects, in addition to the well-documented neurological benefits. While its beneficial effects are widely recognized, rare hepatotoxicity had been associated with use of certain kava preparations, but there are no validations nor consistent mechanisms. Major challenges lie in the diversity of kava products and the lack of standardization, which has produced an unmet need for quality initiatives. This review aims to provide the scientific community and consumers, as well as regulatory agencies, with a broad overview on kava use and its related research. We first provide a historical background for its different uses and then discuss the current state of the research, including its chemical composition, possible mechanisms of action, and its therapeutic potential in treating inflammatory and neurological conditions, as well as cancer. We then discuss the challenges associated with kava use and research, focusing on the need for the detailed characterization of kava components and associated risks such as its reported hepatotoxicity. Lastly, given its growing popularity in clinical and recreational use, we emphasize the urgent need for quality control and quality assurance of kava products, pharmacokinetics, absorption, distribution, metabolism, excretion, and foundational pharmacology. These are essential in order to inform research into the molecular targets, cellular mechanisms, and creative use of early stage human clinical trials for designer kava modalities to inform and guide the design and execution of future randomized placebo controlled trials to maximize kava's clinical efficacy and to minimize its risks.

A UHPLC-UV Method Development and Validation for Determining Kavalactones and Flavokavains in Piper methysticum (Kava)

An ultra-high-performance liquid chromatographic (UHPLC) separation was developed for six kava pyrones (methysticin, dihydromethysticin (DHM), kavain, dihydrokavain (DHK), desmethoxyyangonin (DMY), and yangonin), two unidentified components, and three Flavokavains (Flavokavain A, B, and C) in Piper methysticum (kava). The six major kavalactones and three flavokavains are completely separated (Rs > 1.5) within 15 min using a HSS T3 column and a mobile phase at 60 °C. All the peaks in the LC chromatogram of kava extract or standard solutions were structurally confirmed by LC-UV-MS/MS. The degradations of yangonin and flavokavains were observed among the method development. The degradation products were identified as cis-isomerization by MS/MS spectra. The isomerization was prevented or limited by sample preparation in a non-alcoholic solvent or with no water. The method uses the six kava pyrones and three flavokavains as external standards. The quantitative calibration curves are linear, covering a range of 0.5⁻75 μg/mL for the six kava pyrones and 0.05⁻7.5 μg/mL for the three flavokavains. The quantitation limits for methysticin, DHM, kavain, DHK, DMY, and yangonin are approximately 0.454, 0.480, 0.277, 0.686, 0.189, and 0.422 μg/mL. The limit of quantification (LOQs) of the three flavokavains are about 0.270, 0.062, and 0.303 μg/mL for flavokavain C (FKC), flavokavain A (FKA), and flavokavain B (FKB). The average recoveries at three different levels are 99.0⁻102.3% for kavalactones (KLs) and 98.1⁻102.9% for flavokavains (FKs). This study demonstrates that the method of analysis offers convenience and adequate sensitivity for determining methysticin, DHM, kavain, DHK, yangonin, DMY, FKA, FKB, and FKC in kava raw materials (root and CO₂ extract) and finished products (dry-filled capsule and tablet).

Reduced Disc Shedding and Phagocytosis of Photoreceptor Outer Segment Contributes to Kava Kava Extract-induced Retinal Degeneration in F344/N Rats

There was a significant increase in the incidence of retinal degeneration in F344/N rats chronically exposed to Kava kava extract (KKE) in National Toxicology Program (NTP) bioassay. A retrospective evaluation of these rat retinas indicated a similar spatial and morphological alteration as seen in light-induced retinal degeneration in albino rats. Therefore, it was hypothesized that KKE has a potential to exacerbate the light-induced retinal degeneration. To investigate the early mechanism of retinal degeneration, we conducted a 90-day F344/N rat KKE gavage study at doses of 0 and 1.0 g/kg (dose which induced retinal degeneration in the 2-year NTP rat KKE bioassay). The morphological evaluation indicated reduced number of phagosomes in the retinal pigment epithelium (RPE) of the superior retina. Transcriptomic alterations related to retinal epithelial homeostasis and melatoninergic signaling were observed in microarray analysis. Phagocytosis of photoreceptor outer segment by the underlying RPE is essential to maintain the homeostasis of the photoreceptor layer and is regulated by melatonin signaling. Therefore, reduced photoreceptor outer segment disc shedding and subsequent lower number of phagosomes in the RPE and alterations in the melatonin pathway may have contributed to the increased incidences of retinal degeneration observed in F344/N rats in the 2-year KKE bioassay.

The Pharmacology, Pharmacokinetics, Efficacy, and Adverse Events Associated With Kava

Kava is a plant with numerous kavapyrones that can induce pharmacologic effects and drug interactions through the cytochrome P450 and P-glycoprotein systems. Kava is used recreationally and for the treatment of anxiety. Clinical trials verify anxiolytic effects in excess of placebo, but the effects are not seen immediately and the optimal dose and dosing schedule needs to be determined. Clinical trials usually lasting for 4 weeks found generally good tolerability and safety; however, dermatologic, hepatologic, and cognitive adverse effects may occur. Some of these adverse effects are known to occur from the kavapyrones themselves, while others can be caused or exacerbated by use of substandard kava products. There is tremendous variability in the constitution of a kava product based on the parts of the plant that are being extracted and the extraction method. The most commonly studied extract for the treatment of anxiety is the acetone extract.

Is driving under the influence of kava associated with motor vehicle crashes? A systematic review of the epidemiological literature

OBJECTIVE

Kava is marketed as a herbal anxiolytic in several countries and is consumed recreationally in high doses in many indigenous Pacific and Australian Aboriginal communities. We reviewed the published literature examining the association (if any) between kava use and motor vehicle crashes (MVCs), MVC-related injuries or driving performance.

METHODS

Search of MEDLINE, EMBASE, PsycINFO, CINAHL, Scopus, AMED, Australian Medical Index, Australian Transport Index and trials registries and injury journals up to August 2014.

RESULTS

No studies quantifying the effects of kava on MVCs or related injury were located. Four experimental studies using computer-based driving simulation examined the effects of pharmacological doses of kavalactones on cognitive and visuomotor performance. While no statistically significant adverse changes attributable to kava were found, there was weak evidence of slowed reaction time. One study found the visuo-motor performance on driving simulation to be significantly impaired when kava was consumed with alcohol.

CONCLUSIONS

With equivocal evidence limited to experimental studies using simulated driving settings, the contribution of kava to MVCs is unknown.

IMPLICATIONS

The gap in knowledge regarding the potential risk of injuries associated with therapeutic and recreational use of kava requires priority attention.

Adverse drug reactions in special populations - the elderly

The International Conference on Harmonization considers older people a 'special population', as they differ from younger adults in terms of comorbidity, polypharmacy, pharmacokinetics and greater vulnerability to adverse drug reactions (ADRs). Medical practice is often based on single disease guidelines derived from clinical trials that have not included frail older people or those with multiple morbidities. This presents a challenge caring for older people, as drug doses in trials may not be achievable in real world patients and risks of ADRs are underestimated in clinical trial populations. The majority of ADRs in older people are Type A, potentially avoidable and associated with commonly prescribed medications. Several ADRs are particularly associated with major adverse consequences in the elderly and their reduction is therefore a clinical priority. Falls are strongly associated with benzodiazepines, neuroleptics, antidepressants and antihypertensives. There is good evidence for medication review as part of a multifactorial intervention to reduce falls risk in community dwelling elderly. Multiple medications also contribute to delirium, another multifactorial syndrome resulting in excess mortality particularly in frail older people. Clostridium difficile associated with use of broad spectrum antibiotics mainly affects frail older people and results in prolonged hospital stay with substantial morbidity and mortality. Antipsychotics increase the risk of stroke by more than three-fold in patients with dementia. Inappropriate prescribing can be reduced by adherence to prescribing guidelines, suitable monitoring and regular medication review. Given the heterogeneity within the older population, providing individualized care is pivotal to preventing ADRs.

Fatal kavalactone intoxication by suicidal intravenous injection

Kavalactones are a group of compounds found in kava, a beverage or extract prepared from the rhizome of the kava plant (Piper methysticum). Traditionally kava extracts have been used for their anxiolytic and sedative properties. Sales of kava extracts were severely restricted or prohibited in European countries in 2002 following several cases of serious hepatotoxicity. Here we report a case where high concentrations of kavalactones and ethanol were detected in post mortem femoral blood. An injection needle with a 10-mL syringe containing 7.5 mL of slightly yellowish liquid was found next to the victim, and there were numerous needle prints on both lower arms following the venous tracks. No evidence of other cause of death was found in the medico-legal investigation. The case was therefore classified as suicide using an injection of kavalactones intravenously together with alcohol poisoning.

Herbs and liver injury: a clinical perspective

Despite a perception that herbal and dietary supplements are safe, devastating liver injury has been reported to result from their use. The difficulty in characterizing liver injury attributable to herbal and dietary supplements stems from the permissive regulatory environment, the complexity of marketed products, and underreporting by the patients who use them. Despite these limitations, researchers, clinicians, and regulators have increasing awareness of the need for study in this area.

Herb-drug interactions: an overview of systematic reviews

OBJECTIVES

The aim of this overview of systematic reviews (SRs) is to evaluate critically the evidence regarding interactions between herbal medicinal products (HMPs) and synthetic drugs.

METHODS

Four electronic databases were searched to identify relevant SRs.

RESULTS

Forty-six SRs of 46 different HMPs met our inclusion criteria. The vast majority of SRs were of poor methodological quality. The majority of these HMPs were not associated with severe herb-drug interactions. Serious herb-drug interactions were noted for Hypericum perforatum and Viscum album. The most severe interactions resulted in transplant rejection, delayed emergence from anaesthesia, cardiovascular collapse, renal and liver toxicity, cardiotoxicity, bradycardia, hypovolaemic shock, inflammatory reactions with organ fibrosis and death. Moderately severe interactions were noted for Ginkgo biloba, Panax ginseng, Piper methysticum, Serenoa repens and Camellia sinensis. The most commonly interacting drugs were antiplatelet agents and anticoagulants.

CONCLUSION

The majority of the HMPs evaluated in SRs were not associated with drug interactions with serious consequences. However, the poor quality and the scarcity of the primary data prevent firm conclusions.

Adverse effects of herbal medicines: an overview of systematic reviews

This overview of systematic reviews (SRs) aims to evaluate critically the evidence regarding the adverse effects of herbal medicines (HMs). Five electronic databases were searched to identify all relevant SRs, with 50 SRs of 50 different HMs meeting our inclusion criteria. Most had only minor weaknesses in methods. Serious adverse effects were noted only for four HMs: Herbae pulvis standardisatus, Larrea tridentate, Piper methysticum and Cassia senna. The most severe adverse effects were liver or kidney damage, colon perforation, carcinoma, coma and death. Moderately severe adverse effects were noted for 15 HMs: Pelargonium sidoides, Perna canaliculus, Aloe vera, Mentha piperita, Medicago sativa, Cimicifuga racemosa, Caulophyllum thalictroides, Serenoa repens, Taraxacum officinale, Camellia sinensis, Commifora mukul, Hoodia gordonii, Viscum album, Trifolium pratense and Stevia rebaudiana. Minor adverse effects were noted for 31 HMs: Thymus vulgaris, Lavandula angustifolia Miller, Boswellia serrata, Calendula officinalis, Harpagophytum procumbens, Panax ginseng, Vitex agnus-castus, Crataegus spp., Cinnamomum spp., Petasites hybridus, Agave americana, Hypericum perforatum, Echinacea spp., Silybum marianum, Capsicum spp., Genus phyllanthus, Ginkgo biloba, Valeriana officinalis, Hippocastanaceae, Melissa officinalis, Trigonella foenum-graecum, Lagerstroemia speciosa, Cnicus benedictus, Salvia hispanica, Vaccinium myrtillus, Mentha spicata, Rosmarinus officinalis, Crocus sativus, Gymnema sylvestre, Morinda citrifolia and Curcuma longa. Most of the HMs evaluated in SRs were associated with only moderately severe or minor adverse effects.

Are mould hepatotoxins responsible for kava hepatotoxicity?

Previous studies with kava components such as kavalactones, pipermethystine and flavokavain B have demonstrated hepatotoxicity from these constituents. Regardless, there has recently been speculation that adulterants or impurities such as the mould hepatotoxin aflatoxin are a more likely cause of kava hepatotoxicity, despite a paucity of supporting evidence. Although there is limited similarity between acute kava hepatotoxicity and acute aflatoxicosis, and background levels of aflatoxin have been detected in kava samples, unless epidemiological investigations can uncover direct evidence implicating mould hepatotoxins, it remains more likely that chemical constituents of kava are the cause of the hepatotoxicity from kava.

Complementary medicine and safety: a systematic investigation of design and reporting of systematic reviews

OBJECTIVES

The objective of this study was to examine the methods used in systematic reviews of safety across a range of complementary therapies to assess the variation in approach and the potential for developing guidance on conduct and reporting.

DESIGN

Systematic reviews focusing on safety were retrieved from NHS Evidence and searches of major databases. A pre-prepared template was used for data extraction. Information extracted included details of search strategies, sources, participants, interventions, reported adverse event/effect(s) and causality assessment. Data extraction was carried out by one researcher and a check for accuracy by a second researcher. Methods were assessed against criteria based on guidance provided by the Cochrane Adverse Effects Methods Group.

RESULTS

A total of 2563 citations were screened and 88 systematic reviews were selected for inclusion. The majority focused on the safety of herbs and nutritional supplements. Approximately half the reviews covered all aspects of safety; other reviews addressed specific adverse effects or interactions. Types of data included in the reviews did not always reflect the focus of the review. Search strategies, sources used, quality assessment and assessment of causality also varied.

CONCLUSIONS

Detailed examination and comparison of the methods has highlighted several areas in which there is potential for development of guidelines and consensus on standards. These include search strategies, sources of information, data extraction and assessment of causality. The value of systematic reviews in relation to large outcome studies requires further consideration.

Proposal for a kava quality standardization code

Rare cases of hepatotoxicity emerged with the use of kava drugs and dietary supplements prepared from rhizomes and roots of the South Pacific plant kava (Piper methysticum). Their psychoactive, anxiolytic, relaxing, and recreational ingredients are the kavalactones kavain, dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin, but there is little evidence that these kavalactones or the non-kavalactones pipermethystine and flavokavain B are the culprits of the adverse hepatic reactions. It rather appears that poor quality of the kava material was responsible for the liver toxicity. Analysis of existing kava quality standardizations with focus on chemical, agricultural, manufacturing, nutritional, regulatory, and legislation backgrounds showed major shortcomings that could easily explain quality problems. We therefore suggest a uniform, internationally accepted device for kava quality standardizations that are in the interest of the consumers because of safety reasons and will meet the expectations of kava farmers, pharmaceutical manufacturers, regulators of agencies, and legislators. The initial step resides in the establishment of Pan-Pacific kava quality legislation as an important part of the proposed Kava Quality Standardization Code. In conclusion, a sophisticated approach to establish kava quality standardizations is needed for safe human use of kava as relaxing traditional beverages, the anxiolytic drugs, and recreational dietary supplements.

Toxicokinetics of kava

Kava is traditionally consumed by South Pacific islanders as a drink and became popular in Western society as a supplement for anxiety and insomnia. Kava extracts are generally well tolerated, but reports of hepatotoxicity necessitated an international reappraisal of its safety. Hepatotoxicity can occur as an acute, severe form or a chronic, mild form. Inflammation appears to be involved in both forms and may result from activation of liver macrophages (Kupffer cells), either directly or via kava metabolites. Pharmacogenomics may influence the severity of this inflammatory response.

Kava hepatotoxicity: pathogenetic aspects and prospective considerations

Kava hepatotoxicity is a well-defined herb-induced liver injury, caused by the use of commercial anxyolytic ethanolic and acetonic kava extracts, and of traditional recreational aqueous kava extracts. The aim of this review is to elucidate possible pathogenetic factors for the development of kava-induced liver injury, considering also confounding variables. In patients with liver disease in a causal relation to kava ± comedication, confounding factors include non-adherence to therapy recommendations and comedication consisting of synthetic and herbal drugs and dietary supplements including herbal ones and herbs-kava mixtures. Various possible pathogenetic factors have to be discussed and comprise metabolic interactions with exogenous compounds at the hepatic microsomal cytochrome P450 level; genetic enzyme deficiencies; toxic constituents and metabolites derived from the kava extract including impurities and adulterations; cyclooxygenase inhibition; P-glycoprotein alterations; hepatic glutathione depletion; solvents and solubilizers of the extracts; and kava raw material of poor quality. In particular, inappropriate kava plant parts and unsuitable kava cultivars may have been used sometimes for manufacturing the kava extracts instead of the rhizome of a noble cultivar of the kava plant (Piper methysticum G. Forster). In conclusion, kava hepatotoxicity occurred independently of the extraction medium used for the kava extracts and may primarily be attributed to daily overdose, prolonged treatment and to a few kava extract batches of poor quality; by improving kava quality and adherence to therapy recommendation under avoidance of comedication, liver injury by kava should be a preventable disease, at least to a major extent.

Role of ethanol in kava hepatotoxicity

Kava is known for its recreational, ceremonial and medicinal use in the Pacific. The aqueous non-alcoholic drink of kava rhizome produces intoxicating, relaxing and soothing effects. While kava's medicinal effects receive worldwide recognition, kava-containing products came under scrutiny after over 100 reports of spontaneous adverse hepatic effects. Many mechanisms have been postulated to explain the unexpected toxicity, one being pharmacokinetic interactions between kavalactones and co-administered drugs involving cytochrome P450 enzyme system. Alcohol is often co-injested in kava hepatotoxicity cases. This review evaluates the possible hepatotoxicity mechanisms involving alcohol and kava.

Potential medicinal plants for CNS disorders: an overview

Although very few drugs are currently approved by regulatory authorities for treating multi-factorial ailments and disorders of cognition such as Alzheimer's disease, certain plant-derived agents, including, for example, galantamine and rivastigmine (a semi-synthetic derivative of physostigmine) are finding an application in modern medicine. However, in Ayurveda, the Indian traditional system of medicine which is more than 5000 years old, selected plants have long been classified as 'medhya rasayanas', from the Sanskrit words 'medhya', meaning intellect or cognition, and 'rasayana', meaning 'rejuvenation'. These plants are used both in herbal and conventional medicine and offer benefits that pharmaceutical drugs lack. In the present article, an attempt has been made to review the most important medicinal plants, including Ginkgo biloba, St John's wort, Kava-kava, Valerian, Bacopa monniera and Convolvulus pluricaulis, which are widely used for their reputed effectiveness in CNS disorders.

Herbal hepatotoxicity

There is appropriate concern about the potential risk for hepatotoxicity from herbal products because they are unregulated and therefore not standardized with regard to their contents. This is particularly the case for the crude herbals that are commonly formulated as a mixture, so that their ingredients may be ambiguous and even contain harmful contaminants. Presented here is an overview of the more commonly recognized herbal products that have been reported to be associated with liver injury. Although many of them are clearly implicated, there are some, particularly those identified solely through an occasional case report, for which the relationship is uncertain.

Traditional kava beverage consumption and liver function tests in a predominantly Tongan population in Hawaii

PURPOSE

To determine the effects of traditionally prepared kava beverages on the liver function tests of regular kava beverage consumers in a population of Tongan and non-Tongan residents of Hawaii (Oahu).

METHODS

The liver function tests of 31 healthy adult kava drinkers were compared against a control group of 31 healthy adult non-kava drinkers. Subjects were recruited from the general population, a kava bar, and Tongan kava drinking circles. The liver function profile included AST, ALT, ALP, GGT, and bilirubin (total and direct). Other tests included total protein, albumin, and screens for viral hepatitis and hemochromatosis when indicated.

RESULTS

Chronic kava beverage consumption was associated with elevation of GGT in 65% of the kava drinkers versus 26% in the controls (P = .005). ALP was elevated in 23% of kava drinkers versus 3% in the controls (P = .053).

CONCLUSION

Heavy kava beverage consumption was associated with significantly elevated GGT levels.

Botanical and dietary supplements for mood and anxiety in menopausal women

OBJECTIVE

This paper reviews the commonly used botanicals for treatment of mood and anxiety disorders in perimenopausal and postmenopausal women and presents information on their safety and efficacy.

DESIGN

The MEDLINE and EMBASE databases were searched for clinical trials related to the use of botanicals for depression, anxiety, and mood disturbances. Papers were excluded if they were in a language other than English, did not include midlife women as study participants, or did not report on changes in mood, depression, or anxiety.

RESULTS

Five of seven trials of St. John's wort for mild to moderate depression showed a significant improvement. The one randomized, controlled trial of ginseng in postmenopausal women reported improvements in mood and anxiety. All three randomized, controlled trials of ginkgo found no effect on depression. In four of eight controlled trials, kava significantly reduced anxiety. Black cohosh significantly reduced depression and anxiety in all studies reviewed.

CONCLUSIONS

St. John's wort and black cohosh appear to be the most useful in alleviating mood and anxiety changes during menopause. Ginseng may be effective, but more research needs to be done. Kava holds promise for decreasing anxiety in peri- and postmenopausal women; however, women should be careful in the amount and duration of use. Finally, ginkgo and valerian do not appear to be useful in reducing depression or anxiety in this population.

Supplementation With Goldenseal (Hydrastis canadensis), but not Kava Kava (Piper methysticum), Inhibits Human CYP3A Activity In Vivo

The effects of goldenseal (Hydrastis canadensis) and kava kava (Piper methysticum) supplementation on human CYP3A activity were evaluated using midazolam (MDZ) as a phenotypic probe. Sixteen healthy volunteers were randomly assigned to receive either goldenseal or kava kava for 14 days. Each supplementation phase was followed by a 30-day washout period. MDZ (8 mg, per os) was administered before and after each phase, and pharmacokinetic parameters were determined using standard non-compartmental methods. Comparisons of pre- and post-supplementation MDZ pharmacokinetic parameters revealed significant inhibition of CYP3A by goldenseal (AUC(0-infinity), 107.9+/-43.3 vs 175.3+/-74.8 ng x h/ml; Cl/F/kg, 1.26+/-0.59 vs 0.81+/-0.45 l/h/kg; T(1/2), 2.01+/-0.42 vs 3.15+/-1.12 h; Cmax, 50.6+/-26.9 vs 71.2+/-50.5 ng/ml). MDZ disposition was not affected by kava kava supplementation. These findings suggest that significant herb-drug interactions may result from the concomitant ingestion of goldenseal and CYP3A substrates.

Immunohistochemical analysis of expressions of hepatic cytochrome P450 in F344 rats following oral treatment with kava extract

Kava (Piper methysticum), used for relaxation and pain relief, has been one of the leading dietary supplements and several reports linking hepatic functional disturbances and liver failure to kava have resulted in a ban on sales in Europe and Canada and the issuance of warnings by the US FDA. The National Toxicology Program conducted 14-week rat studies to characterize the toxicology of kava exposure in Fischer 344 rats [National Toxicity Program. 90 day gavage toxicity studies of KAVA KAVA EXTRACT in Fischer rats and B6C3F1 mice. Research Triangle Park, NC; 2005a; National Toxicity Program. Testing status of agents at NTP (KAVA KAVA EXTRACT M990058). Research Triangle Park, NC; 2005b. (http://ntp.niehs.nih.gov/index.cfm?objectid=071516E-C6E1-7AAA-C90C751E23D14C1B)]. Groups of 10 male and 10 female rats were administered kava extract by gavage at 0, 0.125, 0.25, 0.5, 1.0, and 2.0 g/kg/day. Increased gamma-glutamyl-transpeptidase (GGT) activities were observed in the 2.0 g/kg males and 1.0 and 2.0 g/kg females, as well as increased serum cholesterol levels in males and females at 0.5 g/kg and higher. Increases in incidence and severity of hepatocellular hypertrophy (HP) were noted in males at 1.0 g/kg and females at 0.5 g/kg and higher, as well as increased liver weights. Immunohistochemical analyses of the expression of cytochrome-P450 (CYP) enzymes in liver of the control and 1.0- and 2.0-g/kg-treated groups indicated decreased expression of CYP2D1 (human CYP2D6 homolog) in 2.0 g/kg females and increased expression of CYP1A2, 2B1, and 3A1 in 1.0 and 2.0 g/kg groups of both sexes. The no observed adverse effect levels were decided as 0.25 g/kg in both genders, based on neurotoxic effects, increases in GGT, cholesterol, liver weight, and HP and decreases in body weight. Kava-induced hepatic functional changes in the F344 rat might be relevant to human clinical cases of hepatotoxicity following exposure.

Effect of goldenseal (Hydrastis canadensis) and kava kava (Piper methysticum) supplementation on digoxin pharmacokinetics in humans

Phytochemical-mediated modulation of P-glycoprotein (P-gp) and other drug transporters may give rise to many herb-drug interactions. Serial plasma concentration-time profiles of the P-gp substrate, digoxin, were used to determine whether supplementation with goldenseal or kava kava modified P-gp activity in vivo. Twenty healthy volunteers were randomly assigned to receive a standardized goldenseal (3210 mg daily) or kava kava (1227 mg daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (600 mg daily, 7 days) and clarithromycin (1000 mg daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin, 0.5 mg) was administered p.o. before and at the end of each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), C(max,) CL/F, and elimination half-life were used to assess the effects of goldenseal, kava kava, rifampin, and clarithromycin on digoxin pharmacokinetics. Rifampin produced significant reductions (p < 0.01) in AUC((0-3)), AUC((0-24)), CL/F, t(1/2), and C(max), whereas clarithromycin increased these parameters significantly (p < 0.01). With the exception of goldenseal's effect on C(max) (14% increase), no statistically significant effects on digoxin pharmacokinetics were observed following supplementation with either goldenseal or kava kava. When compared with rifampin and clarithromycin, supplementation with these specific formulations of goldenseal or kava kava did not appear to affect digoxin pharmacokinetics, suggesting that these supplements are not potent modulators of P-gp in vivo.