A systematic review of the safety of kava extract in the treatment of anxiety

Neuroimaging Insights: Kava's (Piper methysticum) Effect on Dorsal Anterior Cingulate Cortex GABA in Generalized Anxiety Disorder

Generalised Anxiety Disorder (GAD) is a prevalent, chronic mental health disorder. The measurement of regional brain gamma-aminobutyric acid (GABA) offers insight into its role in anxiety and is a potential biomarker for treatment response. Research literature suggests Piper methysticum (Kava) is efficacious as an anxiety treatment, but no study has assessed its effects on central GABA levels. This study investigated dorsal anterior cingulate (dACC) GABA levels in 37 adult participants with GAD. GABA was measured using proton magnetic resonance spectroscopy (1H-MRS) at baseline and following an eight-week administration of Kava (standardised to 120 mg kavalactones twice daily) (n = 20) or placebo (n = 17). This study was part of the Kava for the Treatment of GAD (KGAD; ClinicalTrials.gov: NCT02219880), a 16-week intervention study. Compared with the placebo group, the Kava group had a significant reduction in dACC GABA (p = 0.049) at eight weeks. Baseline anxiety scores on the HAM-A were positively correlated with GABA levels but were not significantly related to treatment. Central GABA reductions following Kava treatment may signal an inhibitory effect, which, if considered efficacious, suggests that GABA levels are modulated by Kava, independent of reported anxiety symptoms. dACC GABA patterns suggest a functional role of higher levels in clinical anxiety but warrants further research for symptom benefit. Findings suggest that dACC GABA levels previously un-examined in GAD could serve as a biomarker for diagnosis and treatment response.

Investigation of the role of herbal medicine, acupressure, and acupuncture in the menopausal symptoms: An evidence-based systematic review study

Background

Menopause is an important physiological phenomenon in women's lives. Women's concern about taking the hormone treatment to ease menopausal symptoms is increasing. Over the past decade, the use of complementary and alternative medicine for the treatment of menopausal problems instead of hormone therapy has increased.

Objective

This study aimed to investigate the role of herbal medicine, acupressure, and acupuncture in the menopausal symptoms.

Methods

Data source: related articles were searched from internal scientific databases and external databases of "Web of Scopus, Cochrane, PubMed, Science Direct, Ovid, and Google scholar."

Study Eligibility Criteria

The keywords such as menopause, menopausal symptoms, complementary menopausal medicine, acupuncture in menopause, herbal medicine in menopause, and acupuncture in menopause were searched in the studies from 1987 to 2019. Exclusion criteria were inadequate information in the study, lack of access to full-text articles, animal studies, and reports. At the end of the search, 145 articles out of a total of 400 articles were reviewed.

Results

In various studies, different herbs such as licorice, valerian, soy, sage, ginseng, etc., were used to improve menopausal symptoms. In addition, acupuncture and acupressure were used to reduce menopausal symptoms.

Conclusion

The efficacy and use of complementary and alternative medicine, along with other classical medicine care, can be a new model for improving menopausal symptoms in women. It is recommended that further clinical and review studies be conducted to develop complementary and alternative medicine.

Synthetic Kavalactone Analogues with Increased Potency and Selective Anthelmintic Activity against Larvae of Haemonchus contortus In Vitro

Kava extract, an aqueous rhizome emulsion of the plant Piper methysticum, has been used for centuries by Pacific Islanders as a ceremonial beverage, and has been sold as an anxiolytic agent for some decades. Kavalactones are a major constituent of kava extract. In a previous investigation, we had identified three kavalactones that inhibit larval development of Haemonchus contortus in an in vitro-bioassay. In the present study, we synthesized two kavalactones, desmethoxyyangonin and yangonin, as well as 17 analogues thereof, and evaluated their anthelmintic activities using the same bioassay as employed previously. Structure activity relationship (SAR) studies showed that a 4-substituent on the pendant aryl ring was required for activity. In particular, compounds with 4-trifluoromethoxy, 4-difluoromethoxy, 4-phenoxy, and 4-N-morpholine substitutions had anthelmintic activities (IC₅₀ values in the range of 1.9 to 8.9 µM) that were greater than either of the parent natural products-desmethoxyyangonin (IC₅₀ of 37.1 µM) and yangonin (IC₅₀ of 15.0 µM). The synthesized analogues did not exhibit toxicity on HepG2 human hepatoma cells in vitro at concentrations of up to 40 µM. These findings confirm the previously-identified kavalactone scaffold as a promising chemotype for new anthelmintics and provide a basis for a detailed SAR investigation focused on developing a novel anthelmintic agent.

Current Research on Complementary and Alternative Medicine (CAM) in the Treatment of Anxiety Disorders: An Evidence-Based Review

Complementary and alternative medicine (CAM) encompasses a wide range of different nonmainstream therapies that have been increasingly used for treatment or adjunctive treatment of various ailments with anxiety/anxiety disorders being one of the commonly CAM (self)-medicated conditions. Thousands of published papers refer to use of CAM in various psychiatric disorders or in healthy or medically ill patients with mood or anxiety difficulties. In this chapter we focus specifically on clinically diagnosed (in line with the standard criteria) anxiety disorders and overview evidence of efficacy/safety of a range of CAM modalities: biologically based therapies (typically herbal preparations and less so nutraceuticals); manipulative and body-based therapies (acupuncture, aerobic exercise, massage, therapeutic touch, repetitive transcranial magnetic stimulation, balneotherapy, and others); mind-body therapies (yoga, Morita therapy, Tai Chi, reiki, Chinese cognitive therapy, religious and spiritual interventions, relaxation, mediation, and mindfulness-based interventions); and alternative medical systems (Ayurveda, homeopathy). We focus exclusively on randomized controlled trials and attempt to evaluate the existing body of evidence in the same manner that is applied to mainstream treatments.

Liver transplantation and the use of KAVA: Case report

BACKGROUND

Self-medication and the belief that herbal products are free of health risks are common in Brazil. The kava (Piper methysticum), known for its anxiolytic action, has a widespread popular use. Hepatotoxicity of kava is reported, including cases of liver transplantation and death. The kava had its use prohibited or restricted in countries like Germany, France, among others. Toxicity may be related to overdosage; however, factors such as botanical characteristics of the plant, the harvesting, storage, and production process may be associated with the development of hepatotoxic substances, such as triggering idiosyncratic reactions.

HYPOTHESIS

In this case, there is a suspicion that the toxicide is intrinsic to the drug; however, the possibility of adulterants and contaminants must be ruled out.

STUDY DESIGN

This study reports the case of a patient who, after using the herbal kava for 52 days, evolved into acute liver failure and liver transplantation.

METHODS

The data were collected directly with the patient and compared with their clinical records. Causality was determined through the RUCAM algorithm. In addition, a phytochemical analysis of the drug used was performed.

RESULTS

According to the patient's report, there is no evidence of overdosage. Results from RUCAM algorithm infer causality between liver damage and the use of kava. The analysis chemical constituents did not find any possible contaminants and major changes in the active compounds. Seven months after transplantation, the patient is well and continues to be followed up by a medical team.

CONCLUSION

Our investigation indicates that there was kava-induced hepatotoxicity at standard dosages. In Brazil, self-medication by herbal medicines is frequent and many patients and health professionals do not know the risks associated with their use. Diagnosing and notifying cases in which plants and herbal medicine induce liver damage is of paramount importance to increase the knowledge about DILI and to prevent or treat similar cases quickly.

A stable isotope dilution tandem mass spectrometry method of major kavalactones and its applications

Kava is regaining its popularity with detailed characterizations warranted. We developed an ultraperformance liquid chromatography high-resolution tandem mass spectrometry (UPLC-MS/MS) method for major kavalactones (kavain, dihydrokavain, methysticin, dihydromethysticin and desmethoxyyangonin) with excellent selectivity and specificity. The method has been validated for different matrices following the Food and Drug Administration guidance of analytical procedures and methods validation. The scope of this method has been demonstrated by quantifying these kavalactones in two kava products, characterizing their tissue distribution and pharmacokinetics in mice, and detecting their presence in human urines and plasmas upon kava intake. As expected, the abundances of these kavalactones differed significantly in kava products. All of them exhibited a large volume of distribution with extensive tissue affinity and adequate mean residence time (MRT) in mice. This method also successfully quantified these kavalactones in human body fluids upon kava consumption at the recommended human dose. This UPLC-MS/MS method therefore can be used to characterize kava products and its pharmacokinetics in animals and in humans.

Chemical Composition and Acetylcholinesterase Inhibitory Activity of Essential Oils from Piper Species

The essential oils (EOs) derived from aromatic plants such as Piper species are considered to play a role in alleviating neuronal ailments that are associated with inhibition of acetylcholinesterase (AChE). The chemical compositions of 23 EOs prepared from 16 Piper spp. were analyzed by both gas chromatography with a flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). A total of 76 compounds were identified in the EOs from the leaves and stems of 19 samples, while 30 compounds were detected in the EOs from the fruits of four samples. Sesquiterpenes and phenylpropanoids were found to be rich in these EOs, of which asaricin, caryophyllene, caryophyllene oxide, isospathulenol, (+)-spathulenol, and β-bisabolene are the major constituents. The EOs from the leaves and stems of Piper austrosinense, P. puberulum, P. flaviflorum, P. betle, and P. hispidimervium showed strong AChE inhibitory activity with IC₅₀ values in the range of 1.51 to 13.9 mg/mL. A thin-layer chromatography (TLC) bioautography assay was employed to identify active compound(s) in the most active EO from P. hispidimervium. The active compound was isolated and identified as asaricin, which gave an IC₅₀ value of 0.44 ± 0.02 mg/mL against AChE, comparable to galantamine with an IC₅₀ 0.15 ± 0.01 mg/mL.

Poisonous or non-poisonous plants? DNA-based tools and applications for accurate identification

Plant exposures are among the most frequently reported cases to poison control centres worldwide. This is a growing condition due to recent societal trends oriented towards the consumption of wild plants as food, cosmetics, or medicine. At least three general causes of plant poisoning can be identified: plant misidentification, introduction of new plant-based supplements and medicines with no controls about their safety, and the lack of regulation for the trading of herbal and phytochemical products. Moreover, an efficient screening for the occurrence of plants poisonous to humans is also desirable at the different stages of the food supply chain: from the raw material to the final transformed product. A rapid diagnosis of intoxication cases is necessary in order to provide the most reliable treatment. However, a precise taxonomic characterization of the ingested species is often challenging. In this review, we provide an overview of the emerging DNA-based tools and technologies to address the issue of poisonous plant identification. Specifically, classic DNA barcoding and its applications using High Resolution Melting (Bar-HRM) ensure high universality and rapid response respectively, whereas High Throughput Sequencing techniques (HTS) provide a complete characterization of plant residues in complex matrices. The pros and cons of each approach have been evaluated with the final aim of proposing a general user's guide to molecular identification directed to different stakeholder categories interested in the diagnostics of poisonous plants.

A Survey of the Chemical Compounds of Piper spp. (Piperaceae) and Their Biological Activities

The genus Piper is one of the largest genera in the Piperaceae, with most species widely distributed globally, covering all continents. To date, many Piper species have been scientifically investigated for their chemical diversities and interesting broad spectrum of bioactivities, including central nervous system (CNS), pesticidal, antifungal and antibacterial effects. This review systematically summarizes the scaffolds of the alkaloids reported, the major chemicals isolated from Piper spp., and their biological activities. Besides the alkaloids, some neolignans with rearranged skeletons show structural diversities, while the chalcones, flavonoids and kava-pyrones have some potential activities. Herein, the sesquiterpenes and phenolic compounds from Piper species and their bioactivities are also surveyed.

Detection of flavokavins (A, B, C) in cultivars of kava (Piper methysticum) using high performance thin layer chromatography (HPTLC)

Kava (Piper methysticum) is used to prepare the traditional beverage of the Pacific islands. In Europe, kava has been suspected to cause hepatoxicity with flavokavin B (FKB) considered as a possible factor. The present study describes an HPTLC protocol for rapid screening of samples. The objectives are: to detect the presence of flavokavins in extracts and to compare the FKB levels in different cultivars. Overall, 172 samples originating from four cultivars groups (noble, medicinal, two-days and wichmannii), were analysed. Results indicate that the ratio FKB/kavalactones is much higher in two-days (0.39) and wichmannii (0.32) compared to nobles (0.09) and medicinal cultivars (0.10). For each group, the ratios flavokavins/kavalactones do not change significantly between roots, stumps or basal stems and among clones, indicating that they are genetically controlled. This protocol has good accuracy and is cost efficient for routine analysis. We discuss how it could be used for quality control.

Liver injury induced by herbal complementary and alternative medicine

Herbal and dietary supplement use is common. Most marketed products consist of complex mixtures. Although they are perceived as safe, instances of hepatotoxicity attributable to these products underscore their potential for injury, but the exact component that is responsible for injury is difficult to discern. The lenient regulatory environment in the United States, which opens the possibility of adulteration and contamination, adds to the challenge of disease attribution. Although many different herbal and dietary supplements have been reported to cause liver injury, in the United States, products used for bodybuilding and weight loss are the most commonly implicated.

Reduction in colon cancer risk by consumption of kava or kava fractions in carcinogen-treated rats

Epidemiological studies suggest that kava reduces colon cancer risk. However, no experimental studies of the chemopreventive properties of kava toward colon cancer have been reported. Further, there are concerns regarding hepatotoxicity of kava. The goal of this study was to determine whether kava consumption reduces markers of colon cancer in an animal model and to study the safety of kava. An ethanolic extract and polar and nonpolar fractions of the kava extract were fed to rats for 12 days prior to, during, and after administration of dimethylhydrazine, a colon-specific carcinogen. After 14 wk, rats fed the nonpolar extract had a significant reduction in precancerous lesions [aberrant crypt (AC) foci (ACF)] as well as large (≥ 4 AC/ACF) sialomucin-only expressing foci, an indicator of greater tumorigenic potential, compared to the control group. Groups fed the ethanolic extract and polar kava fraction trended toward reductions in ACF and large sialomucin-only expressing foci. The combined kava groups had significantly fewer total AC, ACF, large ACF, and large sialomucin-only expressing foci compared to the control group. Histological examination found no hepatic lesions in animals consuming the kava diets, suggesting that kava is safe to consume. Our results support that kava may reduce colon cancer risk.

Kavalactones and the endocannabinoid system: the plant-derived yangonin is a novel CB₁ receptor ligand

To investigate the possible interactions between kavalactone-based molecules and proteins of the endocannabinoid system and provide novel and synthetically accessible structural scaffolds for the design of cannabinoid receptor ligands sharing pharmacological properties with kavapyrones, a preliminary SAR analysis was performed on five commercially available natural kavalactones and nine kavalactone-analogues properly synthesized. These compounds were investigated for assessing their cannabinoid receptor binding affinity and capability of inhibiting the activity of the two major metabolic enzymes of the endocannabinoid system, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Among the molecules tested, only yangonin exhibited affinity for the human recombinant CB₁ receptor with a K(i)=0.72 μM and selectivity vs. the CB₂ receptor (K(i)>10 μM). None of the compounds exhibited strong inhibitory effects on the two enzymes analyzed. The CB₁ receptor affinity of yangonin suggests that the endocannabinoid system might contribute to the complex human psychopharmacology of the traditional kava drink and the anxiolytic preparations obtained from the kava plant.

Herbal remedies, mood, and cognition

Herbal medicines were the "sole" source of medicine for thousands of years, in every culture since the advent of human civilization. Today, patients are increasing the use of these botanicals for numerous conditions, such as mood and cognition. This article will explore commonly used herbal remedies for mood and cognition functioning. It is imperative that nurses and nurse practitioners obtain expertise with these botanicals with regard to efficacy, adverse effects and contraindications, possible drug interactions, and safety considerations.

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.

Constituents in kava extracts potentially involved in hepatotoxicity: a review

Aqueous kava root preparations have been consumed in the South Pacific as an apparently safe ceremonial and cultural drink for centuries. However, several reports of hepatotoxicity have been linked to the consumption of kava extracts in Western countries, where mainly ethanolic or acetonic extracts are used. The mechanism of toxicity has not been established, although several theories have been put forward. The composition of the major constituents, the kava lactones, varies according to preparation method and species of kava plant, and thus, the toxicity of the individual lactones has been tested in order to establish whether a single lactone or a certain composition of lactones may be responsible for the increased prevalence of kava-induced hepatotoxicity in Western countries. However, no such conclusion has been made on the basis of current data. Inhibition or induction of the major metabolizing enzymes, which might result in drug interactions, has also gained attention, but ambiguous results have been reported. On the basis of the chemical structures of kava constituents, the formation of reactive metabolites has also been suggested as an explanation of toxicity. Furthermore, skin rash is a side effect in kava consumers, which may be indicative of the formation of reactive metabolites and covalent binding to skin proteins leading to immune-mediated responses. Reactive metabolites of kava lactones have been identified in vitro as glutathione (GSH) conjugates and in vivo as mercapturates excreted in urine. Addition of GSH to kava extracts has been shown to reduce cytotoxicity in vitro, which suggests the presence of inherently reactive constituents. Only a few studies have investigated the toxicity of the minor constituents present in kava extract, such as pipermethystine and the flavokavains, where some have been shown to display higher in vitro cytotoxicity than the lactones. To date, there remains no indisputable reason for the increased prevalence of kava-induced hepatotoxicity in Western countries.

Neurocognitive effects of kava (Piper methysticum): a systematic review

RATIONALE

Kava (Piper methysticum) elicits dose-dependent psychotropic effects and thus may potentially deleteriously affect cognitive performance. Clinical trials have assessed the effects of kava on cognition, however, to our knowledge no systematic review has been conducted in this area.

OBJECTIVE

To systematically review the effects of kava on cognition, providing an analysis of the individual study's methodological quality, results and effect sizes.

METHODS

A systematic review was conducted of publications up to June 15th 2010, using the electronic databases MEDLINE, PsychINFO, CINAHL, Web of Science and The Cochrane Library. The search criteria involved kava and cognition related terms, e.g. memory and attention.

RESULTS

Ten human clinical trials met inclusion criteria (acute n = 7, chronic n = 3). One acute study found that kava significantly improved visual attention and working memory processes while another found that kava increased body sway. One chronic study found that kava significantly impaired visual attention during high-cognitive demand. Potential enhanced cognition may be attributed to the ability of kava to inhibit re-uptake of noradrenaline in the pre-frontal cortex, while increased body sway may be due to GABA pathway modulation.

CONCLUSIONS

The majority of evidence suggests that kava has no replicated significant negative effects on cognition.

Kava hepatotoxicity: comparative study of two structured quantitative methods for causality assessment

BACKGROUND AND OBJECTIVE

Ingestion of the medicinal herb kava has been associated with hepatotoxicity. We aimed to compare two different quantitative methods of causality assessment of patients with assumed hepatotoxicity by the herb.

METHODS

We assessed causality in 26 patients from Germany and Switzerland, using two structured quantitative analytical methods: the system of Maria and Victorino (MV) and that of the Council for International Organizations of Medical Sciences (CIOMS). In all 26 patients, regulatory ad hoc evaluation had suggested a causal relationship between liver disease and kava use.

RESULTS AND DISCUSSION

Assessment with the MV scale resulted in no or low graded causality for kava in the 26 patients with liver disease. Causality was probable (n=1), possible (n=2), unlikely (n=7), and excluded (n=16). Causality for kava was more evident with the CIOMS scale: highly probable (n=1), probable (n=2), possible (n=6), unlikely (n=2) and excluded (n=15). However, the results of both quantitative causality assessments are not supportive for most of the regulatory ad hoc causality assessments of the 26 patients.

CONCLUSION

Grades of causality for suspected hepatotoxicity by kava were much lower when evaluated by structured quantitative causality assessment scales than by regulatory ad hoc judgements. The quantitative CIOMS scale is the preferable tool for causality assessment of spontaneous reports of hepatotoxcity involving kava.

Herbal medicines in pediatric neuropsychiatry

An increasing number of studies have evaluated the role of herbal supplements in pediatric disorders, but they have numerous limitations. This review provides an overview of herbal components, regulation of supplements, and importance of product quality assurance. Use of herbal supplements is discussed with reference to factors that influence use in the pediatric population. The remainder of the article discusses the use of St John's wort, melatonin, kava, valerian, eicosapentaenoic acid, and docosahexaenoic acid, focusing on indications, adverse effects, and drug interactions, and providing a limited efficacy review. Herbal supplements used for weight loss are also briefly discussed.

Kava: a comprehensive review of efficacy, safety, and psychopharmacology

OVERVIEW

Kava (Piper methysticum) is a South Pacific psychotropic plant medicine that has anxiolytic activity. This effect is achieved from modulation of GABA activity via alteration of lipid membrane structure and sodium channel function, monoamine oxidase B inhibition, and noradrenaline and dopamine re-uptake inhibition. Kava is available over the counter in jurisdictions such as the USA, Australia and New Zealand. Due to this, a review of efficacy, safety and clinical recommendations is advised.

OBJECTIVE

To conduct a comprehensive review of kava, in respect to efficacy, psychopharmacology, and safety, and to provide clinical recommendations for use in psychiatry to treat generalized anxiety disorder (GAD).

METHODS

A review was conducted using the electronic databases MEDLINE, CINAHL, PsycINFO and the Cochrane Library during mid 2010 of search terms relating to kava and GAD. A subsequent forward search was conducted of key papers using Web of Science cited reference search.

RESULTS

The current weight of evidence supports the use of kava in treatment of anxiety with a significant result occurring in four out of six studies reviewed (mean Cohen's d = 1.1). Safety issues should however be considered. Use of traditional water soluble extracts of the rhizome (root) of appropriate kava cultivars is advised, in addition to avoidance of use with alcohol and caution with other psychotropic medications. Avoidance of high doses if driving or operating heavy machinery should be mandatory. For regular users routine liver function tests are advised.

CONCLUSIONS

While current evidence supports kava for generalized anxiety, more studies are required to assess comparative efficacy and safety (on the liver, cognition, driving, and sexual effects) versus established pharmaceutical comparators.

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.

Kava hepatotoxicity: regulatory data selection and causality assessment

BACKGROUND

Kava hepatotoxicity in 20 patients from Germany has been debated worldwide following a regulatory ad hoc causality assessment and ban of kava, an anxiolytic herbal remedy obtained from the rhizome of Piper methysticum Forster.

AIMS

We assessed causality with a quantitative structured causality analysis in all 20 cases of patients with liver disease, presented by the German regulatory agency that assumed a causal relationship with the use of kava extracts.

METHODS

The quantitative scale of CIOMS (Council for International Organizations of Medical Sciences) in its updated form was employed for causality assessment and quality evaluation of the regulatory data presentation.

RESULTS

The regulatory information is scattered and selective, and items essential for causality assessment, such as exclusion of kava independent causes, were not, or only marginally, considered by the regulator. Quantitative causality assessment for kava was possible (n=2), unlikely (n=12), or excluded (n=6), showing no concordance with the regulatory ad hoc causality evaluation.

CONCLUSION

The regulatory data regarding kava hepatotoxicity is selective and of low quality, not supportive of the regulatory proposed causality; but instead, is an explanation of the overall causality discussions of kava hepatotoxicity. We are proposing that the regulatory agency reports data in full length and reevaluates causality.

Kava and St. John's Wort: current evidence for use in mood and anxiety disorders

BACKGROUND

Mood and anxiety disorders pose significant health burdens on the community. Kava and St. John's wort (SJW) are the most commonly used herbal medicines in the treatment of anxiety and depressive disorders, respectively.

OBJECTIVES

The objective of this study was to conduct a comprehensive review of kava and SJW, to review any evidence of efficacy, mode of action, pharmacokinetics, safety and use in major depressive disorder, bipolar disorder, seasonal affective disorder (SAD), generalized anxiety disorder, social phobia (SP), panic disorder (PD), obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD).

METHODS

A systematic review was conducted using the electronic databases MEDLINE, CINAHL, and The Cochrane Library during late 2008. The search criteria involved mood and anxiety disorder search terms in combination with kava, Piper methysticum, kavalactones, St. John's wort, Hypericum perforatum, hypericin, and hyperforin. Additional search criteria for safety, pharmacodynamics, and pharmacokinetics were employed. A subsequent forward search was conducted of the papers using Web of Science cited reference search.

RESULTS

Current evidence supports the use of SJW in treating mild-moderate depression, and for kava in treatment of generalized anxiety. In respect to the other disorders, only weak preliminary evidence exists for use of SJW in SAD. Currently there is no published human trial on use of kava in affective disorders, or in OCD, PTSD, PD, or SP. These disorders constitute potential applications that warrant exploration.

CONCLUSIONS

Current evidence for herbal medicines in the treatment of depression and anxiety only supports the use of Hypericum perforatum for depression, and Piper methysticum for generalized anxiety.

The Kava Anxiety Depression Spectrum Study (KADSS): a randomized, placebo-controlled crossover trial using an aqueous extract of Piper methysticum

RATIONALE

Piper methysticum (Kava) has been withdrawn in European, British, and Canadian markets due to concerns over hepatotoxic reactions. The WHO recently recommended research into "aqueous" extracts of Kava.

OBJECTIVE

The objective of this study was to conduct the first documented human clinical trial assessing the anxiolytic and antidepressant efficacy of an aqueous extract of Kava.

DESIGN AND PARTICIPANTS

The Kava Anxiety Depression Spectrum Study was a 3-week placebo-controlled, double-blind crossover trial that recruited 60 adult participants with 1 month or more of elevated generalized anxiety. Five Kava tablets per day were prescribed containing 250 mg of kavalactones/day.

RESULTS

The aqueous extract of Kava reduced participants' Hamilton Anxiety Scale score in the first controlled phase by -9.9 (CI = 7.1, 12.7) vs. -0.8 (CI = -2.7, 4.3) for placebo and in the second controlled phase by -10.3 (CI = 5.8, 14.7) vs. +3.3 (CI = -6.8, 0.2). The pooled effect of Kava vs. placebo across phases was highly significant (p < 0.0001), with a substantial effect size (d = 2.24, eta(2)(p)). Pooled analyses also revealed highly significant relative reductions in Beck Anxiety Inventory and Montgomery-Asberg Depression Rating Scale scores. The aqueous extract was found to be safe, with no serious adverse effects and no clinical hepatotoxicity.

CONCLUSIONS

The aqueous Kava preparation produced significant anxiolytic and antidepressant activity and raised no safety concerns at the dose and duration studied. Kava appears equally effective in cases where anxiety is accompanied by depression. This should encourage further study and consideration of globally reintroducing aqueous rootstock extracts of Kava for the management of anxiety.

Identification and characterization of kava-derived compounds mediating TNF-alpha suppression

There is a substantial unmet need for new classes of drugs that block TNF-alpha-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-alpha secretion in lipopolysaccharide-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-alpha-inducing transcription factor lipopolysaccharide-induced TNF-alpha factor. Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of lipopolysaccharide. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared with kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-alpha secretion in the cell-based assay and suppressed lipopolysaccharide-induced TNF-alpha factor expression in the same cells, whereas the other compounds inhibited TNF-alpha secretion without affecting lipopolysaccharide-induced TNF-alpha factor levels, indicating a potential divergence in mechanism of action.

Kava hepatotoxicity: comparison of aqueous, ethanolic, acetonic kava extracts and kava-herbs mixtures

ETHNOPHARMACOLOGICAL RELEVANCE

Ethanolic and acetonic kava extracts have previously been causally related to rare hepatotoxicity observed in patients from Germany and Switzerland, but causality assessment was not performed in cases of patients having taken the traditional aqueous kava extracts of South Pacific islands or kava-herbs mixtures.

AIM OF THE STUDY

To study the possible hepatotoxicity of aqueous kava extracts of the South Pacific Islands.

MATERIALS AND METHODS

Causality of hepatotoxicity by aqueous kava extracts and kava-herbs mixtures was assessed, using the updated score of the quantitative CIOMS (Council for the International Organizations of Medical Sciences).

RESULTS

Causality was established in five patients from New Caledonia, Australia, the United States and Germany for aqueous kava extracts and kava-herbs mixtures. A comparison with 9 patients from Germany and Switzerland with established causality of hepatotoxicity by ethanolic and acetonic kava extracts reveals that the clinical picture in all 14 patients is similar, independently whether aqueous, ethanolic and acetonic kava extracts or kava-herbs mixtures were used.

CONCLUSIONS

Kava hepatotoxicity occurs also with traditional aqueous kava extracts of the South Pacific islands and thereby independently from ethanol or acetone as chemical solvents, suggesting that the toxicity is linked to the kava plant itself with a possibly low quality of the used kava cultivar or kava plant part rather than to chemical solvents.

St. John's wort and Kava in treating major depressive disorder with comorbid anxiety: a randomised double-blind placebo-controlled pilot trial

OBJECTIVE

We report the first randomised controlled trial (RCT) using a combination of St. John's wort (SJW) and Kava for the treatment of major depressive disorder (MDD) with comorbid anxiety.

METHODS

Twenty-eight adults with MDD and co-occurring anxiety were recruited for a double-blind RCT. After a placebo run-in of 2 weeks, the trial had a crossover design testing SJW and Kava against placebo over two controlled phases, each of 4 weeks. The primary analyses used intention-to-treat and completer analyses.

RESULTS

On both intention-to-treat (p = 0.047) and completer analyses (p = 0.003), SJW and Kava gave a significantly greater reduction in self-reported depression on the Beck Depression Inventory (BDI-II) over placebo in the first controlled phase. However, in the crossover phase, a replication of those effects in the delayed medication group did not occur. Nor were there significant effects on anxiety or quality of life.

CONCLUSION

There was some evidence of antidepressant effects using SJW and Kava in a small sample with comorbid anxiety. Possible explanations for the absence of anxiolysis may include a potential interaction with SJW, the presence of depression, or an inadequate dose of Kava.

Toxic hepatitis after consumption of traditional kava preparation

Liver toxicity from the use of kava dietary supplements has been reported, but little is known about the side effects of traditional kava preparations. We present a case study of a tourist who developed serious toxic liver disease after consumption of kava beverages in traditional Samoan kava ceremonies.

Kava hepatotoxicity: a clinical survey and critical analysis of 26 suspected cases

BACKGROUND/AIMS

Hepatotoxicity has been previously suspected by national regulatory agencies in 26 patients in causal relationship with the treatment by kava extracts commonly used as herbal anxiolytic drugs.

METHODS

A quantitative causality assessment was undertaken using the system of the Council for International Organizations of Medical Sciences, scale of objective probability scoring.

RESULTS

Causality was unassessable, unrelated, or excluded in 16 patients owing to lack of temporal association and causes independent of kava or comedicated drugs. Low Council for International Organizations of Medical Sciences scores additionally resulted in excluded or unlikely causality assessments (n=2), leaving a total of eight patients with various degrees of causality for kava +/- comedicated drugs. Only one out of these eight patients adhered to the regulatory recommendations regarding both daily dose (<or=120 mg kavapyrones) and duration of therapy (<or=3 months) and experienced toxic liver injury with a probable causality for kava. In six cases with kava overdose and/or increased duration of kava treatment causality for kava was possible (n=3) and for kava together with the comedicated drug(s) possible (n=2) or probable (n=1).

CONCLUSION

Kava taken as recommended is associated with rare hepatotoxicity, whereas overdose, prolonged treatment, and comedication may carry an increased risk.

Natural health product labels: is more information always better?

OBJECTIVE

To explore how the information provided on labels as mandated by the new Canadian natural health product (NHP) regulations impacts consumers' perceptions of risks associated with using NHPs.

METHODS

Six focus groups were conducted in three locations across Ontario. Consumers were asked to react to two labels for a fictitious product called Saturnflower that represented the "old" standards (label 1) and the new standards (label 2). Groups were audio-taped and transcribed verbatim. Qualitative content analysis was used to identify key themes.

RESULTS

The 38 participants criticized label 1 for lacking information about the uses of the product and discussed their frustration at trying to obtain good quality information about NHPs. The lack of risk information on label 1 reinforced their perceptions of NHPs as natural, mild and safe. The majority of participants found label 2 much more informative, but a few were unsettled by the extent of the risk information, questioning if it was necessary.

CONCLUSION

The label requirements of the new NHP regulations were generally viewed positively by the consumers who participated in this study.

PRACTICE IMPLICATIONS

The additional risk information may generate more NHP-related questions for health care practitioners especially with respect to possible interactions between NHPs and conventional medicines.

Evaluation of commercial kava extracts and kavalactone standards for mutagenicity and toxicity using the mammalian cell gene mutation assay in L5178Y mouse lymphoma cells

Kava (Piper methysticum) is a member of the pepper family and has been cultivated by South Pacific islanders for centuries and used as a social and ceremonial drink. Traditionally, kava extracts are prepared by grinding or chewing the rhizome and mixing with water and coconut milk. The active constituents of kava are a group of approximately 18 compounds collectively referred to as kavalactones or kava pyrones. Kawain, dihydrokawain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin are the six major kavalactones. Kava beverages and other preparations are known to be anxiolytic and are used for anxiety disorders. Dietary supplements containing the root of the kava shrub have been implicated in several cases of liver toxicity in humans, including several who required liver transplants after using kava supplements. In order to study the toxicity and mutagenicity, two commercial samples of kava, Kaviar and KavaPure, and the six pure kavalactones including both D-kawain and DL-kawain, were evaluated in L5178Y mouse lymphoma cells. Neither the kava samples nor the kavalactones induced a mutagenic response in the L5178Y mouse lymphoma mutation assay with the addition of human liver S9 activation.

Herbal medicines in the treatment of psychiatric disorders: a systematic review

This paper reports a critical review of 27 herbal medicines and formulas in treating a broad range of psychiatric disorders (in addition to anxiety and depression), including obsessive-compulsive, seasonal affective, bipolar depressive, psychotic, phobic and somatoform disorders. Ovid Medline, Pubmed and the Cochrane Library were searched for pharmacological and clinical evidence of herbal medicines with psychotropic activity. A forward search of later citations was also conducted. Whilst substantial high-quality evidence exists for the use of kava and St John's wort in the treatment of anxiety and depression respectively, currently there is insufficient robust clinical evidence for the use of many other herbal medicines in psychiatric disorders. Phytotherapies which potentially have significant use in psychiatry, and urgently require more research are Rhodiola rosea (roseroot) and Crocus sativus (saffron) for depression; Passiflora incarnata (passionflower), Scutellaria lateriflora (scullcap) and Zizyphus jujuba (sour date) for anxiety disorders; and Piper methysticum (kava) for phobic, panic and obsessive-compulsive disorders. While depression and anxiety are commonly researched, the efficacy of herbal medicines in other mental disorders requires attention. The review addresses current issues in herbal psychotherapy: herbal safety, future areas of application, the relationship of herbal medicine with pharmaceuticals and the potential prescriptive integration of phytomedicines with synthetic psychotropic medicines. Particular attention is given to clinical and safety issues with St John's wort and kava.

Food-drug interactions via human cytochrome P450 3A (CYP3A)

Food-drug interactions have been reported to occur in various systems in the body. The causes of these interactions are mainly divided into pharmacodynamic and pharmacokinetic processes. Among these processes, drug metabolism plays a crucial role in drug interactions. Metabolic food-drug interactions occur when a certain food alters the activity of a drug-metabolizing enzyme, leading to a modulation of the pharmacokinetics of drugs metabolized by the enzyme. A variety of interactions have been documented so far. Foods consisting of complex chemical mixtures, such as fruits, alcoholic beverages, teas, and herbs, possess the ability to inhibit or induce the activity of drug-metabolizing enzymes. According to results obtained thus far, cytochrome P450 3A4 (CYP3A4) appears to be a key enzyme in food-drug interactions. For example, interactions of grapefruit juice with felodipine and cyclosporine, red wine with cyclosporine, and St John's wort with various medicines including cyclosporine, have been demonstrated. The results indicate the requirement of dosage adjustment to maintain drug concentrations within their therapeutic windows. The CYP3A4-related interaction by food components may be related to the high level of expression of CYP3A4 in the small intestine, as well as its broad substrate specificity, as CYP3A4 is responsible for the metabolism of more than 50% of clinical pharmaceuticals. This review article summarizes the findings obtained to date concerning food-drug interactions and their clinical implications. It seems likely that more information regarding such interactions will accumulate in the future, and awareness is necessary for achieving optimal drug therapy.

Risks of herbal medicinal products

PURPOSE

Herbal medicinal products (HMPs) are again highly popular. Their current popularity renders the assessment of their safety an urgent necessity.

METHOD

Narrative review using examples only.

RESULTS

Constituents of HMPs can be toxic and numerous examples of liver, kidney or other organ damage are on record. All HMPs contain a range of pharmacologically active constituents, and users of HMPs often combine HMPs with prescribed drugs. Thus herb-drug interactions are a real possibility. In most countries, HMPs are not submitted to stringent regulation and control. Thus unreliable quality can be a problem. In particular, this poses a risk when HMPs are contaminated (e.g. with heavy metals) or adulterated (e.g. with prescription drugs). The medical literature holds numerous examples for all of these scenarios and some are used in this article to illustrate the above points. As this area is grossly under-researched, it is rarely possible to define the size of the problem.

CONCLUSIONS

It is concluded that the widespread notion of HMPs being inherently safe is naive at best and dangerous at worst. More research is required to minimise the risk HMPs may pose to consumers' health.