Kava extracts: safety and risks including rare hepatotoxicity

Herbal and Natural Supplements for Improving Sleep: A Literature Review

OBJECTIVE

Herbal and natural supplements have gained popularity as alternative treatments to insomnia and sleep disorders due to their perceived safety and potential effectiveness. This literature review summarizes the current evidence on the efficacy, safety, and mechanisms of action of commonly used supplements for sleep, including valerian, hops, kava, German chamomile, cherry, tryptophan, theanine, melatonin, magnesium, and zinc.

METHODS

We conducted literature review of clinical research on herbal and supplements for sleep reported to date. We summarized key findings and reviewed outcomes related to clinical efficacy and side effects.

RESULTS

Findings suggest that certain supplements, particularly valerian, hops, and melatonin, could be effective in improving sleep quality and reducing insomnia symptoms through modulation of neurotransmitter systems and regulation of sleep-wake cycles. However, the strength of the evidence varies with unestablished optimal dosages, formulations, and treatment durations. Although generally considered safe, these supplements are not without risks, such as rare but serious adverse effects associated with kava and potential interactions with prescription medications. The quality and purity of supplements also vary widely due to a lack of strict regulations.

CONCLUSION

Healthcare providers should remain informed about the latest research and work closely with patients to develop personalized treatment plans. Herbal and natural supplements may offer promising alternatives or adjunct treatments for insomnia and sleep disorders, but their use should be guided by the best available evidence and individual patient requirements. Larger, well-designed clinical trials are needed to establish the efficacy and safety of these supplements for clinical decision-making.

Health policy versus kava (Piper methysticum): Anxiolytic efficacy may be instrumental in restoring the reputation of a major South Pacific crop

ETHNOPHARMACOLOGICAL RELEVANCE

Kava (Piper methysticum G. Forst. f.) is by far the most important plant used in the islands of Melanesia, Polynesia and Micronesia for its relaxing effects. Kava drinking is a pillar of South Pacific societies and is also the foundation of their economies. Preparations of kava extract as herbal medicinal drugs were banned in Germany in 2002 and again in 2019, with dramatic consequences for the South Pacific economies. In 2002, the major regulatory argument for the ban of kava was safety issues. In 2019, the assessment report of the European Medicines Agency's Herbal Medicinal Product Committee (HMPC) justified a negative benefit-to-risk ratio by a supposed lack of efficacy of ethanolic extracts for an indication of which kava extract preparations never had an approval. In this HMPC report the efficacy in the approved indications 'nervous anxiety, tension and restlessness' was attributed to the extract branded as 'WS 1490', which was assumed to have been prepared with acetone as an extraction solvent. In addition to this change of indication and the attribution of efficacy to acetone kava extract alone, the German health authorities and the HMPC still refuse to discuss quality issues as a likely factor impacting drug safety. The first case reports of liver toxicity were observed with an acetone extract in a timely relationship with the introduction of 'two-day kava' instead of 'noble kava' as used in ethanolic kava extracts.

AIM OF THE STUDY

The correlation between clinical benefits and the type of extract preparation was examined.

METHODS

In order to identify the types of kava material and extracts used in clinical trials, the respective publications were compared with regulatory databases and protocols of a German regulatory advisory board.

RESULTS AND CONCLUSIONS

The comparison reveals inconsistencies in the regulatory decisions. In all studies with WS 1490, the evidence points to the use of an ethanolic extract. The efficacy of kava extract for the approved indication was clearly demonstrated. The HMPC report and the recent renewed German regulatory ban of kava therefore require major revision, which should include the impact of the use of "two-day kava" on drug safety. Such a revision could contribute to restoring the reputation of "noble kava" on the international markets.

Evaluation of Anti-Convulsive Properties of Aqueous Kava Extract on Zebrafish Using the PTZ-Induced Seizure Model

Kava roots have been extensively studied in clinical trials as potential candidate anti-anxiety drugs. However, anti-convulsive properties of various tissues of stems of Kava have not been reported to date. The objective of the study was to evaluate the anti-convulsive potential of aqueous extracts prepared from specific tissues of Kava (Piper methysticum) stems in zebrafish, using the PTZ-induced seizure model. The potency of each extract was compared in terms of the intensity of seizure scores and onset time after pre-treating the zebrafish before the PTZ challenge. The results indicate that aqueous extract of Kava stems without peel after 45 min of pre-treatment exhibited anti-convulsive potential at the dose of 50 mg/L. This study provides evidence to the anti-convulsive properties of peeled Kava stems and its potential for investigation and design of candidate anti-convulsive drugs.

Chemical and in vitro toxicity analysis of a supercritical fluid extract of Kava kava (Piper methysticum)

ETHNOPHARMACOLOGICAL RELEVANCE

Kava and kava extracts have shown great potential as a way to minimize anxiety-associated symptoms and to help alleviate pain. Hepatoxicity has been associated with the consumption of kava products. The chemical compounds, kavalactones (KL) and flavokavains (FK) have been implicated in kava's psychotropic and possible hepatotoxic properties.

AIM OF THE STUDY

To investigate the kavalactone and flavokavain content and in vitro toxicity of KAVOA™, a supercritical carbon dioxide extraction (SFE) of kava.

MATERIALS AND METHODS

Kavalactone and flavokavain content of SFE kava and noble kava root were determined following extraction in acetone, cell culture media, and water using ultra high-performance liquid chromatography (UHPLC). Using water extractions of the kava products, the cell viability and toxicity on the human hepatocellular carcinoma cell line (HepG2) were determined using luminescent and fluorescent assays, respectively. The half maximal inhibitory concentration (IC₅₀) of the SFE kava and noble kava root, extracted in cell culture media, were determined utilizing a luminescent cell viability assay.

RESULTS

Quantification of the KAVOA™, a SFE extract of kava and kava root showed similar profiles of kavalactone and flavokavain content. Water extracted SFE and root kava did not show a negative impact on cell viability and toxicity when compared to the vehicle control treated cells. IC₅₀ values were determined for the SFE kava and kava root extracted in cell culture media in respect to cell viability, 78.63 and 47.65 µg/mL, respectively.

CONCLUSIONS

KAVOA™, a supercritical carbon dioxide extract of kava displays a similar kavalactone profile to a noble variety of kava. In relation to total kavalactone content, KAVOA™ also has a lower content of the cytotoxic compound FKB. Aqueous extractions of KAVOA™ and noble kava root had no significant negative impact on cell viability and toxicity on HepG2 cells when compared to vehicle controlled treated cells. Results indicate KAVOA™ demonstrates a similar in vitro safety profile to that of noble kava root when experiments are normalized to kavalactone content.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications

Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Potential Influence of Centrally Acting Herbal Drugs on Transporters at the Blood-Cerebrospinal Fluid Barrier and Blood-Brain Barrier

Complementary and alternative medications (CAM) with known or suspected pharmacologic activity in the central nervous system (CNS) are common. These herbal preparations may cause clinically significant drug-drug interactions (DDIs) when coadministered with medications that act in the CNS. This can result in negative outcomes such as toxicity or loss of efficacy. Most drug interaction reports with CAM focus on cytochrome P450 (CYP) modulation. However, drug interactions between CAM and conventional medications may occur via mechanisms other than CYP inhibition or induction; in particular, modulation of drug transport proteins represents an important mechanism by which such interactions may occur. This article provides an updated review of transporter-mediated mechanisms by which herbal products may theoretically interact with centrally acting medications at the blood-brain barrier and blood-cerebrospinal fluid (CSF) barrier. Further research is required before the true clinical impact of interactions involving modulation of centrally located membrane transporters can be fully understood.

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.

Selected α-pyrones from the plants Cryptocarya novoguineensis (Lauraceae) and Piper methysticum (Piperaceae) with activity against Haemonchus contortus in vitro

Due to the widespread occurrence and spread of anthelmintic resistance, there is a need to develop new drugs against resistant parasitic nematodes of livestock animals. The Nobel Prize-winning discovery and development of the anti-parasitic drugs avermectin and artemisinin has renewed the interest in exploring natural products as anthelmintics. In the present study, we screened 7500 plant extracts for in vitro-activity against the barber's pole worm, Haemonchus contortus, a highly significant pathogen of ruminants. The anthelmintic extracts from two plants, Cryptocarya novoguineensis and Piper methysticum, were fractionated by high-performance liquid chromatography (HPLC). Subsequently, compounds were purified from fractions with significant biological activity. Four α-pyrones, namely goniothalamin (GNT), dihydrokavain (DHK), desmethoxyyangonin (DMY) and yangonin (YGN), were purified from fractions from the two plants, GNT from C. novoguineensis, and DHK, DMY and YGN (= kavalactones) from P. methysticum. The three kavalactones induced a lethal, eviscerated (Evi) phenotype in treated exsheathed third-stage larvae (xL3s), and DMY and YGN had moderate potencies (IC₅₀ values of 31.7 ± 0.23 μM and 23.7 ± 2.05 μM, respectively) at inhibiting the development of xL3s to fourth-stage larvae (L4s). Although GNT had limited potency (IC₅₀ of 200–300 μM) at inhibiting L4 development, it was the only compound that reduced L4 motility (IC₅₀ of 6.25–12.50 μM). The compounds purified from each plant affected H. contortus in an irreversible manner. These findings suggest that structure-activity relationship studies of α-pyrones should be pursued to assess their potential as anthelmintics.

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7500 plant extracts were screened against Haemonchus for anthelmintic activity.

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Three of these extracts were potent inhibitors of larval motility and/or development.

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Pure α-pyrones isolated from active fractions exhibited significant nematocidal activity.

Liver toxicity mechanisms of herbs commonly used in Latin America

Mexico owns approximately 4500 medicinal plants species, a great diversity that position it at the second place after China. According to the Mexican health department, 90% of common population consumes them to treat various diseases. Additionally, herbal remedies in Latin America (LA) are considered a common practice, but the frequency of use and the liver damage related to its consumption is still unknown. Despite the high prevalence and indiscriminate herbal consumption, the exact mechanism of hepatotoxicity and adverse effects is not fully clarified and is still questioned. Some herb products associated with herb induced liver injury (HILI) are characterized by presenting a different chemical composition that may vary from batch to batch, also the biological activity of many medicinal plants and other natural products are directly related to their most active component and its concentration. There are two main biological components that are associated with liver damage, alkaloids, and flavonoids, which are frequent constituents of commonly used herbs. The interaction with the different cytochrome P-450 isoforms, inflammatory, and oxidative activities seem to be the main damage pathway involved in the liver. It is important to know the herbal adverse effects and mechanisms involved; therefore, this article is focused on the beneficial and deleterious effects as well as the possible toxicity mechanisms and interactions of the herbs that are frequently used in LA, since the herb-host interaction may not always be the expected or desired depending on the clinical context in which it is administered.

Therapeutic Effects of Phytochemicals and Medicinal Herbs on Depression

Background. Depression is a recurrent, common, and potentially life-threatening psychiatric disease related to multiple assignable causes. Although conventional antidepressant therapy can help relieve symptoms of depression and prevent relapse of the illness, complementary therapies are required due to disadvantage of the current therapy such as adverse effects. Moreover, a number of studies have researched adjunctive therapeutic approaches to improve outcomes for depression patients. Purpose. One potential complementary method with conventional antidepressants involves the use of medicinal herbs and phytochemicals that provide therapeutic benefits. Studies have revealed beneficial effects of medical herbs and phytochemicals on depression and their central nervous system mechanism. Here, we summarize the current knowledge of the therapeutic benefits of phytochemicals and medicinal herbs against depression and describe their detailed mechanisms. Sections. There are two sections, phytochemicals against depression and medical herbs against depression, in this review. Conclusion. Use of phytomedicine may be an alternative option for the treatment of depression in case conventional drugs are not applicable due to their side effects, low effectiveness, or inaccessibility. However, the efficacy and safety of these phytomedicine treatments for depression have to be supported by clinical studies.

Safety and Efficacy of Herbal Sedatives in Cancer Care

Insomnia and other sleep disturbances are common in cancer patients. Insomnia is a multifactorial health concern that currently affects at least 1 in 3 cancer patients, and yet most insomnia sufferers do not consult their physician regarding pharmaceutical options for relief. Use of hypnotic drugs (primarily benzodiazepines) is associated with increasing tolerance, dependence, and adverse effects on the central nervous system. While hypnotic drug use declined substantially in the past decade, the use of herbal sedatives appeared to increase. Mostly self-prescribed by lay people, herbal sedatives hold widespread appeal, presumably because of their lower cost and higher margin of safety when compared to pharmaceuticals. Studies of better-known herbal sedatives, notably valerian and kava, showed moderate evidence for both safety and efficacy for valerian while revealing disturbing toxicity concerns for kava. Milder sedatives or anxiolytics in need of clinical study include German chamomile, lavender, hops, lemon balm, and passionflower; St. John’s wort may have anxiolytic effects with relevance to sleep. Herb-drug interactions are a possibility for some of these species, including St. John’s wort. Although sufficient evidence exists to recommend some of these agents for short-term relief of mild insomnia, long-term trials and observational studies are needed to establish the safety of prolonged use as well as overall efficacy in the context of cancer treatment and management.

Herbal Hepatotoxicity: Clinical Characteristics and Listing Compilation

Herb induced liver injury (HILI) and drug induced liver injury (DILI) share the common characteristic of chemical compounds as their causative agents, which were either produced by the plant or synthetic processes. Both, natural and synthetic chemicals are foreign products to the body and need metabolic degradation to be eliminated. During this process, hepatotoxic metabolites may be generated causing liver injury in susceptible patients. There is uncertainty, whether risk factors such as high lipophilicity or high daily and cumulative doses play a pathogenetic role for HILI, as these are under discussion for DILI. It is also often unclear, whether a HILI case has an idiosyncratic or an intrinsic background. Treatment with herbs of Western medicine or traditional Chinese medicine (TCM) rarely causes elevated liver tests (LT). However, HILI can develop to acute liver failure requiring liver transplantation in single cases. HILI is a diagnosis of exclusion, because clinical features of HILI are not specific as they are also found in many other liver diseases unrelated to herbal use. In strikingly increased liver tests signifying severe liver injury, herbal use has to be stopped. To establish HILI as the cause of liver damage, RUCAM (Roussel Uclaf Causality Assessment Method) is a useful tool. Diagnostic problems may emerge when alternative causes were not carefully excluded and the correct therapy is withheld. Future strategies should focus on RUCAM based causality assessment in suspected HILI cases and more regulatory efforts to provide all herbal medicines and herbal dietary supplements used as medicine with strict regulatory surveillance, considering them as herbal drugs and ascertaining an appropriate risk benefit balance.

Hepatotoxicity Induced by "the 3Ks": Kava, Kratom and Khat

The 3Ks (kava, kratom and khat) are herbals that can potentially induce liver injuries. On the one hand, growing controversial data have been reported about the hepatotoxicity of kratom, while, on the other hand, even though kava and khat hepatotoxicity has been investigated, the hepatotoxic effects are still not clear. Chronic recreational use of kratom has been associated with rare instances of acute liver injury. Several studies and case reports have suggested that khat is hepatotoxic, leading to deranged liver enzymes and also histopathological evidence of acute hepatocellular degeneration. Numerous reports of severe hepatotoxicity potentially induced by kava have also been highlighted, both in the USA and Europe. The aim of this review is to focus on the different patterns and the mechanisms of hepatotoxicity induced by “the 3Ks”, while trying to clarify the numerous aspects that still need to be addressed.

Herbal hepatotoxicity in traditional and modern medicine: actual key issues and new encouraging steps

Plants are natural producers of chemical substances, providing potential treatment of human ailments since ancient times. Some herbal chemicals in medicinal plants of traditional and modern medicine carry the risk of herb induced liver injury (HILI) with a severe or potentially lethal clinical course, and the requirement of a liver transplant. Discontinuation of herbal use is mandatory in time when HILI is first suspected as diagnosis. Although, herbal hepatotoxicity is of utmost clinical and regulatory importance, lack of a stringent causality assessment remains a major issue for patients with suspected HILI, while this problem is best overcome by the use of the hepatotoxicity specific CIOMS (Council for International Organizations of Medical Sciences) scale and the evaluation of unintentional reexposure test results. Sixty five different commonly used herbs, herbal drugs, and herbal supplements and 111 different herbs or herbal mixtures of the traditional Chinese medicine (TCM) are reported causative for liver disease, with levels of causality proof that appear rarely conclusive. Encouraging steps in the field of herbal hepatotoxicity focus on introducing analytical methods that identify cases of intrinsic hepatotoxicity caused by pyrrolizidine alkaloids, and on omics technologies, including genomics, proteomics, metabolomics, and assessing circulating micro-RNA in the serum of some patients with intrinsic hepatotoxicity. It remains to be established whether these new technologies can identify idiosyncratic HILI cases. To enhance its globalization, herbal medicine should universally be marketed as herbal drugs under strict regulatory surveillance in analogy to regulatory approved chemical drugs, proving a positive risk/benefit profile by enforcing evidence based clinical trials and excellent herbal drug quality.

Measuring the chemical and cytotoxic variability of commercially available kava (Piper methysticum G. Forster)

Formerly used world-wide as a popular botanical medicine to reduce anxiety, reports of hepatotoxicity linked to consuming kava extracts in the late 1990s have resulted in global restrictions on kava use and have hindered kava-related research. Despite its presence on the United States Food and Drug Administration consumer advisory list for the past decade, export data from kava producing countries implies that US kava imports, which are not publicly reported, are both increasing and of a fairly high volume. We have measured the variability in extract chemical composition and cytotoxicity towards human lung adenocarcinoma A549 cancer cells of 25 commercially available kava products. Results reveal a high level of variation in chemical content and cytotoxicity of currently available kava products. As public interest and use of kava products continues to increase in the United States, efforts to characterize products and expedite research of this potentially useful botanical medicine are necessary.

Drug and herb induced liver injury: Council for International Organizations of Medical Sciences scale for causality assessment

Causality assessment of suspected drug induced liver injury (DILI) and herb induced liver injury (HILI) is hampered by the lack of a standardized approach to be used by attending physicians and at various subsequent evaluating levels. The aim of this review was to analyze the suitability of the liver specific Council for International Organizations of Medical Sciences (CIOMS) scale as a standard tool for causality assessment in DILI and HILI cases. PubMed database was searched for the following terms: drug induced liver injury; herb induced liver injury; DILI causality assessment; and HILI causality assessment. The strength of the CIOMS lies in its potential as a standardized scale for DILI and HILI causality assessment. Other advantages include its liver specificity and its validation for hepatotoxicity with excellent sensitivity, specificity and predictive validity, based on cases with a positive reexposure test. This scale allows prospective collection of all relevant data required for a valid causality assessment. It does not require expert knowledge in hepatotoxicity and its results may subsequently be refined. Weaknesses of the CIOMS scale include the limited exclusion of alternative causes and qualitatively graded risk factors. In conclusion, CIOMS appears to be suitable as a standard scale for attending physicians, regulatory agencies, expert panels and other scientists to provide a standardized, reproducible causality assessment in suspected DILI and HILI cases, applicable primarily at all assessing levels involved.

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.

Herbal hepatotoxicity: suspected cases assessed for alternative causes

BACKGROUND AND OBJECTIVES

Alternative explanations are common in suspected drug-induced liver injury (DILI) and account for up to 47.1% of analyzed cases. This raised the question of whether a similar frequency may prevail in cases of assumed herb-induced liver injury (HILI).

METHODS

We searched the Medline database for the following terms: herbs, herbal drugs, herbal dietary supplements, hepatotoxic herbs, herbal hepatotoxicity, and herb-induced liver injury. Additional terms specifically addressed single herbs and herbal products: black cohosh, Greater Celandine, green tea, Herbalife products, Hydroxycut, kava, and Pelargonium sidoides. We retrieved 23 published case series and regulatory assessments related to hepatotoxicity by herbs and herbal dietary supplements with alternative causes.

RESULTS

The 23 publications comprised 573 cases of initially suspected HILI; alternative causes were evident in 278/573 cases (48.5%). Among them were hepatitis by various viruses (9.7%), autoimmune diseases (10.4%), nonalcoholic and alcoholic liver diseases (5.4%), liver injury by comedication (DILI and other HILI) (43.9%), and liver involvement in infectious diseases (4.7%). Biliary and pancreatic diseases were frequent alternative diagnoses (11.5%), raising therapeutic problems if specific treatment is withheld; pre-existing liver diseases including cirrhosis (9.7%) were additional confounding variables. Other diagnoses were rare, but possibly relevant for the individual patient.

CONCLUSION

In 573 cases of initially assumed HILI, 48.5% showed alternative causes unrelated to the initially incriminated herb, herbal drug, or herbal dietary supplement, calling for thorough clinical evaluations and appropriate causality assessments in future cases of suspected HILI.

Suppression of iNOS and COX-2 expression by flavokawain A via blockade of NF-κB and AP-1 activation in RAW 264.7 macrophages

Flavokawain A, a major constituent of chalcones derived from kava extracts, exerts various biological activities such as anti-tumor activities. In this study, we examined the suppressive effect of flavokawain A on LPS-induced expression of pro-inflammatory mediators and the molecular mechanisms responsible for these activities in the murine macrophages. Flavokawain A significantly suppressed expression of iNOS and COX-2, as well as the subsequent production of NO and PGE2 in the LPS-stimulated RAW 264.7 cells. Flavokawain A significantly inhibited LPS-induced activation of NF-κB and AP-1 signaling pathways. In addition, flavokawain A inhibited activation of JNK and p38 MAPK which was responsible for expression of iNOS and COX-2 in the LPS-stimulated RAW 264.7 cells. Furthermore, flavokawain A suppressed LPS-induced expression of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6. These results suggest that flavokawain A may exert anti-inflammatory responses by suppressing LPS-induced expression of pro-inflammatory mediators via blockage of NF-κB-AP-1-JNK/p38 MAPK signaling pathways in the murine macrophages.

Herbal hepatotoxicity: a critical review

This review deals with herbal hepatotoxicity, identical to herb induced liver injury (HILI), and critically summarizes the pitfalls associated with the evaluation of assumed HILI cases. Analysis of the relevant publications reveals that several dozens of different herbs and herbal products have been implicated to cause toxic liver disease, but major quality issues limit the validity of causality attribution. In most of these reports, discussions around quality specifications regarding herbal products, case data presentations and causality assessment methods prevail. Though the production of herbal drugs is under regulatory surveillance and quality aspects are normally not a matter of concern, low quality of the less regulated herbal supplements may be a critical issue considering product batch variability, impurities, adulterants and herb misidentifications. Regarding case data presentation, essential diagnostic information is often lacking, as is the use of valid and liver specific causality assessment methods that also consider alternative diseases. At present, causality is best assessed by using the Council for International Organizations of Medical Sciences scale ( CIOMS) in its original or updated form, which should primarily be applied prospectively by the treating physician when evaluating a patient rather than retrospectively by regulatory agencies. To cope with these problems, a common quality approach by manufacturers, physicians and regulatory agencies should strive for the best quality. We propose steps for improvements with impact on future cases of liver injury by herbs, herbal drugs and herbal supplements.

Herbal hepatotoxicity: a tabular compilation of reported cases

BACKGROUND

Herbal hepatotoxicity is a field that has rapidly grown over the last few years along with increased use of herbal products worldwide.

AIMS

To summarize the various facets of this disease, we undertook a literature search for herbs, herbal drugs and herbal supplements with reported cases of herbal hepatotoxicity.

METHODS

A selective literature search was performed to identify published case reports, spontaneous case reports, case series and review articles regarding herbal hepatotoxicity.

RESULTS

A total of 185 publications were identified and the results compiled. They show 60 different herbs, herbal drugs and herbal supplements with reported potential hepatotoxicity, additional information including synonyms of individual herbs, botanical names and cross references are provided. If known, details are presented for specific ingredients and chemicals in herbal products, and for references with authors that can be matched to each herbal product and to its effect on the liver. Based on stringent causality assessment methods and/or positive re-exposure tests, causality was highly probable or probable for Ayurvedic herbs, Chaparral, Chinese herbal mixture, Germander, Greater Celandine, green tea, few Herbalife products, Jin Bu Huan, Kava, Ma Huang, Mistletoe, Senna, Syo Saiko To and Venencapsan(®). In many other publications, however, causality was not properly evaluated by a liver-specific and for hepatotoxicity-validated causality assessment method such as the scale of CIOMS (Council for International Organizations of Medical Sciences).

CONCLUSIONS

This compilation presents details of herbal hepatotoxicity, assisting thereby clinical assessment of involved physicians in the future.

Kava hepatotoxicity in traditional and modern use: the presumed Pacific kava paradox hypothesis revisited

Kava, a Pacific herb consumed worldwide for medicinal, recreational and cultural purposes, has been associated with rare hepatotoxicity, and there is currently a critical need to determine this causation. The previously proposed Pacific kava paradox was based on the theory that kava hepatotoxicity was not observed following use of traditional aqueous extracts in the Pacific region, but was restricted to use of Western acetonic and ethanolic extracts. Subsequent cases analyzed by the World Health Organization and published case reports revealed that traditional aqueous extracts used in New Caledonia, Australia, the USA and Germany may also be hepatotoxic; thus, there is no longer a basis to sustain the previously proposed Pacific kava paradox. It appears that the primary cause of toxicity may reside in the time before the preparation of the various kava extracts, possibly attributed to poor quality of the raw material caused by mould hepatotoxins. Rigorous testing of kava raw material is urgently advised, in addition to Pan-Pacific kava manufacturing quality standards.

Toxicological actions of plant-derived and anthropogenic methylenedioxyphenyl-substituted chemicals in mammals and insects

The methylenedioxyphenyl (MDP) substituent is a structural feature present in many plant chemicals that deter foraging by predatory insects and herbivores. With increasing use of herbal extracts in alternative medicine, human exposure to MDP-derived plant chemicals may also be significant. Early studies found that most MDP agents themselves possess relatively low intrinsic toxicity, but strongly influence the actions of other xenobiotics in mammals and insects by modulating cytochrome P-450 (CYP)-dependent biotransformation. Thus, after exposure to MDP chemicals an initial phase of CYP inhibition is followed by a sustained phase of CYP induction. In insects CYP inhibition by MDP agents underlies their use as pesticide synergists, but analogous inhibition of mammalian CYP impairs the clearance of drugs and foreign compounds. Conversely, induction of mammalian CYP by MDP agents increases xenobiotic oxidation capacity. Exposure of insects to MDP-containing synergists in the environment, in the absence of coadministered pesticides, may also enhance xenobiotic detoxication. Finally, although most MDP agents are well tolerated, several, typified by safrole, aristolochic acid, and MDP-kavalactones, are associated with significant toxicities, including the risk of hepatotoxicity or tumorigenesis. Thus, the presence of MDP-substituted chemicals in the environment may produce a range of direct and indirect toxicities in target and nontarget species.

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.

Liver toxicity and carcinogenicity in F344/N rats and B6C3F1 mice exposed to Kava Kava

Kava Kava is an herbal supplement used as an alternative to antianxiety drugs. Although some reports suggest an association of Kava Kava with hepatotoxicity , it continues to be used in the United States due to lack of toxicity characterization. In these studies F344/N rats and B6C3F1 mice were administered Kava Kava extract orally by gavage in corn oil for two weeks, thirteen weeks or two years. Results from prechronic studies administered Kava Kava at 0.125 to 2g/kg body weight revealed dose-related increases in liver weights and incidences of hepatocellular hypertrophy. In the chronic studies, there were dose-related increases in the incidences of hepatocellular hypertrophy in rats and mice administered Kava Kava for up to 1g/kg body weight. This was accompanied by significant increases in incidences of centrilobular fatty change. There was no treatment- related increase in carcinogenic activity in the livers of male or female rats in the chronic studies. Male mice showed a significant dose-related increase in the incidence of hepatoblastomas. In female mice, there was a significant increase in the combined incidence of hepatocellular adenoma and carcinoma in the low and mid dose groups but not in the high dose group. These findings were accompanied by several nonneoplastic hepatic lesions.

Herbal hepatotoxicity by kava: update on pipermethystine, flavokavain B, and mould hepatotoxins as primarily assumed culprits

Herbal hepatotoxicity by the anxiolytic kava (Piper methysticum Forst. f.) emerged unexpectedly and was observed in a few patients worldwide. Liver injury occurred after the use of traditional aqueous kava extracts in the South Pacific region and of acetonic and ethanolic extracts in Western countries in rare cases, suggesting that the solvents used play no major causative role. In this review, we discuss actual pathogenetic issues of kava hepatotoxicity with special focus on developments regarding pipermethystine, flavokavain B, and mould hepatotoxins as possible culprits. There is abundant data of in vitro cytotoxicity including apoptosis by pipermethystine and flavokavain B added to the incubation media, yet evidence is lacking of in vivo hepatotoxicity in experimental animals under conditions similar to human kava use. Furthermore, in commercial Western kava extracts, pipermethystine was not detectable and flavokavain B was present as a natural compound in amounts much too low to cause experimental liver injury. There is concern, however, that due to high temperature and humidity in the South Pacific area, kava raw material might have been contaminated by mould hepatotoxins such as aflatoxins after harvest and during storage. Whether kava hepatotoxicity may be due to aflatoxicosis or other mould hepatotoxins, requires further studies.

Reporting natural health product related adverse drug reactions: is it the pharmacist's responsibility?

OBJECTIVES

Herbal medicines and other natural health products (NHPs) are sold in Canadian pharmacies as over-the-counter products, yet there is limited information on their safety and adverse effect profile. Signals of safety concerns associated with medicines can arise through analysis of reports of suspected adverse drug reactions (ADRs) submitted to national pharmacovigilance centres by health professionals, including pharmacists and the public. However, typically such systems experience substantial under-reporting for NHPs. The objective of this paper is to explore pharmacists' experiences with and responses to receiving or identifying reports of suspected ADRs associated with NHPs from pharmacy customers.

METHODS

A qualitative study in which in-depth, semi-structured interviews were conducted with 12 community pharmacists in Toronto, Canada.

KEY FINDINGS

Pharmacists generally did not submit reports of adverse events associated with NHPs to the national ADR reporting system and cited several barriers, including lack of time, complexity of the reporting process and lack of knowledge about NHPs. Pharmacists who accepted responsibility for adverse event reporting appeared to have different perceptions of their professional role: they saw themselves as 'knowledge generators', contributing to overall healthcare knowledge.

CONCLUSIONS

Reporting behaviour for suspected ADRs associated with NHPs may be explained by a pharmacist's perception of his/her professional role and perceptions of the relative importance of generating knowledge to share in the wider system of health care.

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.

Tradition and toxicity: evidential cultures in the kava safety debate

This paper examines the debate about the safety of kava (Piper methysticum Forst. f, Piperaceae), a plant native to Oceania, where it has a long history of traditional use. Kava became popular as an anti-anxiety treatment in Western countries in the late 1990s, but it was subsequently banned in many places due to adverse reports of liver toxicity. This paper focuses on the responses to the bans by scientists involved in kava research, contrasting their evidential culture with that employed by clinicians and regulatory officials. Cultural constructions and social negotiations of risk are shown to be context-specific, and are shaped by professional, disciplinary, and organizational factors, among others. Though the science of hepatotoxicity is uncertain enough to allow for multiple interpretations of the same data, the biomedical/clinical narrative about kava remains dominant. This case study explores the influence of these cultural, social, and political factors on the production of scientific knowledge and the assessment of benefit/risk posed by comestibles.

Kava, the anxiolytic herb: back to basics to prevent liver injury?

The use of the anxiolytic herb kava has caused toxic liver injury in Western countries and economic problems in South Pacific Islands due to tthe regulatory ban on kava. This analysis shows poor quality of kava raw material as a cause for its toxicity and suggests preventative measures by going back to the traditional use of kava for the sake of the patients and the South Pacific economy.

Kava and kava hepatotoxicity: requirements for novel experimental, ethnobotanical and clinical studies based on a review of the evidence

Kava hepatotoxicity is a well described disease entity, yet there is uncertainty as to the culprit(s). In particular, there is so far no clear evidence for a causative role of kavalactones and non-kavalactone constituents, such as pipermethystine and flavokavain B, identified from kava. Therefore, novel enzymatic, analytical, toxicological, ethnobotanical and clinical studies are now required. Studies should focus on the identification of further potential hepatotoxic constituents, considering in particular possible adulterants and impurities with special reference to ochratoxin A and aflatoxins (AFs) producing Aspergillus varieties, which should be urgently assessed and published. At present, Aspergillus and other fungus species producing hepatotoxic mycotoxins have not yet been examined thoroughly as possible contaminants of some kava raw materials. Its occurence may be facilitated by high humidity, poor methods for drying procedures and insufficient storage facilities during the time after harvest. Various experimental studies are recommended using aqueous, acetonic and ethanolic kava extracts derived from different plant parts, such as peeled rhizomes and peeled roots including their peelings, and considering both noble and non-noble kava cultivars. In addition, ethnobotanical studies associated with local expertise and surveillance are required to achieve a good quality of kava as the raw material. In clinical trials of patients with anxiety disorders seeking herbal anxiolytic treatment with kava extracts, long-term safety and efficacy should be tested using traditional aqueous extracts obtained from peeled rhizomes and peeled roots of a noble kava cultivar, such as Borogu, to evaluate the risk: benefit ratio. Concomitantly, more research should be conducted on the bioavailability of kavalactones and non-kavalactones derived from aqueous kava extracts. To be on the side of caution and to ensure lack of liver injury, kava consuming inhabitants of the kava producing or importing South Pacific islands should undergo assessment of their liver function values and serum aflatoxin levels. The primary aim is to achieve a good quality of kava raw material, without the risk of adulterants and impurities including ochratoxin A and AFs, which represent the sum of aflatoxin B1, B2, G1 and G2. Although it is known that kava may naturally be contaminated with AFs, there is at present no evidence that kava hepatotoxicity might be due to aflatoxicosis. However, appropriate studies have yet to be done and should be extended to other mould hepatotoxins, with the aim of publishing the obtained results. It is hoped that with the proposed qualifying measures, the safety of individuals consuming kava will substantially be improved.

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.

Kava hepatotoxicity solution: A six-point plan for new kava standardization

Kava-induced liver injury has been demonstrated in a few patients worldwide and appears to be caused by inappropriate quality of the kava raw material. When cases of liver disease in connection with the use of kava emerged, this was an unexpected and challenging event considering the long tradition of safe kava use. In order to prevent kava hepatotoxicity in future, a set of quality specifications as standard is essential for the preparation not only of kava drugs and kava dietary supplements in the Western world but also for traditional kava drinks in the South Pacific Islands. For all these purposes a uniform approach is required, using water based extracts from the peeled rhizomes and roots of a noble cultivar such as Borogu with at least 5 years of age at the time of harvest. Cultivated in Vanuatu for centuries, noble varieties (as defined in the Vanuatu Kava Act of December 2002) are well tolerated traditional cultivars with a good safety record. At present, Vanuatu kava legislation is inadequately enforced to meet quality issues for kava, and further efforts are required in Vanuatu, in addition to similar legislation in other kava producing South Pacific Islands. Future regulatory and commercial strategies should focus not only on the standardization of kava drugs, kava dietary supplements, and traditional kava extracts, but also on thorough surveillance during the manufacturing process to improve kava quality for safe human use. The efficacy of kava extracts to treat patients with anxiety disorders is well supported, but further clinical trials with aqueous kava extracts are necessary. We thereby propose a six-point kava solution plan: (1) use of a noble kava cultivar such as Borogu, at least 5 years old at time of harvest, (2) use of peeled and dried rhizomes and roots, (3) aqueous extraction, (4) dosage recommendation of ≤250mg kavalactones per day (for medicinal use), (5) systematic rigorous future research, and (6) a Pan Pacific quality control system enforced by strict policing. In conclusion, at different levels of responsibility, new mandatory approaches are now required to implement quality specification for international acceptance of kava as a safe and effective anxiolytic herb.

Regulatory causality evaluation methods applied in kava hepatotoxicity: are they appropriate?

Since 1998 liver injury has been assumed in some patients after the use of kava (Piper methysticum G. Forster) as an anxyolytic herbal extract, but the regulatory causality evaluation of these cases was a matter of international and scientific debate. This review critically analyzes the regulatory issues of causality assessments of patients with primarily suspected kava hepatotoxicity and suggests recommendations for minimizing regulatory risks when assessing causality in these and other related cases. The various regulatory causality approaches were based on liver unspecific assessments such as ad hoc evaluations, the WHO scale using the definitions of the WHO Collaborating Centre for International Drug Monitoring, and the Naranjo scale. Due to their liver unspecificity, however, these causality approaches are not suitable for assessing cases of primarily assumed liver related adverse reactions by drugs and herbs including kava. Major problems emerged trough the combination of regulatory inappropriate causality assessment methods with the poor data quality as presented by the regulatory agency when reassessment was done and the resulting data were heavily criticized worldwide within the scientific community. Conversely, causality of cases with primarily assumed kava hepatotoxicity is best assessed by structured, quantitative and liver specific causality algorithms such as the scale of the CIOMS (Council for International Organizations of Medical Sciences) or the main-test as its update. Future strategies should therefore focus on the implementation of structured, quantitative and liver specific causality assessment methods as regulatory standards to improve regulatory causality assessments for liver injury by drugs and herbs including 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.

Suspected black cohosh hepatotoxicity--challenges and pitfalls of causality assessment

OBJECTIVES

Black cohosh (BC) is a herbal drug or herbal dietary supplement used for treatment of menopausal symptoms. Recently, however, reports have appeared about the occurrence of rare toxic liver disease in an assumed relationship with the use of BC.

METHODS

We have analyzed and reviewed the data of all 69 reported cases with suspected BC hepatotoxicity. Causality for BC was assessed utilizing the scale of the original structured quantitative Council for International Organizations of Medical Sciences (CIOMS), or the main-test as its updated form.

RESULTS

With the hepatotoxicity specific causality assessment methods, there was an excluded, unlikely, unrelated or unassessable causality for BC in 68 of 69 cases with liver disease. One patient had a possible causality for BC and a symptomatic cholelithiasis with confounding variables of fatty liver of unknown etiology; unknown BC brand including possible herbal mixture; unknown daily BC dosage; and an unassessable duration of BC usage. In general, the cases of the 69 patients were poorly documented. Confounding variables were: failure to identify the BC product; use of herbal mixtures with multiple ingredients in addition to BC; co-medication with synthetic drugs and dietary supplements including herbal ones; missing temporal association between BC use and development of liver disease; not specified modalities of BC treatment; failure of dechallenge after BC discontinuation; pre-existing liver diseases; insufficiently excluded other liver diseases; presence of alternative liver diseases.

CONCLUSIONS

The analysis of 69 cases shows little, if any, supportive evidence for a significant hepatotoxic risk of BC.

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.

Suspected hepatotoxicity by Cimicifugae racemosae rhizoma (black cohosh, root): critical analysis and structured causality assessment

Severe hepatotoxicity has been described as spontaneous or case reports in 42 patients in assumed causal relationship with the treatment by Cimicifugae racemosae rhizoma corresponding to the root of black cohosh (BC) for postmenopausal symptoms. However, an assessment by EMEA (European Medicines Agency) has shown a possible or probable causality in only 4 out of 42 patients. A diagnostic algorithm was now applied in the 4 patients with suspected BC hepatotoxicity, which included the qualitative and quantitative causality assessment of the updated system of the Council for International Organizations of Medical Sciences (CIOMS), allowing the study to objectively assess, score and scale the probability in each case. Due to incomplete data, the case of 1 patient was not assessable. In the remaining 3 patients, a severe course of liver disease was apparent, and steroid therapy was initiated under the provisional diagnosis of drug-induced hepatic injury. The analysis shows, however, that the observed liver diseases were unrelated to drugs. Only 1 patient had a favourable course under continued steroid therapy, and the final diagnosis was autoimmune hepatitis. The 2 other patients required liver transplantation under the final diagnosis of herpetic hepatitis established now. Quantitative evaluation showed no causality for BC in all 3 patients regarding the observed severe liver disease. Using a thorough causality assessment in the form of a diagnostic algorithm we have shown that there is no evidence for a causal relationship between treatment by black cohosh and the observed liver disease in the 4 patients.

Causality assessment in hepatotoxicity by drugs and dietary supplements

Structured causality assessment of hepatotoxicity by drugs and dietary supplements (DDS) is a major clinical challenge, since temporal associations as the sole criteria for a valid evaluation are not acceptable. Initially, a clear intuition for an ad hoc evaluation is necessary, but only provisional, and must be followed by a diagnostic algorithm using a pretest, main test and post test. The evaluation is based on a variety of items such as latency period, course of alanine aminotransferase and alkaline phosphatase after DDS discontinuation, risk factors, co-medication, previous information on hepatotoxicity of the DDS, response to rechallenge, and exclusion of other diseases. It is essential that practising and hospital physicians as well as other key health professionals, such as pharmacists, gather all information required for a sound causality assessment, obviating major discussions by expert panels, manufacturers and health agencies in face of scanty and fragmentary data. Because pharmacogenetic alterations may trigger metabolic hepatotoxicity by a few DDS, levels in plasma and urine should be measured and may be helpful for diagnosis. Concomitant genotyping of cytochrome P450 and other enzymes may also be useful in future to minimize the risk of unwanted side-effects, including toxic liver disease elicited by DDS.

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.

High dose of commercial products of kava (Piper methysticum) markedly enhanced hepatic cytochrome P450 1A1 mRNA expression with liver enlargement in rats

Commercial products containing the kava plant (Piper methysticum), known to have the anxiolytic activity, are banned in several European countries and Canada because of the suspicion of a potential liver toxicity. In some reports, kava and kavalactones (major constituents of kava) inhibited activities of cytochrome P450 (CYP) isoforms including CYP1A2. On the other hand, a few studies showed that administration of kava to rats moderately increased CYP1A2 proteins in the liver. CYP1A isoforms are likely responsible for the metabolic activation of potent carcinogenic environmental toxins such as aflatoxins, benzo[a]pyrene, and others. On these bases, we have investigated the effects of administration of commercial kava products on gene expression of hepatic CYP1A isoforms in rats. A high dose (equivalent to approximately 380mg kavalactones/kg/day; 100 times of the suggested dosage for human use) of two different types of kava products for 8 days significantly increased liver weights. CYP1A2 mRNA expression was moderately increased (2.8-7.3 fold). More importantly, the high dose of kava markedly enhanced CYP1A1 mRNA expression (75-220 fold) as well as ethoxyresorufin O-deethylase activities and CYP1A1 immunoreactivities. Thus, no observed adverse effect levels of kavalactones would be lower than 380mg/kg/day. When the safety factor of kavalactones is assumed to be 100, a value most often used upon the risk analysis of chemicals and designed to account for interspecies and intraspecies variations, a number of kava product users likely ingest more kavalactones than acceptable daily intakes. Based on overall evidence, we should pay considerable attention to the possibility that kava products induce hepatic CYP1A1 expression in human especially in sensitive individuals.

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.

Hepatocellular toxicity of kava leaf and root extracts

Kava extracts are used widely for different purposes and were thought to be safe. Recently, several cases of hepatotoxicity have been published. To explore possible mechanisms of kava hepatotoxicity, we prepared and analyzed three different kava extracts (a methanolic and an acetonic root and a methanolic leaf extract), and investigated their toxicity on HepG2 cells and isolated rat liver mitochondria. All three extracts showed cytotoxicity starting at a concentration of 50 microg/ml (lactate dehydrogenase leakage) or 1 microg/ml (MTT test). The mitochondrial membrane potential was decreased (root extracts starting at 50 microg/ml) and the respiratory chain inhibited and uncoupled (root extracts) or only uncoupled (leaf extract) at 150 microg/ml, and mitochondrial beta-oxidation was inhibited by all extracts starting at 100 microg/ml. The ratio oxidized to reduced glutathione was increased in HepG2 cells, whereas the cellular ATP content was maintained. Induction of apoptosis was demonstrated by all extracts at a concentration of 150 microg/ml. These results indicate that the kava extracts are toxic to mitochondria, leading to inhibition of the respiratory chain, increased ROS production, a decrease in the mitochondrial membrane potential and eventually to apoptosis of exposed cells. In predisposed patients, mitochondrial toxicity of kava extract may explain hepatic adverse reactions of this drug.