St John's wort: a hidden risk for transplant patients

Safety and Molecular-Toxicological Implications of Cannabidiol-Rich Cannabis Extract and Methylsulfonylmethane Co-Administration

Cannabidiol (CBD) is a biologically active, non-psychotropic component of Cannabis sativa whose popularity has grown exponentially in recent years. Besides a wealth of potential health benefits, ingestion of CBD poses risks for a number of side effects, of which hepatotoxicity and CBD/herb-drug interactions are of particular concern. Here, we investigated the interaction potential between the cannabidiol-rich cannabis extract (CRCE) and methylsulfonylmethane (MSM), a popular dietary supplement, in the mouse model. For this purpose, 8-week-old male C57BL6/J mice received MSM-containing water (80 mg/100 mL) ad libitum for 17 days. During the last three days of treatment, mice received three doses of CRCE administered in sesame oil via oral gavage (123 mg/kg/day). Administration of MSM alone did not result in any evidence of liver toxicity and did not induce expression of mouse cytochrome P450 (CYP) enzymes. Administration of CRCE did produce significant (p < 0.05) increases in Cyp1a2, Cyp2b10, Cyp2c29, Cyp3a4, Cyp3a11, Cyp2c65, and Cyp2c66 messenger RNA, however, this effect was not amplified by MSM/CRCE co-treatment. Similarly, no evidence of liver toxicity was observed in MSM/CRCE dosed mice. In conclusion, short-term MSM/CRCE co-administration did not demonstrate any evidence of hepatotoxicity in the mouse model.

Herbal Nephropathy

This column is supplied by Amita Jain, MD, and Juan Jose Olivero, MD. Dr. Jain completed an internal medicine residency at Houston Methodist Hospital in Houston, Texas, and recently joined a primary care practice in Delaware. She earned a Bachelor of Medicine and Surgery (MBBS) degree, with a distinction in microbiology, from Terna Medical College at the Maharashtra University of Health Sciences in Navi Mumbai, India. Before coming to Houston, Dr. Jain completed residency training in internal medicine and allied subspecialties at the Dr. Babasaheb Ambedkar Memorial Hospital in Byculla, Mumbai. Dr. Olivero is a nephrologist at Houston Methodist Hospital and a member of the hospital's Nephrology Training Program. He obtained his medical degree from the University of San Carlos School of Medicine in Guatemala, Central America, and completed his residency and nephrology fellowship at Baylor College of Medicine in Houston, Texas.

Consideraciones acerca del reporte y la evaluación del fallo terapéutico en farmacovigilancia

Introducción. Los fallos terapéuticos representan un problema de salud pública. Aunque existe abundante información al respecto, se requiere una revisión crítica de las definiciones existentes.Objetivo. Realizar una revisión crítica del concepto actual de fallo terapéutico, su clasificación y su importancia en farmacovigilancia.Materiales y métodos. Dos revisores independientes realizaron una búsqueda sistemática de las definiciones de fallo terapéutico existentes en la literatura y de los sistemas de clasificación descritos. Con base en esta información, se realizó un análisis crítico y la proposición de una nueva definición consensuada de fallo terapéutico.Resultados. La concepción actual de fallo terapéutico es imperfecta, pues desconoce la disminución del efecto de un medicamento en el uso real en comparación con el periodo de precomercialización, donde la estimación de la eficacia se basa en ensayos clínicos controlados. Aunque la clasificación actual es adecuada, tanto el algoritmo de Vaca-González et al. como las otras herramientas empleadas para evaluar la causalidad en farmacovigilancia dependen de la calidad del reporte.Conclusiones. Es necesario perfeccionar las definiciones actuales de fallo terapéutico y mejorar la calidad del reporte para sacar el máximo provecho de los sistemas de clasificación. Se propone realizar estudios clínicos pragmáticos para los medicamentos comercializados recientemente con el fin de establecer su verdadero perfil de efectividad y seguridad.

What has been the impact of the Traditional Herbal Registration (THR) scheme in the UK on information provided with herbal products bought over the counter?

BACKGROUND

In 2011 there was a strengthening of European Union (EU) legislation on the licencing of herbal products which, in the UK, resulted in the introduction of the Traditional Herbal Registration (THR) scheme. This scheme sets out standards for the safety and quality of herbal medicines and includes the provision of information to the customer on the safe use of the product. The aim of this study is to replicate a survey undertaken in 2011, prior to the implementation of the THR scheme, and evaluate the impact of this scheme on the information provided with herbal products bought over-the-counter.

METHODS

We undertook a survey on 5 herbal products commonly available over-the-counter (St John's wort, echinacea, Ginkgo biloba, Asian ginseng, garlic). The information was searched for key safety messages identified by the National Center for Complementary and Integrative Health (NCCIH). We also explored the presence of risk of harm information.

RESULTS

We recorded a rise in the number of products registered with the THR scheme (37% in 2016 compared to 7% in 2011). We also identified a reduction in the number of products that did not contain key safety information (75% in 2011 compared to 20% of products obtained in 2016). Risk of harm information was only communicated in products containing a PIL. We identified more products containing frequency of risk of harm information but this was not statistically significant.

CONCLUSION

The introduction of the THR scheme appears to be associated with an increase in the provision of information about key safety messages on the safe use of herbal products. However, it is important to note that at least half of the products on the market that are not included in the THR scheme do not contain any information about their safe use; this includes information about precautions, interactions and side effects. The use of NCCIH herbal monographs replicated the methods used in the previous study; we recognise that the use of a different resource might effect the appraisal of the information provided. We also acknowledge that surveying presence of information does not assure that the latter is effectively communicated to patients, for which a close textual analysis would be required. While it is promising that more information is available after the introduction of the THR scheme, the public needs to be informed about ways to optimise safe use of all herbal products.

Interactions between herbs and conventional drugs: overview of the clinical data

This article provides an overview of the clinical evidence of interactions between herbal and conventional medicines. Herbs involved in drug interactions--or that have been evaluated in pharmacokinetic trials--are discussed in this review. While many of the interactions reported are of limited clinical significance and many herbal products (e.g. black cohosh, saw palmetto, echinacea, hawthorn and valerian) seem to expose patients to minor risk under conventional pharmacotherapy, a few herbs, notably St. John's wort, may provoke adverse events sufficiently serious to endanger the patients' health. Healthcare professionals should remain vigilant for potential interactions between herbal medicines and prescribed drugs, especially when drugs with a narrow therapeutic index are used.

Herb-drug interactions with St John's wort (Hypericum perforatum): an update on clinical observations

St John's wort (SJW) extracts, prepared from the aerial parts of Hypericum perforatum, contain numerous pharmacologically active ingredients, including naphthodianthrones (e.g., hypericin and its derivatives), phloroglucinols derivatives (e.g., hyperforin, which inhibits the reuptake of a number of neurotransmitters, including serotonin), and flavonoids. Such extracts are widely used for the treatment of mild-to-moderate depression. As a monotherapy, SJW has an encouraging safety profile. However, relevant and, in some case, life-threatening interactions have been reported, particularly with drugs which are substrate of cytochrome P450 and/or P-glycoprotein. Well-documented SJW interactions include (1) reduced blood cyclosporin concentration, as suggested by multiple case reports as well as by clinical trials, (2) serotonin syndrome or lethargy when SJW was given with serotonin reuptake inhibitors, (3) unwanted pregnancies in women while using oral contraceptives and SJW, and (4) reduced plasma drug concentration of antiretroviral (e.g., indinavir, nevirapine) and anticancer (i.e., irinotecan, imatinib) drugs. Hyperforin, which is believed to contribute to the antidepressant action of St John's wort, is also strongly suspected to be responsible of most of the described interactions.

Nuclear receptors CAR and PXR: Molecular, functional, and biomedical aspects

Nuclear receptors (NRs) are ligand-activated transcription factors sharing a common evolutionary history and having similar sequence features at the protein level. Selective ligand(s) for some NRs is not known, therefore these NRs have been named "orphan receptors". Whenever ligands have been recognized for any of the orphan receptor, it has been categorized and grouped as "adopted" orphan receptor. This group includes the constitutive androstane receptor (CAR) and the pregnane X receptor (PXR). They function as sensors of toxic byproducts derived from endogenous metabolites and of exogenous chemicals, in order to enhance their elimination. This unique function of CAR and PXR sets them apart from the steroid hormone receptors. The broad response profile has established that CAR and PXR are xenobiotic sensors that coordinately regulate xenobiotic clearance in the liver and intestine via induction of genes involved in drug and xenobiotic metabolism. In the past few years, research has revealed new and mostly unsuspected roles for CAR and PXR in modulating hormone, lipid, and energy homeostasis as well as cancer and liver steatosis. The purpose of this review is to highlight the structural and molecular bases of CAR and PXR impact on human health, providing information on mechanisms through which diet, chemical exposure, and environment ultimately impact health and disease.

Application and interpretation of hPXR screening data: Validation of reporter signal requirements for prediction of clinically relevant CYP3A4 inducers

A human pregnane X receptor (PXR) reporter-gene assay was established and validated using 19 therapeutic agents known to be clinical CYP3A4 inducers, 5 clinical non-inducers, and 6 known inducers in human hepatocytes. The extent of CYP3A4 induction (measured as RIF ratio in comparison to rifampicin) and EC50 was obtained from the dose-response curve. All of the clinical inducers (19/19) and human hepatocyte inducers (6/6) showed positive responses in the PXR assay. One out of five clinical non-inducers, pioglitazone, also showed a positive response. An additional series of 18 commonly used drugs with no reports of clinical induction was also evaluated as putative negative controls. Sixteen of these were negative (89%), whereas two of these, flutamide and haloperidol showed 16-fold (RIF ratio 0.79) and 10-fold (RIF ratio 0.48) maximal induction, respectively in the reporter-gene system. Flutamide and haloperidol were further demonstrated to cause CYP3A4 induction in human cryopreserved hepatocytes based on testosterone 6beta-hydroxylation activity. The induction potential index calculated based on the maximum RIF ratio, EC50, and in vivo maximum plasma concentration was used to predict the likelihood of CYP3A4 induction in humans. When the induction potential index is greater than 0.08, the compound is likely to cause induction in humans. A high-throughput screening strategy was developed based on the validation results at 1microM and 10microM for the same set of drugs. A RIF ratio of 0.4 was set as more practical screening cut-off to minimize the possibility of generating false positives. Thus, a tiered approach was implemented to use the human PXR reporter-gene assay from early lead optimization to late lead characterization in drug discovery.

The effect of St John's wort extracts on CYP3A: a systematic review of prospective clinical trials

AIM

The aim of this systematic review was to assess the quality and outcomes of clinical trials investigating the effect of St John's wort extracts on the metabolism of drugs by CYP3A.

METHODS

Prospective clinical trials assessing the effect of St John's wort (SJW) extracts on metabolism by CYP3A were identified through computer-based searches (from their inception to May 2005) of Medline, Cinahl, PsycINFO, AMED, Current Contents and Embase, hand-searches of bibliographies of relevant papers and consultation with manufacturers and researchers in the field. Two reviewers selected trials for inclusion, independently extracted data and recorded details on study design.

RESULTS

Thirty-one studies met the eligibility criteria. More than two-thirds of the studies employed a before-and-after design, less than one-third of the studies used a crossover design, and only three studies were double-blind and placebo controlled. In 12 studies the SJW extract had been assayed, and 14 studies stated the specific SJW extract used. Results from 26 studies, including all of the 19 studies that used high-dose hyperforin extracts (>10 mg day(-1)), had outcomes consistent with CYP3A induction. The three studies using low-dose hyperforin extracts (<4 mg day(-1)) demonstrated no significant effect on CYP3A.

CONCLUSION

There is reasonable evidence to suggest that high-dose hyperforin SJW extracts induce CYP3A. More studies are required to determine whether decreased CYP3A induction occurs after low-dose hyperforin extracts. Future studies should adopt study designs with a control phase or control group, identify the specific SJW extract employed and provide quantitative analyses of key constituents.

Analysis of the Inhibitory Potential ofGinkgo biloba,Echinacea purpurea, andSerenoa repenson the Metabolic Activity of Cytochrome P450 3A4, 2D6, and 2C9

OBJECTIVE

To study the potential of three top-selling herbal products, Ginkgo biloba, Echinacea purpurea, and Serenoa repens to inhibit the in vitro enzymatic activity of three of the most important drug metabolizing enzymes, cytochrome P450 (CYP) 3A4, 2D6, and 2C9.

METHODS

High throughput CYP inhibition screening was used to test the inhibitory capacity of extracts of commercially available herbal medications on the metabolism of CYP enzyme substrates.

RESULTS

S. repens showed potent inhibition of the metabolic activity of all three CYPs tested. The effects of G. biloba and E. purpurea varied. E. purpurea demonstrated mild inhibition of CYP3A4 activity with 7- benzyloxy-4-trifluoromethylcoumarin (BFC) as the model substrate, but mild inducing effects in the presence of the model substrate resorufin benzyl ether (BzRes). Little effect on CYP2D6 and moderate inhibition of CYP2C9 was seen with both E. purpurea and G. biloba. G. biloba also showed mild-to-moderate inhibition of CYP3A4 depending on the model substrate.

CONCLUSIONS

The inhibitory capacity of herbal products varies depending on the concentrations of the model substrate and the herbal extract, as well as the identity of the model substrate, as demonstrated by the varied effects of CYP3A4 enzymatic activity with different model substrates. The potential for strong adverse interactions exists for Serenoa repens, which was a potent inhibitor of all three CYPs examined. Physicians are encouraged to advise patients of the risks of combining herbal products with prescription medications.

The obstetrician and depression during pregnancy

The objective of this article is to review the literature as to the presence of depression during and after pregnancy and some of its clinical implications; and to present a simple statistical aide for screening purposes. Clinical depression affects at least one in five women of childbearing age. During pregnancy, this figure does not diminish and not only signals problems for the pregnant woman but also for the child, measurably so into adolescence. Postpartum depression, but even more so antepartum depression, are medical conditions that negatively affect mother and child, and need to be detected as early as possible to avoid or limit the use of pharmacological treatments with possible side effects. The obstetrician should regularly test for depression from the very first moments of planning for a child, and use the test results for a "pregnancy mood profile". This profile requires only a few minutes and is very simple to complex. It could serve for early control of depression during pregnancy as well as determine the risk for postpartum depression and thus serve as a pre-alert for postpartum suicide.

Immunosuppressants

Immunosuppressants are prescribed to prevent rejection of transplanted tissues and organs and are also used in the treatment of autoimmune disorders. Consultation-liaison psychiatrists increasingly encounter patients taking these agents as the number of transplant recipients increases and the indications for the use of immunosuppressants expands. These drugs have potentially deleterious physical, mental, and biochemical side effects. In addition, transplant recipients and patients with autoimmune disorders commonly have comorbid illnesses that require pharmacologic treatment. The management of these patients is challenging secondary to the severity of these illnesses, the number of medications prescribed, and the potential for adverse drug-drug interactions. Knowledge of the pharmacokinetic properties of these drugs and the potential for serious drug-drug interactions that cause alterations in serum levels of the immunosuppressant medications is essential. Increased serum levels may cause serious toxic effects and decreased serum levels may lead to rejection of the transplanted organ or worsening of the autoimmune disorder. Adverse events may also occur when serum levels of medications prescribed for comorbid illnesses are altered by administration of immunosuppressants. The pharmacokinetic drug-drug interaction profiles of the glucocorticoids, cyclosporine, tacrolimus, sirolimus, mycophenolate mofetil, azathioprine, and monoclonal antibodies are discussed in this review.

St John's wort: a systematic review of adverse effects and drug interactions for the consultation psychiatrist

St. John's wort is an herb commonly used in Europe for decades and more recently the topic of scientific investigation in this country. St. John's wort has been found more effective than placebo and equally as effective as tricyclic antidepressants in the short-term management of mild-to-moderate depression. Comparisons to selective serotonin reuptake inhibitors have provided equivocal data. While it is generally well tolerated in clinical use, there is accumulating evidence of significant interactions with drugs. This evidence-based presentation of the literature includes a brief description of pharmacodynamics and clinical applications, followed by a systematic review of adverse effects, toxicity, and drug interactions.

Herbal agents and over-the-counter medications in pregnancy

Exposures to over-the-counter and herbal products are frequent in pregnant women. Limited information exists on the effects of many of these agents during pregnancy; it is not safe to assume that because these products are available without a prescription that they are without danger to the pregnant woman and her fetus. The basic principles utilized in deciding whether to employ prescription medications such as dose, embryological timing and potential toxic fetal effects also apply to herbal medications and over-the-counter agents. Conventional reasoning indicates that maternal exposure to poorly studied medications should be limited; therefore, many of these agents should be used sparingly or not at all by pregnant women. This chapter includes a review of selected herbal and over-the-counter agents, including those which are considered to be acceptable for use in pregnancy.

Alterations in cyclosporin A pharmacokinetics and metabolism during treatment with St John's wort in renal transplant patients

AIM

This study investigated the effects of St John's wort extract (SJW) on the pharmacokinetics and metabolism of the immunosuppressant cyclosporin A (CSA).

METHODS

In an open-label study, 11 renal transplant patients received 600 mg SJW extract daily for 14 days in addition to their regular regimen of CSA. Blood concentrations of CSA and its metabolites AM1, AM1C, AM9, AM19, and AM4N were measured by HPLC.

RESULTS

After 2 weeks of SJW coadministration, dose-corrected AUC0-12, Cmax and Ctrough values for CSA decreased significantly by 46%[geometric mean ratio baseline/SJW (95% CI): 1.83 (1.63-2.05)], 42%[1.72 (1.42-2.08)], and 41%[1.70 (1.17-2.47)], respectively. CSA doses were increased from a median of 2.7 mg day(-1) kg(-1) at baseline to 4.2 mg day(-1) kg(-1) at day 15, with the first dose adjustment required only 3 days after initiation of SJW treatment. Additionally, the metabolite pattern of CSA was substantially altered during SJW treatment. Whereas dose-corrected AUC values for AM1, AM1c and AM4N significantly decreased by 59%, 61%, and 23% compared with baseline, AUC values for AM9 and AM19 were unchanged. Following the increase in CSA dose, observed AUC and Cmax values for AM9, AM19, and AM4N increased by 20-51% and 43-90%, respectively.

CONCLUSION

Administration of SJW extract to patients receiving CSA treatment resulted in a rapid and significant reduction of plasma CSA concentrations. Additionally, the substantial alterations in CSA metabolite kinetics observed may affect the toxicity profile of the drug.