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

Evidence of the interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and Chinese herbal medicine: A scoping review

OBJECTIVES

Chinese herbal medicine (CHM) has been shown to be effective in autoimmune rheumatic diseases, but harmful herb-drug interactions might be inherent. We aim to review the evidence regarding herb-drug interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and CHM.

METHODS

We searched PubMed, EMBASE and CINAHL from inception till 30 April 2023 using keywords that encompassed 'herb-drug interactions', 'herbs' and 'immunosuppressants'. Articles were included if they contained reports about interactions between immunosuppressive drugs used in the treatment of rheumatic diseases with CHM. Level of evidence for each pair of interaction was graded using the algorithm developed by Colalto.

RESULTS

A total of 65 articles and 44 unique pairs of interactions were identified. HDIs were reported for cyclophosphamide, cyclosporine, tacrolimus, methotrexate, mycophenolic acid, glucocorticoids, sulfasalazine, tofacitinib and biologic disease-modifying antirheumatic drugs. Among these, cyclosporine (n = 27, 41.5%) and tacrolimus (n = 19, 29.2%) had the highest number of documented interactions. Hypericum perforatum had the highest level of evidence of interaction with cyclosporine and tacrolimus. Consumption reduced the bioavailability and therapeutic effects of the drugs. Schisandra sphenanthera had the highest level of evidence of interaction with tacrolimus and increased the bioavailability of the drug. Majority of the articles were animal studies.

CONCLUSION

Overall level of evidence for the included studies were low, though interactions between cyclosporine, tacrolimus, Hypericum perforatum and Schisandra sphenanthera were the most and well-documented. Healthcare professionals should actively enquire about the concurrent use of CHM in patients, especially when drugs with a narrow therapeutic index are consumed.

Hypericum perforatum: Traditional uses, clinical trials, and drug interactions

Hypericum perforatum (Hypericaceae), known as Saint John’s wort (SJW), has been used in different systems of traditional medicine such as Chinese traditional medicine, Greek traditional medicine, and Islamic traditional medicine. The plant and its active constituents such as hyperforin and hypericin have a wide range of medicinal uses, particularly as anti-depressant, wound-healing, and antibacterial agents. In recent decades, many clinical trials have been performed to investigate the safety and efficacy of this medicinal plant. However, to the best on our knowledge, there is no comprehensive review article in this regard. In the current study, we aim to have a comprehensive review of the clinical trials of SJW to evaluate its efficacy and safety as well as its application in traditional medicine. Clinical studies investigating the safety, interactions, and efficacy of SJW were identified and summarized, including contributions from 2000 until December 2021. According to the results, these clinical studies were divided into three main categories based on the type of disease: psychiatric, endocrine, and skin problems. Important details of the studies, including the type and duration of the study, the type and percentage of the effective compounds or the extract used, the number of patients, and the obtained results were also discussed. In addition, co-administration and drug interaction of SJW with other drugs were summarized. SJW is a valuable medicinal plant, especially for psychiatric disorders. However, precautions should be taken while administrating the plant.

Phytochemicals That Interfere With Drug Metabolism and Transport, Modifying Plasma Concentration in Humans and Animals

Phytochemicals (Pch) present in fruits, vegetables and other foods, are known to inhibit or induce drug metabolism and transport. An exhaustive search was performed in five databases covering from 2000 to 2021. Twenty-one compounds from plants were found to modulate CYP3A and/or P-gp activities and modified the pharmacokinetics and the therapeutic effect of 27 different drugs. Flavonols, flavanones, flavones, stilbenes, diferuloylmethanes, tannins, protoalkaloids, flavans, hyperforin and terpenes, reduce plasma concentration of cyclosporine, simvastatin, celiprolol, midazolam, saquinavir, buspirone, everolimus, nadolol, tamoxifen, alprazolam, verapamil, quazepam, digoxin, fexofenadine, theophylline, indinavir, clopidogrel. Anthocyanins, flavonols, flavones, flavanones, flavonoid glycosides, stilbenes, diferuloylmethanes, catechin, hyperforin, alkaloids, terpenes, tannins and protoalkaloids increase of plasma concentration of buspirone, losartan, diltiazem, felodipine, midazolam, cyclosporine, triazolam, verapamil, carbamazepine, diltiazem, aripiprazole, tamoxifen, doxorubicin, paclitaxel, nicardipine. Interactions between Pchs and drugs affect the gene expression and enzymatic activity of CYP3A and P-gp transporter, which has an impact on their bioavailability; such that co-administration of drugs with food, beverages and food supplements can cause a subtherapeutic effect or overdose. Therefore, it is important for the clinician to consider these interactions to obtain a better therapeutic effect.

Drug-Drug Interactions With Over-The-Counter Medicines: Mind the Unprescribed

BACKGROUND

This review provides a summary of the currently available clinical data on drug-drug interactions (DDIs) involving over-the-counter (OTC) medicines. It aims to educate and increase awareness among health care providers and to support decisions in daily practice.

METHODS

An extensive literature search was performed using bibliographic databases available through PubMed.gov. An initial structured search was performed using the keywords "drug-drug-interaction AND (over-the-counter OR OTC)," without further restrictions except for the language. The initial results were screened for all described DDIs involving OTC drugs, and further information was gathered specifically on these drugs using dedicated database searches and references found in the bibliography from the initial hits.

RESULTS

From more than 1200 initial hits (1972-June 2021), 408 relevant publications were screened for DDIs involving OTC drugs, leading to 2 major findings: first, certain types of drug regimens are more prone to DDIs or have more serious DDI-related consequences, such as antiretroviral, anti-infective, and oral anticancer therapies. Second, although most DDIs involve OTC drugs as the perpetrators, some prescription drugs (statins or phosphodiesterase-5 inhibitors) that currently have OTC status can be identified as the victims in DDIs. The following groups were identified to be frequently involved in DDIs: nonsteroidal anti-inflammatory drugs, food supplements, antacids, proton-pump inhibitors, H2 antihistamines, laxatives, antidiarrheal drugs, and herbal drugs.

CONCLUSIONS

The most significant finding was the lack of high-quality evidence for commonly acknowledged interactions. High-quality interaction studies involving different phenotypes in drug metabolism (cytochrome P450) and distribution (transporters) are urgently needed. This should include modern and critical drugs, such as oral anticancer medications and direct oral anticoagulants.

Treatment of Lupus Nephritis from Iranian Traditional Medicine and Modern Medicine Points of View: A Comparative Study

Objective

Nephritis or kidney inflammation is characterized as one of the most common renal disorders leading to serious damage to the kidneys. Nephritis, especially lupus nephritis (LN), has remained as the main cause of chronic renal failure which needs serious therapeutic approaches such as dialysis and kidney transplant. Heredity, infection, high blood pressure, inflammatory diseases such as lupus erythematosus and inflammatory bowel disease, and drug-related side effects are known as the main causes of the disease. According to Iranian traditional medicine (ITM), infectious diseases and fever are the main reasons of nephritis, which is called “Varam-e-Kolye” (VK).

Results

There are various plant-based remedies recommended by ITM for the treatment of nephritis, as discussed herein, comparing with those available in the modern medicine. There is no definite cure for the treatment of nephritis, and immunosuppressive drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, antibiotics, diuretics, analgesics, and finally dialysis and kidney transplantation are usually used. Based on the efficacy of medicinal plants, jujube (Ziziphus jujuba), almond (Prunus amygdalus), pumpkin seeds (Cucurbita pepo), purslane (Portulaca oleracea), and fig (Ficus carica) were found to be effective for the treatment of kidney inflammation in ITM.

Conclusion

Considering the fact that there is no efficient strategy for the treatment of nephritis, use of herbal medicine, particularly based on the fruits or nuts that have been safely used for several years can be considered as a versatile supplement along with other therapeutic methods.

Herbal Interaction With Chemotherapeutic Drugs-A Focus on Clinically Significant Findings

One of the most consequential risks associated with the concomitant use of herbal products and chemotherapeutic agents is herb-drug interactions. The risk is higher in patients with chronic conditions taking multiple medications. Herb-drug interaction is particularly undesirable in cancer management because of the precipitous dose-effect relationship and toxicity of chemotherapeutic agents. The most common mechanism of herb-drug interaction is the herbal-mediated inhibition and/or induction of drug-metabolizing enzymes (DME) and/or transport proteins leading to the alteration in the pharmacokinetic disposition of the victim drug. Most mechanistic research has focused on laboratory-based studies, determining the effects of herbal products on DMEs and extrapolating findings to predict clinical relevance; however, not all DME/transporter protein inhibition/induction results in clinical herb-drug interaction. This study reviews relevant literature and identified six herbal products namely echinacea, garlic, ginseng, grapefruit juice, milk thistle, and St John's wort, which have shown interactions with chemotherapeutic agents in humans. This focus on clinically significant herb-drug interaction, should be of interest to the public including practitioners, researchers, and consumers of cancer chemotherapy.

A Drug-drug Interaction Between Cyclosporine and Nystatin

We present a case of increased cyclosporine concentration and liver function right after the combinational use of cyclosporine and nystatin, which indicated a drug-drug interaction between them. Both the concentration and liver function were decreased after discontinuation of nystatin and remained normal after taking on cyclosporine again. To our knowledge, this is the first case report of the interactions between nystatin and cyclosporine. Enteric P-glycoprotein could play an important role in the pharmacokinetic profile of cyclosporine, which needs further identification by physicians and pharmacists.

A regulatory science viewpoint on botanical-drug interactions

There is a continued predisposition of concurrent use of drugs and botanical products. Consumers often self-administer botanical products without informing their health care providers. The perceived safety of botanical products with lack of knowledge of the interaction potential poses a challenge for providers and both efficacy and safety concerns for patients. Botanical–drug combinations can produce untoward effects when botanical constituents modulate drug metabolizing enzymes and/or transporters impacting the systemic or tissue exposure of concomitant drugs. Examples of pertinent scientific literature evaluating the interaction potential of commonly used botanicals in the US are discussed. Current methodologies that can be applied to advance our efforts in predicting drug interaction liability is presented. This review also highlights the regulatory science viewpoint on botanical–drug interactions and labeling implications.

Understanding drug interactions with St John's wort (Hypericum perforatum L.): impact of hyperforin content

Objective

The aim of this study was to review herb–drug interaction studies with St John's wort (Hypericum perforatum L.) with a focus on the hyperforin content of the extracts used in these studies.

Methods

PUBMED was systematically searched to identify studies describing pharmacokinetic interactions involving St John's wort. Data on study design and the St John's wort extract or product were gathered to extract hyperforin content and daily dose used in interaction studies.

Key findings

This analysis demonstrates that significant herb–drug interactions (resulting in a substantial change in systemic exposure) with St John's wort products were associated with hyperforin daily dosage. Products that had a daily dose of <1 mg hyperforin were less likely to be associated with major interaction for drugs that were CYP3A4 or p-glycoprotein substrates. Although a risk of interactions cannot be excluded even for low-dose hyperforin St. John's wort extracts, the use of products that result in a dose of not more than 1 mg hyperforin per day is recommended to minimise the risk of interactions.

Conclusions

This review highlights that the significance of herb–drug interactions with St John's wort is influenced by the nature of the herbal medicines product, particularly the hyperforin content.

Effect of Oridonin on Cytochrome P450 Expression and Activities in HepaRG Cell

Oridonin, the major terpene found in Rabdosia rubescens, is widely used as a dietary supplement or therapeutic drug. However, the effects of oridonin on major CYP450s are still unclear. As oridonin can enhance the effect of other clinical drugs, in this study, we investigated the influence of oridonin on CYP450s mRNA expression and its impact on activities in human HepaRG cell to evaluate the safety by studying its potential drug interaction. HepaRG cells were cultured with series concentrations of oridonin (1, 5, 10, and 20 μmol/L), and the major CYP450s mRNA and protein expression, as well as enzyme activities were analyzed by real-time polymerase chain reaction, Western blot analysis and UPLC-MS/MS-based metabolite assay. In general, ordonin has induced effects on the major member of CYP450s mRNA and protein expression, as well as on the enzyme activity in human HepaRG cells, especially on CYP3A4 and CYP2C9. To our knowledge, this is the first systematic research about the inductive effects of oridonin on the major member of CYP450s in human cell line. These results may provide at least partly of the basis for potential drug-drug interactions and oridonin should be used with caution to avoid potential risk.

Adulteration and Counterfeiting of Online Nutraceutical Formulations in the United States: Time for Intervention?

Global prevalence of nutraceuticals is noticeably high. The American market is flooded with nutraceuticals claiming to be of natural origin and sold with a therapeutic claim by major online retail stores such as Amazon and eBay. The objective of this commentary is to highlight the possible problems of online-sold nutraceuticals in the United States with respect to claim, adulterants, and safety. Furthermore, there is a lack of strict regulatory laws governing the sales, manufacturing, marketing, and label claims of nutraceutical formulations currently sold in the U.S. market. Major online retail stores and Internet pharmacies aid the widespread sale of nutraceuticals. Finally, according to the literature, many of these products were found to be either counterfeit or adulterated with active pharmaceutical ingredients (API) and mislabeled as being safe and natural. Therefore, regulatory authorities along with the research community should intervene to draw attention to these products and their possible effects.

Natural Health Product Interactions with Medication

Natural health products (or dietary supplements) refer to those products found in oral dosage forms, containing 1 or more active ingredients considered to be a nutrient, an herbal product, or any other nonnutrient/nonherbal substance. Their use continues to increase in the general population and in patients seen by nutrition support clinicians. Aside from an appraisal of product safety and effectiveness, attention should be paid to the potential for these product ingredients to interact with medication. Estimates are that at least 15 million adults in the United States are at risk for supplement-drug interactions. These can occur through both pharmacokinetic and pharmacodynamic mechanisms. This review describes the influence of dietary supplements on both the disposition and the effect of medication and provides numerous examples. Patients at greatest risk for interactions are those with chronic disease, who use multiple medications-particularly those with a narrow therapeutic range-have genetic variants in drug metabolism, impaired organ function, and are at either end of the age spectrum. Knowledge of the specific effects on drug absorption, metabolism, and effect is still incomplete. Relative to the large number of possible interactions between supplements and medication, only a small number of combinations have been examined or reported. The greatest limiting factor remains the quality or reliability of the existing evidence, as many widely accepted interactions are only theoretical based either on in vitro data or known pharmacology. A distinction needs to be clearly drawn between "documented" interactions and "potential" interactions. Although drug-drug interactions have been widely recognized, supplement-drug interactions may be as important to recognize, report, and manage.

Herbal Medicines: challenges in the modern world. Part 5. status and current directions of complementary and alternative herbal medicine worldwide

INTRODUCTION

Herbal medicine (HM) use is growing worldwide. Single herb preparations, ethnic and modern HM formulations are widely used as adjunct therapies or to improve consumer wellbeing. Areas covered: This final part in the publication series summarizes common tendencies in HM use as adjunct or alternative medicine, education of healthcare professionals and consumers, current and proposed guidelines regulating of production. We discuss potential HM-HM and HM-drug interactions that could lead to severe adverse events in situations where HMs are taken without proper medical professional oversight. Expert commentary: A number of serious problems have arisen with the steady global increase in HM use. HM interaction with conventional drugs (CD) may result in inadequate dosing of CD or adverse reactions; HM-HM interaction within herbal supplements could lead to toxicity of formulations. Inadequate education of clinicians and patients regarding medicinal properties of HMs must be addressed regionally and globally to ensure consumer safety.

Pharmacokinetic Herb-Drug Interactions: Insight into Mechanisms and Consequences

Herbal medicines are currently in high demand, and their popularity is steadily increasing. Because of their perceived effectiveness, fewer side effects and relatively low cost, they are being used for the management of numerous medical conditions. However, they are capable of affecting the pharmacokinetics and pharmacodynamics of coadministered conventional drugs. These interactions are particularly of clinically relevance when metabolizing enzymes and xenobiotic transporters, which are responsible for the fate of many drugs, are induced or inhibited, sometimes resulting in unexpected outcomes. This article discusses the general use of herbal medicines in the management of several ailments, their concurrent use with conventional therapy, mechanisms underlying herb-drug interactions (HDIs) as well as the drawbacks of herbal remedy use. The authors also suggest means of surveillance and safety monitoring of herbal medicines. Contrary to popular belief that "herbal medicines are totally safe," we are of the view that they are capable of causing significant toxic effects and altered pharmaceutical outcomes when coadministered with conventional medicines. Due to the paucity of information as well as sometimes conflicting reports on HDIs, much more research in this field is needed. The authors further suggest the need to standardize and better regulate herbal medicines in order to ensure their safety and efficacy when used alone or in combination with conventional drugs.

A Model for Predicting the Interindividual Variability of Drug-Drug Interactions

Pharmacokinetic drug-drug interactions are frequently characterized and quantified by an AUC ratio (Rauc). The typical value of the AUC ratio in case of cytochrome-mediated interactions may be predicted by several approaches, based on in vitro or in vivo data. Prediction of the interindividual variability of Rauc would help to anticipate more completely the consequences of a drug-drug interaction. We propose and evaluate a simple approach for predicting the standard deviation (sd) of Ln(Rauc), a metric close to the interindividual coefficient of variation of Rauc. First, a model was derived to link sd(Ln Rauc) with the substrate fraction metabolized by each cytochrome and the potency of the interactors, in case of induction or inhibition. Second, the parameters involved in these equations were estimated by a Bayesian hierarchical model, using the data from 56 interaction studies retrieved from the literature. Third, the model was evaluated by several metrics based on the fold prediction error (PE) of sd(Ln Rauc). The median PE was 0.998 (the ideal value is 1) and the interquartile range was 0.96-1.03. The PE was in the acceptable interval (0.5 to 2) in 52 cases out of 56. Fourth, a surface plot of sd(Ln Rauc) as a function of the characteristics of the substrate and the interactor has been built. The minimal value of sd(Ln Rauc) was about 0.08 (obtained for Rauc = 1) while the maximal value, 0.7, was obtained for interactions involving highly metabolized substrates with strong interactors.

Isochlorogenic acid A affects P450 and UGT enzymes in vitro and in vivo

Isochlorogenic acid A (ICQA), which has anti-inflammatory, hepatoprotective, and antiviral properties, is commonly presented in fruits, vegetables, coffee, plant-based food products, and herbal medicines. These herbal medicines are usually used in combination with other medicines in the clinic. However, little is known about the regulatory effects of ICQA on drug-metabolizing enzymes and the herb-drug interactions. In the present study, we evaluated the inhibitory potentials of ICQA on CYP1A2, CYP2C9, CYP2C19, CYP3A4, CYP2D6, and CYP2E1 in vitro based on a cocktail approach. The P450 and UGT activities in mice treated with ICQA for a prolonged period were also determined. Our results demonstrated that ICQA exhibited a weak inhibitory effect on CYP2C9 in human liver microsomes with IC₅₀ being 57.25 μmol·L^-1 and Ki being 26.77 μmol·L^-1. In addition, ICQA inhibited UGT1A6 activity by 25%, in the mice treated with ICQA (i.p.) at 30 mg·kg^-1 for 14 d, compared with the control group. Moreover, ICQA showed no mechanism-based inhibition on CYP2C9 or UGT1A6. In conclusion, our results further confirm a safe use of ICQA in clinical practice.

Use of Antidepressant Drugs in Transplant Recipients

Depression is the most prevalent psychiatric disorder in transplant recipients and may lead to noncompliance and negative outcomes without psychosocial and pharmacologic interventions. The pharmacologic treatment of depression in this patient population is complicated by complex immunosuppressant drug regimens and multiple potential drug interactions that can adversely affect the newly transplanted organs. This review provides a brief overview of the currently available antidepressant medications and highlights the clinically important features each class of agents in transplant recipients. Newer agents selective serotonin reuptake inhibitors, venlafaxine, bupropion, nefazodone, and mirtazapine are discussed as well as tricyclic antidepressants and monoamine oxidase inhibitors. A brief discussion of St. John's wort and its impact on posttransplant drug therapy is also included.

Chinese herbal medicines and chronic kidney disease: a positive outcome in a large patient study in Taiwan

The worth of traditional Chinese herbal medicines for chronic kidney disease (CKD) patients remains in debate. Lin et al. used a research database in Taiwan to identify almost 25,000 stage 3-5 newly diagnosed CKD patients who, after diagnosis, did or did not use prescribed Chinese herbal medicines for CKD. Reduced risk of end-stage kidney disease from specific traditional medicines warrants reflection on a CKD therapy resource that is largely ignored by Western medicine.

Intake of St John's wort improves the glucose tolerance in healthy subjects who ingest metformin compared with metformin alone

AIMS

Our objective was to investigate the steady-state pharmacokinetic and pharmacodynamic interaction between the antidepressive herbal medicine St John's wort and the antidiabetic drug metformin.

METHODS

We performed an open cross-over study in 20 healthy male subjects, who received 1 g of metformin twice daily for 1 week with and without 21 days of preceding and concomitant treatment with St John's wort. The pharmacokinetics of metformin was determined, and a 2 h oral glucose tolerance test was performed.

RESULTS

St John's wort decreased the renal clearance of metformin but did not affect any other metformin pharmacokinetic parameter. The addition of St John's wort decreased the area under the glucose concentration-time curve [702 (95% confidence interval, 643-761) vs. 629 min*mmol/L (95% confidence interval, 568-690), P = 0.003], and this effect was caused by a statistically significant increase in the acute insulin response.

CONCLUSIONS

St John's wort improves glucose tolerance by enhancing insulin secretion independently of insulin sensitivity in healthy male subjects taking metformin.

Ophiopogon japonicus strains from different cultivation regions exhibit markedly different properties on cytotoxicity, pregnane X receptor activation and cytochrome P450 3A4 induction

Maidong, known as Ophiopogon japonicus, is one of the two basic ingredients of Shenmai injection, which is a widely used herbal preparation in traditional Chinese medicine (TCM) for the treatment of atherosclerotic coronary heart disease and viral myocarditis. Previously, the ethanol extract of Maidong activated the pregnane X receptor (PXR) signaling pathway and induced the cytochrome P450 3A4 (CYP3A4) reporter gene and raised the concern of herb-drug interactions (HDIs) when Maidong was used in combination with prescribed drugs metabolized by CYP3A4. Therefore, the present study further investigated and compared the differences of the ethanol and aqueous extracts (ee- and ae-, respectively) of two Maidong strains, known as Zhe Maidong (ZM) and Chuan Maidong (CM). Cytotoxicity, PXR activation and CYP3A4 induction by the 3-(4,5)-dimethylthiahiazo-(-z-y1)-3,5-diphenytetrazoliumromide assay, reporter gene assay and reverse transcription-quantitative polymerase chain reaction analysis were examined. The observations showed that ee-ZM demonstrated a significantly higher cytotoxicity, a relatively weaker PXR activation capability and a markedly stronger CYP3A4-inducing capacity than ee-CM. Compared to ae-CM, ae-ZM exhibited only a slight or no difference on cytotoxicity and CYP3A4 induction, while a significant lower level of PXR activation was apparent. Collectively, Maidong from different producing areas possess different properties upon cytotoxicity and the drug-metabolizing enzyme inducing effect, and attention should be paid to the selection of Maidong strains from different planting regions into TCM preparations for reducing potential adverse reactions and HDIs.

Ciclosporin 10 years on: indications and efficacy

Ciclosporin is a lipophilic cyclic polypeptide with powerful immunosuppressive and immunomodulatory properties that has been used in veterinary medicine for two decades. It is a calcineurin inhibitor whose principal mode of action is to inhibit T cell activation. The drug is principally absorbed from the small intestine and is metabolised in the intestine and liver by the cytochrome P450 enzyme system. Ciclosporin is known to interact with a wide range of pharmacological agents. Numerous studies have demonstrated good efficacy for the management of canine atopic dermatitis and this has been a licensed indication since 2003. In addition to the treatment of atopic dermatitis, it has been used as an aid in the management of numerous other dermatological conditions in animals including perianal fistulation, sebaceous adenitis, pododermatitis, chronic otitis externa and pemphigus foliaceus. This article reviews the mode of action, pharmacokinetics, indications for use and efficacy of ciclosporin in veterinary dermatology.

Cyclosporine and herbal supplement interactions

Cyclosporine (CyA) is a well-known immunosuppressant with a narrow therapeutic window. Its bioavailability is affected by many other traditional drugs and herbal extracts. Cytochrome P-450 isoenzymes CYP3A4 and CYP3A5 and protein P-glycoprotein (P-gp) are involved in CyA bioavailability. Interactions of CyA with herbal extracts are not well known, but, given their increased concomitant use, it is important to know which extracts, many of which are commonly self-prescribed, can affect CyA blood concentrations. Decreased CyA blood concentration has been shown with St John's wort in case reports and, in vivo animal studies, with ginger, liquorice, scutellariae radix, and quercetin. Increased CyA concentration has been reported in patients with grapefruit juice, chamomile, or berberine, and with cannabidiol or resveratrol in animal studies. Effects of Echinacea and Serenoa repens on CyA levels have not been shown consistently, but concomitant use should be avoided. Although findings from animal studies cannot be directly translated into humans, avoiding concomitant use of herbal extracts is prudent until human clinical studies have ruled out any possible interaction. Clinicians should interview their patients carefully about their use of herbal supplements before CyA administration, and those receiving CyA should be warned about possible interactions between herbal preparations and CyA.

Sucralose, a synthetic organochlorine sweetener: overview of biological issues

Sucralose is a synthetic organochlorine sweetener (OC) that is a common ingredient in the world's food supply. Sucralose interacts with chemosensors in the alimentary tract that play a role in sweet taste sensation and hormone secretion. In rats, sucralose ingestion was shown to increase the expression of the efflux transporter P-glycoprotein (P-gp) and two cytochrome P-450 (CYP) isozymes in the intestine. P-gp and CYP are key components of the presystemic detoxification system involved in first-pass drug metabolism. The effect of sucralose on first-pass drug metabolism in humans, however, has not yet been determined. In rats, sucralose alters the microbial composition in the gastrointestinal tract (GIT), with relatively greater reduction in beneficial bacteria. Although early studies asserted that sucralose passes through the GIT unchanged, subsequent analysis suggested that some of the ingested sweetener is metabolized in the GIT, as indicated by multiple peaks found in thin-layer radiochromatographic profiles of methanolic fecal extracts after oral sucralose administration. The identity and safety profile of these putative sucralose metabolites are not known at this time. Sucralose and one of its hydrolysis products were found to be mutagenic at elevated concentrations in several testing methods. Cooking with sucralose at high temperatures was reported to generate chloropropanols, a potentially toxic class of compounds. Both human and rodent studies demonstrated that sucralose may alter glucose, insulin, and glucagon-like peptide 1 (GLP-1) levels. Taken together, these findings indicate that sucralose is not a biologically inert compound.

Cyclosporine inhibition of hepatic and intestinal CYP3A4, uptake and efflux transporters: application of PBPK modeling in the assessment of drug-drug interaction potential

PURPOSE

To apply physiologically-based pharmacokinetic (PBPK) modeling to investigate the consequences of reduction in activity of hepatic and intestinal uptake and efflux transporters by cyclosporine and its metabolite AM1.

METHODS

Inhibitory potencies of cyclosporine and AM1 against OATP1B1, OATP1B3 and OATP2B1 were investigated in HEK293 cells +/- pre-incubation. Cyclosporine PBPK model implemented in Matlab was used to assess interaction potential (+/- metabolite) against different processes (uptake, efflux and metabolism) in liver and intestine and to predict quantitatively drug-drug interaction with repaglinide.

RESULTS

Cyclosporine and AM1 were potent inhibitors of OATP1B1 and OATP1B3, IC(50) ranging from 0.019-0.093 μM following pre-incubation. Cyclosporine PBPK model predicted the highest interaction potential against liver uptake transporters, with a maximal reduction of >70% in OATP1B1 activity; the effect on hepatic efflux and metabolism was minimal. In contrast, 80-97% of intestinal P-gp and CYP3A4 activity was reduced due to the 50-fold higher cyclosporine enterocytic concentrations relative to unbound hepatic inlet. The inclusion of AM1 resulted in a minor increase in the predicted maximal reduction of OATP1B1/1B3 activity. Good predictability of cyclosporine-repaglinide DDI and the impact of dose staggering are illustrated.

CONCLUSIONS

This study highlights the application of PBPK modeling for quantitative prediction of transporter-mediated DDIs with concomitant consideration of P450 inhibition.

Effect of Wuzhi tablet (Schisandra sphenanthera extract) on the pharmacokinetics of cyclosporin A in rats

In our previous reports, Wuzhi tablet (an herbal preparation of ethanol extract of Wuweizi (Schisandra sphenanthera)) can significantly increase the blood concentration of tacrolimus and paclitaxel in rats by inhibiting the CYP3A-mediated metabolism and the P-gp-mediated efflux. Cyclosporin A (CsA), a well-known immunosuppressant agent, is also a substrate of CYP3A and P-gp. Therefore, this study aimed to investigate whether and how WZ affects pharmacokinetics of CsA in rats. The AUC0-48 h and Cmax of CsA were increased by 40.1% and 13.1%, respectively, with a single oral co-administration of WZ and high dose of CsA (37.8 mg/kg). Interestingly, after a single oral co-administration of WZ and low dose of CsA (1.89 mg/kg), the AUC0-36 h and Cmax of CsA were dramatically increased by 293.1% (from 1103.2 ± 293.0 to 4336.5 ± 1728.3 ng.h/mL; p < 0.05) and 84.1% (from 208.5 ± 67.9 to 383.1 ± 92.5 ng/mL; p < 0.05), respectively. The CL/F was decreased from 1.7 L/h/kg to 0.5 L/h/kg. Thus, the effect of WZ on high dose of CsA was not significant, but pharmacokinetic parameters of CsA at low dose were significantly influenced by co-administration of WZ. The herb-drug interaction should be taken into consideration at this situation.

A brief study of toxic effects of some medicinal herbs on kidney

Increased use of complementary and alternative herbal medicines in the treatment of various diseases.Some herbal therapies may be causes of potential toxicity that may be renal toxicity caused by the ingestion of herbs. The goal of this study is the toxic and beneficial effects of medicinal herbs on renal health by which evidence for benefit or toxicity has been found. Included are nephrotoxicity from aristolochic acid and other components within herbs, herb-drug interactions, heavy metal toxicity in herbs and adulterants during careless preparation of herbal medicine, resulting in adverse renal effects and renal toxicity from contaminants within the extracts. The review aims to provide knowledge and guide to encourage future toxicity studies on the kidney by medicinal herbs.

Case-based online modules to teach graduate-level nursing students about complementary and alternative medical therapies

We integrated complementary and alternative medicine (CAM)-related content into selected core courses in our master's-level curriculum. To facilitate students' application of the content, we developed evidence-based online case studies and evaluated their effectiveness by comparing students' pretest and posttest scores on multiple-choice quizzes. Findings suggest that evidence-based online case studies are an effective strategy for teaching graduate nursing students about the clinical issues surrounding patients' use of CAM therapies.

Time-course effects of St John's wort on the pharmacokinetics of cyclosporine in dogs: interactions between herbal extracts and drugs

To clarify the interaction between St John's wort (SJW) and cyclosporine (CsA) in dogs, the pharmacokinetics of CsA before and during the repeated administration of SJW were analyzed. In the SJW group, SJW (300 mg) was given orally to four dogs every 24 h for 14 days. A single dose of CsA (5 mg/kg) was given orally 7 days before and 7 and 14 days after the initiation of the repeated administration of SJW. In the Control group, a single dose of CsA (5 mg/kg) was given orally to four other dogs in accordance with that in the SJW group. Blood samples from both groups were collected, and whole-blood concentrations of CsA were determined using high-performance liquid chromatography with UV detection. The maximum whole-blood concentration and AUC(0-∞) of the SJW group were significantly lower and the CL(tot) /F and V(d) /F were significantly higher than those in the Control group 7 and 14 days after the initiation of repeated SJW. Thus, repeated administrations of SJW affect the pharmacokinetic profiles of CsA in dogs. Further studies are necessary to elucidate the mechanisms of interaction between SJW and CsA in dogs.

Identification of novel pregnane X receptor activators from traditional Chinese medicines

AIM OF THE STUDY

To investigate the ability of traditional Chinese medicines (TCMs) and their bioactive compounds to activate pregnane X receptor (PXR) signalling pathway.

MATERIALS AND METHODS

We screened ethanol extracts of 28 commonly used TCMs for their capability to induce cytochrome P450 3A4 (CYP3A4) via PXR signalling pathway using a cell-based reporter gene assay combined with RT-PCR analysis. In addition, 34 bioactive components from these TCMs were examined for their potential to activate PXR.

RESULTS

Our observations showed that 22 ethanol extracts and 8 compounds could activate human PXR and induce CYP3A4 reporter construct in HepG2 cells. Among them, Ginkgo biloba, Ligusticum chuanxiong, Chinese angelica, prepared Rehmannia root, Epimedium brevicornum, Atractylodes macrocephala, Schisandra chinensis, Paeonia lactiflora, Ophiopogon japonicus, Polygonum multiflorum, Coptis chinensis, Artemisia scoparia, Trichosanthes kirilowii, Silybum marianum, Gardenia fruit and Lycium chinense could strongly trans-activate PXR. Moreover, ligustilide, schisantherin A, berberine hydrochloride and trans-resveratrol were identified for the first time as efficacious PXR agonists.

CONCLUSIONS

Twenty-two TCM ethanol extracts and eight bioactive compounds could activate PXR signalling pathway and induce CYP3A4 reporter gene. Therefore, caution should be taken when these PXR activators are used in combination with prescribed drugs metabolized by CYP3A4.

Effects of herbal products on the metabolism and transport of anticancer agents

IMPORTANCE OF THE FIELD

Cancer patients on chemotherapy treatment often seek herbal therapies and this may alter the clearance of anticancer drugs.

AREAS COVERED IN THIS REVIEW

Many anticancer drugs are metabolized by CYPs and are substrates of P-glycoprotein, breast cancer resistance protein and multi-drug resistance proteins. CYPs and drug transporters are subject to inhibition and/or induction by the herbal medicines used by cancer patients and the metabolism and pharmacokinetics of anticancer agents may be altered by herbal products. There are increased reports on the interaction of herbal medicines with anticancer agents. A clinical study in cancer patients reported that treatment of St John's wort at 900 mg/day orally for 18 days decreased the plasma levels of the active metabolite of irinotecan, SN-38, by 42%. In healthy subjects, treatment with St John's wort for 2 weeks significantly decreased the systemic exposure of imatinib by 32%. Induction and/or inhibition of CYPs and transporters is considered an important mechanism for these interactions.

WHAT THE READER WILL GAIN

Potential interactions of herbal medicines with anticancer agents have become a safety concern in cancer chemotherapy.

TAKE HOME MESSAGE

Further studies are warranted to investigate the efficacy and safety profiles of herbal medicines commonly used by cancer patients.

[Pharmacokinetic drug interactions by herbal drugs: Critical evaluation and clinical relevance]

Pharmacokinetic herb-drug interactions are caused by an induction or inhibition of cytochrome P450 (CYP) enzymes or transporters e.g. P-glycoprotein. St. John's wort extracts containing hyperforin increase the expression of CYP-enzymes and P-glycoprotein mainly in the gut and liver which leads to a clinically relevant decrease of the bioavailability of CYP and P-glycoprotein substrates. Contrarily, the bioactivation of the prodrug losartan is reduced by milk thistle extracts which is due to an inhibition of CYP2C9. However, the 15 % reduction of the bioavailability of the active metabolite E-3174 is clinically not relevant. Also, minor changes in drug bioavailability observed in clinical studies for valerian, echinacea, ginkgo and hawthorne are clinically not relevant, although in vitro studies point to drug interactions in vivo. Since for herbal extracts a positive in vitro - in vivo correlation regarding the impact on drug bioavailability is rare, results from in vitro studies should be carefully interpreted.