Pharmacokinetic modelling of the interaction between St John's wort and ciclosporin A

The prevalence and impact of polypharmacy in rheumatology

Polypharmacy is increasingly common in rheumatology due to the complex nature of managing chronic autoimmune diseases. To date there has been limited research into the impact of polypharmacy on rheumatology patients. In this article we reviewed the literature to characterize the prevalence of polypharmacy and its effect on patients. In addition, we have highlighted some key drug-drug interactions to consider involving DMARDs as well as complementary and alternative medicines. There is emerging evidence demonstrating that polypharmacy contributes to adverse outcomes and alters treatment response. This association is best described in RA and is less clear in other patient cohorts. It is also unclear whether polypharmacy is directly harmful or just a surrogate marker for other factors affecting outcomes. Rheumatologists should be aware of the risk of polypharmacy as well as specific drug-drug interactions that can occur in managing chronic autoimmune disease.

MicroRNA-655-3p regulates Echinacea purpurea mediated activation of ABCG2

1. The aim of this study was to investigate the regulatory effect of Echinacea purpurea (EP) on efflux transporters ABCB1 and ABCG2 and to identify specific microRNAs contributing to their post-transcriptional regulation. 2. ABCB1 and ABCG2 levels were assessed in human hepatoblastoma HepG2 cells treated with 50 µg/mL methanolic extract of commercial EP capsules for different durations. The microRNA expression profile of HepG2 cells after EP treatment was evaluated and in silico target prediction was subsequently conducted to identify specific microRNAs with binding sites in the 3'-UTR of ABCB1 and ABCG2. Luciferase reporter gene assays and site-directed mutagenesis were used to confirm the binding site of identified microRNA within the 3'-UTR of the target gene. 3. EP increased ABCB1 (10-fold ± 3.4, p < 0.001) and ABCG2 (2.7-fold ± 0.5, p < 0.01) mRNA levels after 12 h exposure. Twenty-four microRNAs showed significant expression differences at all durations of exposure to EP. MiR-655-3p showed a 6.79-fold decrease in expression after 12 h exposure compared to 0 h, was predicted in silico to bind ABCG2 3'-UTR and showed a significant negative correlation (p = 0.01) to ABCG2 expression level. The binding of miR-655-3p to ABCG2 3'-UTR was confirmed by reporter gene assays (reduction of reporter gene activity to 60%; p = 0.0001). 4. These results suggest that EP regulates ABCG2 expression via downregulation of miR-655-3p in the liver cells. Thus, miR-655-3p downregulation could be applied to predict EP mediated drug interactions.

Therapeutic Risk and Benefits of Concomitantly Using Herbal Medicines and Conventional Medicines: From the Perspectives of Evidence Based on Randomized Controlled Trials and Clinical Risk Management

Despite increased awareness of the potential of herb-drug interactions (HDIs), the lack of rigorous clinical evidence regarding the significance provides a challenge for clinicians and consumers to make rational decisions about the safe combination of herbal and conventional medicines. This review addressed HDIs based on evidence from randomized controlled trials (RCTs). Literature was identified by performing a PubMed search till January 2017. Risk description and clinical risk management were described. Among 74 finally included RCTs, 17 RCTs (22.97%) simply addressed pharmacodynamic HDIs. Fifty-seven RCTs (77.03%) investigated pharmacokinetic HDIs and twenty-eight of them showed potential or actual clinical relevance. The extent of an HDI may be associated with the factors such as pharmacogenomics, dose of active ingredients in herbs, time course of interaction, characteristics of the object drugs (e.g., administration routes and pharmacokinetic profiles), modification of herbal prescription compositions, and coexistence of inducers and inhibitors. Clinical professionals should enhance risk management on HDIs such as increasing awareness of potential changes in therapeutic risk and benefits, inquiring patients about all currently used conventional medicines and herbal medicines and supplements, automatically detecting highly substantial significant HDI by computerized reminder system, selecting the alternatives, adjusting dose, reviewing the appropriateness of physician orders, educating patients to monitor for drug-interaction symptoms, and paying attention to follow-up visit and consultation.

Adverse events associated with interactions with dietary and herbal supplements among inpatients

AIMS

Dietary and herbal supplements (DHS) are commonly used among inpatients and may cause interactions with drugs or other DHS. This study explored whether adverse events were actually associated with such interactions and examined specific characteristics among inpatient DHS users prone to such adverse events.

METHODS

This was a cross-sectional study of 947 patients hospitalized in 12 departments of a tertiary academic medical centre in Haifa, Israel. It evaluated the rate of DHS use among inpatients, the potential for interactions, and actual adverse events during hospitalization associated with DHS use. It also assessed whether DHS consumption was documented in patients' medical files. Statistical analysis was used to delineate DHS users at risk for adverse events associated with interactions with conventional drugs or other DHS.

RESULTS

In 17 (3.7%) of the 458 DHS users, an adverse event may have been caused by DHS-drug-DHS interactions. According to the Drug Interaction Probability Scale, 14 interactions 'probably' caused the adverse events, and 11 'possibly' caused them. Interactions occurred more frequently in older patients (P = 0.025, 95% CI: 2.26-19.7), patients born outside Israel (P = 0.025, 95% CI: 0.03-0.42), those with ophthalmologic (P = 0.032, 95% CI: 0.02-0.37) or gastrointestinal (P = 0.008, 95% CI: 0.05-0.46) comorbidities, and those using higher numbers of DHS (P < 0.0001, 95% CI: 0.52-2.48) or drugs (P = 0.027, 95% CI: 0.23-3.77).

CONCLUSIONS

Approximately one in 55 hospitalizations in this study may have been caused by adverse events associated with DHS-drug-DHS interactions. To minimize the actual occurrence of adverse events, medical staff education regarding DHS should be improved.

The safety and efficacy of acute graft-versus-host disease prophylaxis with a higher target blood concentration of cyclosporine around 500 ng/mL

Cyclosporine (CsA) is the most widely used immunosuppressive agent for the prevention of acute graft-versus-host disease (GVHD). In a previous report, the incidence of acute GVHD was decreased by increasing the target blood concentration of CsA during a continuous infusion from 300 to 500 ng/mL without excessive toxicities. To confirm these results, we retrospectively analyzed 69 patients who received a continuous infusion of CsA at a higher target CsA level between 450 and 550 ng/mL (CsA500 group) and compared the clinical outcome with 29 patients who received CsA with a lower target concentration between 250 and 350 ng/mL (CsA300 group). The target concentration was determined based on the status of background diseases. Multivariate analysis revealed that the incidence of grade III-IV acute GVHD was significantly lower in the CsA500 group, although the incidence of grade II-IV acute GVHD was not different. Toxicities were equivalently observed between the two groups. Concomitant administration of voriconazole or itraconazole and higher hematocrit were identified as independent significant factors for higher concentration/dose ratio of CsA. The average dose of CsA to maintain CsA level around 500 ng/mL was higher compared with the previous study (3.4 mg/kg vs. 2.7 mg/kg at three wk), probably due to the difference in measuring method of CsA concentration. We conclude that continuous infusion of CsA with a target level between 450 and 550 ng/mL is a feasible and effective GVHD prophylaxis, but caution should be paid for the difference in measuring method.

An overview of the evidence and mechanisms of herb-drug interactions

Despite the lack of sufficient information on the safety of herbal products, their use as alternative and/or complementary medicine is globally popular. There is also an increasing interest in medicinal herbs as precursor for pharmacological actives. Of serious concern is the concurrent consumption of herbal products and conventional drugs. Herb-drug interaction (HDI) is the single most important clinical consequence of this practice. Using a structured assessment procedure, the evidence of HDI presents with varying degree of clinical significance. While the potential for HDI for a number of herbal products is inferred from non-human studies, certain HDIs are well established through human studies and documented case reports. Various mechanisms of pharmacokinetic HDI have been identified and include the alteration in the gastrointestinal functions with consequent effects on drug absorption; induction and inhibition of metabolic enzymes and transport proteins; and alteration of renal excretion of drugs and their metabolites. Due to the intrinsic pharmacologic properties of phytochemicals, pharmacodynamic HDIs are also known to occur. The effects could be synergistic, additive, and/or antagonistic. Poor reporting on the part of patients and the inability to promptly identify HDI by health providers are identified as major factors limiting the extensive compilation of clinically relevant HDIs. A general overview and the significance of pharmacokinetic and pharmacodynamic HDI are provided, detailing basic mechanism, and nature of evidence available. An increased level of awareness of HDI is necessary among health professionals and drug discovery scientists. With the increasing number of plant-sourced pharmacological actives, the potential for HDI should always be assessed in the non-clinical safety assessment phase of drug development process. More clinically relevant research is also required in this area as current information on HDI is insufficient for clinical applications.

A comprehensive review of immunosuppression used for liver transplantation

Since liver transplantation was approved for the treatment of end stage liver disease, calcineurin inhibitors (CNI's) have played a critical role in the preservation of allograft function. Unfortunately, these medications cause a variety of Side effects such as diabetes, hypertension and nephrotoxicity which in turn result in significant morbidity and reduced quality of life. A variety of newer immunosuppressants have been evaluated over the last decade in an attempt to either substitute for CNI's or use with reduced dose CNI's while still preserving allograft function However, current data does not recommend complete cessation of CNI's due to unacceptably high rates of allograft rejection. As these medications have their own unique adverse effects, a careful assessment on their risks and benefits is essential, particularly when additive or synergistic effects with CNI's may occur. Furthermore, the impact of these newer medications on the risk of hepatitis C recurrence and progression remains to be elucidated. Controlled trials are urgently required to assist transplant physicians with choosing the optimum immunosuppressive regimen for their patients. This review will discuss commonly used immunosuppressants prescribed in liver transplantation, emerging therapties and where appropriate, the impact of these medications on the recurrence of hepatitis C after liver transplantation.

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.

The pregnane X receptor: from bench to bedside

BACKGROUND

The pregnane X receptor (PXR; NR1I2), a member of the nuclear receptor superfamily, regulates the expression of metabolic enzymes and transporters involved in the response of mammals to their chemical environment.

OBJECTIVE

To summarize the functions and clinical implications of PXR.

METHODS

In the current review, the clinical implications of PXR are discussed, and the use of genetically engineered PXR mouse models is highlighted.

RESULTS/CONCLUSION

Recent advances in mouse models, including Pxr-null and PXR-humanized mice, provide in vivo tools for evaluating the physiological functions of PXR and its role in controlling xenobiotic metabolism and transport. By using the PXR knockout and humanized mouse models, PXR was found to influence drug-drug interactions, hepatic steatosis, and the homeostasis of vitamin D, bile acids, and steroid hormones. PXR was also shown to influence inflammatory bowel diseases.