Effects of grapefruit juice on the pharmacokinetics of pitavastatin and atorvastatin

An Investigation in the Comparability of the Exposure and Recommended Dose of Selected Pfizer Drugs in East Asian Countries: Is Mutual Usage of Clinical Data Among East Asian Countries Feasible?

The current regulatory path for new drug registration in East Asian countries has led to significant delay of the new medicines in these countries. A unified regulatory path and allowance of mutual usage of clinical data in East Asian countries would lead to cost saving in drug development and expedite the new drug registration in these countries. The objectives of the present analysis are to compare the approval dates of a selection of products developed by Pfizer in the United States and East Asian countries (China, Japan, Korea) and compare the pharmacokinetics and recommended doses of these products in East Asian countries. Eighteen products (20 drugs, 2 products with 2 combination drugs) with exposure data available in at least 2 of the 3 East Asian countries across different therapeutic areas were included in the analyses. The results showed that most products had delayed approval in East Asian countries (up to 8 years) after US or EU approval. No distinct differences were observed in the drug exposure and recommended doses for the selected products in East Asian countries. These results together with literature data of genetic similarity of the East Asian populations support the mutual usage of the clinical data in the East Asian countries for expedited regulatory submission and approval.

Physiologically based pharmacokinetic (PBPK) modeling of pitavastatin in relation to SLCO1B1 genetic polymorphism

Pitavastatin, a potent 3-hydroxymethylglutaryl coenzyme A reductase inhibitor, is indicated for the treatment of hypercholesterolemia and mixed dyslipidemia. Hepatic uptake of pitavastatin is predominantly occupied by the organic anion transporting polypeptide 1B1 (OATP1B1) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene, which is a polymorphic gene that encodes OATP1B1. SLCO1B1 genetic polymorphism significantly alters the pharmacokinetics of pitavastatin. This study aimed to establish the physiologically based pharmacokinetic (PBPK) model to predict pitavastatin pharmacokinetics according to SLCO1B1 genetic polymorphism. PK-Sim® version 10.0 was used to establish the whole-body PBPK model of pitavastatin. Our pharmacogenomic data and a total of 27 clinical pharmacokinetic data with different dose administration and demographic properties were used to develop and validate the model, respectively. Physicochemical properties and disposition characteristics of pitavastatin were acquired from previously reported data or optimized to capture the plasma concentration-time profiles in different SLCO1B1 diplotypes. Model evaluation was performed by comparing the predicted pharmacokinetic parameters and profiles to the observed data. Predicted plasma concentration-time profiles were visually similar to the observed profiles in the non-genotyped populations and different SLCO1B1 diplotypes. All fold error values for AUC and Cmax were included in the two fold range of observed values. Thus, the PBPK model of pitavastatin in different SLCO1B1 diplotypes was properly established. The present study can be useful to individualize the dose administration strategy of pitavastatin in individuals with various ages, races, and SLCO1B1 diplotypes.

Food effects on gastrointestinal physiology and drug absorption

Food ingestion affects the oral absorption of many drugs in humans. In this review article, we summarize the physiological factors in the gastrointestinal (GI) tract that affect the in vivo performance of orally administered solid dosage forms in fasted and fed states in humans. In particular, we discuss the effects of food ingestion on fluid characteristics (pH, bile concentration, and volume) in the stomach and small intestine, GI transit of water and dosage forms, and microbiota. Additionally, case examples of food effects on GI physiology and subsequent changes in oral drug absorption are provided. Furthermore, the effects of food, especially fruit juices (e.g., grapefruit, orange, apple) and green tea, on transporter-mediated permeation and enzyme-catalyzed metabolism of drugs in intestinal epithelial cells are also summarized comprehensively.

Pharmacokinetics and pharmacodynamic interaction of bergamottin with atorvastatin in rats

1. The pharmacokinetics and pharmacodynamic of concomitant administration of atorvastatin with bergamottin were investigated perspectives to reveal the potential herb-drug interaction between these two drugs.2. The hyperlipidaemia-induced Wistar rats received atorvastatin with or without bergamottin (2.5 mg/kg). The concentration of atorvastatin in the rats' serum was determined using an established HPLC/MS/MS method. The pharmacokinetic parameters were calculated using DAS software. Lipid levels were determined.3. Bergamottin increases the C_max (from 48 ± 5 ng/mL to 89 ± 7 ng/mL), AUC_0-∞ (from 176 ± 27 to 552 ± 131 h∗μg/L), and the elimination half-life of atorvastatin (t_1/2) of atorvastatin. Co-administration of atorvastatin with bergamottin decreased total cholesterol (by 14%), low-density lipoproteins-cholesterol (by 20%), and triglyceride (by 12%), but increased thigh-density lipoprotein-cholesterol, when compared with atorvastatin alone.4. Co-administration of bergamottin and atorvastatin alters both pharmacokinetics and pharmacodynamics of atorvastatin. This study provides pre-clinical information evidence that bergamottin could potentiate the therapeutic efficacy of atorvastatin or increase its accumulation and adverse effects.

The Challenge and Importance of Integrating Drug-Nutrient-Genome Interactions in Personalized Cardiovascular Healthcare

Despite the rich armamentarium of available drugs against different forms of cardiovascular disease (CVD), major challenges persist in their safe and effective use. These include high rates of adverse drug reactions, increased heterogeneity in patient responses, suboptimal drug efficacy, and in some cases limited compliance. Dietary elements (including food, beverages, and supplements) can modulate drug absorption, distribution, metabolism, excretion, and action, with significant implications for drug efficacy and safety. Genetic variation can further modulate the response to diet, to a drug, and to the interaction of the two. These interactions represent a largely unexplored territory that holds considerable promise in the field of personalized medicine in CVD. Herein, we highlight examples of clinically relevant drug–nutrient–genome interactions, map the challenges faced to date, and discuss their future perspectives in personalized cardiovascular healthcare in light of the rapid technological advances.

Pharmacogenomics and circadian rhythms as mediators of cardiovascular drug-drug interactions

This article summarizes the current literature and documents new evidence concerning drug-drug interactions (DDI) stemming from pharmacogenomic and circadian rhythm determinants of therapies used to treat common cardiovascular diseases (CVD), such as atherosclerosis and hypertension. Patients with CVD often have more than one pathophysiologic condition, namely metabolic syndromes, hypertension, hyperlipidemia, and hyperglycemia, among others, which necessitate polytherapeutic or polypharmaceutic management. Interactions between drugs, drugs and food/food supplements, or drugs and genetic/epigenetic factors may have adverse impacts on the cardiovascular and other systems of the body. The mechanisms underlying cardiovascular DDI may involve the formation of a complex pharmacointeractome, including the absorption, distribution, metabolism, and elimination of drugs, which affect their respective bioavailability, efficacy, and/or harmful metabolites. The pharmacointeractome of cardiovascular drugs is likely operated with endogenous rhythms controlled by circadian clock genes. Basic and clinical investigations have improved the knowledge and understanding of cardiovascular pharmacogenomics and pharmacointeractomes, and additionally they have presented new evidence that the staging of deterministic circadian rhythms, according to the dosing time of drugs, e.g., upon awakening vs. at bedtime, cannot only differentially impact their pharmacokinetics and pharmacodynamics but also mediate agonistic/synergetic or antagonistic DDI. To properly manage CVD patients and avoid DDI, it is important that clinicians have sufficient knowledge of their multiple risk factors, i.e., age, gender, and life style elements (like diet, smoking, psychological stress, and alcohol consumption), and comorbidities, such as diabetes, hypertension, dyslipidemia, and depression, and the potential interactions between genetic or epigenetic background of their prescribed therapeutics.

Computational studies on statins photoactivity

Statins are popular drugs widely prescribed to control hypercholesterolaemia and to prevent cardiovascular diseases. Synthetic statins constitute a group of pharmaceuticals which are very sensitive to exposure to light in both UVA and UVB ranges. Light, by causing drugs degradation, can essentially change their pharmaceutical properties leading even to the loss of therapeutic activity and/or to the formation of deleterious photoproducts. Drugs which exhibit photochemical reactivity may elicit undesired adverse effects. A detailed understanding of mechanisms involved in molecular basis of these effects origin is very important for evaluating the photobiological risk associated with therapy in which drugs prone to exposure to light are involved. In this work we critically discussed finding regarding the mechanisms of synthetic statins phototransformation. We showed inconsistency of some previously reported facts and revised earlier presented studies. We also completed the lack of information on pitavastatin photobehaviour. This all together resulted in proposal of new schemes for the statins photodecomposition. We reviewed data derived from both experimental and computational methods. Studies of photochemical problems by the use of theoretical methods enable getting insight into areas of some fascinating events that experimental techniques can touch only indirectly. Besides effect of light, phenomenon of statins’ sensitivity to pH and resulting implications were discussed. Statins undergo pH-dependent interconversion between their pharmacologically active hydroxy acid and inactive lactone forms, and it was shown that for both forms, drugs’ interactions should be considered. Knowledge of the statins interconversion mechanisms is important for understanding how differences in the structures of their molecules can affect the drugs’ activity.

Cholesterol-lowering drug pitavastatin targets lung cancer and angiogenesis via suppressing prenylation-dependent Ras/Raf/MEK and PI3K/Akt/mTOR signaling

Therapeutic agents that target both tumor cell and vascular endothelial cell may achieve additional anti-tumor efficacy, particularly in lung cancer due to the critical roles of angiogenesis during lung cancer progression and metastasis. In this work, we showed that pitavastatin, a novel cholesterol-lowering drug, potently inhibited lung cancer cells and angiogenesis. This was achieved by the induction of apoptosis and inhibition of proliferation of lung cancer cells and human lung tumor-associated endothelial cell. Pitavastatin was not only effective to chemo-sensitive but also chemo-resistant lung cancer cells. This was also consistent with the finding that pitavastatin significantly enhanced cisplatin's efficacy in lung cancer xenograft model without causing toxicity in mice. We further showed that pitavastatin inhibited lung tumor angiogenesis in vitro and in vivo through suppressing human lung tumor-associated endothelial cell migration and morphogenesis without affecting adhesion. Mechanistically, we showed that pitavastatin acted on lung cancer cells and human lung tumor-associated endothelial cell through suppressing prenylation-dependent Ras/Raf/MEK and PI3K/Akt/mTOR signaling. Our work is the first to demonstrate the inhibitory effects of pitavastatin on Ras-mediated signaling. Our findings provide pre-clinical evidence to repurpose pitavastatin for the treatment of lung cancer.

Enteral Medication for the Tube-Fed Patient: Making This Route Safe and Effective

The administration of medication through an enteral access device requires important forethought. Meeting a patient's therapeutic needs requires achieving expected drug bioavailability without increasing the risk for toxicity, therapeutic failure, or feeding tube occlusion. Superimposing gut dysfunction, critical illness, or enteral nutrition-drug interaction further increases the need for a systematic approach to prescribing, evaluating, and preparing a drug for administration through an enteral access device. This review will explain the fundamental factors involved in drug bioavailability through the gut, address the influencing considerations for the enterally fed patient, and describe best practices for enteral drug preparation and administration.

Effects of acid and lactone forms of statins on S-warfarin 7-hydroxylation catalyzed by human liver microsomes and recombinant CYP2C9 variants (CYP2C9.1 and CYP2C9.3)

The inhibition of CYP2C9-mediated warfarin metabolism by acid or lactone forms of statin converted in the body and effects of CYP2C9 genetic variants on their inhibition are not fully understood. Here, the effects of acid and lactone forms of statins on S-warfarin 7-hydroxylation were investigated in vitro. S-Warfarin 7-hydroxylase activities of human liver microsomes (HLMs), recombinant CYP2C9.1 (rCYP2C9.1), and rCYP2C9.3 (Ile359Leu variant) in the presence of statins were determined by high-performance liquid chromatography. Lactone forms of atorvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin inhibited the activity of HLMs more potently than the corresponding acid forms, whereas fluvastatin acid showed stronger inhibition than fluvastatin lactone. When the effects of statins on rCYP2C9 variants were examined, inhibition profiles of acid versus lactone forms of statins except for fluvastatin were similar between rCYP2C9.1 and rCYP2C9.3. However, the degrees of inhibition by atorvastatin lactone, fluvastatin acid, fluvastatin lactone, lovastatin lactone, and pitavastatin lactone (K_i values) were significantly different between these variants. These results indicated that lactone forms of statins other than fluvastatin showed more potent inhibition of CYP2C9-catalyzed S-warfarin 7-hydroxylation than the corresponding acid forms. Furthermore, our results indicated that Ile359Leu substitution in CYP2C9 affected the inhibitory potencies of statins.

Protocol for systematic review and meta-analysis: impact of statins as immune-modulatory agents on inflammatory markers in adults with chronic diseases

INTRODUCTION

Statins, also known as 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitors, are lipid-lowering agents that are central in preventing or reducing the complications of atherosclerotic cardiovascular disease. Because statins have anti-inflammatory properties, there is considerable interest in their therapeutic potential in other chronic inflammatory conditions. We aim to identify the statin with the greatest ability to reduce systemic inflammation, independent of the underlying disease entity.

METHODS AND ANALYSIS

We aim to conduct a comprehensive search of published and peer-reviewed randomised controlled clinical trials, with at least one intervention arm of a Food & Drug Administration-licensed or European Medicines Agency-licensed statin and a minimum treatment duration of 12 weeks. Our objective is to investigate the effect of statins (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin) on lipid profile, particularly, cholesterol low-density lipoprotein and inflammation markers such as high-sensitive C reactive protein (hsCRP), CRP, tumour necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-8, soluble cluster of differentiation 14 (sCD14) or sCD16 in adults, published in the last 20 years (between January 1999 and December 2019). We aim to identify the most potent statin to reduce systemic inflammation and optimal dosing. The following databases will be searched: Medline, Scopus, Web of Science and Cochrane Library of Systematic Reviews. The risk of bias of included studies will be assessed by Cochrane Risk of Bias Tool and Quality Assessment Tool for Quantitative Studies. The quality of studies will be assessed, to show uncertainty, by the Jadad Score. If sufficient evidence is identified, a meta-analysis will be conducted with risk ratios or ORs with 95% CIs in addition to mean differences.

ETHICS AND DISSEMINATION

Ethics approval is not required as no primary data will be collected. Results will be presented at conferences and published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42020169919.

Transporter-Mediated Drug-Drug Interactions and Their Significance

Drug transporters are considered to be determinants of drug disposition and effects/toxicities by affecting the absorption, distribution, and excretion of drugs. Drug transporters are generally divided into solute carrier (SLC) family and ATP binding cassette (ABC) family. Widely studied ABC family transporters include P-glycoprotein (P-GP), breast cancer resistance protein (BCRP), and multidrug resistance proteins (MRPs). SLC family transporters related to drug transport mainly include organic anion-transporting polypeptides (OATPs), organic anion transporters (OATs), organic cation transporters (OCTs), organic cation/carnitine transporters (OCTNs), peptide transporters (PEPTs), and multidrug/toxin extrusions (MATEs). These transporters are often expressed in tissues related to drug disposition, such as the small intestine, liver, and kidney, implicating intestinal absorption of drugs, uptake of drugs into hepatocytes, and renal/bile excretion of drugs. Most of therapeutic drugs are their substrates or inhibitors. When they are comedicated, serious drug-drug interactions (DDIs) may occur due to alterations in intestinal absorption, hepatic uptake, or renal/bile secretion of drugs, leading to enhancement of their activities or toxicities or therapeutic failure. This chapter will illustrate transporter-mediated DDIs (including food drug interaction) in human and their clinical significances.

Physiologically-Based Pharmacokinetic Modeling of Atorvastatin Incorporating Delayed Gastric Emptying and Acid-to-Lactone Conversion

The drug-drug interaction profile of atorvastatin confirms that disposition is determined by cytochrome P450 (CYP) 3A4 and organic anion transporting polypeptides (OATPs). Drugs that affect gastric emptying, including dulaglutide, also affect atorvastatin pharmacokinetics (PK). Atorvastatin is a carboxylic acid that exists in equilibrium with a lactone form in vivo. The purpose of this work was to assess gastric acid-mediated lactone equilibration of atorvastatin and incorporate this into a physiologically-based PK (PBPK) model to describe atorvastatin acid, lactone, and their major metabolites. In vitro acid-to-lactone conversion was assessed in simulated gastric fluid and included in the model. The PBPK model was verified with in vivo data including CYP3A4 and OATP inhibition studies. Altering the gastric acid-lactone equilibrium reproduced the change in atorvastatin PK observed with dulaglutide. The model emphasizes the need to include gastric acid-lactone conversion and all major atorvastatin-related species for the prediction of atorvastatin PK.

Progress in the Consideration of Possible Sex Differences in Drug Interaction Studies

Background:

Anecdotal evidence suggests that there may be sex differences in Drug-drug Interactions (DDI) involving specific drugs. Regulators have provided general guidance for the inclusion of females in clinical studies. Some clinical studies have reported sex differences in the Pharmacokinetics (PK) of CYP3A4 substrates, suggesting that DDI involving CYP3A4 substrates could potentially show sex differences.

Objective:

The aim of this review was to investigate whether recent prospective DDI studies have included both sexes and whether there was evidence for the presence or absence of sex differences with the DDIs.

Methods:

The relevant details from 156 drug interaction studies within 124 papers were extracted and evaluated.

Results:

Only eight studies (five papers) compared the outcome of the DDI between males and females. The majority of the studies had only male volunteers. Five studies had females only while 60 had males only, with 7.7% of the studies having an equal proportion of both sexes. Surprisingly, four studies did not specify the sex of the subjects.

:

Based on the limited number of studies comparing males and females, no specific trends or conclusions were evident. Sex differences in the interaction were reported between ketoconazole and midazolam as well as clarithromycin and midazolam. However, no sex difference was observed with the interaction between clarithromycin and triazolam or erythromycin and triazolam. No sex-related PK differences were observed with the interaction between ketoconazole and domperidone, although sex-related differences in QT prolongation were observed.

Conclusion:

This review has shown that only limited progress had been made with the inclusion of both sexes in DDI studies.

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.

ABT-737 and pictilisib synergistically enhance pitavastatin-induced apoptosis in ovarian cancer cells

There is considerable interest in redeploying drugs for use in combination with other oncology therapeutics. The single-agent activity of statins in ovarian cancer has been widely reported, however the drug concentration required to cause cell death is considerably higher than that achieved in patients receiving statin treatment for hypercholesterolemia. Unfortunately, statins can cause myopathy when administered in high doses. One solution to this is to identify drugs that could be used in combination with statins to reduce the dose required and those that may potentially reduce the incidence of adverse side effects. When the BH3 mimetic ABT-737, or the phosphatidylinositol 3-kinase inhibitor pictilisib, were combined with pitavastatin in cell growth assays using Ovcar-3 and Igrov-1 cells, the drug combinations were more effective than pitavastatin alone. In support of this, ABT-737 or pictilisib markedly increased cell death induced by pitavastatin in several ovarian cancer cell lines. The drugs were also synergistic in apoptosis assays. These observations suggested that either BH3 mimetics or pictilisib in combination with pitavastatin could be used in a subset of ovarian tumours, particularly those sensitive to BH3 mimetics, and phosphatase and tensin homolog inhibition, in the treatment of ovarian cancer.

Grapefruit Juice and Statins

We determined the validity of current medical advice to avoid grapefruit juice consumption while taking 3 widely used statins. A daily glass of grapefruit juice increases blood levels of simvastatin and lovastatin by about 260% if taken at the same time (about 90% if taken 12 hours apart), and atorvastatin by about 80% (whenever taken). Simvastatin 40 mg, lovastatin 40 mg, and atorvastatin 10 mg daily reduce low-density lipoprotein (LDL) cholesterol levels in a 60-year-old man with an LDL cholesterol of 4.8 mmol/L by 37%, reducing ischemic heart disease risk by 61%. When simvastatin or lovastatin are taken at the same time as grapefruit juice, the estimated reduction in LDL cholesterol is 48%, and in heart disease is 70%. If the juice is taken 12 hours before these statins, the reductions are, respectively, 43% and 66%, and for atorvastatin, 42% and 66%. The increased rhabdomyolysis risk from grapefruit juice consumption due to the increased effective statin dose is minimal compared with the greater effect in preventing heart disease. Grapefruit juice should not be contraindicated in people taking statins.

Drug-drug interactions that interfere with statin metabolism

INTRODUCTION

Lipid-lowering drugs, especially hydroxymethylglutaryl-CoA reductase inhibitors (statins), are widely used in the treatment and prevention of atherosclerotic diseases. The benefits of statins are well documented. However, myotoxic side effects, which can sometimes be severe, including myopathy or rhabdomyolysis, have been associated with the use of statins. In some cases, this toxicity is associated with pharmacokinetic alterations. Potent inhibitors of CYP 3A4 significantly increase plasma concentrations of the active forms of simvastatin, lovastatin and atorvastatin. Fluvastatin is metabolized by CYP2C9, while pravastatin, rosuvastatin and pitavastatin are not susceptible to inhibition by any CYP.

AREAS COVERED

This review discusses the pharmacokinetic aspects of the drug-drug interaction with statins and genetic polymorphisms in CYPs, which are involved in the metabolism of statins, and highlights the importance of establishing a system utilizing electronic medical information practically to avoid adverse drug reactions.

EXPERT OPINION

An understanding of the mechanisms underlying statin interactions will help to minimize drug interactions and develop statins that are less prone to adverse interactions. Quantitatively analyzed information for the low-density lipoprotein cholesterol lowering effects of statin based on electronic medical records may be useful for avoiding the adverse effect of statins.

Quantitative Analysis of the ABCG2 c.421C>A Polymorphism Effect on In Vivo Transport Activity of Breast Cancer Resistance Protein (BCRP) Using an Intestinal Absorption Model

ABCG2 c.421C>A is one of the most frequent polymorphisms in ABCG2, which encodes the breast cancer resistance protein (BCRP). Clinical pharmacogenetic studies have shown that the plasma area under the concentration-time curve (AUC) values after oral administration of BCRP substrate drugs are significantly higher in subjects homozygous for the c.421C>A polymorphism (421AA) than in wild-type subjects (421CC). The aim of this study was to quantitatively estimate the in vivo decrease of BCRP function caused by the c.421C>A polymorphism based on clinical pharmacokinetic data. Assuming that the pharmacokinetic alteration is accounted for by intestinal BCRP, the ratio of the transport activity of the mutated BCRP to that of the wild-type was optimized by comparing calculations from an intestinal absorption model and clinical pharmacokinetic data. In conclusion, the in vivo intestinal BCRP transport activity in 421AA subjects is estimated to be approximately 23% of that in the 421CC subjects.

Drug safety: The concept, inception and its importance in patients' health

BACKGROUND

Drug safety is one of the hottest topics in daily medical practice, particularly with regard to approving new medication or questioning the possibility of withdrawing a drug from the market.

AIM

The aim of this review is to highlight the importance of the drug safety concept and its impact on patients' health.

METHODS

A literature search was conducted using Pubmed®, EMBASE®, EBSCO and Medline in the period between 1980 and 2013. The terms used in the search included "Drug Safety", "Medication Safety", "Patient Safety", "Drug Interaction", "Drug Pharmacokinetic", and "Adverse Drug Reaction". All retrieved abstracts were evaluated within the context of the review objectives. The full texts of the selected articles were included in this review. Studies in non-English language were excluded in this review.

RESULTS

Since the early days of the past century, many acts, laws, or amendments have been created to make sure that approved drugs are first safe and then effective. Furthermore, these regulations are continuing to change to make sure that these drugs have a positive benefit-risk balance. Personalized medicine should be considered when medications are given to patients because the pharmacokinetic process inside the body varies from patient to patient and from one specific disease state to another. However, adverse drug reactions can be minimized if more precautions are taken by healthcare professionals, especially including the patient as one pillar of the therapeutic plan and providing more patient counseling, which will improve drug safety.

CONCLUSION

The drug safety concept has earned a lot of attention during the past decade due to the fact it plays a major role in patients' health. Recent laws stress this concept should be included in the process of new medications' approval and continued conduct of post-marketing drug evaluations. Benefit-risk assessment should be considered by all health care professionals when they need to give specific drugs to specific groups of patients. Therefore, more care should be given to some patients, such as pregnant women, children and the elderly, since they are considered vulnerable populations.

Evaluation of the pharmacokinetics and drug interactions of the two recently developed statins, rosuvastatin and pitavastatin

INTRODUCTION

Statins are the cornerstone of lipid-lowering therapy to reduce the risk of coronary heart disease. Rosuvastatin and pitavastatin are the two recently developed statins with less potential for drug interaction resulting in improved safety profiles.

AREAS COVERED

This review summarizes the pharmacokinetics and drug interactions of rosuvastatin and pitavastatin. The materials reviewed were identified by searching PubMed for publications using 'rosuvastatin', 'pitavastatin', 'statins', 'pharmacokinetics' and 'drug interaction' as the search terms.

EXPERT OPINION

Rosuvastatin and pitavastatin have favorable pharmacokinetic and safety profiles as their disposition does not depend on or is only marginally influenced by cytochrome P450 (CYP) enzymes, thus potentially reducing the risk of drug-drug interactions of these two statins with other drugs known to inhibit CYP enzymes. However, drug transporters play a significant role in the disposition of rosuvastatin and pitavastatin and drug interactions may occur through these. Genetic polymorphisms in drug transporters may also affect the pharmacokinetics, drug interactions and/or the lipid-lowering effect of these statins to a different extent.

Pitavastatin and Atorvastatin double-blind randomized comPArative study among hiGh-risk patients, including thOse with Type 2 diabetes mellitus, in Taiwan (PAPAGO-T Study)

Background

Evidence about the efficacy and safety of statin treatment in high-risk patients with hypercholesterolemia is available for some populations, but not for ethnic Chinese. To test the hypothesis that treatment with pitavastatin (2 mg/day) is not inferior to treatment with atorvastatin (10 mg/day) for reducing low-density lipoprotein cholesterol (LDL-C), a 12-week multicenter collaborative randomized parallel-group comparative study of high-risk ethnic Chinese patients with hypercholesterolemia was conducted in Taiwan. In addition, the effects on other lipid parameters, inflammatory markers, insulin-resistance-associated biomarkers and safety were evaluated.

Methods and Results

Between July 2011 and April 2012, 251 patients were screened, 225 (mean age: 58.7 ± 8.6; women 38.2% [86/225]) were randomized and treated with pitavastatin (n = 112) or atorvastatin (n = 113) for 12 weeks. Baseline characteristics in both groups were similar, but after 12 weeks of treatment, LDL-C levels were significantly lower: pitavastatin group = −35.0 ± 14.1% and atorvastatin group = −38.4 ± 12.8% (both: p < 0.001). For the subgroup with diabetes mellitus (DM) (n = 125), LDL-C levels (−37.1 ± 12.9% vs. −38.0 ± 13.1%, p = 0.62) were similarly lowered after either pitavastatin (n = 63) or atorvastatin (n = 62) treatment. Triglycerides, non-high density lipoprotein cholesterol, and apoprotein B were similarly and significantly lower in both treatment groups. In non-lipid profiles, HOMA-IR and insulin levels were higher to a similar degree in both statin groups. Hemoglobin A₁C was significantly (p = 0.001) higher in the atorvastatin group but not in the pitavastatin group. Both statins were well tolerated, and both groups had a similar low incidence of treatment-emergent adverse events.

Conclusion

Both pitavastatin (2 mg/day) and atorvastatin (10 mg/day) were well tolerated, lowered LDL-C, and improved the lipid profile to a comparable degree in high-risk Taiwanese patients with hypercholesterolemia.

Trial Registration

ClinicalTrials.gov NCT01386853 http://clinicaltrials.gov/ct2/show/NCT01386853?term=NCT01386853&rank=1

Drug and nutrition interactions: not just food for thought

WHAT IS KNOWN AND OBJECTIVE

The management of drug-drug interactions - from recognition of the interaction potential, to addressing the negative consequences - are well-recognized and avoided, or rapidly addressed when identified clinically. Drug-nutrition interactions are no less important than drug-drug interactions in patient care. Unfortunately, beyond those caused by food, these interactions are less commonly recognized or identified and managed. This article will re-introduce the topic of drug-nutrition interactions to clinicians.

COMMENT

Although many clinicians are acutely aware of and vigilant for potential drug-drug interactions, most are less aware of the possibility of drug-nutrition interactions beyond classic food-drug interactions. Interaction can occur between a drug and a nutrient, multiple nutrients, food in general, specific foods or components, or nutrition status. An interaction is considered clinically significant if it alters therapeutic drug response and/or compromises nutrition status. Mechanistically the interactions may be physicochemical reactions, actions at membrane transporters or metabolizing enzymes, or an influence on physiologic function. Appreciating the many types of drug-nutrition interactions will aid the clinician and have the potential to influence patient outcome.

WHAT IS NEW AND CONCLUSION

Ongoing advances in knowledge about drug and nutrition interactions have potential to improve patient care. Drug-nutrition interactions need to be better recognized, understood on a mechanistic basis, predicted, and managed as necessary.

Grapefruit-Drug Interactions: Can Interactions With Drugs Be Avoided?

Grapefruit is rich in flavonoids, which have been demonstrated to have a preventive influence on many chronic diseases, such as cancer and cardiovascular disease. However, since the early 1990s, the potential health benefits of grapefruit have been overshadowed by the possible risk of interactions between drugs and grapefruit and grapefruit juice. Several drugs interacting with grapefruit are known in different drug classes, such as HMG-CoA reductase inhibitors, calcium antagonists, and immunosuppressives. Currently known mechanisms of interaction include the inhibition of cytochrome P450 as a major mechanism, but potential interactions with P-glycoprotein and organic anion transporters have also been reported. This review is designed to provide a comprehensive summary of underlying mechanisms of interaction and human clinical trials performed in the area of grapefruit drug interactions and to point out possible replacements for drugs with a high potential for interactions.

Almorexant effects on CYP3A4 activity studied by its simultaneous and time-separated administration with simvastatin and atorvastatin

PURPOSE

To characterise further the previously observed cytochrome P450 3A4 (CYP3A4) interaction of the dual orexin receptor antagonist almorexant.

METHODS

Pharmacokinetic interactions were investigated (n = 14 healthy male subjects in two treatment groups) between almorexant at steady-state when administered either concomitantly or 2 h after administration of single doses of simvastatin (40 mg) or atorvastatin (40 mg).

RESULTS

Almorexant dose-dependently increased simvastatin exposure (AUC0-∞) when administered concomitantly [geometric mean ratios (90 % CI): 2.5 (2.1, 2.9) (100 mg), 3.9 (3.3, 4.6) (200 mg)], but not Cmax [3.7 (3.0, 4.5) for both doses]. Time-separated administration resulted in relevant reductions of the interaction [AUC0-∞: 1.4 (1.2, 1.7) (100 mg), 1.7 (1.5, 2.0) (200 mg); Cmax: 1.5 (1.3, 1.9) (100 mg), 1.9 (1.6, 2.4) (200 mg)]. Similar results were obtained for hydroxyacid simvastatin. Independent of almorexant dose and relative time of administration, AUC0-∞ and Cmax of atorvastatin increased (ratios ranged from 1.1 to 1.5). AUC0-∞ and Cmax of o-hydroxy atorvastatin decreased dose-independently [AUC0-∞: 0.8 (0.8, 0.9) (100 mg), 0.6 (0.5, 0.6) (200 mg); Cmax: 0.3 (0.3, 0.4) (100 mg), 0.2 (0.2, 0.3) (200 mg)] when atorvastatin was concomitantly administered. Cmax of o-hydroxy atorvastatin slightly decreased (0.8 for both doses) following time-separated administration; AUC0-∞ was unchanged.

CONCLUSIONS

Whereas almorexant increased simvastatin exposure dose- and relative time of administration-dependently, atorvastatin exposure increased to a smaller extent and irrespective of dose and time. This suggests that the observed interaction of almorexant with simvastatin is mainly caused by intestinal CYP3A4 inhibition, whereas the interaction with atorvastatin is more due to hepatic CYP3A4 inhibition.

Fruit juices as perpetrators of drug interactions: the role of organic anion-transporting polypeptides

Grapefruit juice is widely recognized to cause important drug interactions via inhibition of CYP3A4, and a wider variety of fruit juices have been shown to inhibit influx transporters in enterocytes known as organic anion-transporting polypeptides (OATPs). Fruit juice coadministration significantly reduces the oral bioavailability of numerous important medicines relying on this anion transporter pathway for absorption. This article reviews the current literature on interactions between clinically used OATP substrates and fruit juice consumption.

Mechanisms underlying food-drug interactions: inhibition of intestinal metabolism and transport

Food-drug interaction studies are critical to evaluate appropriate dosing, timing, and formulation of new drug candidates. These interactions often reflect prandial-associated changes in the extent and/or rate of systemic drug exposure. Physiologic and physicochemical mechanisms underlying food effects on drug disposition are well-characterized. However, biochemical mechanisms involving drug metabolizing enzymes and transport proteins remain underexplored. Several plant-derived beverages have been shown to modulate enzymes and transporters in the intestine, leading to altered pharmacokinetic (PK) and potentially negative pharmacodynamic (PD) outcomes. Commonly consumed fruit juices, teas, and alcoholic drinks contain phytochemicals that inhibit intestinal cytochrome P450 and phase II conjugation enzymes, as well as uptake and efflux transport proteins. Whereas myriad phytochemicals have been shown to inhibit these processes in vitro, translation to the clinic has been deemed insignificant or undetermined. An overlooked prerequisite for elucidating food effects on drug PK is thorough knowledge of causative bioactive ingredients. Substantial variability in bioactive ingredient composition and activity of a given dietary substance poses a challenge in conducting robust food-drug interaction studies. This confounding factor can be addressed by identifying and characterizing specific components, which could be used as marker compounds to improve clinical trial design and quantitatively predict food effects. Interpretation and integration of data from in vitro, in vivo, and in silico studies require collaborative expertise from multiple disciplines, from botany to clinical pharmacology (i.e., plant to patient). Development of more systematic methods and guidelines is needed to address the general lack of information on examining drug-dietary substance interactions prospectively.

Effects of grapefruit juice and SLCO1B1 388A>G polymorphism on the pharmacokinetics of pitavastatin

Pitavastatin undergoes little hepatic metabolism but it is a substrate for uptake and efflux transporters, particularly OATP1B1 (gene SLCO1B1). A previous study in 8 Japanese healthy subjects showed that co-administration with grapefruit juice (GFJ) resulted in a small increase in systemic exposure to pitavastatin. We examined whether common polymorphisms in SLCO1B1 might influence the pharmacokinetics of pitavastatin or the interaction with GFJ. Twelve Chinese healthy male volunteers took pitavastatin 2 mg orally with water or with GFJ on separate occasions and plasma concentrations of pitavastatin acid and lactone were measured over 48 h. GFJ increased the mean area under the plasma concentration-time curve (AUC0-48 h) for both pitavastatin acid and lactone by 14% (p<0.05). Subjects with SLCO1B1 *1b/*1b haplotype (388GG-521TT) had 47% and 44% higher systemic exposure for pitavastatin acid and lactone than the SLCO1B1 *1a carriers (388AA/AG-521TT, p<0.05 and p=0.005, respectively). The SLCO1B1 388A>G polymorphism, which increases transporter activity for some statins, was associated with higher plasma levels of pitavastatin acid and lactone in subjects with the homozygous variant indicating decreased hepatic uptake. Co-administration of pitavastatin with GFJ resulted in a small but significant increase in plasma levels in healthy Chinese subjects.

Elucidating the role of dose in the biopharmaceutics classification of drugs: the concepts of critical dose, effective in vivo solubility, and dose-dependent BCS

PURPOSE

To develop a dose dependent version of BCS and identify a critical dose after which the amount absorbed is independent from the dose.

METHODS

We utilized a mathematical model of drug absorption in order to produce simulations of the fraction of dose absorbed (F) and the amount absorbed as function of the dose for the various classes of BCS and the marginal cases in between classes.

RESULTS

Simulations based on the mathematical model of F versus dose produced patterns of a constant F throughout a wide range of doses for drugs of Classes I, II and III, justifying biowaiver claim. For Classes I and III the pattern of a constant F stops at a critical dose Dose(cr) after which the amount of drug absorbed, is independent from the dose. For doses higher than Dose(cr), Class I drugs become Class II and Class III drugs become Class IV. Dose(cr) was used to define an in vivo effective solubility as S(eff) = Dose(cr)/250 ml. Literature data were used to support our simulation results.

CONCLUSIONS

A new biopharmaceutic classification of drugs is proposed, based on F, separating drugs into three regions, taking into account the dose, and Dose(cr), while the regions for claiming biowaiver are clearly defined.

Are all statins the same? Focus on the efficacy and tolerability of pitavastatin

Pitavastatin is the newest member of the HMG-CoA reductase inhibitor family and is approved as adjunctive therapy to diet to reduce elevated levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein (Apo) B, and triglycerides and to increase levels of high-density lipoprotein (HDL) cholesterol in adult patients with primary hyperlipidemia or mixed dyslipidemia. Pitavastatin undergoes minimal metabolism by cytochrome P450 (CYP) enzymes and, therefore, has a low propensity for drug-drug interactions with drugs metabolized by CYP enzymes or the CYP3A4 substrate grapefruit juice. In clinical trials, pitavastatin potently and consistently reduced serum levels of total, LDL, and non-HDL cholesterol, and triglycerides in patients with primary hypercholesterolemia where diet and other non-pharmacological measures were inadequate. Mean reductions from baseline in serum total and LDL cholesterol and triglyceride levels were 21-32%, 30-45%, and 10-30%, respectively. Moreover, a consistent trend towards increased HDL cholesterol levels of 3-10% was seen. Long-term extension studies show that the beneficial effects of pitavastatin are maintained for up to 2 years. Pitavastatin produces reductions from baseline in serum total and LDL cholesterol levels to a similar extent to those seen with the potent agent atorvastatin and to a greater extent than those seen with simvastatin or pravastatin. In the majority of other studies comparing pitavastatin and atorvastatin, no significant differences in the favorable effects on lipid parameters were seen, although pitavastatin was consistently associated with trends towards increased HDL cholesterol levels. Pitavastatin also produces beneficial effects on lipids in patients with type 2 diabetes mellitus and metabolic syndrome without deleterious effects on markers of glucose metabolism, such as fasting blood glucose levels or proportion of glycosylated hemoglobin. Pitavastatin appears to exert a number of beneficial effects on patients at risk of cardiovascular events independent of lipid lowering. In the JAPAN-ACS (Japan Assessment of Pitavastatin and Atorvastatin in Acute Coronary Syndrome) study, pitavastatin was non-inferior to atorvastatin at reducing plaque volume in patients with ACS undergoing percutaneous coronary intervention. Further beneficial effects, including favorable effects on the size and composition of atherosclerotic plaques, improvements in cardiovascular function, and improvements in markers of inflammation, oxidative stress, and renal function, have been demonstrated in a number of small studies. Pitavastatin is generally well tolerated in hyperlipidemic patients with or without type 2 diabetes, with the most common treatment-related adverse events being musculoskeletal or gastrointestinal in nature. Increases in plasma creatine kinase levels were seen in <5% of pitavastatin recipients and the incidence of myopathy or rhabdomyolysis was extremely low. In summary, pitavastatin, the latest addition to the statin family, produces potent and consistent beneficial effects on lipids, is well tolerated, and has a favorable pharmacokinetic profile. The combination of a potent decrease in total and LDL cholesterol levels and increase in HDL cholesterol levels suggest that pitavastatin may produce substantial cardiovascular protection.

Food-drug interaction of tacrolimus with pomelo, ginger, and turmeric juice in rats

Tacrolimus is a well-known potent immunosuppressant agent, which has various drug-drug or food-drug interactions. Previously, we found a renal transplant recipient who increased tacrolimus blood concentrations after ingestion of pomelo as a rare case. So, we investigated the effect of pomelo after its administration for one day or 3 consecutive days on the pharmacokinetics of tacrolimus in rats. We also confirmed the effects of grapefruit, turmeric, and ginger. The tacrolimus blood concentrations of the rats pre-treated with 100% pomelo juice were significantly higher than those pre-treated with water. On the other hand, the tacrolimus blood concentrations of the rats pre-treated with 50% pomelo juice were not significantly different from those pre-treated with water. The pomelo-tacrolimus interaction showed concentration dependency. Even low concentration of pomelo juice could enhance the blood concentrations of tacrolimus by repeated administration. The inhibitory effect of 100% pomelo juice disappeared 3 days after intake. The AUC values of tacrolimus in the rats pre-treated with grapefruit juice, ginger juice, and turmeric juice were significantly larger than those pre-treated with water. We could confirm the pomelo-tacrolimus interaction, which we discovered in a case study, quantitatively. We newly found the influence of turmeric and ginger on tacrolimus pharmacokinetics, comparable to pomelo.

Comparative efficacy of pitavastatin and simvastatin in high-risk patients: a randomized controlled trial

INTRODUCTION

Despite the proven efficacy of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) in lowering total and low-density lipoprotein cholesterol (LDL-C), many patients do not reach recommended lipid targets. This study compared pitavastatin, a new and highly effective statin, and simvastatin in patients at high risk of coronary heart disease (CHD). The primary objective was to demonstrate noninferiority of pitavastatin to simvastatin.

METHODS

The study was a phase 3, randomized, double-blind, double-dummy, parallel-group, active-controlled study conducted at 37 centers in five European countries. Following a dietary run-in period of 6-8 weeks, patients with primary hypercholesterolemia or combined dyslipidemia and at least two CHD risk factors were randomized 2:1 to receive pitavastatin 4 mg or simvastatin 40 mg once daily for 12 weeks. The primary efficacy variable was the change in LDL-C from baseline.

RESULTS

In total, 355 patients were randomized, 236 to pitavastatin and 119 to simvastatin; 330 patients (223 and 107, respectively) completed the study. In the pitavastatin group, mean (± SD) reduction in LDL-C concentrations from baseline was -44.0 ± 12.8% compared with -43.8 ± 14.4% in the simvastatin group. The adjusted mean treatment difference (simvastatin--pitavastatin) was 0.31% (95% confidence interval -2.47, 3.09; P = 0.829), which was within the predefined noninferiority range. More than 80% of patients in each group reached recommended LDL-C targets. Pitavastatin provided a greater increase in high-density lipoprotein cholesterol (HDL-C; 6.8% vs. 4.5%; P = 0.083) and a significantly greater decrease in triglycerides (-19.8% vs. -14.8%; P = 0.044) than simvastatin. Both treatments were well tolerated.

CONCLUSION

Pitavastatin 4 mg is as effective as simvastatin 40 mg in lowering LDL-C in dyslipidemic patients at high risk of CHD, with additional effects on HDL-C and triglycerides. Therefore, pitavastatin may be appropriate for the management of dyslipidemic patients at high cardiovascular risk.

[Specific considerations on the prescription and therapeutic interchange of statins]

OBJECTIVE

The pharmaceutical industry currently offers six different statins in Spain and there is one more soon to be available. Choosing the most appropriate drug and dose is determined by the therapeutic target (reduction in LDL-C levels). Statin doses that decrease LDL-C at the same percentage are considered equivalent. Evaluating the pharmacokinetic characteristics of each statin can be useful when setting selection criteria, helping to determine which statin may be more appropriate for a patient based on their individual characteristics and on the other co-administered drugs.

METHODS

We reviewed the pharmacokinetics properties of each statin and its possible involvement in drug interactions.

RESULTS

CYP3A4 was responsible for the metabolism of lovastatin, simvastatin and atorvastatin; fluvastatin depends on CYP2C9; P-glycoprotein is responsible for decreased atorvastatin, pravastatin, simvastatin and lovastatin concentrations. The OATPA1B1 transporter involved in all statins' access to the hepatocyte, except for fluvastatin, is essential for rosuvastatin and pravastatin. These circumstances cause those drugs inhibiting or inducing isoenzymes or transporters' activity not to have the same effect on the different statins.

CONCLUSION

The pharmacokinetics is important when choosing the best statin and could be a limitation in the use of interchange therapeutic programmes when other drugs are present.

Place of pitavastatin in the statin armamentarium: promising evidence for a role in diabetes mellitus

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, known as statins, have revolutionized the treatment of hypercholesterolemia and coronary artery disease prevention. However, there are considerable issues regarding statin safety and further development of residual risk control, particularly for diabetic and metabolic syndrome patients. Pitavastatin is a potent statin with low-density lipoprotein (LDL) cholesterol-lowering effects comparable to those of atorvastatin or rosuvastatin. Pitavastatin has a high-density lipoprotein (HDL) cholesterol raising effect, may improve insulin resistance, and has little influence on glucose metabolism. Considering these factors along with its unique pharmacokinetic properties, which suggest minimal drug–drug interaction, pitavastatin could provide an alternative treatment choice, especially in patients with glucose intolerance or diabetes mellitus. Many clinical trials are now underway to test the clinical efficacy of pitavastatin in various settings and are expected to provide further information.

Grapefruit-drug interactions

Grapefruit juice and grapefruit product consumption have potential health benefits; however, their intake is also associated with interactions with certain drugs, including calcium channel blockers, immunosuppressants and antihistamines. The primary mechanism through which interactions are mediated is mechanism-based intestinal cytochrome P450 3A4 inhibition by furanocoumarins resulting in increased bioavailability of administered medications that are substrates. Grapefruit products have also been associated with interactions with P-glycoprotein (P-gp) and uptake transporters (e.g. organic anion-transporting polypeptides [OATPs]). Polyphenolic compounds such as flavonoids have been proposed as the causative agents of the P-gp and OATP interactions. The mechanisms and magnitudes of the interactions can be influenced by the concentrations of furanocoumarins and flavonoids in the grapefruit product, the volume of juice consumed, and the inherent variability of specific enzymes and transporter components in humans. It is therefore challenging to predict the extent of grapefruit product-drug interactions and to compare available in vitro and in vivo data. The clinical significance of such interactions also depends on the disposition and toxicity profile of the drug being administered. The aim of this review is to outline the mechanisms of grapefruit-drug interactions and present a comprehensive summary of those agents affected and whether they are likely to be of clinical relevance.

Fruit juice inhibition of uptake transport: a new type of food-drug interaction

A new type of interaction in which fruit juices diminish oral drug bioavailability through inhibition of uptake transport is the focus of this review. The discovery was based on an opposite to anticipated finding when assessing the possibility of grapefruit juice increasing oral fexofenadine bioavailability in humans through inhibition of intestinal MDR1-mediated efflux transport. In follow-up investigations, grapefruit or orange juice at low concentrations potentially and selectively inhibited in vitro OATP1A2-mediated uptake compared with MDR1-caused efflux substrate transport. These juices at high volume dramatically depressed oral fexofenadine bioavailability. Grapefruit was the representative juice to characterize the interaction subsequently. A volume-effect relationship study using a normal juice amount halved average fexofenadine absorption. Individual variability and reproducibility data indicated the clinical interaction involved direct inhibition of intestinal OATP1A2. Naringin was a major causal component suggesting that other flavonoids in fruits and vegetables might also produce the effect. Duration of juice clinical inhibition of fexofenadine absorption lasted more than 2 h but less than 4 h indicating the interaction was avoidable with appropriate interval of time between juice and drug consumption. Grapefruit juice lowered the oral bioavailability of several medications transported by OATP1A2 (acebutolol, celiprolol, fexofenadine, talinolol, L-thyroxine) while orange juice did the same for others (atenolol, celiprolol, ciprofloxacin, fexofenadine). Juice clinical inhibition of OATP2B1 was unresolved while that of OATP1B1 seemed unlikely. The interaction between grapefruit juice and etoposide also seemed relevant. Knowledge of both affected uptake transporter and drug hydrophilicity assisted prediction of the clinical interaction with grapefruit or orange juice.

The effect of grapefruit juice on drug disposition

INTRODUCTION

Since their initial discovery in 1989, grapefruit juice (GFJ)-drug interactions have received extensive interest from the scientific, medical, regulatory and lay communities. Although knowledge regarding the effects of GFJ on drug disposition continues to expand, the list of drugs studied in the clinical setting remains relatively limited.

AREAS COVERED

This article reviews the in vitro effects of GFJ and its constituents on the activity of CYP enzymes, organic anion-transporting polypeptides (OATPs), P-glycoprotein, esterases and sulfotransferases. The translational applicability of the in vitro findings to the clinical setting is discussed for each drug metabolizing enzyme and transporter. Reported AUC ratios for available GFJ-drug interaction studies are also provided. Relevant investigations were identified by searching the PubMed electronic database from 1989 to 2010.

EXPERT OPINION

GFJ increases the bioavailability of some orally administered drugs that are metabolized by CYP3A and normally undergo extensive presystemic extraction. In addition, GFJ can decrease the oral absorption of a few drugs that rely on OATPs in the gastrointestinal tract for their uptake. The number of drugs shown to interact with GFJ in vitro is far greater than the number of clinically relevant GFJ-drug interactions. For the majority of patients, complete avoidance of GFJ is unwarranted.