Impact ofSLCO1B1(OATP1B1) andABCG2(BCRP) genetic polymorphisms and inhibition on LDL-C lowering and myopathy of statins

Utilization of OATP1B Biomarker Coproporphyrin-I to Guide Drug-Drug Interaction Risk Assessment: Evaluation by the Pharmaceutical Industry

Drug-drug interactions (DDIs) involving hepatic organic anion transporting polypeptides 1B1/1B3 (OATP1B) can be substantial, however, challenges remain for predicting interaction risk. Emerging evidence suggests that endogenous biomarkers, particularly coproporphyrin-I (CP-I), can be used to assess in vivo OATP1B activity. The present work under the International Consortium for Innovation and Quality in Pharmaceutical Development was aimed primarily at assessing CP-I as a biomarker for informing OATP1B DDI risk. Literature and unpublished CP-I data along with pertinent in vitro and clinical DDI information were collected to identify DDIs primarily involving OATP1B inhibition and assess the relationship between OATP1B substrate drug and CP-I exposure changes. Static models to predict changes in exposure of CP-I, as a selective OATP1B substrate, were also evaluated. Significant correlations were observed between CP-I area under the curve ratio (AUCR) or maximum concentration ratio (Cmax R) and AUCR of substrate drugs. In general, the CP-I Cmax R was equal to or greater than the CP-I AUCR. CP-I Cmax R < 1.25 was associated with absence of OATP1B-mediated DDIs (AUCR < 1.25) with no false negative predictions. CP-I Cmax R < 2 was associated with weak OATP1B-mediated DDIs (AUCR < 2). A correlation was identified between CP-I exposure changes and OATP1B1 static DDI predictions. Recommendations for collecting and interpreting CP-I data are discussed, including a decision tree for guiding DDI risk assessment. In conclusion, measurement of CP-I is recommended to inform OATP1B inhibition potential. The current analysis identified changes in CP-I exposure that may be used to prioritize, delay, or replace clinical DDI studies.

Association Between ABCG2, ABCB1, ABCC2 Efflux Transporter Single-Nucleotide Variants and Irinotecan Adverse Effects in Patients With Colorectal Cancer: A Real-Life Study

Among patients treated with irinotecan, homozygous carriers of the UGT1A1*28 allele are at increased risk for neutropenia, but UGT1A1 genotype alone does not account for irinotecan-induced toxicity. Our aim was to study the association between single-nucleotide variants in genes encoding for efflux transporters of irinotecan (ABCG2, ABCB1, and ABCC2) and toxicity in real life. The source population was a cohort of patients with colorectal cancer (CRC) in Northern Israel, who had undergone genome-wide association study. From the source population we chose the patients with CRC prescribed irinotecan, and a comparative cohort of patients with CRC treated with other anticancer systemic therapies. Using Clalit Health Services electronic medical records (including laboratory results) we ascertained hematological and gastrointestinal adverse effects and mortality, within 90 days of the first dose, as a composite outcome. There were 601 patients with CRC who received irinotecan, and 756 patients with CRC treated with other anticancer regimens. The minor allele in rs2231142 (ABCG2) was associated with lower incidence of the composite outcome (odds ratio (OR) = 0.54 (0.33, 0.91); P = 0.02) in irinotecan-treated patients with CRC, but not in patients with CRC treated with other regimens. ABCB1 rs1045642 and ABCC2 rs3740066 were not associated with the composite outcome. In a sensitivity analysis, adjusted for UGT1A1 status and for possible demographic and clinical confounders, adjusted OR was 0.56 (0.33, 0.94) for the association between rs2231142 (ABCG2) and the composite outcome. In conclusion, we describe a novel association between the minor allele of rs2231142 in the efflux transporter gene ABCG2 and protection against severe side effects in CRC patients treating with irinotecan.

Reimagining the Framework Supporting the Static Analysis of Transporter Drug Interaction Risk; Integrated Use of Biomarkers to Generate Pan‐Transporter Inhibition Signatures

Solute carrier (SLC) transporters present as the loci of important drug-drug interactions (DDIs). Therefore, sponsors generate in vitro half-maximal inhibitory concentration (IC₅₀ ) data and apply regulatory agency-guided "static" methods to assess DDI risk and the need for a formal clinical DDI study. Because such methods are conservative and high false-positive rates are likely (e.g., DDI study triggered when liver SLC R value ≥ 1.04 and renal SLC maximal unbound plasma (C_max,u )/IC₅₀ ratio ≥ 0.02), investigators have attempted to deploy plasma- and urine-based SLC biomarkers in phase I studies to de-risk DDI and obviate the need for drug probe-based studies. In this regard, it was possible to generate in-house in vitro SLC IC₅₀ data for various clinically (biomarker)-qualified perpetrator drugs, under standard assay conditions, and then estimate "% inhibition" for each SLC and relate it empirically to published clinical biomarker data (area under the plasma concentration vs. time curve (AUC) ratio (AUCR, AUC_inhibitor /AUC_reference ) and % decrease in renal clearance (ΔCL_renal )). After such a "calibration" exercise, it was determined that only compounds with high R values (> 1.5) and C_max,u /IC₅₀ ratios (> 0.5) are likely to significantly modulate liver (AUCR > 1.25) and renal (ΔCL_renal  > 25%) biomarkers and evoke DDI risk. The % inhibition approach supports integration of liver and renal SLC data and allows one to generate pan-SLC inhibition signatures for different test perpetrators (e.g., SLC % inhibition ranking). In turn, such signatures can guide the selection of the most appropriate individual (or combinations of) biomarkers for testing in phase I studies.

Protective Effects of Statin Therapy in Cirrhosis Are Limited by a Common SLCO1B1 Transporter Variant

Complications of cirrhosis and portal hypertension (PH) can be reduced by statin therapy. The common loss-of-function variant p.V174A in the solute carrier organic anion transporter gene 1B1 (SLCO1B1) gene encoding the organic anion transporting polypeptide 1B1 results in decreased hepatic uptake of statins. Our specific aim was to assess the impact of this variant in patients with cirrhosis and statin treatment while controlling for the stage of cirrhosis and other potential confounders with propensity score matching (PSM), availing of a large cohort of genotyped study patients. In total, from 1,088 patients with cirrhosis in two German academic medical centers, PSM yielded 154 patients taking statins and 154 matched controls. The effect on PH was assessed by the liver stiffness-spleen size-to-platelet score (LSPS), and complications of cirrhosis were retrospectively recorded applying consensus criteria. As hypothesized, patients on statin treatment presented less frequently with signs of PH: Esophageal varices (41% vs. 62%; P < 0.001) were less common, and LSPS (4.8 ± 11.5 vs. 5.6 ± 6.4; P = 0.01) was reduced. Correspondingly, decompensation events were also reduced in patients on statins (odds ratio [OR] = 0.54, 95% confidence interval [CI] 0.32-0.90; P = 0.02). When the variant in SLCO1B1 was present in patients on statins, esophageal varices (OR = 2.68, 95% CI 1.24-5.81; P = 0.01) and bacterial infections (OR = 2.50, 95% CI 1.14-5.47; P = 0.02) were more common as compared with wild type carriers on statins. Conclusion: In this cohort, signs and complications of PH were reduced in patients with cirrhosis treated with statins. Notably, this effect was diminished by the common loss-of-function variant in SLCO1B1. Further prospective studies in independent cohorts are warranted to confirm these genotype-specific observations.

Effect of Oral Semaglutide on the Pharmacokinetics of Levonorgestrel and Ethinylestradiol in Healthy Postmenopausal Women and Furosemide and Rosuvastatin in Healthy Subjects

Background

The first oral glucagon-like peptide-1 receptor agonist (GLP-1RA) comprises semaglutide co-formulated with the absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). Oral semaglutide may alter the pharmacokinetics of co-administered drugs via effects of semaglutide or SNAC. Two separate one-sequence crossover trials investigated the effects of oral semaglutide and SNAC on the pharmacokinetics of ethinylestradiol, levonorgestrel, furosemide and rosuvastatin.

Methods

Healthy, postmenopausal women (n = 25) received once-daily combined ethinylestradiol and levonorgestrel (Trial 1) and healthy male and female subjects (n = 41) received single doses of furosemide and rosuvastatin (Trial 2), either alone, with SNAC alone or with oral semaglutide. Lack of drug–drug interaction was concluded if 90% confidence intervals (CIs) for the ratio of area under the plasma concentration–time curve (AUC) or maximum concentration (C_max), with/without oral semaglutide, were within a pre-specified interval (0.80–1.25).

Results

The AUC values of ethinylestradiol and levonorgestrel were not affected by oral semaglutide co-administration (estimated ratios [90% CI] 1.06 [1.01–1.10] and 1.06 [0.97–1.17], respectively); C_max was not affected. The no-effect criterion was not met for furosemide or rosuvastatin for the AUC (1.28 [1.16–1.42] and 1.41 [1.24–1.60], respectively) or C_max. SNAC alone did not affect the AUC or C_max of ethinylestradiol, levonorgestrel or rosuvastatin; the C_max of furosemide was slightly decreased. Adverse events were similar to those previously observed for GLP-1RAs (both trials).

Conclusion

Co-administration with oral semaglutide did not affect the pharmacokinetics of ethinylestradiol or levonorgestrel. There was a small increase in exposure of furosemide and rosuvastatin; however, these increases are not expected to be of clinical relevance.

Clinical Trial Registration Numbers

NCT02845219 and NCT03010475.

Supplementary Information

The online version contains supplementary material available at (10.1007/s40262-020-00976-x).

The Role of Pharmacogenomics in Contemporary Cardiovascular Therapy: A position statement from the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy

There is a strong and ever-growing body of evidence regarding the use of pharmacogenomics to inform cardiovascular pharmacology. However, there is no common position taken by international cardiovascular societies to unite diverse availability, interpretation and application of such data, nor is there recognition of the challenges of variation in clinical practice between countries within Europe. Aside from the considerable barriers to implementing pharmacogenomic testing and the complexities of clinically actioning results, there are differences in the availability of resources and expertise internationally within Europe. Diverse legal and ethical approaches to genomic testing and clinical therapeutic application also require serious thought. As direct-to-consumer genomic testing becomes more common, it can be anticipated that data may be brought in by patients themselves, which will require critical assessment by the clinical cardiovascular prescriber. In a modern, pluralistic and multi-ethnic Europe, self-identified race/ethnicity may not be concordant with genetically detected ancestry and thus may not accurately convey polymorphism prevalence. Given the broad relevance of pharmacogenomics to areas such as thrombosis and coagulation, interventional cardiology, heart failure, arrhythmias, clinical trials, and policy/regulatory activity within cardiovascular medicine, as well as to genomic and pharmacology subspecialists, this position statement attempts to address these issues at a wide-ranging level.

Coproporphyrin I Can Serve as an Endogenous Biomarker for OATP1B1 Inhibition: Assessment Using a Glecaprevir/Pibrentasvir Clinical Study

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are involved in the disposition of a variety of commonly prescribed drugs. The evaluation of OATP1B1/1B3 inhibition potential by investigational drugs is of interest during clinical drug development due to various adverse events associated with increased exposures of their substrates. Regulatory guidance documents on the in vitro assessment of OATP1B1/1B3 inhibition potential are conservative with up to a third of predictions resulting in false positives. This work investigated the utility of OATP1B1/1B3 endogenous biomarkers, coproporphyrin (CP)‐I and CP‐III, to assess clinical inhibition of OATP1B1/1B3 and potentially eliminate the need for prospective clinical drug‐drug interaction (DDI) studies. Correlations between CP‐I exposures and various OATP1B1 static DDI predictions were also evaluated. Glecaprevir/pibrentasvir (GLE/PIB) 300/120 mg fixed‐dose combination is known to cause clinical inhibition of OATP1B1/1B3. In a clinical study evaluating the relative bioavailability of various formulations of GLE/PIB regimen, CP‐I peak plasma concentration (C_max) ratio and 0–16‐hour area under the concentration‐time curve (AUC_0–16) ratio relative to baseline increased with increasing GLE exposures, whereas there was a modest correlation between GLE exposure and CP‐III C_max ratio but no correlation with CP‐III AUC_0–16 ratio. This suggests that CP‐I is superior to CP‐III as an endogenous biomarker for evaluation of OATP1B1 inhibition. There was a significant correlation between CP‐I and GLE C_max (R² = 0.65; P < 0.001) across individual subjects. Correlation analysis between GLE OATP1B1 R values and CP‐I exposures (C_max ratio and AUC_0–16 ratio) suggests that an R value of > 3 can predict a biologically meaningful inhibition of OATP1B1 when the inhibitor clinical pharmacokinetic parameters are available.

The Impact of Statin Therapy on the Survival of Patients with Gastrointestinal Cancer

Statins are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors that may play an important role in the evolution of cancers, due to their effects on cancer cell metabolism. Statins affect several potential pathways, including cell proliferation, angiogenesis, apoptosis and metastasis. The number of trials assessing the putative clinical benefits of statins in cancer is increasing. Currently, there are several trials listed on the global trial identifier website clinicaltrials.gov. Given the compelling evidence from these trials in a variety of clinical settings, there have been calls for a clinical trial of statins in the adjuvant gastrointestinal cancer setting. However, randomized controlled trials on specific cancer types in relation to statin use, as well as studies on populations without a clinical indication for using statins, have elucidated some potential underlying biological mechanisms, and the investigation of different statins is probably warranted. It would be useful for these trials to incorporate the assessment of tumour biomarkers predictive of statin response in their design. This review summarizes the recent preclinical and clinical studies that assess the application of statins in the treatment of gastrointestinal cancers with particular emphasize on their association with cancer risk.

Statin-Related Myotoxicity: A Comprehensive Review of Pharmacokinetic, Pharmacogenomic and Muscle Components

Statins are a cornerstone in the pharmacological prevention of cardiovascular disease. Although generally well tolerated, a small subset of patients experience statin-related myotoxicity (SRM). SRM is heterogeneous in presentation; phenotypes include the relatively more common myalgias, infrequent myopathies, and rare rhabdomyolysis. Very rarely, statins induce an anti-HMGCR positive immune-mediated necrotizing myopathy. Diagnosing SRM in clinical practice can be challenging, particularly for mild SRM that is frequently due to alternative aetiologies and the nocebo effect. Nevertheless, SRM can directly harm patients and lead to statin discontinuation/non-adherence, which increases the risk of cardiovascular events. Several factors increase systemic statin exposure and predispose to SRM, including advanced age, concomitant medications, and the nonsynonymous variant, rs4149056, in SLCO1B1, which encodes the hepatic sinusoidal transporter, OATP1B1. Increased exposure of skeletal muscle to statins increases the risk of mitochondrial dysfunction, calcium signalling disruption, reduced prenylation, atrogin-1 mediated atrophy and pro-apoptotic signalling. Rare variants in several metabolic myopathy genes including CACNA1S, CPT2, LPIN1, PYGM and RYR1 increase myopathy/rhabdomyolysis risk following statin exposure. The immune system is implicated in both conventional statin intolerance/myotoxicity via LILRB5 rs12975366, and a strong association exists between HLA-DRB1*11:01 and anti-HMGCR positive myopathy. Epigenetic factors (miR-499-5p, miR-145) have also been implicated in statin myotoxicity. SRM remains a challenge to the safe and effective use of statins, although consensus strategies to manage SRM have been proposed. Further research is required, including stringent phenotyping of mild SRM through N-of-1 trials coupled to systems pharmacology omics- approaches to identify novel risk factors and provide mechanistic insight.

The characteristics and mechanism of co-administration of lovastatin solid dispersion with kaempferol to increase oral bioavailability

Lovastatin shows low bioavailability (lower than 5%) after oral administration because of the poor aqueous solubility and widely metabolized by CYP3A4.Lovastatin solid dispersion was designed to enhance the dissolution. The in vitro intestinal absorption study indicated an increase in the apparent permeability of different intestinal segments compared with crude lovastatin. In the range of 12.5-50 μg/ml, the absorption of both lovastatin and lovastatin solid dispersion were found to be a passive process in rat's jejunum and ileum, but not endocytosis process. CYP3A4 inhibitor (ketoconazole) significantly increased the intestinal absorption of lovastatin and lovastatin solid dispersion. However, P-glycoprotein efflux inhibitor (verapamil) had little effect on them.The absolute bioavailability of lovastatin and lovastatin acid after oral administration of lovastatin solid dispersion were increased by about 2.01-fold and 1.40-fold than that of lovastatin suspension. The oral bioavailability of lovastatin and lovastatin acid after oral administration of lovastatin solid dispersion with 10 mg/kg kaempferol (CYP3A4 inhibitor) were increased about 3.79-fold and 2.51-fold than that of lovastatin suspension, and the absolute bioavailability of lovastatin was up to 33.0%.As a result, co-administration of lovastatin solid dispersion with kaempferol could be a promising delivery system to improve the oral bioavailability of lovastatin.

Prediction of Atorvastatin Pharmacokinetics in High-Fat Diet and Low-Dose Streptozotocin-Induced Diabetic Rats Using a Semiphysiologically Based Pharmacokinetic Model Involving Both Enzymes and Transporters

Atorvastatin is a substrate of cytochrome P450 3a (CYP3a), organic anion-transporting polypeptides (OATPs), breast cancer-resistance protein (BCRP), and P-glycoprotein (P-gp). We aimed to develop a semiphysiologically based pharmacokinetic (semi-PBPK) model involving both enzyme and transporters for predicting the contributions of altered function and expression of CYP3a and transporters to atorvastatin transport in diabetic rats by combining high-fat diet feeding and low-dose streptozotocin injection. Atorvastatin metabolism and transport parameters comes from in situ intestinal perfusion, primary hepatocytes, and intestinal or hepatic microsomes. We estimated the expressions and functions of these proteins and their contributions. Diabetes increased the expression of hepatic CYP3a, OATP1b2, and P-gp but decreased the expression of intestinal CYP3a, OATP1a5, and P-gp. The expression and function of intestinal BCRP were significantly decreased in 10-day diabetic rats but increased in 22-day diabetic rats. Based on alterations in CYP3a and transporters by diabetes, the developed semi-PBPK model was successfully used to predict atorvastatin pharmacokinetics after oral and intravenous doses to rats. Contributions to oral atorvastatin PK were intestinal OATP1a5 < intestinal P-gp < intestinal CYP3a < hepatic CYP3a < hepatic OATP1b2 < intestinal BRCP. Contributions of decreased expression and function of intestinal CYP3a and P-gp by diabetes to oral atorvastatin plasma exposure were almost attenuated by increased expression and function of hepatic CYP3a and OATP1b2. Opposite alterations in oral plasma atorvastatin exposure in 10- and 22-day diabetic rats may be explained by altered intestinal BCRP. In conclusion, the altered atorvastatin pharmacokinetics by diabetes was the synergistic effects of altered intestinal or hepatic CYP3a and transporters and could be predicted using the developed semi-PBPK.

Effects of statins on the chemoresistance-The antagonistic drug-drug interactions versus the anti-cancer effects

There has been growing interest in the potential anti-cancer activity of statins based on evidence of their anti-proliferative, pro-apoptotic, and radiosensitizing properties, but no studies have focused on the effects of statins on the chemoresistance. In spite of their direct cytostatic/cytotoxic effects on the cancer cells, statins via drug interactions may affect therapeutic effects of the chemotherapy agents and so cause chemoresistance in cancer cells. Here, we aim to present the molecular mechanisms underlying cytotoxic effects of statins on the cancer cells against those mechanisms by which statins may lead to chemoresistance, in order to clarify whether the positive effects of the co-treatment of statins on the efficiency of chemotherapeutic agents is due to the natural anti-cancer effects of statins or it is due to increasing the cellular concentrations of chemotherapy drugs in cancer cells.

Analysis of SLCO1B1 and APOE genetic polymorphisms in a large ethnic Hakka population in southern China

OBJECTIVE

Statins are the most widely used lipid-lowering drugs, which have a significant effect on the inhibition of cardiovascular disease. The efficacy and side effects of statins are associated with the polymorphisms of SLCO1B1 and APOE genes. The purpose of this study was to analyze the SLCO1B1 and APOE gene polymorphisms in the Hakka population of southern China.

METHODS

A total of 3249 subjects including 2019 males and 1230 females participated in this study. Polymerase chain reaction (PCR)-fluorescence probe technique for polymorphisms analysis and analyzed the genotypes frequencies of SLCO1B1 and APOE genes.

RESULTS

The frequencies of SLCO1B1 521T>C between men and women were statistically significant (SLCO1B1 521TT, χ2  = 8.431, P = .004; SLCO1B1 521TC, χ2  = 7.436, P = .007). The frequencies of haplotypes *1b/*1b (40.07%) and *1a/*1b (32.56%) of SLCO1B1 gene accounted for 72.63%, followed by *1b/*15(14.40%), *1a/*1a (5.82%), *1a/*15 (5.57%), *15/*15 (1.45%), and *1a/*5 (0.12%). The frequencies of haplotypes *1a/*15 and *1b/*1b of SLCO1B1 gene between men and women were statistically significant (*1a/*15, χ2  = 6.789, P = .009; *1b/*1b, χ2  = 3.998, P = .004). In this study, genotype ɛ3/ɛ3 accounted for 69.04%, followed by ɛ3/ɛ4 (16.19%), ɛ2/ɛ3 (11.60%), ɛ2/ɛ4 (1.35%), ɛ4/ɛ4 (1.08%), and ɛ2/ɛ2 (0.74%) in all subjects, in which ɛ3 had the greatest allele frequency (82.93%), followed by ɛ4 (9.85%) and ɛ2 (7.22%). We found that 47 subjects carrying the SLCO1B1 521 (CC) polymorphism who had not any myopathy caused by statins.

CONCLUSIONS

We analyzed the SLCO1B1 and APOE gene polymorphisms in the Hakka population of southern China. This study provides a reference for the individualized meditation for Hakka population in this area.

Rare Variants in the ABCG2 Promoter Modulate In Vivo Activity

ABCG2 encodes the breast cancer resistance protein (BCRP), an efflux membrane transporter important in the detoxification of xenobiotics. In the present study, the basal activity of the ABCG2 promoter in liver, kidney, intestine, and breast cell lines was examined using luciferase reporter assays. The promoter activities of reference and variant ABCG2 sequences were compared in human hepatocellular carcinoma cell (HepG2), human embryonic kidney cell (HEK293T), human colorectal carcinoma cell (HCT116), and human breast adenocarcinoma cell (MCF-7) lines. The ABCG2 promoter activity was strongest in the kidney and intestine cell lines. Four variants in the basal ABCG2 promoter (rs76656413, rs66664036, rs139256004, and rs59370292) decreased the promoter activity by 25%-50% in at least three of the four cell lines. The activity of these four variants was also examined in vivo using the hydrodynamic tail vein assay, and two single nucleotide polymorphisms (rs76656413 and rs59370292) significantly decreased in vivo liver promoter activity by 50%-80%. Electrophoretic mobility shift assays confirmed a reduction in nuclear protein binding to the rs59370292 variant probe, whereas the rs76656413 probe had a shift in transcription factor binding specificity. Although both rs59370292 and rs76656413 are rare variants in all populations, they could contribute to patient-level variation in ABCG2 expression in the kidney, liver, and intestine.

The Promises of Quantitative Proteomics in Precision Medicine

Precision medicine approach has a potential to ensure optimum efficacy and safety of drugs at individual patient level. Physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) models could play a significant role in precision medicine by predicting interindividual variability in drug disposition and response. In order to develop robust PBPK/PD models, it is imperative that the critical physiological parameters affecting drug disposition and response and their variability are precisely characterized. Currently used PBPK/PD modeling software, for example, Simcyp and Gastroplus, encompass information such as organ volumes, blood flows to organs, body fat composition, glomerular filtration rate, etc. However, the information on the interindividual variability of the majority of the proteins associated with PK and PD, for example, drug metabolizing enzymes, transporters, and receptors, are not fully incorporated into these PBPK modeling platforms. Such information is significant because the population factors such as age, genotype, disease, and gender can affect abundance or activity of these proteins. To fill this critical knowledge gap, mass spectrometry-based quantitative proteomics has emerged as an important technique to characterize interindividual variability in the protein abundance of drug metabolizing enzymes, transporters, and receptors. Integration of these quantitative proteomics data into in silico PBPK/PD modeling tools will be crucial toward precision medicine.

The role of organic anion transporting polypeptides in drug absorption, distribution, excretion and drug-drug interactions

INTRODUCTION

The in vivo fate and effectiveness of a drug depends highly on its absorption, distribution, metabolism, excretion and toxicity (ADME-Tox). Organic anion transporting polypeptides (OATPs) are membrane proteins involved in the cellular uptake of various organic compounds, including clinically used drugs. Since OATPs are significant players in drug absorption and distribution, modulation of OATP function via pharmacotherapy with OATP substrates/inhibitors, or modulation of their expression, affects drug pharmacokinetics. Given their cancer-specific expression, OATPs may also be considered anticancer drug targets. Areas covered: We describe the human OATP family, discussing clinically relevant consequences of altered OATP function. We offer a critical analysis of published data on the role of OATPs in ADME and in drug-drug interactions, especially focusing on OATP1A2, 1B1, 1B3 and 2B1. Expert opinion: Four members of the OATP family, 1A2, 1B1, 1B3 and 2B1, have been characterized in detail. As biochemical and pharmacological knowledge on the other OATPs is lacking, it seems timely to direct research efforts towards developing the experimental framework needed to investigate the transport mechanism and substrate specificity of the poorly described OATPs. In addition, elucidating the role of OATPs in tumor development and therapy response are critical avenues for further research.

In vitro assessment of the roles of drug transporters in the disposition and drug-drug interaction potential of olaparib

1. In vitro assessments were conducted to examine interactions between olaparib (a potent oral inhibitor of poly[ADP-ribose] polymerase) and drug transporters. 2. Olaparib showed inhibition of the hepatic drug uptake transporters OATP1B1 (IC₅₀ values of 20.3 μM and 27.1 μM) and OCT1 (IC₅₀ 37.9 μM), but limited inhibition of OATP1B3 (25% at 100 μM); inhibition of the renal uptake transporters OCT2 (IC₅₀ 19.9 μM) and OAT3 (IC₅₀ 18.4 μM), but limited inhibition of OAT1 (13.5% at 100 μM); inhibition of the renal efflux transporters MATE1 and MATE2K (IC₅₀s 5.50 μM and 47.1 μM, respectively); inhibition of the efflux transporter MDR1 (IC₅₀ 76.0 μM), but limited inhibition of BCRP (47% at 100 μM) and no inhibition of MRP2. At clinically relevant exposures, olaparib has the potential to cause pharmacokinetic interactions via inhibition of OCT1, OCT2, OATP1B1, OAT3, MATE1 and MATE2K in the liver and kidney, as well as MDR1 in the liver and GI tract. Olaparib was found to be a substrate of MDR1 but not of several other transporters. 3. Our assessments indicate that olaparib is a substrate of MDR1 and may cause clinically meaningful inhibition of MDR1, OCT1, OCT2, OATP1B1, OAT3, MATE1 and MATE2K.

Hepatic drug transporters: the journey so far

INTRODUCTION

The key role of transporter biology in both the manifestation and treatment of disease is now firmly established. Experiences of sub-optimal drug exposure due to drug-transporter interplay have supported incorporation of studies aimed at understanding the interactions between compounds and drug transporters much earlier in drug discovery. While drug transporters can impact the most pivotal pharmacokinetic parameter with respect to human dose and exposure projections, clearance, at a renal or hepatobiliary level, the latter will form the focus of this perspective.

AREAS COVERED

A synopsis of guidelines on which transporters to study together with an overview of the currently available toolkit is presented. A perspective on when to conduct studies with various hepatic transporters is also provided together with structural "alerts" which should prompt early investigation.

EXPERT OPINION

Great progress has been made in individual laboratories and via consortia to understand the role of drug transporters in disease, drug disposition, drug-drug interactions and toxicity. A systematic analysis of the value posed by the available approaches and an inter-lab comparison now seems warranted. The emerging ability to use physico-chemical properties to guide future screening cascades promises to revolutionise the efficiency of early drug discovery.

Drug interaction profile of the HIV integrase inhibitor cabotegravir: assessment from in vitro studies and a clinical investigation with midazolam

1. Cabotegravir (CAB; GSK1265744) is a potent HIV integrase inhibitor in clinical development as an oral lead-in tablet and long-acting injectable for the treatment and prevention of HIV infection. 2. This work investigated if CAB was a substrate for efflux transporters, the potential for CAB to interact with drug-metabolizing enzymes and transporters to cause clinical drug interactions, and the effect of CAB on the pharmacokinetics of midazolam, a CYP3A4 probe substrate, in humans. 3. CAB is a substrate for Pgp and BCRP; however, its high intrinsic membrane permeability limits the impact of these transporters on its intestinal absorption. 4. At clinically relevant concentrations, CAB did not inhibit or induce any of the CYP or UGT enzymes evaluated in vitro and had no effect on the clinical pharmacokinetics of midazolam. 5. CAB is an inhibitor of OAT1 (IC50 0.81 µM) and OAT3 (IC50 0.41 µM) but did not or only weakly inhibited Pgp, BCRP, MRP2, MRP4, MATE1, MATE2-K, OATP1B1, OATP1B3, OCT1, OCT2 or BSEP. 6. Based on regulatory guidelines and quantitative extrapolations, CAB has a low propensity to cause clinically significant drug interactions, except for coadministration with OAT1 or OAT3 substrates.

Statins and breast cancer prognosis: evidence and opportunities

Much preclinical and epidemiological evidence supports the anticancer effects of statins. Epidemiological evidence does not suggest an association between statin use and reduced incidence of breast cancer, but does support a protective effect of statins--especially simvastatin--on breast cancer recurrence. Here, we argue that the existing evidence base is sufficient to justify a clinical trial of breast cancer adjuvant therapy with statins and we advocate for such a trial to be initiated without delay. If a protective effect of statins on breast cancer recurrence is supported by trial evidence, then the indications for a safe, well tolerated, and inexpensive treatment can be expanded to improve outcomes for breast cancer survivors. We discuss several trial design opportunities--including candidate predictive biomarkers of statin safety and efficacy--and offer solutions to the key challenges involved in the enrolment, follow-up, and analysis of such a trial.

Toward Prospective Prediction of Pharmacokinetics in OATP1B1 Genetic Variant Populations

Physiologically based pharmacokinetic (PBPK) models are increasingly being used to provide human pharmacokinetic (PK) predictions for organic anion-transporting polypeptide (OATP) substrates based on in vitro assay data. As a natural extension in the application of these models, in this study, we incorporated in vitro information of three major OATP1B1 genetic variants into a previously reported PBPK model to predict the impact of OATP1B1 polymorphisms on human PK. Using pravastatin and rosuvastatin as examples, we showed that the predicted plasma concentration-time profiles in groups carrying different OATP1B1 genetic variants reasonably matched the clinical observations from multiple studies. This modeling and simulation approach may aid decision making in early pharmaceutical research and development as well as patient-specific dose adjustment in clinical practice.

Resistance and intolerance to statins

BACKGROUND AND AIMS

Many patients treated with statins are considered statin-resistant because they fail to achieve adequate reduction of low density lipoprotein cholesterol (LDL-C) levels. Some patients are statin-intolerant because they are unable to tolerate statin therapy at all or to tolerate a full therapeutic statin dose because of adverse effects, particularly myopathy and increased activity of liver enzymes.

RESULTS

The resistance to statins has been associated with polymorphisms in the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-R), P-glycoprotein (Pg-P/ABCB1), breast cancer resistance protein (BCRP/ABCG2), multidrug resistance-associated proteins (MRP1/ABCC1 and MRP2/ABCC2), organic anion transporting polypeptides (OATP), RHOA, Nieman-Pick C1-like1 protein (NPC1L1), farnesoid X receptor (FXR), cholesterol 7alpha-hydroxylase (CYP7A1), Apolipoprotein E (ApoE), proprotein convertase subtilisin/kexin type 9 (PCSK9), low density lipoprotein receptor (LDLR), lipoprotein (a) (LPA), cholesteryl ester transfer protein (CETP), and tumor necrosis factor α (TNF-α) genes. However, currently, there is still not enough evidence to advocate pharmacogenetic testing before initiating statin therapy. Patients with inflammatory states and HIV infection also have diminished LDL-C lowering as a response to statin treatment. Pseudo-resistance due to nonadherence or non-persistence in real-life circumstances is probably the main cause of insufficient LDL-C response to statin treatment.

CONCLUSIONS

If a patient is really statin-resistant or statin-intolerant, several other treatment possibilities are nowadays available: ezetimibe alone or in combination with bile acid sequestrants, and possibly in the near future mipomersen, lomitapide, or monoclonal antibodies against PCSK9.

Mechanisms and assessment of statin-related muscular adverse effects

Statin-associated muscular adverse effects cover a wide range of symptoms, including asymptomatic increase of creatine kinase serum activity and life-threatening rhabdomyolysis. Different underlying pathomechanisms have been proposed. However, a unifying concept of the pathogenesis of statin-related muscular adverse effects has not emerged so far. In this review, we attempt to categorize these mechanisms along three levels. Firstly, among pharmacokinetic factors, it has been shown for some statins that inhibition of cytochrome P450-mediated hepatic biotransformation and hepatic uptake by transporter proteins contribute to an increase of systemic statin concentrations. Secondly, at the myocyte membrane level, cell membrane uptake transporters affect intracellular statin concentrations. Thirdly, at the intracellular level, inhibition of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase results in decreased intracellular concentrations of downstream metabolites (e.g. selenoproteins, ubiquinone, cholesterol) and alteration of gene expression (e.g. ryanodine receptor 3, glycine amidinotransferase). We also review current recommendations for prescribers.

Effect of CYP2C19 polymorphism on the pharmacokinetics of rosuvastatin in healthy Taiwanese subjects

CYP2C19 contributes to N-desmethyl rosuvastatin formation in "in vitro" models. Approximately 80% of Taiwanese are CYP2C19 extensive metabolizers (EMs, CYP2C19*1/*1, *1/*2, or *1/*3). We studied the potential effect of CYP2C19 genotypes on rosuvastatin pharmacokinetics in healthy Taiwanese subjects following single and multiple daily oral doses of rosuvastatin calcium (20 mg). Geometric mean ratios for poor metabolizers (PMs): EMs for rosuvastatin were 0.974 and 0.872 for area under the curve and maximum plasma concentration on day 1 (1.01 and 0.965 on day 17) and for N-desmethyl rosuvastatin, 1.21 and 1.07 on day 1 (1.14 and 1.09 on day 17), respectively. Changes of lipid profiles from baseline to day 18 for PMs and EMs were -52.4% and -53.3% (low-density lipoprotein cholesterol), and -34.2% and -30.0% (total cholesterol), respectively. Rosuvastatin was generally well-tolerated by both PMs and EMs. These results suggest that CYP2C19 polymorphism does not affect rosuvastatin pharmacokinetics in healthy Taiwanese in a clinically meaningful way.

Translational insight into statin-induced muscle toxicity: from cell culture to clinical studies

Statins are lipid-lowering drugs used widely to prevent and treat cardiovascular and coronary heart diseases. These drugs are among the most commonly prescribed medicines intended for long-term use. In general, statins are well tolerated. However, muscular adverse effects appear to be the most common obstacle that limits their use, resulting in poor patient compliance or even drug discontinuation. In addition, rare but potentially fatal cases of rhabdomyolysis have been reported with the use of these drugs, especially in the presence of certain risk factors. Previous reports have investigated statin-induced myotoxicity in vivo and in vitro using a number of cell lines, muscle tissues, and laboratory animals, in addition to randomized clinical trials, observational studies, and case reports. None of them have compared directly results from laboratory investigations with clinical observations of statin-related muscular adverse effects. To the best of our knowledge this is the first review article that combines laboratory investigation with clinical aspects of statin-induced myotoxicity. By reviewing published literature of in vivo, in vitro, and clinically relevant studies of statin myotoxicity, we aim to translate this important drug-related problem to establish a clear picture of proposed mechanisms that explain the risk factors and describe the diagnostic approaches currently used for evaluating the degree of muscle damage induced by these agents. This review provides baseline novel translational insight that can be used to enhance the safety profile, to minimize the chance of progression of these adverse effects to more severe and potentially fatal rhabdomyolysis, and to improve the overall patient compliance and adherence to long-term statin therapy.

Pharmacogenetics of membrane transporters: a review of current approaches

This chapter provides a review of the pharmacogenetics of membrane transporters, including ABC transporters and OATPs. Membrane transporters are heavily involved in drug disposition, by actively transporting substrate drugs between organs and tissues. As such, polymorphisms in the genes encoding these proteins may have a significant effect on the absorption, distribution, metabolism, excretion, and activity of compounds. Although few drug transporter polymorphisms have transitioned from the bench to the bedside, this chapter discusses clinical development of transporter pharmacogenetic markers. Finally, development of SLCO1B1 genotyping to avoid statin induced adverse drug reactions is discussed as a model case for transporter pharmacogenetics clinical development.

SLCO1B1 Polymorphisms and Statin-Induced Myopathy

Statin drugs are highly effective in lowering blood concentrations of LDL-cholesterol, with concomitant reduction in risk of major cardiovascular events. Although statins are generally regarded as safe and well-tolerated, some users develop muscle symptoms that are mostly mild but in rare cases can lead to life-threatening rhabdomyolysis. The SEARCH genome-wide association study, which has been independently replicated, found a significant association between the rs4149056 (c.521T>C) single-nucleotide polymorphism (SNP) in the SLCO1B1 gene, and myopathy in individuals taking 80 mg simvastatin per day, with an odds ratio of 4.5 per rs4149056 C allele. The purpose of this paper is to assemble evidence relating to the analytical validity, clinical validity and clinical utility of using SLCO1B1 rs4149056 genotyping to inform choice and dose of statin treatment, with the aim of minimising statin-induced myopathy and increasing adherence to therapy. Genotyping assays for the rs4149056 SNP appear to be robust and accurate, though direct evidence for the performance of array-based platforms in genotyping individual SNPs was not found. Using data from the SEARCH study, calculated values for the clinical sensitivity, specificity, positive- and negative-predictive values of a test for the C allele to predict definite or incipient myopathy during 5 years of 80 mg/day simvastatin use were 70.4%, 73.7%, 4.1% and 99.4% respectively. There is a need for studies comparing the clinical validity of SLCO1B1 rs4149056 genotyping with risk scores for myopathy based on other factors such as racial background, statin type and dose, gender, body mass index, co-medications and co-morbidities. No direct evidence was found for clinical utility of statin prescription guided by SLCO1B1 genotype.

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.

Atorvastatin treatment induces uptake and efflux transporters in human liver

The metabolism and disposition of statins are highly dependent on different cytochrome P450 enzymes, such as CYP3A4 and CYP2C9, as well as membrane transporters SLCO1B1, SLCO2B1, ABCB1, and ABCG2. Interindividual gene expression differences among these enzymes may explain part of the variability in tolerance and effect for statin treatment. The aim of the present study was to investigate the effect of statin treatment on these genes in human liver tissue. Levels of CYP3A4, CYP2C9, SLCO1B1, SLCO2B1, ABCB1, and ABCG2 mRNA in liver tissue from a previously performed clinical trial in 29 patients randomized to treatment with placebo, 80 mg/day of atorvastatin, or 20 mg/day of fluvastatin for 4 weeks were measured using quantitative polymerase chain reaction. Treatment with atorvastatin (n = 10), but not with fluvastatin (n = 10), resulted in 3-fold higher expression of SLCO2B1 compared with placebo-treated patients (n = 9) (P < 0.05). Atorvastatin increased the expression of both ABCB1 and ABCG2 by more than 2-fold (P < 0.05). No difference was found in CYP2C9, CYP3A4, or SLCO1B1 mRNA expression in patients administered statins or those administered placebo. Premenopausal women (n = 8) had higher expression of CYP3A4 (P < 0.05) and lower expression of CYP2C9 (P < 0.05) compared with postmenopausal women (n = 10) and men (n = 11), respectively. Here we show for the first time that atorvastatin treatment leads to increased expression of the membrane transporters SLCO2B1, ABCB1, and ABCG2 in human liver tissue, which potentially may counteract the efficacy of the treatment, and our findings may cast light on the mechanisms of clinical problems with adverse reactions and drug interactions in statin treatment.

Transporter studies in drug development: experience to date and follow-up on decision trees from the International Transporter Consortium

The International Transporter Consortium (ITC) organized a second workshop in March 2012 to expand on the themes developed during the inaugural ITC workshop held in 2008. The final session of the workshop provided perspectives from regulatory and industry-based scientists, with input from academic scientists, and focused primarily on the decision trees published from the first workshop. These decision trees have become a central part of subsequent regulatory drug-drug interaction (DDI) guidances issued over the past few years.

Alcohol cirrhosis alters nuclear receptor and drug transporter expression in human liver

Unsafe use of alcohol results in approximately 2.5 million deaths worldwide, with cirrhosis contributing to 16.6% of reported deaths. Serum insulin levels are often elevated in alcoholism and may result in diabetes, which is why alcoholic liver disease and diabetes often are present together. Because there is a sizable population with these diseases alone or in combination, the purpose of this study was to determine whether transporter expression in human liver is affected by alcoholic cirrhosis, diabetes, and alcoholic cirrhosis coexisting with diabetes. Transporters aid in hepatobiliary excretion of many drugs and toxic chemicals and can be determinants of drug-induced liver injury. Drug transporter expression and transcription factor-relative mRNA and protein expression in normal, diabetic, cirrhotic, and cirrhosis with diabetes human livers were quantified. Cirrhosis significantly increased ABCC4, 5, ABCG2, and solute carrier organic anion (SLCO) 2B1 mRNA expression and decreased SLCO1B3 mRNA expression in the liver. ABCC1, 3-5, and ABCG2 protein expression was also upregulated by alcoholic cirrhosis. ABCC3-5 and ABCG2 protein expression was also upregulated in diabetic cirrhosis. Cirrhosis increased nuclear factor E2-related factor 2 mRNA expression, whereas it decreased pregnane-X-receptor and farnesoid-X-receptor mRNA expression in comparison with normal livers. Hierarchical cluster analysis indicated that expressions of ABCC2, 3, and 6; SLCO1B1 and 1B3; and ABCC4 and 5 were more closely related in the livers from this cohort. Overall, alcoholic cirrhosis altered transporter expression in human liver.

Individualized risk for statin-induced myopathy: current knowledge, emerging challenges and potential solutions

Skeletal muscle toxicity is the primary adverse effect of statins. In this review, we summarize current knowledge regarding the genetic and nongenetic determinants of risk for statin induced myopathy. Many genetic factors were initially identified through candidate gene association studies limited to pharmacokinetic (PK) targets. Through genome-wide association studies, it has become clear that SLCO1B1 is among the strongest PK predictors of myopathy risk. Genome-wide association studies have also expanded our understanding of pharmacodynamic candidate genes, including RYR2. It is anticipated that deep resequencing efforts will define new loci with rare variants that also contribute, and sophisticated computational approaches will be needed to characterize gene-gene and gene-environment interactions. Beyond environment, race is a critical covariate, and its influence is only partly explained by geographic differences in the frequency of known pharmacodynamic and PK variants. As such, admixture analyses will be essential for a full understanding of statin-induced myopathy.

Simvastatin evokes an unpredicted inhibition of β-adrenoceptor-mediated vasodilatation in porcine coronary artery

HMG-CoA reductase inhibitors, or statins, are widely used as cholesterol-lowering agents in the treatment of dyslipidemias. Statins have also been reported to have pleiotropic effects, independent of their effects on cholesterol synthesis, possibly through inhibition of the monomeric G proteins Ras and Rho, which are able to signal through ERK and Rho kinase activities, respectively. We have previously demonstrated that inhibition of ERK activation enhances β-adrenoceptor-mediated vasodilatation in the porcine isolated coronary artery. As statins can also inhibit ERK activation, the initial aim of this study was to determine whether statins have a similar influence on β-adrenoceptor-evoked vasodilatation. Segments of porcine distal coronary artery were mounted in a Mulvany wire myograph and bathed in Krebs-Henseleit buffer gassed with 95% O(2)/5% CO(2) and maintained at 37 °C. Tissues were pre-contracted with the thromboxane mimetic U46619 prior to cumulative concentration-response curves to the β-adrenoceptor agonist salbutamol in the absence or presence of simvastatin (1, 5 or 10 μM), pravastatin (10 μM), or lovastatin (10 μM). Simvastatin inhibited the salbutamol-induced relaxation of the coronary artery. Similar effects were seen with lovastatin, but not pravastatin or the sodium salt of simvastatin. Simvastatin, but not pravastatin also inhibited the relaxations to the Ca(2+)-activated K(+) channel opener NS1619 and the K(ATP) channel opener pinacidil. Unexpectedly, these data indicate that, rather than enhancing β-adrenoceptor-mediated vasodilatation, lipophilic statins impair these responses. This is likely to be due to effects on K(+) channels.

Membrane transporters in drug development

Membrane transporters have wide, but specific tissue distributions. They can impact on multiple endogenous and xenobiotic processes. Knowledge and awareness within the pharmaceutical industry of their impact on drug absorption, distribution, metabolism and elimination (ADME) and drug safety is growing rapidly. Clinically important transporter-mediated drug-drug interactions (DDIs) have been observed. Up to nine diverse transporters are implicated in the DDIs of a number of widely prescribed drugs, posing a significant challenge to the pharmaceutical industry. There is a complex interplay between multiple transporters and/or enzymes in the ADME and pharmacogenomics of drugs. Integrating these different mechanisms to understand their relative contributions to ADME is a key challenge. Many different factors complicate the study of membrane transporters in drug development. These include a lack of specific substrates and inhibitors, non-standard in vitro tools, and competing/complementary mechanisms (e.g. passive permeability and metabolism). Discovering and contextualizing the contribution of membrane transporters to drug toxicity is a significant new challenge. Drug interactions with key membrane transporters are routinely assessed for central nervous system (CNS) drug discovery therapies, but are not generally considered across the wider drug discovery. But, there is interest in utilizing membrane transporters as drug delivery agents. Computational modeling approaches, notably physiology-based/pharmacokinetic (PB/PK) modeling are increasingly applied to transporter interactions, and permit integration of multiple ADME mechanisms. Because of the range of tissues and transporters of interest, robust transporter, in vitro to in vivo, scaling factors are required. Empirical factors have been applied, but absolute protein quantitation will probably be required.

Differential effects of pravastatin and simvastatin on the growth of tumor cells from different organ sites

3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) inhibitors, commonly known as statins, may possess cancer preventive and therapeutic properties. Statins are effective suppressors of cholesterol synthesis with a well-established risk-benefit ratio in cardiovascular disease prevention. Mechanistically, targeting HMGCR activity primarily influences cholesterol biosynthesis and prenylation of signaling proteins. Pravastatin is a hydrophilic statin that is selectively taken up by a sodium-independent organic anion transporter protein-1B1 (OATP1B1) exclusively expressed in liver. Simvastatin is a hydrophobic statin that enters cells by other mechanisms. Poorly-differentiated and well-differentiated cancer cell lines were selected from various tissues and examined for their response to these two statins. Simvastatin inhibited the growth of most tumor cell lines more effectively than pravastatin in a dose dependent manner. Poorly-differentiated cancer cells were generally more responsive to simvastatin than well-differentiated cancer cells, and the levels of HMGCR expression did not consistently correlate with response to statin treatment. Pravastatin had a significant effect on normal hepatocytes due to facilitated uptake and a lesser effect on prostate PC3 and colon Caco-2 cancer cells since the OATP1B1 mRNA and protein were only found in the normal liver and hepatocytes. The inhibition of cell growth was accompanied by distinct alterations in mitochondrial networks and dramatic changes in cellular morphology related to cofilin regulation and loss of p-caveolin. Both statins, hydrophilic pravastatin and hypdrophobic simvastatin caused redistribution of OATP1B1 and HMGCR to perinuclear sites. In conclusion, the specific chemical properties of different classes of statins dictate mechanistic properties which may be relevant when evaluating biological responses to statins.