The influence of SLCO1B1 (OATP1B1) gene polymorphisms on response to statin therapy

Off-target effects of statins: molecular mechanisms, side effects and the emerging role of kinases

Statins are one of the most important classes of drugs. In this analytical review, we elucidate the intricate molecular mechanisms and toxicological rationale regarding both the on- (targeting 3-hydroxy-3-methylglutaryl-coenzyme A reductase [HMGCR]) and off-target effects of statins. Statins interact with a number of membrane kinases, such as epidermal growth factor receptor (EGFR), erb-b2 receptor tyrosine kinase 2 (HER2) and MET proto-oncogene, receptor tyrosine kinase (MET), as well as cytosolic kinases, such as SRC proto-oncogene, non-receptor tyrosine kinase (Src) and show inhibitory activity at nanomolar concentrations. In addition, they interact with calcium ATPases and peroxisome proliferator-activated receptor α (PPARα/NR1C1) at higher concentrations. Statins interact with mitochondrial complexes III and IV, and their inhibition of coenzyme Q10 synthesis also impairs the functioning of complexes I and II. Statins act as inhibitors of kinases, calcium ATPases and mitochondrial complexes, while activating PPARα. These off-target effects likely contribute to the side effects observed in patients undergoing statin therapy, including musculoskeletal symptoms and hepatic effects. Interestingly, some off-target effects of statins could also be the cause of favourable outcomes, relating to repurposing statins in conditions such as inflammatory disorders and cancer.

The impact of SLCO1B1 rs4149056 on LDL-C target achievement after lipid lowering therapy optimization in men and women with familial hypercholesterolemia

Background and aims

FH women are less likely to receive intensive statin treatment and to obtain a 50% reduction of LDL-C from baseline compared to men with FH. SLCO1B1 rs4149056 might influence statin therapy compliance and thus LDL-C target achievement. Our aim was to evaluate the impact of SLCO1B1 rs4149056 on LDL-C target achievement after lipid lowering therapy (LLT) optimization in men and women with FH.

Methods

This was a retrospective observational study involving 412 FH subjects with a probable or defined clinical diagnosis of FH who had had genetic analysis from June 2016 to September 2022. Biochemical analysis was obtained from all subjects at baseline and at the last follow-up after LLT optimization.

Results

After LLT optimization the percentage of FH subjects on high-intensity statins decreased from the M/SLCO1B1- group to the W/SLCO1B1+ group and the same was found in LDL-C target distribution (for both p for trend < 0.01). The prevalence of SASE fear increased from the M/SLCO1B1- group to the W/SLCO1B1+ group and the same was observed in reported myalgia distribution (for both p for trend < 0.01). Logistic regression analysis showed that the W/SCLO1B1-, M/SCLO1B1+ and W/SCLO1B1+ groups were inversely associated with LDL-C target achievement (p for trend < 0.001) and the W/SCLO1B1+ group exhibited the strongest association.

Conclusion

A low prevalence of FH women with SLCO1B1 rs4149056 were on high intensity statins and they rarely achieved LDL-C target. The genotype effect of SLCO1B1 rs4149056 could be more pronounced in FH women than men.

Statins and risk of type 2 diabetes: mechanism and clinical implications

Statins are widely used to prevent cardiovascular disease events. Cardiovascular diseases and type 2 diabetes are tightly connected since type 2 diabetes is a major risk factor for cardiovascular diseases. Additionally, cardiovascular diseases often precede the development of type 2 diabetes. These two diseases have common genetic and environmental antecedents. Statins are effective in the lowering of cardiovascular disease events. However, they have also important side effects, including an increased risk of type 2 diabetes. The first study reporting an association of statin treatment with the risk of type 2 diabetes was the WOSCOPS trial (West of Scotland Coronary Prevention Study) in 2001. Other primary and secondary cardiovascular disease prevention studies as well as population-based studies have confirmed original findings. The purpose of our review is to examine and summarize the most important findings of these studies as well as to describe the mechanisms how statins increase the risk of type 2 diabetes.

Approach to the Patient With a Suboptimal Statin Response: Causes and Algorithm for Clinical Management

CONTEXT

Statins are the lipid-lowering therapy of choice for the prevention of atherosclerotic cardiovascular disease (ASCVD) but their effectiveness in lowering low-density lipoprotein cholesterol (LDL-C) can substantially differ between individuals. In this mini-review, we describe the different causes for a suboptimal statin response and an algorithm for the diagnosis and clinical management of these patients.

EVIDENCE ACQUISITION

A PubMed search using the terms "statin resistance," "statin sensitivity," "statin pharmacokinetics," "cardiovascular disease," and "lipid-lowering therapies" was performed. Published papers in the past 10 years that were relevant to the topic were examined to provide content for this mini-review.

EVIDENCE SYNTHESIS

Suboptimal lowering of LDL-C by statins is a major problem in the clinical management of patients and limits the value of this therapeutic approach. There are multiple causes of statin hyporesponsiveness with compliance being the most common explanation. Other causes, such as analytical issues with LDL-C measurement and the presence of common lipid disorders (familial hypercholesterolemia, elevated lipoprotein[a] and secondary dyslipidemias) should be excluded before considering primary statin resistance from rare genetic variants in lipoprotein-related or drug-metabolism genes. A wide variety of nonstatin lipid-lowering drugs are now available and can be added to statins to achieve more effective LDL-C lowering.

CONCLUSIONS

The evaluation of statin hyporesponsiveness is a multistep process that can lead to the optimization of lipid-lowering therapy for the prevention of ASCVD. It may also lead to the identification of distinct types of dyslipidemias that require specific therapies and/or the genetic screening of family members.

Model-based meta-analysis of ethnic differences and their variabilities in clearance of oral drugs classified by clearance mechanism

In this study, the ethnic ratios (ERs) of oral clearance between Japanese and Western populations were subjected to model-based meta-analysis (MBMA) for 81 drugs evaluated in 673 clinical studies. The drugs were classified into eight groups according to the clearance mechanism, and the ER for each group was inferred together with interindividual variability (IIV), interstudy variability (ISV), and inter-drug variability within a group (IDV) using the Markov chain Monte Carlo (MCMC) method. The ER, IIV, ISV, and IDV were dependent on the clearance mechanism, and, except for particular groups such as drugs metabolized by polymorphic enzymes or their clearance mechanism is not confirmative, the ethnic difference was found to be generally small. The IIV was well-matched across ethnicities, and the ISV was approximately half of the IIV as the coefficient of variation. To adequately assess ethnic differences in oral clearance without false detections, phase I studies should be designed with full consideration of the mechanism of clearance. This study suggests that the methodology of classifying drugs based on the mechanism that causes ethnic differences and performing MBMA with statistical techniques such as MCMC analysis is helpful for a rational understanding of ethnic differences and for strategic drug development.

Effects of the SLCO1B1 A388G single nucleotide polymorphism on the development, clinical parameters, treatment, and survival of multiple myeloma cases in a Polish population

BACKGROUND

Multiple myeloma is one of the most common hematological malignancies worldwide. Genetic alterations may lead to the progression from monoclonal gammopathy to multiple myeloma. Additionally, the genetic background of the disease might influence therapy outcomes, including survival time. SLCO1B1, belonging to the OATPs family, is a membrane protein that mediates the uptake of a wide range of endogenous and exogenous (including drugs) compounds.

METHODS AND RESULTS

In this study, the A388G single nucleotide polymorphism in the SLCO1B1 gene in Polish multiple myeloma patients was determined. This polymorphism affects the amino acid change of the protein, so it may be responsible for treatment effectiveness or risk of disease development. A388G was evaluated by the PCR-RFLP method. The presented study showed a statistically significant association between the GG genotype with longer survival of patients with multiple myeloma with Melphalan-Prednisone therapy compared to other treatment regimens (p = 0.0271). There was no statistically significant association in the frequency of genotypes (p = 0.8211) and alleles: allele A (p = 0.5442); allele G (p = 0.8020) between multiple myeloma patients and a control group.

CONCLUSIONS

The A388G polymorphism does not seem to affect the increased risk of the development of multiple myeloma. However, the occurrence of the GG genotype may prolong of patients overall survival in the case of Melphalan-Prednisone therapy.

Statin-associated muscle symptoms: Myth or reality?

Statin-associated muscle symptoms is an entity that encompasses a constellation of various clinical manifestations of variyng severity. Since the introduction of the first statins, numerous studies have been published regarding its incidence, pathophysiology, diagnosis and treatment; however, to this day these aspects are still controversial. With the progressive increase in the use of statins in the general population, notifications of adverse reactions related to its use have multiplied, particularly those related to muscular toxicity. Nevertheless, the differences between the published studies, both in methodology and in the results obtained, make this relationship a complex issue of great interest for clinicians and patients. The integration of the evidence that we currently have can help us understand better this entity and facilitate its management in clinical practice.

CYP3A5*3 and SLCO1B1 c.521T>C Polymorphisms Influence the Pharmacokinetics of Atorvastatin and 2-Hydroxy Atorvastatin

There is a large variability in individual responses to atorvastatin administration. This study assessed the pharmacogenetic effects of solute carrier organic anion transporter family member 1B1 (SLCO1B1, c.388A>G and c.521T>C) and cytochrome P450 3A5 (CYP3A5, CYP3A5*3) genetic polymorphisms on the pharmacokinetics of atorvastatin and its active metabolite, 2-hydroxy (2-OH) atorvastatin, in 46 individuals who were administered a clinically used single oral dosage of 80 mg. The Cmax and AUC of atorvastatin in CYP3A5*3/*3 carriers were 2.6- and 2.8-fold higher, respectively, than those in CYP3A5*1/*1 carriers, and similar results were observed for 2-OH atorvastatin pharmacokinetics. SLCO1B1 c.521T>C also increased the AUC of atorvastatin and 2-OH atorvastatin. The AUC ratio of atorvastatin and 2-OH atorvastatin were not affected by SLCO1B1 c.388A>G or c.521T>C, whereas CYP3A5*3 reduced the AUC ratio. In an analysis evaluating the simultaneous effect of the SLCO1B1 c.521T>C and CYP3A5*3 polymorphisms, SLCO1B1 c.521TT/CYP3A5*1/*1 carriers showed lower Cmax and AUC values for atorvastatin and 2-OH atorvastatin than in individuals with the SLCO1B1 c.521T>C and/or CYP3A5*3 genotypes. Among the participants with the SLCO1B1 c.521TT genotype, the CYP3A5*3 carriers had a higher systemic exposure to atorvastatin and 2-OH atorvastatin than the CYP3A5*1/*1 carriers. Thus, SLCO1B1 c.521T>C and CYP3A5*3 polymorphisms affect the pharmacokinetics of atorvastatin and 2-OH atorvastatin.

Quantitative Proteomics in Translational Absorption, Distribution, Metabolism, and Excretion and Precision Medicine

A reliable translation of in vitro and preclinical data on drug absorption, distribution, metabolism, and excretion (ADME) to humans is important for safe and effective drug development. Precision medicine that is expected to provide the right clinical dose for the right patient at the right time requires a comprehensive understanding of population factors affecting drug disposition and response. Characterization of drug-metabolizing enzymes and transporters for the protein abundance and their interindividual as well as differential tissue and cross-species variabilities is important for translational ADME and precision medicine. This review first provides a brief overview of quantitative proteomics principles including liquid chromatography-tandem mass spectrometry tools, data acquisition approaches, proteomics sample preparation techniques, and quality controls for ensuring rigor and reproducibility in protein quantification data. Then, potential applications of quantitative proteomics in the translation of in vitro and preclinical data as well as prediction of interindividual variability are discussed in detail with tabulated examples. The applications of quantitative proteomics data in physiologically based pharmacokinetic modeling for ADME prediction are discussed with representative case examples. Finally, various considerations for reliable quantitative proteomics analysis for translational ADME and precision medicine and the future directions are discussed. SIGNIFICANCE STATEMENT: Quantitative proteomics analysis of drug-metabolizing enzymes and transporters in humans and preclinical species provides key physiological information that assists in the translation of in vitro and preclinical data to humans. This review provides the principles and applications of quantitative proteomics in characterizing in vitro, ex vivo, and preclinical models for translational research and interindividual variability prediction. Integration of these data into physiologically based pharmacokinetic modeling is proving to be critical for safe, effective, timely, and cost-effective drug development.

The pharmacogenetics of mycophenolate mofetil in Tunisian renal transplant patients

Aim: The effects of variants in IMPDH, UGT1A9, UGT1A8, UGT2B7 and SLCO1B1 genes on the efficacy and safety of mycophenolate mofetil (MMF) in the Tunisian population were investigated. Materials & methods: A total of 245 kidney transplant patients being treated with MMF were recruited and cotreated with cyclosporine or tacrolimus. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. MMF, cyclosporine and tacrolimus trough levels were measured by immunoassay. The AUC (AUC_0-12hMPA) was estimated by a Bayesian method. Results: In the tacrolimus-treated group, anemia and diarrhea were associated with the UGT1A9-98C and UGT1A9-275T alleles, respectively (p < 0.05). In the cyclosporine-treated group, leukopenia was associated with the SLCO1B1-521T allele (p < 0.05). Both groups had an increased risk of rejection (p < 0.05) associated with the variant alleles of IMPDH2-3757T>C, UGT1A9-2152C>T and UGT1A9-275C>A and the common allele of SLCO1B1-388A>G. However, no significant association was found between the studied genotypes and AUC_0-12hMPA or cotreatment levels. Conclusion: The results constitute preliminary evidence for the inclusion of the pharmacogenetics of MMF in kidney pretransplantation evaluations.

Association of Drug-Metabolizing Enzyme and Transporter Gene Polymorphisms and Lipid-Lowering Response to Statins in Thai Patients with Dyslipidemia

Purpose

Statins are increasingly widely used in the primary and secondary prevention of cardiovascular disease. However, there is an inter-individual variation in statin response among patients. The study aims to determine the association between genetic variations in drug-metabolizing enzyme and transporter (DMET) genes and lipid-lowering response to a statin in Thai patients with hyperlipidemia.

Patients and Methods

Seventy-nine patients who received statin at steady-state concentrations were recruited. Serum lipid profile was measured at baseline and repeated after 4-month on a statin regimen. The genotype profile of 1936 DMET markers was obtained using Affymetrix DMET Plus genotyping microarrays.

Results

In this DMET microarray platform, five variants; SLCO1B3 (rs4149117, rs7311358, and rs2053098), QPRT (rs13331798), and SLC10A2 (rs188096) showed a suggestive association with LDL-cholesterol-lowering response. HDL-cholesterol-lowering responses were found to be related to CYP7A1 gene variant (rs12542233). Seven variants, SLCO1B3 (rs4149117, rs7311358, and rs2053098); SULT1E1 (rs3736599 and rs3822172); and ABCB11 (rs4148768 and rs3770603), were associated with the total cholesterol-lowering response. One variant of the ABCB4 gene (rs2109505) was significantly associated with triglyceride-lowering response.

Conclusion

This pharmacogenomic study identifies new genetic variants of DMET genes that are associated with the lipid-lowering response to statins. Genetic polymorphisms in DMET genes may impact the pharmacokinetics and lipid-lowering response to statin. The validation studies confirmations are needed in future pharmacogenomic studies.

SLCO1B1 *15 allele is associated with methotrexate-induced nausea in pediatric patients with inflammatory bowel disease

Low-dose methotrexate (MTX) is an immunosuppressant used to treat inflammatory bowel disease (IBD). SLCO1B1 genetic variation has been associated with delayed MTX clearance and increased toxicity. The purpose of this study was to evaluate the association between SLCO1B1 genetic variation and MTX-induced nausea in children with IBD. We performed a single center retrospective chart analysis of 278 patients who were prescribed MTX for IBD. Two hundred two patients had banked DNA and were genotyped for three SLCO1B1 single nucleotide polymorphisms (SNPs; rs4149056, rs2306283, and rs11045819). Diplotypes were determined by combining the SNPs into *1, *4, *5, *14, *15, and *37 alleles. Incidence of nausea was abstracted from clinician notes. Prescriptions and demographics were extracted from the medical record. The cohort was 69.8% boys, 89.1% White, and 87.6% had a diagnosis of Crohn's disease with a mean age of 16.0 (± 3.8) years. MTX-induced nausea was noted in 34% of the cohort. MTX-induced nausea was associated with the number of reduced-function *15 alleles (p = 0.034) and occurred 2.26 times more often in patients with at least one *15 allele who did not initiate MTX treatment with concomitant ondansetron (p = 0.034). MTX-induced nausea was significantly independently associated with SLCO1B1 diplotype (p = 0.006) after controlling for MTX dose group and concomitant ondansetron. Our data demonstrate that the SLCO1B1 *15 allele is associated with MTX-induced nausea in pediatric patients with IBD. Additionally, *15 allele carriers could benefit from a dose reduction of MTX to reduce exposure and treatment initiation with concomitant ondansetron to reduce nausea.

Inter-ethnic differences in pharmacokinetics-is there more that unites than divides?

Inter-ethnic variability in pharmacokinetics (PK) has been attributed to several factors ranging from genetic to environmental. It is not clear how current teaching in higher education (HE) reflects what published literature suggests on this subject. This study aims to gain insights into current knowledge about inter-ethnic differences in PK based on reports from published literature and current teaching practices in HE. A systematic literature search was conducted on PubMed and Scopus to identify suitable literature to be reviewed. Insights into inter-ethnic differences in PK teaching among educators in HE and industry were determined using a questionnaire. Thirty-one percent of the studies reviewed reported inter-ethnic differences in PK, of these, 37% of authors suggested genetic polymorphism as possible explanation for the inter-ethnic differences observed. Other factors authors proposed included diet and weight differences between ethnicities. Most respondents (80%) who taught inter-ethnic difference in PK attributed inter-ethnic differences to genetic polymorphism. While genetic polymorphism is one source of variability in PK, the teaching of genetic polymorphism is better associated with interindividual variabilities rather than inter-ethnic differences in PK as there are no genes with PK implications specific to any one ethnic group. Nongenetic factors such as diet, weight, and environmental factors, should be highlighted as potential sources of interindividual variation in the PK of drugs.

Quantification of CYP3A and Drug Transporters Activity in Healthy Young, Healthy Elderly and Chronic Kidney Disease Elderly Patients by a Microdose Cocktail Approach

Background: Ageing and chronic kidney disease (CKD) affect pharmacokinetic (PK) parameters. Since mechanisms are related and remain unclear, cytochrome P450 (CYP) 3A and drug transporter activities were investigated in the elderly with or without CKD and compared to healthy adults using a microdose cocktail. Methods: Healthy young participants (n = 20), healthy elderly participants (n = 16) and elderly patients with CKD (n = 17) received, in study period 1, a single dose of microdose cocktail probe containing 30 µg midazolam, 750 µg dabigatran etexilate, 100 µg atorvastatin, 10 µg pitavastatin, and 50 µg rosuvastatin. After a 14-day wash-out period, healthy young participants continued to study period 2 with the microdose cocktail plus rifampicin. PK parameters including area under the plasma concentration-time curve (AUC), maximum plasma drug concentration (C_max), and half-life were estimated before making pairwise comparisons of geometric mean ratios (GMR) between groups. Results: AUC and C_max GMR (95% confidence interval; CI) of midazolam, a CYP3A probe substrate, were increased 2.30 (1.70-3.09) and 2.90 (2.16-3.88) fold in healthy elderly and elderly patients with CKD, respectively, together with a prolonged half-life. AUC and C_max GMR (95%CI) of atorvastatin, another CYP3A substrate, was increased 2.14 (1.52-3.02) fold in healthy elderly and 4.15 (2.98-5.79) fold in elderly patients with CKD, indicating decreased CYP3A activity related to ageing. Associated AUC changes in the probe drug whose activity could be modified by intestinal P-glycoprotein (P-gp) activity, dabigatran etexilate, were observed in patients with CKD. However, whether the activity of pitavastatin and rosuvastatin is modified by organic anion transporting polypeptide 1B (OATP1B) and of breast cancer resistance protein (BCRP), respectively, in elderly participants with or without CKD was inconclusive. Conclusions: CYP3A activity is reduced in ageing. Intestinal P-gp function might be affected by CKD, but further confirmation appears warranted. Clinical Trial Registration:http://www.thaiclinicaltrials.org/ (TCTR 20180312002 registered on March 07, 2018).

Real-life management of drug-drug interactions between antiretrovirals and statins

BACKGROUND

PIs cause drug-drug interactions (DDIs) with most statins due to inhibition of drug-metabolizing enzymes and/or the hepatic uptake transporter OATP1B1, which may alter the pharmacodynamic (PD) effect of statins.

OBJECTIVES

To assess the management of DDIs between antiretrovirals (ARVs) and statins in people living with HIV (PLWH) considering statin plasma concentrations, compliance with dosing recommendations and achievement of lipid targets.

METHODS

PLWH of the Swiss HIV Cohort Study were eligible if they received a statin concomitantly with ARVs. HDL, total cholesterol (TC) and statin plasma concentration were measured during follow-up visits. Individual non-HDL and TC target values were set using the Framingham score and the 2018 European AIDS Clinical Society recommendations.

RESULTS

Data were analysed for rosuvastatin (n = 99), atorvastatin (n = 92), pravastatin (n = 46) and pitavastatin (n = 21). Rosuvastatin and atorvastatin underdosing frequently led to suboptimal PD response. Insufficient lipid control was observed with PIs despite high atorvastatin concentrations, likely explained by inhibition of OATP1B1 resulting in less statin uptake in the liver. Target lipid values were more often achieved with unboosted integrase inhibitors due to both their favourable DDI profiles and neutral effect on lipids. Insufficient lipid control was common with pravastatin and pitavastatin regardless of co-administered ARVs and despite using maximal recommended statin doses. The latter suggests lower efficacy compared with rosuvastatin or atorvastatin.

CONCLUSIONS

Suboptimal management of DDIs with statin underdosing was observed in 29% of prescriptions. Integrase inhibitor-based regimens and/or treatment with rosuvastatin or atorvastatin should be favoured in patients with refractory dyslipidaemia.

Evaluation of the drug-drug interaction potential for trazpiroben (TAK-906), a D2/D3 receptor antagonist for gastroparesis, towards cytochrome P450s and transporters

Trazpiroben (TAK-906), a peripherally selective dopamine D2/D3 receptor antagonist, is being developed for the treatment of patients with gastroparesis. The potential of trazpiroben to act as a perpetrator or a victim for cytochrome P450 (CYP)- or transporter- mediated drug-drug interactions (DDIs) was evaluated following the latest regulatory guidelines.In vitro studies revealed that trazpiroben is metabolised mainly through a non-CYP pathway (56.7%) by multiple cytosolic, NADPH-dependent reductase, such as aldo-keto reductase and short-chain dehydrogenase/reductase including carbonyl reductases. Remaining metabolism occurs through CYP3A4 and CYP2C8 (43.3%). Trazpiroben is neither an inhibitor nor an inducer of major CYP enzymes at a clinically relevant dose. It is a substrate of P-glycoprotein (P-gp) and organic anion transporting polypeptide (OATP) 1B1/1B3, but is not an inhibitor of transporters listed in the DDI guidelines at a clinically relevant dose. This is consistent with findings from CYP3A and P-gp-based clinical assessment showing no substantial change (≤2-fold) in trazpiroben exposure when co-administered with itraconazole.Collectively, trazpiroben has low potential of enzyme-mediated DDIs and is unlikely to act as a perpetrator of transporter-mediated DDIs but there may be a potential to act as a victim of OATP1B1/1B3 DDI that will be evaluated clinically.

SLCO1B1 Phenotype and CYP3A5 Polymorphism Significantly Affect Atorvastatin Bioavailability

Atorvastatin, prescribed for the treatment of hypercholesterolemia, demonstrated overwhelming benefits in reducing cardiovascular morbidity and mortality. However, many patients discontinue therapy due to adverse reactions, especially myopathy. The Dutch Pharmacogenetics Working Group (DPWG) recommends an alternative agent to atorvastatin and simvastatin or a dose adjustment depending on other risk factors for statin-induced myopathy in SLCO1B1 rs4149056 CC or TC carriers. In contrast, the Clinical Pharmacogenetics Implementation Consortium (CPIC) published their guideline on simvastatin, but not on atorvastatin. In this work, we aimed to demonstrate the effect of SLCO1B1 phenotype and other variants (e.g., in CYP3A4/5, UGT enzymes or SLC transporters) on atorvastatin pharmacokinetics. For this purpose, a candidate-gene pharmacogenetic study was proposed. The study population comprised 156 healthy volunteers enrolled in atorvastatin bioequivalence clinical trials. The genotyping strategy comprised a total of 60 variants in 15 genes. Women showed higher exposure to atorvastatin compared to men (p = 0.001), however this difference disappeared after dose/weight (DW) correction. The most relevant pharmacogenetic differences were the following: AUC/DW and Cmax /DW based on (a) SLCO1B1 phenotype (p < 0.001 for both) and (b) CYP3A5*3 (p = 0.004 and 0.018, respectively). As secondary findings: SLC22A1 *2/*2 genotype was related to higher Cmax/DW (ANOVA p = 0.030) and SLC22A1 *1/*5 genotype was associated with higher Vd/F (ANOVA p = 0.032) compared to SLC22A1 *1/*1, respectively. Finally, UGT2B7 rs7439366 *1/*1 genotype was associated with higher tmax as compared with the *1/*3 genotype (ANOVA p = 0.024). Based on our results, we suggest that SLCO1B1 is the best predictor for atorvastatin pharmacokinetic variability and that prescription should be adjusted based on it. We suggest that the CPIC should include atorvastatin in their statin-SLCO1B1 guidelines. Interesting and novel results were observed based on CYP3A5 genotype, which should be confirmed with further studies.

SLCO1B1 and ABCG2 Gene Polymorphisms in a Thai Population

Introduction

Genetic polymorphisms of drug transporters influence drug transporter activity and alter pharmacokinetic profiles of the drugs. Organic anion transporting polypeptide 1B1 (OATP1B1) and breast cancer resistance protein (BCRP) are important transporters encoded by solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene and ATP-binding cassette subfamily G member 2 (ABCG2) gene, respectively. Polymorphisms in these genes are associated with increased plasma statins concentrations, statin-induced myopathy and poor response to allopurinol treatment.

Purpose

We explored allele and genotype frequencies of SLCO1B1 and ABCG2 genes including their predicted phenotypes in 53 Thai participants. Of these, 17 had chronic kidney disease and were on statins.

Materials and Methods

Genotyping analysis for SLCO1B1 c.521T>C (rs4149056), c.388A>G (rs2306283), g.-11187G>A (rs4149015), and ABCG2 c.421C>A (rs2231142) was done by using TaqMan^® Real time PCR. All were tested for Hardy–Weinberg Equilibrium.

Results

Most of the participants (80%) had normal function haplotypes SLCO1B1 (*1A and *1B) while decreased (*5, *15, and *17) and unknown (*21) function haplotypes were less observed. Four phenotypes of SLCO1B1 were observed: 69.81% had normal function (*1A/*1A,*1A/*1B, and *1B/*1B), 13.21% had intermediate function (*1A/*17, *1B/*15 and *1B/*17), 9.43% had indeterminate function (*1A/*21 and *1B/*21) and 7.55% had low function (*5/*15, *15/*15, and *15/*17). ABCG2 c.421A allele frequency was 25%. The frequency of ABCG2 c.421CA and AA phenotypes were 37.7% and 5.7%, respectively. The allele and genotype frequencies observed are consistent with reports in Asians. However, there were differences in major allele distributions between Asians and Caucasians for SLCO1B1 c.388A>G; SLCO1B1 c.388G were highly found in Asians, but c.388A were more observed in Caucasians.

Conclusion

This study showed that in the Thai population, there were 4 SNPs of SLCO1B1 and ABCG2 genes. This finding may be clinically applied to minimize inter-individual variability of drugs such as statins and allopurinol. Further study with a larger sample size is needed to assess the drug profiles and responses to treatment.

Physicochemical Properties, Biotransformation, and Transport Pathways of Established and Newly Approved Medications: A Systematic Review of the Top 200 Most Prescribed Drugs vs. the FDA-Approved Drugs Between 2005 and 2016

BACKGROUND

Enzyme-mediated biotransformation of pharmacological agents is a crucial step in xenobiotic detoxification and drug disposition. Herein, we investigated the metabolism and physicochemical properties of the top 200 most prescribed drugs (established) as well as drugs approved by the US Food and Drug Administration (FDA) between 2005 and 2016 (newly approved).

OBJECTIVE

Our objective was to capture the changing trends in the routes of administration, physicochemical properties, and prodrug medications, as well as the contributions of drug-metabolizing enzymes and transporters to drug clearance.

METHODS

The University of Washington Drug Interaction Database (DIDB^®) as well as other online resources (e.g., CenterWatch.com, Drugs.com, DrugBank.ca, and PubChem.ncbi.nlm.nih.gov) was used to collect and stratify the dataset required for exploring the above-mentioned trends.

RESULTS

Analyses revealed that ~ 90% of all drugs in the established and newly approved drug lists were administered systemically (oral or intravenous). Meanwhile, the portion of biologics (molecular weight > 1 kDa) was 15 times greater in the newly approved list than established drugs. Additionally, there was a 4.5-fold increase in the number of compounds with a high calculated partition coefficient (cLogP > 3) and a high total polar surface area (> 75 Å²) in the newly approved drug vs. the established category. Further, prodrugs in established or newly approved lists were found to be converted to active compounds via hydrolysis, demethylases, and kinases. The contribution of cytochrome P450 (CYP) 3A4, as the major biotransformation pathway, has increased from 40% in the established drug list to 64% in the newly approved drug list. Moreover, the role of CYP1A2, CYP2C19, and CYP2D6 were decreased as major metabolizing enzymes among the newly approved medications. Among non-CYP major metabolizers, the contribution of alcohol dehydrogenases/aldehyde dehydrogenases (ADH/ALDH) and sulfotransferases decreased in the newly approved drugs compared with the established list. Furthermore, the highest contribution among uptake and efflux transporters was found for Organic Anion Transporting Polypeptide 1B1 (OATP1B1) and P-glycoprotein (P-gp), respectively.

CONCLUSIONS

The higher portion of biologics in the newly approved drugs compared with the established list confirmed the growing demands for protein- and antibody-based therapies. Moreover, the larger number of hydrophilic drugs found in the newly approved list suggests that the probability of toxicity is likely to decrease. With regard to CYP-mediated major metabolism, CYP3A5 showed an increased involvement owing to the identification of unique probe substrates to differentiate CYP3As. Furthermore, the contribution of OATP1B1 and P-gp did not show a significant shift in the newly approved drugs as compared to the established list because of their broad substrate specificity.

The atorvastatin metabolic phenotype shift is influenced by interaction of drug-transporter polymorphisms in Mexican population: results of a randomized trial

Atorvastatin (ATV) is a blood cholesterol-lowering drug used to prevent cardiovascular events, the leading cause of death worldwide. As pharmacokinetics, metabolism and response vary among individuals, we wanted to determine the most reliable metabolic ATV phenotypes and identify novel and preponderant genetic markers that affect ATV plasma levels. A controlled, randomized, crossover, single-blind, three-treatment, three-period, and six-sequence clinical study of ATV (single 80-mg oral dose) was conducted among 60 healthy Mexican men. ATV plasma levels were measured using high-performance liquid chromatography mass spectrometry. Genotyping was performed by real-time PCR with TaqMan probes. Four ATV metabolizer phenotypes were found: slow, intermediate, normal and fast. Six gene polymorphisms, SLCO1B1-rs4149056, ABCB1-rs1045642, CYP2D6-rs1135840, CYP2B6-rs3745274, NAT2-rs1208, and COMT- rs4680, had a significant effect on ATV pharmacokinetics (P < 0.05). The polymorphisms in SLCO1B1 and ABCB1 seemed to have a greater effect and were especially important for the shift from an intermediate to a normal metabolizer. This is the first study that demonstrates how the interaction of genetic variants affect metabolic phenotyping and improves understanding of how SLCO1B1 and ABCB1 variants that affect statin metabolism may partially explain the variability in drug response. Notwithstanding, the influence of other genetic and non-genetic factors is not ruled out.

The impact of statins on physical activity and exercise capacity: an overview of the evidence, mechanisms, and recommendations

PURPOSE

Statins are among the most widely prescribed medications worldwide. Considered the 'gold-standard' treatment for cardiovascular disease (CVD), statins inhibit HMG-CoA reductase to ultimately reduce serum LDL-cholesterol levels. Unfortunately, the main adverse event of statin use is the development of muscle-associated problems, referred to as SAMS (statin-associated muscle symptoms). While regular moderate physical activity also decreases CVD risk, there is apprehension that physical activity may induce and/or exacerbate SAMS. While much work has gone into identifying the epidemiology of SAMS, only recent research has focused on the extent to which these muscle symptoms are accompanied by functional declines. The purpose of this review is to provide an overview of possible mechanisms underlying SAMS and summarize current evidence regarding the relationship between statin treatment, physical activity, exercise capacity, and SAMS development.

METHODS

PubMed and Google Scholar databases were used to search the most relevant and up-to-date peer-reviewed research on the topic.

RESULTS

The mechanism(s) behind SAMS, including altered mitochondrial metabolism, reduced coenzyme Q10 levels, reduced vitamin D levels, impaired calcium homeostasis, elevated extracellular glutamate, and genetic polymorphisms, still lack consensus and remain up for debate. Our summation of the evidence leads us to suggest that the etiology of SAMS development is likely multifactorial. Our review also demonstrates that there is limited evidence for statins impairing exercise adaptations or reducing exercise capacity for the majority of the investigated populations.

CONCLUSION

The available evidence indicates that the benefits of engaging in physical activity while on statin medication largely outweigh the risks.

Influence of the OATP Polymorphism on the Population Pharmacokinetics of Methotrexate in Chinese Patients

Background:

The Pharmacokinetics of Methotrexate (MTX) has been reported to show significant inter-subject variability. MTX is metabolized by SHMT1 and transported by OATP1B1 and OATP1B3 both of which show genetic polymorphisms. The non-genetic and genetic factors may influence the pharmacokinetics of MTX.

Objective:

This study aimed to determine the pharmacokinetic parameters of MTX in Chinese patients and to investigate the effect of various non-genetic factors and genetic variants of OATP1B1, OATP1B3 on MTX’s pharmacokinetics.

Methods:

MTX concentration and clinical characteristics data were collected from 71 rheumatoid arthritis patients. For each patient, SLC19A1, SHMT1, OATP1B1, and OATP1B3 genotyping were tested. Population pharmacokinetic analysis was performed by Nonlinear Mixed-Effect Modeling (NONMEM). MTX pharmacokinetic properties analysis was executed using the one-compartment pharmacokinetic model which incorporated first-order conditional estimation methods with interaction. Besides, the impact of genetic factors and demographic factors on MTX disposition were explored.

Results:

All the genotypes of steady-state plasma concentrations and OATP1B1 rs4149056, OATP1B1 rs2306283, and OATP1B3 rs7311358 were determined. The detected blood drug concentration reached the standard. Genotypes were all measured. At the same time, the population pharmacokinetic model of methotrexate was obtained CL(L•h-1) =8.25× e0.167× SNP (SNP: SLCO1B1 388A/A=3; SLCO1B1 388A/G=2; SLCO1B1 388G/G=1); V(L)= 32.8; Ka(h-1)=1.69.

Conclusion:

In our study, it was showed that OATP1B1-388 G>A SNP had a significant effect on CL/F. The factor should be considered when determining MTX dosing. However, prospective studies with a large number of participants are needed to validate the results of this study.

CYP2C9 and OATP1B1 genetic polymorphisms affect the metabolism and transport of glimepiride and gliclazide

The therapeutic use of glimepiride and gliclazide shows substantial inter-individual variation in pharmacokinetics and pharmacodynamics in human populations, which might be caused by genetic differences among individuals. The aim of this study was to assess the effect of CYP2C9 and OATP1B1 genetic polymorphisms on the metabolism and transport of glimepiride and gliclazide. The uptake of glimepiride and gliclazide was measured in OATP1B1*1a, *5 and *15-HEK293T cells, and their metabolism was measured using CYP2C9*1, *2 and *3 recombinase by LC-MS. Glimepiride in OATP1B1*1a, *5 and *15-HEK293T cells had V_max values of 155 ± 18.7, 80 ± 9.6, and 84.5 ± 8.2 pmol/min/mg, while gliclazide had V_max values of 15.7 ± 4.6, 7.2 ± 2.5, and 8.7 ± 2.4 pmol/min/mg, respectively. The clearance of glimepiride and gliclazide in OATP1B1*5 and *15 was significantly reduced compared to the wild-type. Glimepiride in the presence of CYP2C9*1, *2 and *3 recombinase had V_max values of 21.58 ± 7.78, 15.69 ± 5.59, and 9.17 ± 3.03 nmol/min/mg protein, while gliclazide had V_max values of 15.73 ± 3.11, 10.53 ± 4.06, and 6.21 ± 2.94 nmol/min/mg protein, respectively. The clearance of glimepiride and gliclazide in CYP2C9*2 and *3 was significantly reduced compared to the wild-type. These findings collectively indicate that OATP1B1*5 and *15 and CYP2C9*2 and *3 have a significant effect on the transport and metabolism of glimepiride and gliclazide.

A comprehensive review and meta-analysis of risk factors for statin-induced myopathy

PURPOSE

To aid prescribers in assessing a patient's risk for statin-induced myopathy (SIM), we performed a comprehensive review of currently known risk factors and calculated aggregated odds ratios for each risk factor through a meta-analysis.

METHODS

This meta-analysis was done through four phases: (1) Identification of the relevant primary literature; (2) abstract screening using inclusion and exclusion criteria; (3) detailed review and data extraction; and (4) synthesis and statistical analysis.

RESULTS

Out of 44 papers analyzed from 836 papers searched from MEDLINE, 18 different potential risk factors were collected, divided into three categories: three demographics (11 papers), ten clinical factors (31 papers), and five pharmacogenetics/biomarkers (12 papers). Risk factors significant for myopathy and/or rhabdomyolysis included age, gender, diabetes, renal impairment, cardiovascular disease, certain interacting drugs, and mutations of the SLCO1B1 gene, which encodes a transporter protein in the liver. Several factors, such as gender, race, cardiovascular disease, and the GATM gene, which encodes a protein for creatine synthesis, appeared to be protective in terms of the outcomes of interest.

CONCLUSIONS

This comprehensive assessment of risk factors can help support clinicians in reducing the incidence of SIM in their patient population on statins.

Lack of association between SLCO1B1 polymorphisms and lipid-lowering response to simvastatin therapy in Thai hypercholesterolaemic patients

WHAT IS KNOWN

SLCO1B1 polymorphisms have been reported to affect the responses to statin therapy. However, the association of these polymorphisms and lipid-lowering responses has been inconsistent.

OBJECTIVE

To investigate the effect of SLCO1B1 c.388A>G, c.521T>C and g.89595T>C polymorphisms on the lipid-lowering response to simvastatin therapy in Thai hypercholesterolaemic patients.

METHODS

Three hundred and 91 hypercholesterolaemic patients in Southern Thailand were enrolled and treated with simvastatin 20 or 40 mg per day. Among them, 191 and 200 patients were treated for 3 and 12 months, respectively. Serum lipids were measured before and after the treatment. SLCO1B1 c.388A>G, c.521T>C and g.89595T>C polymorphisms were analysed using polymerase chain reaction-high-resolution melting (PCR-HRM).

RESULTS

The allele frequencies of the SLCO1B1 c.388A>G, c.521T>C and g.89595T>C polymorphisms in Thai hypercholesterolaemic patients were 74.9%, 11.8% and 37.2%, respectively. After treatment with 20-40 mg simvastatin daily for 3 and 12 months, TC, TG and LDL-C concentrations were significantly lower than at baseline (P < .05). However, there was no a significant change in serum HDL-C after simvastatin treatment for 3 and 12 months (P > .05). Moreover, there was no association between SLCO1B1 c.388A>G, c.521T>C and g.89595T>C polymorphisms and lipid-lowering response to 3 and 12 months of either 20 or 40 mg/day simvastatin treatment.

WHAT IS NEW AND CONCLUSION

SLCO1B1 c.388A>G, c.521T>C and g.89595T>C polymorphisms may not be useful as genetic markers of lipid-lowering response to simvastatin therapy in Thai hypercholesterolaemic patients.

Establishment of a novel microscale thermophoresis ligand-binding assay for characterization of SLC solute carriers using oligopeptide transporter PepT1 (SLC15 family) as a model system

INTRODUCTION

Membrane proteins represent roughly one third of the human proteome and many of them serve as targets of therapeutic drugs. An exception is the SLC solute carrier superfamily with only a handful of approved drugs targeting SLCs. Indeed, for many of the SLCs, the natural transport substrates are still unknown. A major limitation for SLCs has been the difficulty to thoroughly characterize these multimembrane spanning proteins. The intrinsic properties of membrane proteins with alternative hydrophobic and hydrophilic domains lead to instability, making the purification tasks even more challenging compared to soluble proteins. This issue also holds true for conventional ligand-binding assays (LBAs) which usually require high-quality, pure and concentrated protein samples. Herein, we report a novel binding assay strategy to overcome these issues, taking advantage of a unique combination of yeast expression and microscale thermophoresis (MST). Following yeast overexpression of SLC15A1/PepT1 ortholog from moss Physcomitrella patens, PepT_Pp, which exhibits remarkable similarity to human PepT1, the approach was validated using dipeptide glycylsarcosine (Gly-Sar) and antiviral prodrug valacyclovir as test substrates.

METHOD

The originality of our approach is based on the comparative analysis of solubilized total membrane preparations with or without expression of the SLC target of interest, using a yeast strain (S. cerevisiae), in which the corresponding endogenous SLC homolog is depleted. MST is a recently developed technique that takes advantage of the properties of biomolecules in solution to migrate along a temperature gradient. Importantly, this migration is affected by substrate binding. It is being monitored by fluorescence using labelled SLC molecules in the presence of different ligand concentrations.

RESULTS

We herein report a novel MST/yeast-based method to characterize binding of ligands to SLCs without the need for a prior SLC-purification step. For validation purposes, we used a close eukaryotic homolog of the human H⁺-coupled oligopeptide transporter PepT1 (SLC15A1) that mediates uptake of di-tripeptides and peptide-like drugs as a test model. This approach allowed the successful confirmation of the binding of Gly-Sar at the mM range and revealed for the first time the K_D of the antiviral prodrug valacyclovir to the PepT1 homolog at around 50 μM.

DISCUSSION

This novel LBA approach is independent of protein purification. It is suitable for drug discovery as it is upscalable to high throughput compound screening. It works well for SLC transporters which are underrepresented targets due to their difficulties to study them. Moreover, this approach could make a significant contribution toward "deorphanization" of SLCs, revealing their transport substrates.

Mapping SLCO1B1 Genetic Variation for Global Precision Medicine in Understudied Regions in Africa: A Focus on Zulu and Cape Admixed Populations

The U.S. President Barack Obama has announced, in his State of the Union address on January 20, 2015, the Precision Medicine Initiative, a US$215-million program. For global precision medicine to become a reality, however, biological and environmental "variome" in previously understudied populations ought to be mapped and catalogued. Chief among the molecular targets that warrant global mapping is the organic anion-transporting polypeptide 1B1 (OATP1B1), encoded by solute carrier organic anion transporter family member 1B1 (SLCO1B1), a hepatic uptake transporter predominantly expressed in the basolateral side of hepatocytes. Human OATP1B1 plays a crucial role in the transport of a wide variety of substrates. This includes endogenous compounds such as bile salts as well as medicines, including benzylpenicillin, methotrexate, pravastatin, and rifampicin, and natural toxins microcystin and phalloidin. Genetic variations observed in the SLCO1B1 gene have been associated with altered in vitro and in vivo OATP1B1 transport activity, and consequently influencing patients' response to medicines, toxins, and susceptibility to common complex diseases. Well-characterized haplotypes, *5 (RS4149056C) and *15 (RS4149056T), have been associated with a strikingly reduced uptake of multiple OATP1B1 substrates, including estrone-3-sulfate, estradiol-17β-d-glucuronide, atorvastatin, cerivastatin, pravastatin, and rifampicin. In particular, RS4149056C is observed in 60% of the Cape admixed (CA) population and is associated with increased plasma concentrations of many statins as well as fexofenadine and repaglinide. We designed and optimized a SNaPshot minisequencing panel to characterize the variants of relevance for precision medicine in the clinic. We report here the first study on allele and genotype frequencies for 10 nonsynonymous, 4 synonymous, and 6 intronic single-nucleotide polymorphisms of SLCO1B1 in the Zulu and CA populations of South Africa. These variants are further contextualized here, in relation to their potential clinical relevance. These observations collectively contribute to current efforts to advance global precision medicine in understudied populations and resource-limited regions of the world.

No signal of interactions between influenza vaccines and drugs used for chronic diseases: a case-by-case analysis of the vaccine adverse event reporting system and vigibase

BACKGROUND

An increasing number of reports indicates that vaccines against influenza may interact with specific drugs via drug metabolism. To date, actual impact of vaccine-drug interactions observed in the real world clinical practice has not been investigated.

METHODS

From VAERS and VigiBase, we collected Adverse Event Following Immunization (AEFI) reports for individuals receiving vaccines against influenza recorded as suspect and selected cases where predictable toxicity was recorded with oral anticoagulants, antiepileptics and statins (i.e. hemorrhages, overdosage and rhabdomyolysis, respectively). We applied AEFI and Drug Interaction Probability Scale (DIPS) Algorithms to assess causality of drug-vaccine interactions.

RESULTS

116 AEFI reports submitted to VAERS and 83 from Vigibase were included in our analysis; antiepileptics and statins were related to the highest number of indeterminate/consistent (93.7%; 65.3%) and possible/probable (50%; 57.7%) cases according to the AEFI and DIPS, respectively. The majority of cases occurred within the first week after vaccine administration (5-7 days).

CONCLUSION

The relative paucity of detected interactions does not impact on the benefit of the vaccination against influenza, which remains strongly recommended; this does not exclude that closer monitoring for selected patients exposed to concomitant chronic pharmacological therapies and affected by predisposing factors may be useful.

Rhabdomyolysis after co-administration of a statin and fusidic acid: an analysis of the literature and of the WHO database of adverse drug reactions

Following a severe case of rhabdomyolysis in our University Hospital after a co-administration of atorvastatin and fusidic acid, we describe this interaction as this combination is not clearly contraindicated in some countries, particularly for long-term treatment by fusidic acid. All cases of rhabdomyolysis during a co-administration of a statin and fusidic acid were identified in the literature and in the World and Health Organization database, VigiBase^® . In the literature, 29 cases of rhabdomyolysis were identified; mean age was 66 years, median duration of co-administration before rhabdomyolysis occurrence was 21 days, 28% of cases were fatal. In the VigiBase^® , 182 cases were retrieved; mean age was 68 years, median duration of co-administration before rhabdomyolysis was 31 days and 24% of cases were fatal. Owing to the high fatality associated with this co-administration and the long duration of treatment before rhabdomyolysis occurrence, fusidic acid should be used if there is no appropriate alternative, as long as statin therapy is interrupted for the duration of fusidic acid therapy, and perhaps a week longer. Rarely will interruption of this sort have adverse consequences for the patient.

Pharmacogenetics: An Important Part of Drug Development with A Focus on Its Application

Since the human genome project in 2003, the view of personalized medicine to improve diagnosis and cure diseases at the molecular level became more real. Sequencing the human genome brought some benefits in medicine such as early detection of diseases with a genetic predisposition, treating patients with rare diseases, the design of gene therapy and the understanding of pharmacogenetics in the metabolism of drugs. This review explains the concepts of pharmacogenetics, polymorphisms, mutations, variations, and alleles, and how this information has helped us better understand the metabolism of drugs. Multiple resources are presented to promote reducing the gap between scientists, physicians, and patients in understanding the use and benefits of pharmacogenetics. Some of the most common clinical examples of genetic variants and how pharmacogenetics was used to determine treatment options for patients having these variants were discussed. Finally, we evaluated some of the challenges of implementing pharmacogenetics in a clinical setting and proposed actions to be taken to make pharmacogenetics a standard diagnostic tool in personalized medicine.

Effects of Polymorphisms in NR1H4, NR1I2, SLCO1B1, and ABCG2 on the Pharmacokinetics of Rosuvastatin in Healthy Chinese Volunteers

The nuclear receptors (NR)-farnesoid X receptor (FXR, NR1H4) and pregnane X receptor (PXR, NR1I2)-have important effects on the expression of genes related to the pharmacokinetics (PKs) of rosuvastatin. This study was designed to investigate whether the genetic variants in drug disposition genes (SLCO1B1 and ABCG2) combined with their upstream regulators (NR1H4 and NR1I2) would affect the PKs of rosuvastatin in a Chinese population. Sixty-one healthy male volunteers were enrolled and the plasma concentrations of rosuvastatin were measured using the liquid chromatographic-tandem mass spectrometry/MS method. All subjects were analyzed and grouped according to the genotypes of NR1H4, NR1I2, SLCO1B1, and ABCG2. The exposure of rosuvastatin was higher in subjects carrying the SLCO1B1 521C or ABCG2 421A allele compared with noncarriers. No association was observed of single-nucleotide polymorphisms in NR1H4 or NR1I2 genes with the PKs of rosuvastatin. After adjusting for the 421C>A and 521T>C variants, the Cmax in subjects with NR1I2 63396TT wild type were about 2-fold of those of NR1I2 mutant type (63396CC and CT) (10.7 vs. 20.4 ng/mL, P = 0.023), whereas no significant differences were observed for other parameters. Polymorphisms investigated in the genes of NR1H4 and NR1I2 seemed to play no significant role in the disposition of rosuvastatin.

SLCO1A2, SLCO1B1 and SLCO2B1 polymorphisms influences chloroquine and primaquine treatment in Plasmodium vivax malaria

AIM

The association of transporters gene polymorphisms with chloroquine/primaquine malaria treatment response was investigated in a Brazilian population.

PATIENTS & METHODS

Totally, 164 Plasmodium vivax malaria infected patients were included. Generalized estimating equations were performed to determine gene influences on parasitemia and/or gametocytemia clearance over treatment time.

RESULTS

Significant interaction between SLCO2B1 genotypes and treatment over time for parasitemia clearance rate on day 2 were observed (p FDR = 0.002). SLCO1A2 and SLCO1B1 gene treatment over time interactions were associated with gametocytemia clearance rate (p FDR = 0.018 and p FDR = 0.024). ABCB1, ABCC4 and SLCO1B3 were not associated with treatment response.

CONCLUSION

The present work presents the first pharmacogenetic report of an association between chloroquine/primaquine responses with OATP transporters.

Statin use and hip fractures in U.S. kidney transplant recipients

Background

Basic and translational research supports beneficial effects of statins on bone metabolism. Clinical studies suggest that statin use may reduce the risk of hip fractures in the general population. Whether statin use is associated with hip fracture risk in kidney transplant recipients, a particularly high-risk group for this outcome, is unknown.

Methods

From the U.S. Renal Data System (2007–2011), we identified all hip fracture events recorded in Medicare billing claims of first-time kidney transplant recipients. We then matched all cases to an unlimited number of controls on age (±3 years), sex, race (black vs. non-black), and time since transplant. Cases and controls were required to have >1 year of Medicare Parts A + B + D coverage and be without a recorded history of hip fracture. We ascertained any statin use in the previous year and defined adherent statin use as those who had filled prescriptions for statins to cover >80% of days in that year (proportion of days covered, PDC). We ascertained several potential confounders (demographics, comorbidities, BMI, transplant-related factors) and applied conditional logistic regression with multiple imputation for missing data to estimate odds ratios (OR) and 95% confidence intervals (CI).

Results

We identified 231 hip fracture cases (mean age 51.8 years; 53% female; 11.3% black; 6.9 years from transplant, and 9.9 years from ESRD) and 15,575 matched controls. Any prior statin use was present in 64.1% of cases and 60.3% of controls with 37.2% of cases and 33.9% of controls being found adherent. Unadjusted conditional logistic regression showed an OR of 1.17 (0.89-1.54) for any statin use, and a fully-adjusted OR of 0.89 (0.67-1.19). Compared with statin non-users, the adjusted OR for patients with lesser adherence (PDC ≤80%) and those with greater adherence (PDC >80%) were 0.93 (0.66-1.31) and 0.87 (0.63-1.20), respectively.

Conclusion

Statin use was not associated with hip fracture risk in first-time kidney transplant recipients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0559-9) contains supplementary material, which is available to authorized users.

Rosuvastatin Pharmacokinetics in Asian and White Subjects Wild Type for Both OATP1B1 and BCRP Under Control and Inhibited Conditions

The Food and Drug Administration recommends rosuvastatin dosage reductions in Asian patients because pharmacokinetic studies have demonstrated an approximate 2-fold increase in median exposure to rosuvastatin in Asian subjects compared with Caucasian controls. Yet, no explanation for this ethnic difference has been confirmed. Here we show that rosuvastatin exposure in Asians and Whites does not differ significantly when all subjects are wild-type carriers for both solute carrier organic anion transporter 1B1 *1a and ATP-binding cassette subfamily G member 2 c.421 transporters in a 2-arm, randomized, cross-over rosuvastatin pharmacokinetics study in healthy white and Asian volunteers. For single rosuvastatin doses, AUC_0-48 were 92.5 (±36.2) and 83.5 (±32.2) ng/mL × h and C_max were 10.0 (±4.1) and 7.6 (±3.0) ng/mL for Asians and Whites, respectively. When transporters were inhibited by intravenous rifampin, rosuvastatin AUC_0-48 and C_max also showed no ethnic differences. Our study suggests that both SLCO1B1 and ABCG2 polymorphisms are better predictors of rosuvastatin exposure than ethnicity alone and could be considered in precision medicine dosing of rosuvastatin.

Pharmacogenetic considerations in the treatment of HIV

After the introduction of highly active antiretroviral therapy in the 1990s, the perception of the diagnosis of HIV infection gradually shifted from a 'death sentence' to a chronic disease requiring long-term treatment. The host genetic variability has been shown to play a relevant role in both antiretroviral drugs bioavailability and adverse effects susceptibility. Knowledge about pharmacogenetics role in HIV infection treatment has largely increased over the last years, and is reviewed in the present report, as well as future perspectives for the inclusion of pharmacogenetics information in the directing of HIV infection treatment.

Rhabdomyolysis After Coadministration of Atorvastatin and Sacubitril/Valsartan (Entresto™) in a 63-Year-Old Woman

A 63-year-old woman previously stable on a regimen of atorvastatin 40 mg daily, carvedilol 25 mg twice daily, digoxin 0.125 mg daily, furosemide 40 mg daily, spironolactone 25 mg daily, rivaroxaban 15 mg daily, and enalapril 20 mg twice daily for heart failure developed rhabdomyolysis 26 days after enalapril was stopped and sacubitril/valsartan (Entresto™) started. The patient received sacubitril/valsartan at 24/26 mg twice daily for heart failure; however, after 26 days she developed muscle and skin pain. Investigations revealed elevated creatine kinase and liver function tests, and rhabdomyolysis with raised transaminases was diagnosed. Sacubitril/valsartan and atorvastatin were discontinued and the patient was hydrated. She returned to baseline in 23 days and has not had any reoccurrence of rhabdomyolysis and elevated transaminases for 46 days. A Naranjo assessment score of 5 was obtained, indicating a probable relationship between the patient's rhabdomyolysis and her use of sacubitril/valsartan. The Drug Interaction Probability Scale score was 3, consistent with a possible interaction as a cause for the reaction, with sacubitril/valsartan as the precipitant drug and atorvastatin as the object drug.

Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins

Drug transporters govern the absorption, distribution, and elimination of pharmacologically active compounds. Members of the solute carrier and ATP binding-cassette drug transporter family mediate cellular drug uptake and efflux processes, thereby coordinating the vectorial movement of drugs across epithelial barriers. To exert their physiologic and pharmacological function in polarized epithelia, drug transporters must be targeted and stabilized to appropriate regions of the cell membrane (i.e., apical versus basolateral). Despite the critical importance of drug transporter membrane targeting, the mechanisms that underlie these processes are largely unknown. Several clinically significant drug transporters possess a recognition sequence that binds to PSD-95/Drosophila discs large/ZO-1 (PDZ) proteins. PDZ proteins, such as the Na(+)/H(+) exchanger regulatory factor (NHERF) family, act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is particularly high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia, tissues important to drug disposition. Several recent studies have highlighted NHERF proteins as determinants of drug transporter function secondary to their role in controlling membrane abundance and localization. Mounting evidence strongly suggests that NHERF proteins may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development.

A pharmacogenetic pilot study reveals MTHFR, DRD3, and MDR1 polymorphisms as biomarker candidates for slow atorvastatin metabolizers

Background

The genetic variation underlying atorvastatin (ATV) pharmacokinetics was evaluated in a Mexican population. Aims of this study were: 1) to reveal the frequency of 87 polymorphisms in 36 genes related to drug metabolism in healthy Mexican volunteers, 2) to evaluate the impact of these polymorphisms on ATV pharmacokinetics, 3) to classify the ATV metabolic phenotypes of healthy volunteers, and 4) to investigate a possible association between genotypes and metabolizer phenotypes.

Methods

A pharmacokinetic study of ATV (single 80-mg dose) was conducted in 60 healthy male volunteers. ATV plasma concentrations were measured by high-performance liquid chromatography mass spectrometry. Pharmacokinetic parameters were calculated by the non-compartmental method. The polymorphisms were determined with the PHARMAchip® microarray and the TaqMan® probes genotyping assay.

Results

Three metabolic phenotypes were found in our population: slow, normal, and rapid. Six gene polymorphisms were found to have a significant effect on ATV pharmacokinetics: MTHFR (rs1801133), DRD3 (rs6280), GSTM3 (rs1799735), TNFα (rs1800629), MDR1 (rs1045642), and SLCO1B1 (rs4149056). The combination of MTHFR, DRD3 and MDR1 polymorphisms associated with a slow ATV metabolizer phenotype.

Conclusion

Further studies using a genetic preselection method and a larger population are needed to confirm these polymorphisms as predictive biomarkers for ATV slow metabolizers.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12614000851662, date registered: August 8, 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2062-2) contains supplementary material, which is available to authorized users.

Practical recommendations for the management of hyperlipidemia

Hyperlipidemia is a risk factor for atherosclerosis. Raised low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) levels are severe risk factors for atherosclerosis. The role of high-density lipoprotein cholesterol (HDL-C) is controversial. Total cholesterol, LDL-C, HDL-C, triglycerides and lipoprotein(a) levels should be determined in a fasting state. The basis of treating hyperlipidemia remains diet, physical exercise and weight reduction. Olive oil and nuts have been shown to be beneficial. Statins remain first line drug treatment. Further treatment options are ezetimibe, bile acid sequestrants, fibrates and fish oil. Side effects of statins include myopathies and, as shown during the last years, also an increased risk of diabetes mellitus. In patients with statin-related myopathies first results of a gene analysis have been published showing a means of predicting which statin can be administered at which dose for the individual patient with least risk of side effects. Most convincing data have been shown for simvastatin. Patients with renal insufficiency have been shown to have a raised cardiovascular risk. In the SHARP Study the combination of simvastatin plus ezetimibe was effective in reducing cardiovascular events in patients with severe renal insufficiency (especially before dialysis but also in dialysis dependent patients). Important aspects of treating patients with chylomicronemia syndrome are illustrated. Treating young patients with hyperlipidemia as primary prevention remains problematic.

Effects of the SLCO1B1 *1 and SLCO1B1 *5 polymorphisms on IL-6 and IL-10 levels in patients under pravastatin treatment prior to inguinal hernia repair

BACKGROUND

Different genetic variants in the SLCO1B1 gene have been shown to have functional importance in individual variability in pravastatin pharmacokinetics, resulting in different inflammatory responses to surgical inguinal hernia repair. The aim of this study was to determine IL-6 and IL-10 serum concentrations in the presence and absence of the SLCO1B1*1 and SLCO1B1*5 polymorphisms in patients under pravastatin treatment that underwent inguinal hernia repair.

METHODS

The study included 26 subjects that were under pravastatin treatment (40 mg/day) at least 1 month prior to inguinal hernia repair open technique. All the subjects were genotyped for the SLCO1B1*1 and SLCO1B1*5 polymorphisms through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and their preoperative and postoperative serum IL-6 and IL-10 levels were quantified through the ELISA technique. The IL-6 and IL-10 levels were analyzed in the presence or absence of the mutated polymorphism for SLCO1B1*1 and SLCO1B1*5.

RESULTS

The SLCO1B1*1 polymorphism had a frequency of 38.5% and the SLCO1B1*5 polymorphism had a frequency of 19.2%. The preoperative and postoperative serum concentrations of IL-6 were 0.252 pg/ml ± 0.19 and 0.206 pg/ml ± 0.20, respectively, with a p = 0.525, whereas the preoperative and postoperative serum concentrations for IL-10 were 4.943 pg/ml ± 3.13 and 4.611 pg/ml ± 3.01, respectively, with a p = 0.004.

CONCLUSIONS

The patients under pravastatin treatment presented with lower postoperative IL-10 levels with respect to the baseline concentration (p = 0.004), regardless of the presence or absence of the two polymorphisms.

A Review of New Pharmacologic Treatments for Patients With Chronic Heart Failure With Reduced Ejection Fraction

Heart failure (HF) impacts an estimated 5.7 million Americans, and its prevalence is projected to increase to more than 8 million Americans in the next 15 years. Key clinical trials have established an evidence-based foundation for treatment of heart failure with reduced ejection fraction (HFrEF). Ivabradine and sacubitril/valsartan, which inhibit the f-channel and the angiotensin receptor and neprilysin, respectively, were recently approved by the Food and Drug Administration for HFrEF. In systolic heart failure, treatment with the If inhibitor ivabradine significantly reduced the combined endpoint of cardiovascular mortality or heart failure hospital admission vs placebo (P < .05). In the Prospective Comparison of angiotensin receptor-neprilysin inhibitor (ARNI) with angiotensin-converting enzyme inhibitor (ACEI) to Determine Impact on Global Mortality and Morbidity in Heart Failure trial, sacubitril/valsartan significantly reduced the combined endpoint of cardiovascular death or heart failure hospitalization vs enalapril (P < .001). The place of therapy with ivabradine and sacubitril/valsartan is defined by these trials and their interplay with guideline-directed medical therapy. Ivabradine and sacubitril/valsartan increase pharmacotherapy options for the treatment of HFrEF but are not yet first-line agents. Clinical application will be better defined in the coming years as practitioners increase their familiarity with ivabradine and sacubitril/valsartan.

Marked differences in frequencies of statin therapy relevant SLCO1B1 variants and haplotypes between Roma and Hungarian populations

Background

SLCO1B1 polymorphisms are relevant in statin pharmacokinetics. Aim of this study was to investigate the genetic variability and haplotype profile of SLCO1B1 polymorphisms in Roma and Hungarian populations. Genotypes of 470 Roma and 442 Hungarian subjects for c.388A > G, c.521T > C and c.1498-1331T > C polymorphisms were determined by PCR-RFLP assay. Using these SNPs eight different haplotypes could be differentiated.

Results

Differences were found between Roma and Hungarians in SLCO1B1 388AA (24.5 vs. 45.5 %), GG (33.4 vs. 17.9 %) genotypes, AG + GG (75.5 vs. 54.5 %) carriers, in G allele frequency (0.545 vs. 0.362), respectively (p < 0.001). The most common SLCO1B1 haplotype was the ht8 (GTT) both in Roma (43.6 %) and in Hungarian (59.1 %) samples. The ht6 (GCT) was not present in Roma population samples Haplotype analyses showed striking differences between the Roma and Hungarian samples in ht4 (ATT, 37.2 % vs 20.8 %), ht5 (GCC, 1.15 % vs. 3.62 %) and ht8 (GTT, 43.6 % vs. 59.1 %) haplotypes (p < 0.01), respectively. Linkage disequilibrium analysis showed that the studied variants are in different linkage disequilibrium patterns depending on the ethnic origin.

Conclusions

Similarly to Caucasians the 388G is the minor allele in Hungarians, however, in Roma the 388A was found to be the minor allele contrary to Indians (India). The minor allele frequency of 521T > C and 1498-1331T > C SNPs are almost three times higher in Romas than in Indians (Singapore and Gujarati, respectively). Observed allele frequency for 1498-1331T > C polymorphism reflects the measured average European rates in Hungarians. The results can be applied in population specific treatment algorithms when developing effective programs for statin therapy.