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

Statin-Associated muscle symptoms and vitamin D supplementation

PURPOSE OF REVIEW

Statin medications play a pivotal role in the primary and secondary prevention and management of cardiovascular disease due to their potent lipid-lowering and anti-inflammatory effects. Nevertheless, the clinical application of statins is often hampered by statin-associated muscle symptoms (SAMS), which deter patient adherence and treatment efficacy considerably. SAMS currently affects 10-20% of statin users, thus understanding potential mitigation strategies is crucial. This review focuses on the role of vitamin D in mitigating SAMS, given the growing interest in vitamin D deficiency as a potentially modifiable risk factor.

RECENT FINDINGS

Despite observational suggestions linking vitamin D deficiency to heightened SAMS risk, recent studies have yielded conflicting results on the role of vitamin D supplementation in preventing SAMS. Some studies report an improvement in statin tolerance following vitamin D repletion. However, recent large-scale clinical trials, particularly the Vitamin D and Omega-3 trial (VITAL) report no significant benefit of vitamin D supplementation in preventing SAMS or reducing statin discontinuation rates, regardless of baseline vitamin D levels.

SUMMARY

Observational data provides evidence for the use of vitamin D supplementation in SAMS management, however conflicting evidence in recent clinical trials do not support its routine use for preventing or treating SAMS. To explore alternative strategies in improving statin tolerance and adherence, this discourse aims to elucidate the current understanding the complex mechanisms underlying SAMS, the influence of serum vitamin D levels, and the implications for clinical management.

Comprehensive Review of Lipid Management in Chronic Kidney Disease and Hemodialysis Patients: Conventional Approaches, and Challenges for Cardiovascular Risk Reduction

Background/Objectives: Lipid disorders are very prevalent in patients with chronic kidney disease (CKD) and end-stage kidney disease (ESKD), leading to heightened cardiovascular risk. This review examines the effectiveness of lipid-lowering agents in these populations and explores gaps in the current research. The goal of this review is to assess the efficacy of lipid-lowering therapies in CKD and ESRD patients and identify future research needs. It aims to provide a clearer understanding of how these treatments impact cardiovascular risk in high-risk populations. Methods: We conducted a literature search in Embase, PubMed, Cochrane, and Google Scholar databases using keywords including but not limited to: chronic kidney diseases, dialysis, hemodialysis, dyslipidemia, statins, ezetimibe, and lipid-lowering drugs. Findings from included studies were synthetized to provide an overview of the current management of dyslipidemia in ESRD and HD. Results: Statins show mixed results in CKD and ESRD, with limited benefits in reducing cardiovascular events in dialysis patients. Agents like PCSK9 inhibitors show promising results but require further research, while non-statin therapies like fibrates and omega-3 fatty acids have limited evidence for use in this population. Conclusions: The review underscores the need for further research into lipid-lowering agents in CKD and ESRD patients, highlighting the need for tailored lipid management strategies in vulnerable patients with unique risk factors. More studies are needed to refine treatment strategies and assess the role of exercise and accurate risk calculators in managing cardiovascular outcomes.

Development and Validation of the Pharmacological Statin-Associated Muscle Symptoms Risk Stratification Score Using Electronic Health Record Data

Statin-associated muscle symptoms (SAMS) can lead to statin nonadherence. This paper aims to develop a pharmacological SAMS risk stratification (PSAMS-RS) score using a previously developed PSAMS phenotyping algorithm that distinguishes objective vs. nocebo SAMS using electronic health record (EHR) data. Using our PSAMS phenotyping algorithm, SAMS cases and controls were identified from Minnesota Fairview EHR, with the statin user cohort divided into derivation (January 1, 2010, to December 31, 2018) and validation (January 1, 2019, to December 31, 2020) cohorts. A Least Absolute Shrinkage and Selection Operator regression model was applied to identify significant features for PSAMS. PSAMS-RS scores were calculated and the clinical utility of stratifying PSAMS risk was assessed by comparing hazard ratios (HRs) between fourth vs. first score quartiles. PSAMS cases were identified in 1.9% (310/16,128) of the derivation and 1.5% (64/4,182) of the validation cohorts. Sixteen out of 38 clinical features were determined to be significant predictors for PSAMS risk. Patients within the fourth quartile of the PSAMS scores had an over sevenfold (HR: 7.1, 95% confidence interval (CI): 4.03-12.45, derivation cohort) or sixfold (HR: 6.1, 95% CI: 2.15-17.45, validation cohort) higher hazard of developing PSAMS vs. those in their respective first quartile. The PSAMS-RS score is a simple tool to stratify patients' risk of developing PSAMS after statin initiation which could inform clinician-guided pre-emptive measures to prevent PSAMS-related statin nonadherence.

Development and validation of the pharmacological statin-associated muscle symptoms risk stratification (PSAMS-RS) score using real-world electronic health record data

Introduction

Statin-associated muscle symptoms (SAMS) contribute to the nonadherence to statin therapy. In a previous study, we successfully developed a pharmacological SAMS (PSAMS) phenotyping algorithm that distinguishes objective versus nocebo SAMS using structured and unstructured electronic health records (EHRs) data. Our aim in this paper was to develop a pharmacological SAMS risk stratification (PSAMS-RS) score using these same EHR data.

Method

Using our PSAMS phenotyping algorithm, SAMS cases and controls were identified using University of Minnesota (UMN) Fairview EHR data. The statin user cohort was temporally divided into derivation (1/1/2010 to 12/31/2018) and validation (1/1/2019 to 12/31/2020) cohorts. First, from a feature set of 38 variables, a Least Absolute Shrinkage and Selection Operator (LASSO) regression model was fitted to identify important features for PSAMS cases and their coefficients. A PSAMS-RS score was calculated by multiplying these coefficients by 100 and then adding together for individual integer scores. The clinical utility of PSAMS-RS in stratifying PSAMS risk was assessed by comparing the hazard ratio (HR) between 4th vs 1st score quartile.

Results

PSAMS cases were identified in 1.9% (310/16128) of the derivation and 1.5% (64/4182) of the validation cohort. After fitting LASSO regression, 16 out of 38 clinical features were determined to be significant predictors for PSAMS risk. These factors are male gender, chronic pulmonary disease, neurological disease, tobacco use, renal disease, alcohol use, ACE inhibitors, polypharmacy, cerebrovascular disease, hypothyroidism, lymphoma, peripheral vascular disease, coronary artery disease and concurrent uses of fibrates, beta blockers or ezetimibe. After adjusting for statin intensity, patients in the PSAMS score 4th quartile had an over seven-fold (derivation) (HR, 7.1; 95% CI, 4.03-12.45) and six-fold (validation) (HR, 6.1; 95% CI, 2.15-17.45) higher hazard of developing PSAMS versus those in 1st score quartile.

Conclusion

The PSAMS-RS score can be a simple tool to stratify patients' risk of developing PSAMS after statin initiation which can facilitate clinician-guided preemptive measures that may prevent potential PSAMS-related statin non-adherence.

Pharmacogenetic Testing in a 70-Year-Old Woman with Polypharmacy and Multiple Comorbidities: A Case Report

BACKGROUND Comorbidities and polypharmacy are difficult to manage, as polypharmacy hinders identification and prevention of medication-related problems. Risk for adverse drug events (ADEs) can be minimized through pharmacogenomic (PGx) testing and related therapeutic adjustments. CASE REPORT A 70-year-old woman with comorbidities and medications enrolled in the Program of All-inclusive Care for the Elderly presented with left lower extremity (LLE) pain, generalized weakness, and major depressive disorder. The provider requested a medication safety review, where the clinical pharmacist-recommended PGx testing given the LLE pain and weakness while taking a statin and inconsistent INR readings taking warfarin. The pharmacist recommended switching atorvastatin to pravastatin to minimize the risk for statin-associated ADEs due to CYP3A4 inhibition and switching fluoxetine to citalopram due to uncontrolled depression/anxiety and to mitigate drug-drug interactions with carvedilol to reduce the risk of orthostatic hypotension. Recommendations were accepted and upon follow-up the patient reported minor LLE pain and improved wellbeing on citalopram. Following PGx testing, the patient had decreased function at SLCO1B1 and was an intermediate metabolizer for CYP2C9 and CYP2D6. This case demonstrates how preemptive PGx testing would have identified drug-gene interactions (DGIs) at the time of prescribing and reduced the risk of statin-associated muscular symptoms, highlighting the utility of panel-based PGx testing in older adults at high risk for ADEs and/or therapy failure. CONCLUSIONS Decreased function at SLCO1B1 increases exposure to statins, leading to statin-induced myalgias, as displayed in this case. PGx testing can help identify DGIs, choose optimal therapies in medically complex older adults, and minimize ADE risk.

Prevalence of Self-Reported Muscle Pain Among Statin Users From National Guard Hospital, Riyadh

Background

Statin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor, is one of the commonly used lipid-lowering drugs that is used for lowering lipid levels in the body. Muscle pain is a commonly reported adverse effect of statins, yet little is known about the prevalence of muscle pain and statin use in the general population.

Methods

The cross-sectional study was conducted in National Guard Hospital, Riyadh, Saudi Arabia. All study subjects were adult statin users aged 18 years old or above. A total of 313 patients were included in the study. The study was conducted based on a questionnaire distributed among patients according to inclusion and exclusion criteria.

Results

Among 313 statin users, patients underwent cardiac catheterization (39, 12.5%), stress test (62; 19.8%), percutaneous coronary intervention (three; 1.0%), and coronary artery bypass graft (six, 1.9%), while 203 patients didn’t have any intervention (64.9%). Most of the study subjects were on atorvastatin (139; 44.4%).

The prevalence of muscle pain was 73.5%; 95% CI = (68.4% - 78.1%). The most common sites of pain were lower limb pain (160; 51.1%), upper limb pain (145; 46.3%), and trunk pain (96; 30.7%). The common types of pain were joint pain (52; 16.6%), muscle weakness (51; 16.3%), muscle aches (43; 13.7%), and muscle cramps (41; 13.1%); and patients who reported that they stopped statin at some point because of muscle pain were 92 (29.4%).

Conclusion

Statins are important for managing and preventing ischemic heart diseases. Our study found that muscle pain is highly associated with statin use with a prevalence of 73.5%, which causes many patients to tend to stop taking their medication. Therefore, preventing the side effects by adjusting the proper dose or switching to another type of statin for high-risk patients will help them to continue using the drug. Also, it is important to rule out secondary causes of myopathy such as physical activity, fracture, thyroid dysfunction, or infection.

Effect of SLCO1B1 T521C on Statin-Related Myotoxicity With Use of Lovastatin and Atorvastatin

The association between the c.521T>C variant allele in SLCO1B1 (reference single nucleotide polymorphism (rs)4149056) and simvastatin-induced myotoxicity was discovered over a decade ago; however, whether this relationship represents a class effect is still not fully known. The aim of this study was to investigate the relationship between rs4149056 genotype and statin-induced myotoxicity in patients taking atorvastatin and lovastatin. Study participants were from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort. A total of 233 statin-induced myopathy + rhabdomyolysis cases met the criteria for inclusion and were matched to 2,342 controls. To validate the drug response phenotype, we replicated the previously established association between rs4149056 genotype and simvastatin-induced myotoxicity. In particular, compared with homozygous T allele carriers, there was a significantly increased risk of simvastatin-induced myopathy + rhabdomyolysis in homozygous carriers of the C allele (CC vs. TT, odds ratio [OR] 4.62, 95% confidence interval [CI] 1.58-11.90, P = 0.003). For lovastatin users, homozygous carriers of the C allele were also at increased risk of statin-induced myopathy + rhabdomyolysis (CC vs. TT, OR 4.49, 95% CI 1.68-10.80, P = 0.001). In atorvastatin users, homozygous carriers of the C allele were twice as likely to experience statin-induced myopathy, though this association did not achieve statistical significance (CC vs. TT, OR 2.00, 95% CI 0.44-6.59, P = 0.30). In summary, our findings suggest that the association of rs4149056 with simvastatin-related myotoxicity may also extend to lovastatin. More data is needed to determine the extent of the association in atorvastatin users. Altogether, these data expand the evidence base for informing guidelines of pharmacogenetic-based statin prescribing practices.

Medically Important Alterations in Transport Function and Trafficking of ABCG2

Several polymorphisms and mutations in the human ABCG2 multidrug transporter result in reduced plasma membrane expression and/or diminished transport function. Since ABCG2 plays a pivotal role in uric acid clearance, its malfunction may lead to hyperuricemia and gout. On the other hand, ABCG2 residing in various barrier tissues is involved in the innate defense mechanisms of the body; thus, genetic alterations in ABCG2 may modify the absorption, distribution, excretion of potentially toxic endo- and exogenous substances. In turn, this can lead either to altered therapy responses or to drug-related toxic reactions. This paper reviews the various types of mutations and polymorphisms in ABCG2, as well as the ways how altered cellular processing, trafficking, and transport activity of the protein can contribute to phenotypic manifestations. In addition, the various methods used for the identification of the impairments in ABCG2 variants and the different approaches to correct these defects are overviewed.

Pharmacokinetics and Pharmacodynamics of the Dual Orexin Receptor Antagonist Daridorexant in Japanese and Caucasian Subjects

PURPOSE/BACKGROUND

Daridorexant is a dual orexin receptor antagonist in development for the treatment of sleep disorders. Thus far, it has not yet been studied in Japanese subjects. Study objectives were to evaluate the pharmacokinetics (PK), pharmacodynamics (PD), and safety of single- and multiple-dose administration of daridorexant in healthy Caucasian and Japanese subjects.

METHODS/PROCEDURES

This was a double-blind, placebo-controlled, randomized study. Subjects received once-daily doses of daridorexant (25 or 50 mg) or placebo for 5 days. Pharmacokinetics and safety were investigated using standard assessments. To assess PD effects, a battery of tests (saccadic peak velocity, body sway, adaptive tracking performance, and visual analog scales for alertness, mood, and calmness), known to be sensitive to sleep-promoting drugs was used.

FINDINGS/RESULTS

On day 1, PK variables were similar between Caucasian and Japanese subjects. On day 5, slight accumulation occurred in Japanese but not in Caucasian subjects, resulting in a higher maximum concentration (1403 vs 1006 ng/mL) and area under the curve (8256 vs 6306 ng·h/mL) at a dose of 50 mg, whereas values for time to maximum concentration and half-life were similar. Daridorexant dose-dependently reduced vigilance, attention, visuomotor coordination, and postural stability. Pharmacokinetic effects were detectable within 1 hour after drug administration and returned to baseline 4 to 8 hours postdose. Overall, Japanese showed slightly larger PD effects and reported more adverse events than Caucasians. The most frequently reported were somnolence, fatigue, and headache. Changes in other safety assessments were unremarkable.

IMPLICATIONS/CONCLUSIONS

The PK, PD, and safety profile of daridorexant were similar in Japanese and Caucasian subjects.

Modeling statin myopathy in a human skeletal muscle microphysiological system

Statins are used to lower cholesterol and prevent cardiovascular disease. Musculoskeletal side effects known as statin associated musculoskeletal symptoms (SAMS), are reported in up to 10% of statin users, necessitating statin therapy interruption and increasing cardiovascular disease risk. We tested the hypothesis that, when exposed to statins ex vivo, engineered human skeletal myobundles derived from individuals with (n = 10) or without (n = 14) SAMS and elevated creatine-kinase levels exhibit statin-dependent muscle defects. Myoblasts were derived from muscle biopsies of individuals (median age range of 62-64) with hyperlipidemia with (n = 10) or without (n = 14) SAMS. Myobundles formed from myoblasts were cultured with growth media for 4 days, low amino acid differentiation media for 4 days, then dosed with 0 and 5μM of statins for 5 days. Tetanus forces were subsequently measured. To model the change of tetanus forces among clinical covariates, a mixed effect model with fixed effects being donor type, statin concentration, statin type and their two way interactions (donor type*statin concentration and donor type* statin type) and the random effect being subject ID was applied. The results indicate that statin exposure significantly contributed to decrease in force (P<0.001) and the variability in data (R2C [R square conditional] = 0.62). We found no significant differences in force between myobundles from patients with/without SAMS, many of whom had chronic diseases. Immunofluorescence quantification revealed a positive correlation between the number of straited muscle fibers and tetanus force (R2 = 0.81,P = 0.015) and negative correlation between number of fragmented muscle fibers and tetanus force (R2 = 0.482,P = 0.051) with no differences between donors with or without SAMS. There is also a correlation between statin exposure and presence of striated fibers (R2 = 0.833, P = 0.047). In patient-derived myobundles, statin exposure results in myotoxicity disrupting SAA organization and reducing force. We were unable to identify differences in ex vivo statin myotoxicity in this system. The results suggest that it is unlikely that there is inherent susceptibility to or persistent effects of statin myopathy using patient-derived myobundles.

Pharmacogenetics of Statin-Induced Myotoxicity

Statins, a class of lipid-lowering medications, have been a keystone treatment in cardiovascular health. However, adverse effects associated with statin use impact patient adherence, leading to statin discontinuation. Statin-induced myotoxicity (SIM) is one of the most common adverse effects, prevalent across all ages, genders, and ethnicities. Although certain demographic cohorts carry a higher risk, the impaired quality of life attributed to SIM is significant. The pathogenesis of SIM remains to be fully elucidated, but it is clear that SIM is multifactorial. These factors include drug-drug interactions, renal or liver dysfunction, and genetics. Genetic-inferred risk for SIM was first reported by a landmark genome-wide association study, which reported a higher risk of SIM with a polymorphism in the SLCO1B1 gene. Since then, research associating genetic factors with SIM has expanded widely and has become one of the foci in the field of pharmacogenomics. This review provides an update on the genetic risk factors associated with SIM.

The ABCG2/BCRP transporter and its variants - from structure to pathology

The ABCG2 protein has a key role in the transport of a wide range of structurally dissimilar endo- and xenobiotics in the human body, especially in the tissue barriers and the metabolizing or secreting organs. The human ABCG2 gene harbors a high number of polymorphisms and mutations, which may significantly modulate its expression and function. Recent high-resolution structural data, complemented with molecular dynamic simulations, may significantly help to understand intramolecular movements and substrate handling, as well as the effects of mutations on the membrane transporter function of ABCG2. As reviewed here, structural alterations may result not only in direct alterations in drug binding and transporter activity, but also in improper folding or problems in the carefully regulated process of trafficking, including vesicular transport, endocytosis, recycling, and degradation. Here, we also review the clinical importance of altered ABCG2 expression and function in general drug metabolism, cancer multidrug resistance, and impaired uric acid excretion, leading to gout.

Statin use and safety concerns: an overview of the past, present, and the future

INTRODUCTION

Dyslipidemia is a significant risk factor for cardiovascular disorders and contributes to significant morbidity and mortality associated with CAD and stroke worldwide. Statins are the most commonly prescribed drugs for the prevention and management of dyslipidemia globally. Although they provide immense therapeutic benefit, they are associated with clinically significant adverse effects, predominantly muscle, nerve, liver, and cognition-related besides new-onset diabetes. This has sparked various controversies, bringing to the fore, ambiguities that continue to exist in the scientific evidence, in relation to statin-associated harms. Therefore, it becomes essential to have a better understanding of safety issues related to statin use in various populations.

AREAS COVERED

This review describes the most common adverse effects of statins, examines available evidence and highlights the role of ethnicity, lipophilicity and other biological factors that could mediate and/or influence the relationship. MEDLINE was searched via PubMed to obtain relevant articles on dyslipidemia and statin safety.

EXPERT OPINION

The effectiveness of statins is presently unmatched. Further research is warranted to gain insights into the diverse pharmacological effects of statins in various population subgroups. This would assist prescribers in making better informed decisions. Specific treatment strategies for vulnerable groups can significantly attenuate harms, improve risk-benefit ratios, and ultimately enhance patient experience.

Rosuvastatin/Ezetimibe: A Review in Hypercholesterolemia

Rosuvastatin/ezetimibe combines two lipid-lowering agents: rosuvastatin, an HMG-CoA reductase inhibitor (i.e. statin) with particularly strong inhibitory effects on hepatic cholesterol synthesis, and ezetimibe, which inhibits the intestinal absorption of cholesterol. A fixed-dose combination (FDC) of rosuvastatin/ezetimibe is indicated as an adjunctive therapy to diet for the management of primary hypercholesterolemia in adults in numerous countries worldwide. In well-designed clinical trials evaluating the therapeutic efficacy of rosuvastatin/ezetimibe administered as either separate agents or as an FDC, rosuvastatin/ezetimibe was significantly more effective than rosuvastatin monotherapy (including at double the dose of rosuvastatin) or simvastatin/ezetimibe in reducing low-density lipoprotein cholesterol (LDL-C) and total cholesterol in adults with hypercholesterolemia. Furthermore, rosuvastatin/ezetimibe enabled significantly higher proportions of patients to achieve recommended LDL-C levels than rosuvastatin monotherapy or simvastatin/ezetimibe. Rosuvastatin/ezetimibe did not significantly differ from rosuvastatin monotherapy with respect to incidences of treatment-related or serious adverse events in these short-term trials and displayed a similar safety profile to simvastatin/ezetimibe. While additional cardiovascular outcomes data and head-to-head comparisons with atorvastatin/ezetimibe would be of interest, rosuvastatin/ezetimibe is a potent and generally well-tolerated drug combination that extends the range of options available for the pharmacological management of primary hypercholesterolemia in adults.

Temporal trends in the incidence, treatment patterns, and outcomes of coronary artery disease and peripheral artery disease in the UK, 2006–2015

Aims

Most reports estimating national incidence rates of coronary (CAD) and peripheral arterial disease (PAD) have focused on stable outpatients or acute or elective hospital admissions, but not on the overall burden of disease. In this study, we report the changing trends in the population-level incidence of CAD and PAD, respectively from 2006 to 2015, statin utilization for secondary prevention and survival outcomes using multiple nationally representative data sources from the UK (primary care encounters, hospital admissions, and procedure-level data).

Methods and results

A nationally representative study of linked primary and secondary care electronic health records of 4.6 million individuals from the UK. We calculated crude and standardized annual incidence rates separately for CAD and PAD. Statin use for secondary prevention, trends in annual major vascular event rates, and mortality between 2006 and 2015, were estimated for CAD and PAD, respectively. We identified 160 376 and 70 753 patients with incident CAD and PAD, respectively. The age- and sex-standardized incidence of CAD was similar in 2006 (443 per 100 000 person-years) and 2015 [436 per 100 000 person-years; adjusted incidence rate ratio (IRR) 0.98, 95% confidence interval (CI) 0.96–1.00]. In contrast, there was a 15% decline in the standardized incidence of PAD (236 per 100 000 person-years in 2006 to 202 per 100 000 person-years in 2015; adjusted IRR 0.85, 95% CI 0.82–0.88). The proportion of incident CAD and PAD patients prescribed long-term statins, was only 66% and 55%, respectively and was less common amongst women, patients aged &gt;70 years, with heart failure, chronic lung disease, or depression. Cardiovascular mortality declined by 43% for incident CAD (adjusted IRR 0.57, 95% CI 0.50–0.64) between 2006 and 2015 but did not decline for incident PAD (adjusted IRR 0.84, 95% CI 0.70–1.00).

Conclusion and relevance

In the UK, the standardized incidence of CAD appears stable but mortality rates are falling, whereas the standardized incidence of PAD is falling but mortality rates are not.

Cellular Processing of the ABCG2 Transporter-Potential Effects on Gout and Drug Metabolism

The human ABCG2 is an important plasma membrane multidrug transporter, involved in uric acid secretion, modulation of absorption of drugs, and in drug resistance of cancer cells. Variants of the ABCG2 transporter, affecting cellular processing and trafficking, have been shown to cause gout and increased drug toxicity. In this paper, we overview the key cellular pathways involved in the processing and trafficking of large membrane proteins, focusing on ABC transporters. We discuss the information available for disease-causing polymorphic variants and selected mutations of ABCG2, causing increased degradation and impaired travelling of the transporter to the plasma membrane. In addition, we provide a detailed in silico analysis of an as yet unrecognized loop region of the ABCG2 protein, in which a recently discovered mutation may actually promote ABCG2 membrane expression. We suggest that post-translational modifications in this unstructured loop at the cytoplasmic surface of the protein may have special influence on ABCG2 processing and trafficking.

Satisfaction With Statin Treatment Among Adult Coronary Artery Disease Patients: An Experience From a Resource-Constrained Setting

BACKGROUND

Statins are the most widely prescribed hypolipidaemic drugs for coronary artery disease (CAD) patients, but have been found to cause muscle and nerve related adverse effects which can affect patient satisfaction with treatment. Literature on treatment satisfaction among statin users, especially from resource-limited settings is inadequate. The aim of this cross-sectional study was to assess the level of satisfaction with treatment among statin users and evaluate the relationship between adverse effects experienced by patients and their satisfaction with the medication.

METHODS

This study included 300 adult CAD patients visiting the cardiology department of a tertiary care hospital in the northern region of India, who were prescribed statins for their diagnoses. An interviewer administered, validated and standardised Treatment Satisfaction Questionnaire for Medication (version 1.4) was used for data collection.

RESULTS

Around three quarters of the population reported being overall satisfied with their medication. Mean scores were calculated for Effectiveness, Convenience, Side-Effects and Global Satisfaction. The patients reported high scores (above 60%) for all domains. Those experiencing any adverse effect were found to be more likely to report lower effectiveness. Additionally, medication effectiveness showed a positive correlation with overall treatment satisfaction.

CONCLUSIONS

The study shows that treatment satisfaction is critical to gauge patient experiences with the treatment which can impact medication adherence and compliance. It's a crucial measure especially among CAD and other chronic disease patients since greater satisfaction can improve clinical outcomes. More research is warranted to better understand the relationship between medication effectiveness and treatment satisfaction.

Statin related adverse effects and patient education: a study from resource limited settings

BACKGROUND

Statins are the most widely prescribed class of drugs for coronary artery disease (CAD) patients and yet literature on the prevalence of statin related adverse effects (AEs) and gaps in patient education is quite limited especially in resource-limited settings of developing world.

OBJECTIVES

The present study was conducted to determine the prevalence of myopathy (muscle ailments) and other statin associated adverse effects among CAD patients on statin therapy. The study also aimed to assess patient perceptions, attitudes and awareness concerning the use of statins.

METHODS

It was a cross-sectional study conducted among 300 adult CAD patients visiting the out-patient department of a tertiary care hospital in North India, who were receiving statins for their diagnosis. An interviewer administered questionnaire was used to collect data on statin use among patients and adverse effects experienced.

RESULTS

Myopathy or muscle related ailments like muscle pain, cramps and muscle weakness were the most prevalent (32, 34 and 47%, respectively), followed by numbness, tingling and burning in the extremities (31%). Joint pain and cognitive impairments were seen in nearly 20% of the patients. The level of awareness among participants regarding the use of statins was sub-optimal. Lack of knowledge and under-reporting of adverse effects were major concerns.

CONCLUSION

The study shows that a considerable proportion of statin users experience adverse effects and knowledge and awareness amongst patients is inadequate. Awareness programmes and counselling for patients, sensitisation of healthcare professionals and better screening systems for monitoring AEs can help improve the scenario.

Genetic and Clinical Factors Are Associated With Statin-Related Myotoxicity of Moderate Severity: A Case-Control Study

We evaluated the contribution of patient-specific clinical and genetic factors to statin-related muscle toxicity (SRM) without a significant creatine kinase elevation (125 cases related to simvastatin or atorvastatin and 481 controls). The association between 12 single nucleotide polymorphisms (SNPs) in nine candidate genes and clinical factors with SRM was evaluated. Of the 12 SNPs genotyped, only rs4149056 in SLCO1B1 was associated with SRM in univariate analysis (with any statin, odd ratio (OR) = 1.73, 95% confidence interval (CI) = 1.14-2.62, P = 0.010) and this association was influenced by sex (P = 0.006) and BMI (P = 0.02). In multivariate and binary logistic regression analyses, SLCO1B1 rs4149056 genotype (OR = 1.66, 95% CI: 1.08-2.54, P = 0.014) and sex (OR = 1.72, 95% CI = 1.15-2.59, P = 0.006) were independently associated with muscle toxicity related to statin treatment. Patient-specific genetic and clinical factors associated with increased systemic exposure to statins are implicated in the full spectrum of SRM, including myalgia in addition to severe myopathy.

Patients experiencing statin-induced myalgia exhibit a unique program of skeletal muscle gene expression following statin re-challenge

Statins, the 3-hydroxy-3-methyl-glutaryl (HMG)-CoA reductase inhibitors, are widely prescribed for treatment of hypercholesterolemia. Although statins are generally well tolerated, up to ten percent of statin-treated patients experience myalgia symptoms, defined as muscle pain without elevated creatinine phosphokinase (CPK) levels. Myalgia is the most frequent reason for discontinuation of statin therapy. The mechanisms underlying statin myalgia are not clearly understood. To elucidate changes in gene expression associated with statin myalgia, we compared profiles of gene expression in skeletal muscle biopsies from patients with statin myalgia who were undergoing statin re-challenge (cases) versus those of statin-tolerant controls. A robust separation of case and control cohorts was revealed by Principal Component Analysis of differentially expressed genes (DEGs). To identify putative gene expression and metabolic pathways that may be perturbed in skeletal muscles of patients with statin myalgia, we subjected DEGs to Ingenuity Pathways (IPA) and DAVID (Database for Annotation, Visualization and Integrated Discovery) analyses. The most prominent pathways altered by statins included cellular stress, apoptosis, cell senescence and DNA repair (TP53, BARD1, Mre11 and RAD51); activation of pro-inflammatory immune response (CXCL12, CST5, POU2F1); protein catabolism, cholesterol biosynthesis, protein prenylation and RAS-GTPase activation (FDFT1, LSS, TP53, UBD, ATF2, H-ras). Based on these data we tentatively conclude that persistent myalgia in response to statins may emanate from cellular stress underpinned by mechanisms of post-inflammatory repair and regeneration. We also posit that this subset of individuals is genetically predisposed to eliciting altered statin metabolism and/or increased end-organ susceptibility that lead to a range of statin-induced myopathies. This mechanistic scenario is further bolstered by the discovery that a number of single nucleotide polymorphisms (e.g., SLCO1B1, SLCO2B1 and RYR2) associated with statin myalgia and myositis were observed with increased frequency among patients with statin myalgia.

Changes in drug transport and metabolism and their clinical implications in non-alcoholic fatty liver disease

INTRODUCTION

The incidence of non-alcoholic fatty liver disease (NAFLD) is rising, especially in Western countries. Drug treatment in patients with NAFLD is common since it is linked to other conditions like diabetes, obesity, and cardiovascular disease. Consequently, changes in drug metabolism may have serious clinical implications. Areas covered: A literature search for studies in animal models or patients with obesity, fatty liver, non-alcoholic steatohepatitis (NASH) or NASH cirrhosis published before November 2016 was performed. After discussing epidemiology and animal models for NAFLD, we summarized both basic as well as clinical studies investigating changes in drug transport and metabolism in NAFLD. Important drug groups were assessed separately with emphasis on clinical implications for drug treatment in patients with NAFLD. Expert opinion: Given the frequency of NAFLD even today, a high degree of drug treatment in NAFLD patients appears safe and well-tolerated despite considerable changes in hepatic uptake, distribution, metabolism and transport of drugs in these patients. NASH causes changes in biliary excretion, systemic concentrations, and renal handling of drugs leading to alterations in drug efficacy or toxicity under specific circumstances. Future clinical drug studies should focus on this special patient population in order to avoid serious adverse events in NAFLD patients.

Cardiovascular Ion Channel Inhibitor Drug-Drug Interactions with P-glycoprotein

P-glycoprotein (Pgp) is an ATP-binding cassette (ABC) transporter that plays a major role in cardiovascular drug disposition by effluxing a chemically and structurally diverse range of cardiovascular therapeutics. Unfortunately, drug-drug interactions (DDIs) with the transporter have become a major roadblock to effective cardiovascular drug administration because they can cause adverse drug reactions (ADRs) or reduce the efficacy of drugs. Cardiovascular ion channel inhibitors are particularly susceptible to DDIs and ADRs with Pgp because they often have low therapeutic indexes and are commonly coadministered with other drugs that are also Pgp substrates. DDIs from cardiovascular ion channel inhibitors with the transporter occur because of inhibition or induction of the transporter and the transporter's tissue and cellular localization. Inhibiting Pgp can increase absorption and reduce excretion of drugs, leading to elevated drug plasma concentrations and drug toxicity. In contrast, inducing Pgp can have the opposite effect by reducing the drug plasma concentration and its efficacy. A number of in vitro and in vivo studies have already demonstrated DDIs from several cardiovascular ion channel inhibitors with human Pgp and its animal analogs, including verapamil, digoxin, and amiodarone. In this review, Pgp-mediated DDIs and their effects on pharmacokinetics for different categories of cardiovascular ion channel inhibitors are discussed. This information is essential for improving pharmacokinetic predictions of cardiovascular therapeutics, for safer cardiovascular drug administration and for mitigating ADRs emanating from Pgp.

Advances in the Pharmacogenomics of Adverse Drug Reactions

Rapid developments in pharmacogenomics have been noticeable in recent years, and much of this knowledge has improved understanding of adverse drug reactions. This improved knowledge has largely been the result of improved sequencing technologies and falling costs in this area, as well as improved statistical techniques to analyse the data derived from studies. While the genetic reasons behind adverse drug reactions are becoming better understood, translation of this knowledge, particularly in terms of biomarkers that might be clinically applicable at the bedside, has been more difficult. Understanding of the technologies and their application is limited among practising clinicians. The cost of some of the technologies available may also be prohibitive in stretched healthcare economies. As education about the potential for applying pharmacogenomics improves and costs fall, understanding of adverse drug reactions and application of this knowledge in a clinical setting should improve.

Pharmacogenomics of statins: understanding susceptibility to adverse effects

Statins are a cornerstone of the pharmacologic treatment and prevention of atherosclerotic cardiovascular disease. Atherosclerotic disease is a predominant cause of mortality and morbidity worldwide. Statins are among the most commonly prescribed classes of medications, and their prescribing indications and target patient populations have been significantly expanded in the official guidelines recently published by the American and European expert panels. Adverse effects of statin pharmacotherapy, however, result in significant cost and morbidity and can lead to nonadherence and discontinuation of therapy. Statin-associated muscle symptoms occur in ~10% of patients on statins and constitute the most commonly reported adverse effect associated with statin pharmacotherapy. Substantial clinical and nonclinical research effort has been dedicated to determining whether genetics can provide meaningful insight regarding an individual patient’s risk of statin adverse effects. This contemporary review of the relevant clinical research on polymorphisms in several key genes that affect statin pharmacokinetics (eg, transporters and metabolizing enzymes), statin efficacy (eg, drug targets and pathways), and end-organ toxicity (eg, myopathy pathways) highlights several promising pharmacogenomic candidates. However, SLCO1B1 521C is currently the only clinically relevant pharmacogenetic test regarding statin toxicity, and its relevance is limited to simvastatin myopathy.

Association between SLCO1B1 -521T>C and -388A>G polymorphisms and risk of statin-induced adverse drug reactions: A meta-analysis

An increasing number of studies have investigated the association between SLCO1B1 -521T>C and -388A>G polymorphisms and the risk of statin-induced adverse drug reactions (ADRs), but the results have been inconsistent. This meta-analysis was performed to gain more insight into the relationship. PubMed, Embase, Cochrane Library and Web of Science were searched for relevant articles published before March 5th, 2015. The quality of included studies was evaluated by the Newcastle-Ottawa Quality scale. Pooled effect estimates (odds ratios [ORs] or hazard ratios [HRs) and corresponding 95 % confidence intervals (CIs) were calculated to assess the association in overall and subgroup analyses for various genetic models. Begg's rank correlation test and Egger's linear regression test were used to examine the publication bias. A total of nine cohort and four case-control studies involving 11, 246 statin users, of whom 2, 355 developing ADRs were included in the analysis. Combined analysis revealed a significant association between the SLCO1B1-521T>C polymorphism and increased risk for ADRs caused by various statins, but the synthesis heterogeneity was generally large (dominant model: pooled effect estimate = 1.85, 95 % CI 1.20-2.85, P = 0.005; I (2) = 80.70 %, Pheterogeneity < 0.001). Subgroup analysis by statin type showed that the ADRs risk was significantly elevated among simvastatin users (dominant model: pooled effect estimate = 3.43, 95 % CI 1.80-6.52, P = 0.001; I (2) = 59.60 %, Pheterogeneity = 0.060), but not among atorvastatin users. No significant relationship was found between the -388A>G polymorphism and ADRs caused by various statins (dominant model: pooled effect estimate = 0.94, 95 % CI 0.79-1.13, P = 0.526; I (2) = 40.10 %, Pheterogeneity = 0.196). The meta-analysis suggests that SLCO1B1 -521T>C polymorphism may be a risk factor for statin-induced ADRs, especially in simvastatin therapy. Conversely, there may be no significant association for -388A>G polymorphism.

Molecular mechanisms of statin intolerance

Statins reduce cardiovascular morbidity and mortality in primary and secondary prevention. Despite their efficacy, many persons are unable to tolerate statins due to adverse events such as hepatotoxicity and myalgia/myopathy. In the case of most patients, it seems that mild-to-moderate abnormalities in liver and muscle enzymes are not serious adverse effects and do not outweigh the benefits of coronary heart disease risk reduction. The risk for mortality or permanent organ damage ascribed to statin use is very small and limited to cases of myopathy and rhabdomyolysis. Statin-induced muscle-related adverse events comprise a highly heterogeneous clinical disorder with numerous, complex etiologies and a variety of genetic backgrounds. Every patient who presents with statin-related side effects cannot undergo the type of exhaustive molecular characterization that would include all of these mechanisms. Frequently the only solution is to either discontinue statin therapy/reduce the dose or attempt intermittent dosing strategies at a low dose.

Downregulation of Organic Anion Transporting Polypeptide (OATP) 1B1 Transport Function by Lysosomotropic Drug Chloroquine: Implication in OATP-Mediated Drug-Drug Interactions

Organic anion transporting polypeptide (OATP) 1B1 mediates the hepatic uptake of many drugs including lipid-lowering statins. Decreased OATP1B1 transport activity is often associated with increased systemic exposure of statins and statin-induced myopathy. Antimalarial drug chloroquine (CQ) is also used for long-term treatment of rheumatoid arthritis and systemic lupus erythematosus. CQ is lysosomotropic and inhibits protein degradation in lysosomes. The current studies were designed to determine the effects of CQ on OATP1B1 protein degradation, OATP1B1-mediated transport in OATP1B1-overexpressing cell line, and statin uptake in human sandwich-cultured hepatocytes (SCH). Treatment with lysosome inhibitor CQ increased OATP1B1 total protein levels in HEK293-OATP1B1 cells and in human SCH as determined by OATP1B1 immunoblot. In HEK293-FLAG-tagged OATP1B1 stable cell line, co-immunofluorescence staining indicated that intracellular FLAG-OATP1B1 is colocalized with lysosomal associated membrane glycoprotein (LAMP)-2, a marker protein of late endosome/lysosome. Enlarged LAMP-2-positive vacuoles with FLAG-OATP1B1 protein retained inside were readily detected in CQ-treated cells, consistent with blocking lysosomal degradation of OATP1B1 by CQ. In HEK293-OATP1B1 cells, without pre-incubation, CQ concentrations up to 100 μM did not affect OATP1B1-mediated [(3)H]E217G accumulation. However, pre-incubation with CQ at clinically relevant concentration(s) significantly decreased [(3)H]E217G and [(3)H]pitavastatin accumulation in HEK293-OATP1B1 cells and [(3)H]pitavastatin accumulation in human SCH. CQ pretreatment (25 μM, 2 h) resulted in ∼1.9-fold decrease in Vmax without affecting Km of OATP1B1-mediated [(3)H]E217G transport in HEK293-OATP1B1 cells. Pretreatment with monensin and bafilomycin A1, which also have lysosome inhibition activity, significantly decreased OATP1B1-mediated transport in HEK293-OATP1B1 cells. Pharmacoepidemiologic studies using data from the U.S. Food and Drug Administration Adverse Event Reporting System indicated that CQ plus pitavastatin, rosuvastatin, and pravastatin, which are minimally metabolized by the cytochrome P450 enzymes, led to higher myopathy risk than these statins alone. In summary, the present studies report novel findings that lysosome is involved in degradation of OATP1B1 protein and that pre-incubation with lysosomotropic drug CQ downregulates OATP1B1 transport activity. Our in vitro data in combination with pharmacoepidemiologic studies support that CQ has potential to cause OATP-mediated drug-drug interactions.

ABCB1 C3435T polymorphism and the lipid-lowering response in hypercholesterolemic patients on statins: a meta-analysis

BACKGROUND

A number of researches have evaluated the association between the ABCB1 polymorphism and the lipid-lowering response of statins, but the results have been inconclusive. To examine the lipid-lowering efficacy and safety associated with the ABCB1 C3435T polymorphism in hypercholesterolemic patients receiving statin, all available studies were included in this meta-analysis.

METHODS

A systematic search for eligible studies in the Cochrane library database, Scopus and PubMed was performed. Articles meeting the inclusion criteria were comprehensively reviewed, and the available data were accumulated by the meta-analysis.

RESULTS

The results indicated that the comparisons of CC+CT vs. TT were associated with a significant elevation of the serum HDL-C levels after statin treatment (CC+CT vs. TT: MD, 2.46; 95 % CI, 0.36 to 4.55; P = 0.02), and the ABCB1 C3435T variant in homozygotes was correlated with decreases in LDL-C (CC vs. TT: MD, 2.29; 95 % CI, 0.37 to 4.20; P = 0.02) as well as TC (CC vs. TT: MD, 3.05; 95 % CI, 0.58 to 5.53; P = 0.02) in patients treated with statin. However, we did not observe a significant association in the TG group or an association between other genetic models serum lipid parameters. In addition, statin treatment more than 5 months led to a higher risk of muscle toxicity.

CONCLUSIONS

The evidence from the meta-analysis demonstrated that the ABCB1 C3435T polymorphism may represent a pharmacogenomic biomarker for predicting treatment outcomes in patients on statins and that statin treatment for more than 5 months can increase the risk of myopathy.

The role of mitochondria in statin-induced myopathy

BACKGROUND

Statins inhibit hydroxymethylglutaryl-coenzyme A reductase, decrease plasma low-density lipoprotein cholesterol and reduce cardiovascular morbidity and mortality. They can also exert adverse effects, mostly affecting skeletal muscle, ranging from mild myalgia to rhabdomyolysis.

MATERIALS AND METHODS

Based on a PubMed search until December 2014, this review summarizes studies on statin effects on muscle mitochondrial morphology and function in the context of myopathy.

RESULTS

Possible mechanisms of statin-induced myopathy include lower cholesterol synthesis and production of prenylated proteins, reduced dolichols and increased atrogin-1 expression. Statin-treated patients frequently feature decreased muscle coenzyme Q10 (CoQ10) contents, suggesting that statins might impair mitochondrial function. In cell cultures, statins diminish muscle oxygen consumption, promote mitochondrial permeability transient pore opening and generate apoptotic proteins. Animal models confirm the statin-induced decrease in muscle CoQ10, but reveal no changes in mitochondrial enzyme activities. Human studies yield contradictory results, with decreased CoQ10, elevated lipids, decreased enzyme activities in muscle and impaired maximal oxygen uptake in several but not all studies. Some patients are susceptible to statin-induced myopathy due to variations in genes encoding proteins involved in statin uptake and biotransformation such as the solute carrier organic anion transporter family member 1B1 (SLCO1B1) or cytochrome P450 (CYP2D6, CYP3A4, CYP3A5). Carriers for carnitine palmitoyltransferase II deficiency and McArdle disease also present with higher prevalence of statin-induced myopathy.

CONCLUSIONS

Despite the widespread use of statins, the pathogenesis of statin-induced myopathy remains unclear, requiring prospective randomized controlled trials with intensive phenotyping also for identifying strategies for its risk assessment, prevention and treatment.

Neuromuscular issues in systemic disease

The neuromuscular system can be involved in several systemic conditions. Clinical manifestations can appear at onset or throughout the course of the disease process. New investigational methods, including imaging of peripheral nerves, new laboratory tests, and antibodies, are available. In addition to symptomatic therapies, specific treatment options, such as for familial amyloid neuropathy and Fabry's disease, are becoming increasingly available. Pathomechanisms vary depending on the underlying disease process. In addition to metabolic, hormonal, immune, and antibody-mediated mechanisms, in some generalized diseases, genetic causes need to be considered. This review focuses on different aspects of the peripheral nervous system including the nerve roots, plexuses, mononeuropathies and generalized neuropathies, neuromuscular junction disorders, muscle, and autonomic nervous system.

Management and outcomes of patients with reduced ejection fraction after acute myocardial infarction in cardiac rehabilitation centers

BACKGROUND

We aimed to describe the contemporary management of patients with systolic chronic heart failure (CHF) during a cardiac rehabilitation (CR) stay and present outcomes with focus on lipids, blood pressure, exercise capacity, and clinical events.

METHODS

Comparison of 3199 patients with moderately or severely impaired left ventricular ejection fraction (low EF, 13.3%) and 20,913 patients with slightly reduced or normal LVEF (normal EF, 86.7%) who underwent an inpatient CR period of about 3 weeks in 2009-2010.

RESULTS

Patients with low EF compared to those with normal EF were somewhat older (65.1 vs. 63.0 years, p < 0.0001), and more often had risk factors such as diabetes mellitus (39.7% vs. 32.0%, p < 0.0001) or other comorbidities. The overall rate of patients with regular physical activity of at least 90 minutes per week prior to CR was low overall (54.4%), and reduced in patients with low EF compared to those with normal EF (47.7% vs. 55.5%, p < 0.0001). The rate of patients that achieved lower LDL cholesterol (<100 mg/dl), total cholesterol (<200 mg/dl) and triglyceride (<150 mg/dl) values at discharge increased compared to baseline. Mean blood pressure was substantially lower in the low EF group compared to the normal EF group both at baseline (124/75 vs. 130/78 mmHg, p < 0.0001) and at discharge (119/72 vs. 124/74 mmHg, p < 0.0001). Maximum exercise improved substantially in both groups (at baseline 71 vs. 91 Watts, p < 0.0001; at discharge 85 vs. 105 Watts, p < 0.0001). Event rates during CR were low, and only 0.3% in the low EF group died. As limitations to this study, information on brain natriuretic peptide (BNP), N-terminal pro-brain natriuretic peptide (NT-pro BNP) and/or cardiac troponin were not documented, and no long-term information was collected beyond the 3-week CR stay.

CONCLUSIONS

Patients with CHF account for a considerable proportion of patients in CR. Also patients with moderate/severe EF benefited from participation in CR, as their lipid profile and physical fitness improved.

Management of patients with ST-segment elevation or non-ST-segment elevation acute coronary syndromes in cardiac rehabilitation centers

BACKGROUND

Current data on the management of patients in cardiac rehabilitation (CR) after an acute hospital stay due to ST-segment elevation or non-ST segment elevation acute coronary syndromes (STE-ACS or NSTE-ACS) are limited. We aimed to describe patient characteristics, risk factor management, and lipid target achievement of patients in CR in Germany and compare the 2 groups.

HYPOTHESIS

With respect to the risk factor pattern and treatment effects during a CR stay, there are important differences between STE-ACS and NSTE-ACS patients.

METHODS

Comparison of 7950 patients by STE-ACS or NSTE-ACS status in the Transparency Registry to Objectify Guideline-Oriented Risk Factor Management registry (2010) who underwent an inpatient CR period of about 3 weeks.

RESULTS

STE-ACS patients compared to NSTE-ACS patients were significantly younger (60.5 vs 64.4 years, P < 0.0001), and had diabetes mellitus, hypertension, or any risk factor (exception: smoking) less often. At discharge, in STE-ACS compared to NSTE-ACS patients, the low-density lipoprotein cholesterol (LDL-C) <100 mg/dL goal was achieved by 75.3% and 76.2%, respectively (LDL-C <70 mg/dL by 27.7% and 27.4%), the high-density lipoprotein cholesterol goal of >50 mg/dL in women and >40 mg/dL in men was achieved by 49.3% and 49.0%, respectively, and the triglycerides goal of <150 mg/dl was achieved by 72.3% and 74.3%, respectively (all comparisons not significant). Mean systolic and diastolic blood pressure were 121/74 and 123/74 mm Hg, respectively (P < 0.0001 systolic, diastolic not significant). The maximum exercise capacity was 110 and 102 W, respectively (P < 0.0001), and the maximum walking distance was 581 and 451 meters, respectively (P value not significant).

CONCLUSIONS

Patients with STE-ACS and NSTE-ACS differed moderately in their baseline characteristics. Both groups benefited from the participation in CR, as their lipid profile, blood pressure, and physical fitness improved.

Pharmacogenomics of statin therapy: any new insights in efficacy or safety?

PURPOSE OF REVIEW

To examine the current evidence concerning the effects of genetic variation on statin-related low-density lipoprotein cholesterol reductions, clinical efficacy, and adverse events and the relevance for patient care.

RECENT FINDINGS

Recent years have seen the emergence of large-scale genetic experiments, including genome-wide association studies and candidate gene studies, exploring the impact of common genetic variation on patient response to statins. These studies have built on previous smaller scale evidence, providing improved statistical power and enhanced ability to explore the genome. Current evidence suggests that common genetic variants do not alter low-density lipoprotein cholesterol response by more than a few percent, or materially alter the effect of statin on vascular risk reduction, and therefore that patients benefit from statins independent of common genetic variation. However, knowledge of SLCO1B1 genotypes is believed to have clinical utility for predicting myopathy risk and ensuring that statins are prescribed as safely as possible. Furthermore, new hypothesis-generating studies, such as those associating GATM with myopathy risk, offer potential insights for the future.

SUMMARY

Common genetic variation does not appear to be an important determinant of statin response, with the exception of SLCO1B1 and risk of myopathy. Future studies will help to determine the impact of low-frequency and rare genetic variation on statin response.

Personalized sequencing and the future of medicine: discovery, diagnosis and defeat of disease

The potential for personalized sequencing to individually optimize medical treatment in diseases such as cancer and for pharmacogenomic application is just beginning to be realized, and the utility of sequencing healthy individuals for managing health is also being explored. The data produced requires additional advancements in interpretation of variants of unknown significance to maximize clinical benefit. Nevertheless, personalized sequencing, only recently applied to clinical medicine, has already been broadly applied to the discovery and study of disease. It is poised to enable the earlier and more accurate diagnosis of disease risk and occurrence, guide prevention and individualized intervention as well as facilitate monitoring of healthy and treated patients, and play a role in the prevention and recurrence of future disease. This article documents the advancing capacity of personalized sequencing, reviews its impact on disease-oriented scientific discovery and anticipates its role in the future of medicine.

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.

Association between statin-induced creatine kinase elevation and genetic polymorphisms in SLCO1B1, ABCB1 and ABCG2

PURPOSE

Treatment with statins requires close monitoring of serum creatine kinase (CK) levels to prevent myopathy, a common and potentially serious dose-dependent adverse effect of these drugs. We have investigated the correlation between elevated CK levels and polymorphisms in the genes encoding transporters involved in statin disposition.

METHODS

Patients with and without statin-induced elevated serum CK levels were genotyped for polymorphisms in SLCO1B1 (SLCO1B1 A388G and SLCO1B1 T521C), ABCB1 (ABCB1 C1236T and ABCB1 C3435T) and ABCG2 (ABCG2 C421A).

RESULTS

Patients carrying SLCO1B1 T521C or ABCB1 C1236T single nucleotide polymorphisms (SNPs) had an odds ratio (OR) for statin-induced elevated serum CK levels of 8.86 (p<0.01) and 4.67 (p<0.05), respectively, while patients carrying the SLCO1B1 A388G SNP had an OR of 0.24 (p<0.05). An arbitrary score based on genotype combination discriminated patients with and without CK elevation at a specificity of 97 % and a sensitivity of 39 %.

CONCLUSION

Genotyping of the SLCO1B1, ABCB1 and ABCG2 genes deserves consideration as a clinical approach to improve statin safety while concomitantly reducing the burden of blood tests for CK measurements.

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.

Characterization of statin dose response in electronic medical records

Efforts to define the genetic architecture underlying variable statin response have met with limited success, possibly because previous studies were limited to effect based on a single dose. We leveraged electronic medical records (EMRs) to extract potency (ED50) and efficacy (Emax) of statin dose-response curves and tested them for association with 144 preselected variants. Two large biobanks were used to construct dose-response curves for 2,026 and 2,252 subjects on simvastatin and atorvastatin, respectively. Atorvastatin was more efficacious, was more potent, and demonstrated less interindividual variability than simvastatin. A pharmacodynamic variant emerging from randomized trials (PRDM16) was associated with Emax for both. For atorvastatin, Emax was 51.7 mg/dl in subjects homozygous for the minor allele vs. 75.0 mg/dl for those homozygous for the major allele. We also identified several loci associated with ED50. The extraction of rigorously defined traits from EMRs for pharmacogenetic studies represents a promising approach to further understand the genetic factors contributing to drug response.

Statin myotoxicity: a review of genetic susceptibility factors

The 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitors (statins) are among the most common medications prescribed worldwide, but their efficacy and toxicity vary between individuals. One of the major factors contributing to intolerance and non-compliance are the muscle side-effects, which range from mild myalgia through to severe life-threatening rhabdomyolysis. One way to address this is pharmacogenomic screening, which aims to individualize therapy to maximize efficacy whilst avoiding toxicity. Genes encoding proteins involved in the metabolism of statins as well as genes known to cause inherited muscle disorders have been investigated. To-date only polymorphisms in the SLCO1B1 gene, which encodes the protein responsible for hepatic uptake of statins, and the COQ2 gene, important in the synthesis of coenzyme Q10, have been validated as being strongly associated with statin-induced myopathy. The aim of this review is to summarize studies investigating genetic factors predisposing to statin myopathy and myalgia, as the first step towards pharmacogenomic screening to identify at risk individuals.

Diagnosis, prevention, and management of statin adverse effects and intolerance: Canadian Working Group Consensus update

The Proceedings of a Canadian Working Group Consensus Conference, first published in 2011, provided a summary of statin-associated adverse effects and intolerance and management suggestions. In this update, new clinical studies identified since then that provide further insight into effects on muscle, cognition, cataracts, diabetes, kidney disease, and cancer are discussed. Of these, the arenas of greatest controversy pertain to purported effects on cognition and the emergence of diabetes during long-term therapy. Regarding cognition, the available evidence is not strongly supportive of a major adverse effect of statins. In contrast, the linkage between statin therapy and incident diabetes is more firm. However, this risk is more strongly associated with traditional risk factors for new-onset diabetes than with statin itself and any possible negative effect of new-onset diabetes during statin treatment is far outweighed by the cardiovascular risk reduction benefits. Additional studies are also discussed, which support the principle that systematic statin rechallenge, and lower or intermittent statin dosing strategies are the main methods for dealing with suspected statin intolerance at this time.