Statin therapy induces ultrastructural damage in skeletal muscle in patients without myalgia

Rosuvastatin: Beyond the cholesterol-lowering effect

Rosuvastatin is a fully synthetic statin wich acts by interfering with the endogenous synthesis of cholesterol through competitively inhibiting the 3-hydroxy-3-methylglutaryl coenzyme A reductase, a liver enzyme responsible of the rate-limiting step in cholesterol synthesis. When compared to other molecules of the same class, it shows high efficacy in the improvement of lipid profile, and, thanks to its non-cholesterol-lowering actions (anti-inflammatory, antioxidant and antithrombotic), represents a crucial tool for cardiovascular primary and secondary prevention. Moreover, recent data highlight rosuvastatin beneficial effects in several other fields. In this manuscript we analyzed literature sources in order to better define rosuvastatin features and discuss some critical issues.

Statin Adverse Events in Primary Prevention: Between Randomized Trials and Observational Studies

Considerable debate exists regarding who might benefit from statins for primary prevention. Statins have wide pleotropic effects, which contribute to their efficacy in lowering cardiovascular disease but may also result in adverse events (AEs). Caveats in identifying AEs in randomized controlled trials (RCTs) include the lack of a standardized definition of statin-associated AEs, the differences in properties of different statins, the selectivity of RCTs in choosing their participants, the presence of high rate of nonadherence/withdrawal from trials and other concerns related to study design and conflict of interest. Caveats in identifying or overestimating AEs in observational studies include failure to identify baseline confounders, ascertainment bias, confounding by indication and healthy user bias. Statin use in observational studies may be a surrogate marker for higher socioeconomic standards, access to health care or use of other preventive services. Integrating evidence from both RCTs and observational studies is of paramount importance for appropriate patient-centered decision.

Skeletal muscle ultrastructure and function in statin-tolerant individuals

INTRODUCTION

Statins have well-known benefits on cardiovascular mortality, though up to 15% of patients experience side effects. With guidelines from the American Heart Association, American College of Cardiology, and American Diabetes Association expected to double the number of statin users, the overall incidence of myalgia and myopathy will increase.

METHODS

We evaluated skeletal muscle structure and contractile function at the molecular, cellular, and whole tissue levels in 12 statin tolerant and 12 control subjects.

RESULTS

Myosin isoform expression, fiber type distributions, single fiber maximal Ca(2+) -activated tension, and whole muscle contractile force were similar between groups. No differences were observed in myosin-actin cross-bridge kinetics in myosin heavy chain I or IIA fibers.

CONCLUSIONS

We found no evidence for statin-induced changes in muscle morphology at the molecular, cellular, or whole tissue levels. Collectively, our data show that chronic statin therapy in healthy asymptomatic individuals does not promote deleterious myofilament structural or functional adaptations.

Different effects of statins on induction of diabetes mellitus: an experimental study

Background

To determine the effect of different statins on the induction of diabetes mellitus.

Materials and methods

Four statins (atorvastatin, pravastatin, rosuvastatin, and pitavastatin) were used. Cytotoxicity, insulin secretion, glucose-stimulated insulin secretion, and G₀/G₁ phase cell cycle arrest were investigated in human pancreas islet β cells, and glucose uptake and signaling were studied in human skeletal muscle cells (HSkMCs).

Results

Human pancreas islet β cells treated with 100 nM atorvastatin, pravastatin, rosuvastatin, and pitavastatin had reduced cell viability (32.12%, 41.09%, 33.96%, and 29.19%, respectively) compared to controls. Such cytotoxic effect was significantly attenuated by decreasing the dose to 10 and 1 nM, ranged from 1.46% to 17.28%. Cells treated with 100 nM atorvastatin, pravastatin, rosuvastatin, and pitavastatin had a reduction in the rate of insulin secretion rate by 34.07%, 30.06%, 26.78%, and 19.22%, respectively. The inhibitory effect was slightly attenuated by decreasing the dose to 10 and 1 nM, ranging from 10.84% to 29.60%. Insulin secretion stimulated by a high concentration of glucose (28 mmol/L) was significantly higher than a physiologic concentration of glucose (5.6 mmol/L) in all treatment groups. The glucose uptake rates at a concentration of 100 nM were as follows: atorvastatin (58.76%) < pravastatin (60.21%) < rosuvastatin (72.54%) < pitavastatin (89.96%). We also found that atorvastatin and pravastatin decreased glucose transporter (GLUT)-2 expression and induced p-p38 MAPK levels in human pancreas islet β cells. Atorvastatin, pravastatin, and rosuvastatin inhibited GLUT-4, p-AKT, p-GSK-3β, and p-p38 MAPK levels in HSkMCs.

Conclusion

Statins similar but different degree of effects on pancreas islet β cells damage and induce insulin resistance in HSkMC.

Atorvastatin induced hepatic oxidative stress and apoptotic damage via MAPKs, mitochondria, calpain and caspase12 dependent pathways

Atorvastatin (ATO), a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor, is used widely for the treatment of hypercholesterolemia and hypertriglyceridemia. Application of this drug has now been made somehow limited because of ATO associated several acute and chronic side effects. The present study has been carried out to investigate the dose-dependent hepatic tissue toxicity in ATO induced oxidative impairment and cell death in mice. Administration of ATO enhanced ALT, ALP level, increased reactive oxygen species (ROS) production and altered the pro oxidant-antioxidant status of liver by reducing intracellular GSH level, anti-oxidant enzymes activities and increasing intracellular lipid peroxidation. Our experimental evidence suggests that ATO markedly decreased mitochondrial membrane potential, disturbed the Bcl-2 family protein balance, enhanced cytochrome c release in the cytosol, increased the levels of Apaf1, caspase-9, -3, cleaved PARP protein and ultimately led to apoptotic cell death. Besides, ATO distinctly increased the phosphorylation of p38, JNK, and ERK MAPKs, enhanced Caspase12 and calpain level. Histological studies also support the dose-dependent toxic effect of ATO in these organs pathophysiology. These results reveal that ATO induces hepatic tissue toxicity via MAPKs, mitochondria and ER dependent signaling pathway, in which calcium ions and ROS act as the pivotal mediators of the apoptotic signaling.

Pathogenesis and management of the diabetogenic effect of statins: a role for adiponectin and coenzyme Q10?

There is growing evidence to suggest that statin therapy is associated with an increased risk of incident diabetes. The risk for statin-related diabetes depends upon many factors including age, pre-existing diabetic risk, type and potency of statin. Several mechanisms have been suggested for the diabetogenic effects of statins involving processes that alter islet ß-cell function, resulting in impaired glucose metabolism. Recent evidence suggests that the association of statin therapy with the development of diabetes may be partly mediated by a statin-induced decrease in circulating adiponectin and coenzyme Q10. The available evidence suggests the benefit of statins in reducing cardiovascular events outweigh the risk of developing diabetes. Moreover, statin therapy does not impair glycemic control in diabetic patients. Expert recommendations for the use of statins in people at risk of developing diabetes have recently been published. However, further research is required to elucidate both the association between statin use and incident diabetes as well as underlying mechanisms.

Statin Intolerance Because of Myalgia, Myositis, Myopathy, or Myonecrosis Can in Most Cases be Safely Resolved by Vitamin D Supplementation

Background:

Low serum vitamin D can cause myalgia, myositis, myopathy, and myonecrosis. Statin-induced myalgia is a major and common cause of statin intolerance. Low serum vitamin D and statins, additively or synergistically, cause myalgia, myositis, myopathy, and/or myonecrosis. Statin-induced myalgia in vitamin D deficient patients can often be resolved by vitamin D supplementation, normalizing serum vitamin D levels.

Aims:

In 74 men and 72 women (age 59 ± 14 years) intolerant to ≥2 statins because of myalgia, myositis, myopathy, or myonecrosis and found to have low (<32 ng/mL) serum vitamin D, we prospectively assessed whether vitamin D supplementation (vitamin D2: 50,000-100,000 units/week) to normalize serum vitamin D would allow successful rechallenge therapy with statins.

Materials and Methods:

Follow-up evaluation on vitamin D supplementation was done on 134 patients at 6 months (median 5.3), 103 patients at 12 months (median 12.2), and 82 patients at 24 months (median 24).

Results:

Median entry serum vitamin D (22 ng/mL, 23 ng/mL, and 23 ng/mL) rose at 6 months, 12 months, and 24 months follow-up to 53 ng/mL, 53 ng/mL, and 55 ng/mL, respectively, (P < .0001 for all) on vitamin D therapy (50,000-100,000 units/week). On vitamin D supplementation, serum vitamin D normalized at 6 months, 12 months, and 24 months follow-up in 90%, 86%, and 91% of the patients, respectively. On rechallenge with statins while on vitamin D supplementation, median low-density lipoprotein cholesterol (LDLC) fell from the study entry (167 mg/dL, 164 mg/dL, and 158 mg/dL) to 90 mg/dL, 91 mg/dL, and 84 mg/dL, respectively, (P < .0001 for all). On follow-up at median 6 months, 12 months, and 24 months on statins and vitamin D, 88%, 91%, and 95% of the previously statin-intolerant patients, respectively, were free of myalgia, myositis, myopathy, and/or myonecrosis.

Conclusions:

Statin intolerance because of myalgia, myositis, myopathy, or myonecrosis associated with low serum vitamin D can be safely resolved by vitamin D supplementation (50,000-100,000 units /week) in most cases (88-95%).

Risk of diabetes in patients treated with HMG-CoA reductase inhibitors

OBJECTIVE

3-Hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) are used to control blood cholesterol levels and reduce cardiovascular disease. It has been repeatedly reported that statins may cause new-onset diabetes mellitus (DM). However, limited evidence exists from direct head to head comparisons of statins on whether the risk of DM differs among statins. We investigated the risk of development of new-onset diabetes in subjects treated with different statins.

METHODS

We retrospectively enrolled consecutive 3680 patients without DM or impaired fasting glucose who started receiving statin treatment for cholesterol control. We evaluated the incidence of new-onset diabetes according to the type of statin.

RESULTS

The mean duration of follow-up was 62.6±15.3 months. The incidence of DM was significantly higher in the pitavastatin group (49 of 628; 7.8%) compared to that in the other statin groups [atorvastatin (68 of 1327; 5.1%), rosuvastatin (77 of 1191; 6.5%), simvastatin (11 of 326; 3.4%), and pravastatin (12 of 298; 5.8%); p=0.041]. The risk of diabetes was the highest in the pitavastatin group compared with that in the simvastatin group [hazard ratio (HR)=2.68, p=0.011]. Other statins showed no significant risk differences compared to that for simvastatin. Fasting blood glucose (FBG) level at baseline and body-mass index (BMI) were associated with the development of diabetes [FBG, HR=1.11, p<0.001; BMI, HR=1.02, p=0.005].

CONCLUSIONS

Among the five statins, pitavastatin showed the strongest effect on the development of new-onset diabetes.

Risk identification and possible countermeasures for muscle adverse effects during statin therapy

The use of statins for cardiovascular disease prevention is clearly supported by clinical evidence. However, in January 2014 the U.S. Food and Drug Administration released an advice on statin risk reporting that "statin benefit is indisputable, but they need to be taken with care and knowledge of their side effects". Among them the by far most common complication is myopathy, ranging from common but clinically benign myalgia to rare but life-threatening rhabdomyolysis. This class side effect appears to be dose dependent, with more lipophilic statin (i.e., simvastatin) carrying a higher overall risk. Hence, to minimize statin-associated myopathy, clinicians should take into consideration a series of factors that potentially increase this risk (i.e., drug-drug interactions, female gender, advanced age, diabetes mellitus, hypothyroidism and vitamin D deficiency). Whenever it is appropriate to stop statin treatment, the recommendations are to stay off statin until resolution of symptoms or normalization of creatine kinase values. Afterwards, clinicians have several options to treat dyslipidemia, including the use of a lower dose of the same statin, intermittent non-daily dosing of statin, initiation of a different statin, alone or in combination with nonstatin lipid-lowering agents, and substitution with red yeast rice.

Increased dosage of cyclosporine induces myopathy with increased seru creatine kinase in an elderly patient on chronic statin therapy

WHAT IS KNOWN AND OBJECTIVE

The concomitant administration of atorvastatin and cyclosporine has been shown to increase the serum concentration of 3-hydroxy-3-methylglutaryl coenzyme A, which may be associated with the elevation of creatine kinase and an increased risk of myopathy. Our objective is to report on a case of statin-induced myopathy associated with concomitant use of cyclosporine and other contributing factors.

CASE SUMMARY

An 88-year-old Chinese male patient with comorbidities received polypharmacy treatment, including atorvastatin and cyclosporine. After the dosage of cyclosporine was increased to 300 mg every day for 8 months, the patient developed body pain and leg weakness, with a serum creatine kinase increase and evidence on magnetic resonance imaging of muscle oedema.

WHAT IS NEW AND CONCLUSION

Cyclosporine is a moderate inhibitor of the cytochrome P450 CYP3A4 isoenzyme, which is known to increase the serum level of atorvastatin. We hypothesized that the pharmacological and pharmacokinetic properties of atorvastatin-induced myopathy are the result of its interaction with high dosage of cyclosporine.

Mechanisms and assessment of statin-related muscular adverse effects

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

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.

Statins and succinylcholine interaction: A cause of concern for serious muscular damage in anesthesiology practice!

Statins are being extensively used in cardiac patient throughout the globe. Succinylcholine has been the mainstay of profound relaxation during induction and intubation of anesthesia for almost six decades now. The interactive properties of these drugs have been of major concern during routine anesthesiology practice in the last few years. However, no major research trial, prospective studies or meta-analysis are available, which can truly allay the fears of possible potential negative synergistic interactions between these two commonly used drugs. Whatever the evidence is available is hardly enough to support a positive outcome and the results have been drawn from observations of only few small studies. As a result, a continuous need among anesthesiologist fraternity is felt to arrive at a suitable inference, which can predict definite consequences of this synergistic interaction. The present article reviews some of the important observations of few handful studies which were carried out to observe any potential adverse interactions between succinylcholine and statins.

Statins and skeletal muscles toxicity: from clinical trials to everyday practice

The mechanism(s) underlying the occurrence of statin-induced myopathy are ill defined, but the results of observational studies and clinical trials provide compelling evidence that skeletal muscle toxicity is a frequent, dose-dependent, adverse event associated with all statins. It has been suggested that reduced availability of metabolites produced by the mevalonate pathway rather than intracellular cholesterol lowering per se might be the primary trigger of toxicity, however other alternative explanations have gained credibility in recent years. Aim of this review is: (i) to describe the molecular mechanisms associated to statin induced myopathy including defects in isoprenoids synthesis followed by altered prenylation of small GTPase, such as Ras and Rab proteins; (ii) to present the emerging aspects on pharmacogenetics, including CYP3A4, OATP1B1 and glycine amidinotransferase (GATM) polymorphisms impacting either statin bioavailability or creatine synthesis; (iii) to summarize the available epidemiological evidences; and (iii) to discuss the concepts that would be of interest to the clinicians for the daily management of patients with statin induced myopathy. The interplay between drug-environment and drug-drug interaction in the context of different genetic settings contribute to statins and skeletal muscles toxicity. Until specific assays/algorithms able to combine genetic scores with drug-drug-environment interaction to identify patients at risk of myopathies will become available, clinicians should continue to monitor carefully patients on polytherapy which include statins and be ready to reconsider dose, statin or switching to alternative treatments. The beneficial effects of adding agents to provide the muscle with the metabolites, such as CoQ10, affected by statin treatment will also be addressed.

Statin therapy is associated with the development of new-onset diabetes after transplantation in liver recipients with high fasting plasma glucose levels

New-onset diabetes after transplantation (NODAT) and dyslipidemia are important metabolic complications after liver transplantation (LT) that can adversely affect both allograft and patient survival. Statins are used as first-line therapies for dyslipidemia because of their effectiveness and safety profile. However, it has recently been reported that statin therapy is associated with new-onset diabetes in the nontransplant population. The aim of this study was to investigate the association between statin therapy and the development of NODAT in LT recipients. Three hundred sixty-four LT recipients who underwent transplantation between the ages of 20 and 75 years without a previous history of diabetes were enrolled in this study. We evaluated the incidence of NODAT with respect to statin use as well as other risk factors. The incidence of NODAT was significantly higher in the statin group (31.7%) versus the control group (17.6%, P = 0.03). The mean follow-up period was 37.8 ± 19.0 months for the statin group and 42.7 ± 16.0 months for the control group (P = 0.07). Statin use was significantly associated with NODAT development after adjustments for other risk factors [hazard ratio (HR) = 2.32, 95% confidence interval (CI) = 1.23-4.39, P = 0.01]. Impaired fasting glucose before transplantation was also a risk factor for NODAT development (HR = 2.21, 95% CI = 1.36-3.62, P = 0.001). There were no significant differences in age, body mass index, cumulative corticosteroid dose, or fasting plasma glucose (FPG) levels between the groups. Patients with high FPG levels were more likely to develop NODAT when they were placed on statins after LT (P = 0.002). In conclusion, statin treatment could contribute to the development of NODAT in LT recipients, especially if they have high baseline FPG levels.

Red yeast rice and coenzyme Q10 as safe alternatives to surmount atorvastatin-induced myopathy in hyperlipidemic rats

Statins are the first line treatment for the management of hyperlipidemia. However, the primary adverse effect limiting their use is myopathy. This study examines the efficacy and safety of red yeast rice (RYR), a source of natural statins, as compared with atorvastatin, which is the most widely used synthetic statin. Statin interference with the endogenous synthesis of coenzyme Q10 (CoQ10) prompted the hypothesis that its deficiency may be implicated in the pathogenesis of statin-associated myopathy. Hence, the effects of combination of CoQ10 with either statin have been evaluated. Rats were rendered hyperlipidemic through feeding them a high-fat diet for 90 days, during the last 30 days of the diet they were treated daily with either atorvastatin, RYR, CoQ10, or combined regimens. Lipid profile, liver function tests, and creatine kinase were monitored after 15 and 30 days of drug treatments. Heart contents of CoQ9 and CoQ10 were assessed and histopathological examination of the liver and aortic wall was performed. RYR and CoQ10 had the advantage over atorvastatin in that they lower cholesterol without elevating creatine kinase, a hallmark of myopathy. RYR maintained normal levels of heart ubiquinones, which are essential components for energy production in muscles. In conclusion, RYR and CoQ10 may offer alternatives to overcome atorvastatin-associated myopathy.

Hypovitaminosis D presenting as diffuse myalgia in a 22-year-old woman: a case report

BACKGROUND

Caused predominantly by insufficient conversion of vitamin D precursors by sunlight, hypovitaminosis D is an issue of increasing importance worldwide. Although it has been associated with a range of diseases, musculoskeletal effects dominate the clinical picture and can lead to significant physical debility, whether acute or chronic. Although diagnosis of vitamin D deficiency typically occurs in the outpatient setting, it is an easily treatable condition, and timely intervention can dramatically improve one's quality of life. As highlighted by this case report, hypovitaminosis D may be an important but underappreciated etiology of undifferentiated myalgia that, when present, warrants initiation of vitamin D repletion therapy even from the emergency department (ED).

CASE REPORT

A 22-year-old African-American female presented to our ED with diffuse myalgia for 4 months. She reported significant debility from these symptoms with difficulty ambulating and performing activities of daily living. There had been no upper respiratory infection symptoms. The patient had discussed all of this with her primary care physician who, despite an extensive laboratory work-up, had not identified a definitive etiology. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Chronic pain has stricken the ED patient population across the board. Studies demonstrate that the myalgia caused by hypovitaminosis D can have a profound and negative impact on an individual's lifestyle. Our patient was found to have hypovitaminosis D and had substantial improvement with her myalgia and quality of life after treatment. The purpose of this report is to help the emergency physician appreciate this disease and consider it when clinically appropriate.

The pharmacology of statins

Statins, inhibitors of the hydroxymethylglutaryl-CoA (HMG-CoA) reductase enzyme, are molecules of fungal origin. By inhibiting a key step in the sterol biosynthetic pathway statins are powerful cholesterol lowering medications and have provided outstanding contributions to the prevention of cardiovascular disease. Their detection in mycetes traces back to close to 40 years ago: there were, originally, widely opposing views on their therapeutic potential. From then on, intensive pharmaceutical development has led to the final availability in the clinic of seven statin molecules, characterized by differences in bioavailability, lipo/hydrophilicity, cytochrome P-450 mediated metabolism and cellular transport mechanisms. These differences are reflected in their relative power (mg LDL-cholesterol reduction per mg dose) and possibly in parenchymal or muscular toxicities. The impact of the antagonism of statins on a crucial step of intermediary metabolism leads, in fact, both to a reduction of cholesterol biosynthesis as well as to additional pharmacodynamic (so called "pleiotropic") effects. In the face of an extraordinary clinical success, the emergence of some side effects, e.g. raised incidence of diabetes and cataracts as well as frequent muscular side effects, have led to increasing concern by physicians. However, also in view of the present relatively low cost of these drugs, their impact on daily therapy of vascular patients is unlikely to change.

Diabetogenic effect of statins: a double-edged sword?

Statins are widely prescribed cholesterol-lowering agents, which have been demonstrated to significantly reduce cardiovascular morbidity and mortality. However, recent trials have reported that statins cause worsening of hyperglycemia and increase the risk of new-onset diabetes. The association between the diabetogenic effect of statins with intensive dose and accompanying major risk factors for diabetes has been demonstrated. However, statins do not appear to have a class effect on insulin sensitivity in non-diabetic patients. Numerous mechanisms have been suggested to explain how statins cause β-cell insulin secretory dysfunction and peripheral insulin resistance leading to incident diabetes. According to findings from an aggregate of large clinical trials, the benefits of statin treatment appear to outweigh the risk of new-onset diabetes. Therefore, it would be inappropriate to discontinue the use of statins for prevention of cardiovascular events because of its potential risk for development of incident diabetes. This review addresses the currently available evidence related to statin use and new-onset diabetes from a clinical perspective.

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.

Do statins cause diabetes?

A wealth of evidence has established that cholesterol-lowering statin drugs, widely used for the prevention of cardiovascular disease, do increase the risk of new-onset diabetes, possibly by impairing pancreatic beta cell function and decreasing peripheral insulin sensitivity. Groups at particular risk include the elderly, women, and Asians. The diabetogenic effect of statins appear directly related to statin dose and the degree of attained cholesterol lowering. Statins can cause hyperinsulinemia even in the absence of hyperglycemia and the potential mitogenic effects and implications of prolonged hyperinsulinemia are discussed. Suggestions are made as to how physicians might avert the hyperinsulinemic and diabetogenic effects of statin therapy in clinical practice, and modulate the detrimental effects of these drugs on exercise performance. Finally, long-term studies are needed to determine if the deleterious hyperinsulinemic and diabetogenic effects of statin therapy undermine the beneficial cardiovascular disease risk outcomes in various segments of the population.

The controversy of a wider statin utilization: why?

INTRODUCTION

Several medical journals published viewpoints and counter-viewpoints supporting or opposing a wider utilization of statins for primary prevention. The objective of this article is not to weigh in the benefits versus risks of statin use, but to discuss various aspects of this controversy.

AREAS COVERED

This review discusses the challenges in examining the pleotropic effects/adverse events of statins. It also discusses the pitfalls in assessment of adverse events in randomized controlled trials and observational studies.

EXPERT OPINION

The challenges in solving this controversy include that the pleotropic effect of statins results in an extremely wide spectrum of reported benefits or adverse events, the reported harms/benefits are contradictory, there is basic research ground supporting both sides of the controversy, it is difficult to separate if adverse events are due to statins or due to lower cholesterol, and that there is a lack of standardized definition of statin-associated adverse events and their methods of ascertainment. Both randomized controlled trials and observational studies have pitfalls and caveats in assessment of adverse events. Understanding the points of debate is of paramount significance to enable clinicians to individualize patient care.

Annexin A1 is a biomarker of T-tubular repair in skeletal muscle of nonmyopathic patients undergoing statin therapy

Skeletal muscle complaints are a common consequence of cholesterol-lowering therapy. Transverse tubular (T-tubular) vacuolations occur in patients having statin-associated myopathy and, to a lesser extent, in statin-treated patients without myopathy. We have investigated quantitative changes in T-tubular morphology and looked for early indicators of T-tubular membrane repair in skeletal muscle biopsy samples from patients receiving cholesterol-lowering therapy who do not have myopathic side effects. Gene expression and protein levels of incipient membrane repair proteins were monitored in patients who tolerated statin treatment without myopathy and in statin-naive subjects. In addition, morphometry of the T-tubular system was performed. Only the gene expression for annexin A1 was up-regulated, whereas the expression of other repair genes remained unchanged. However, annexin A1 and dysferlin protein levels were significantly increased. In statin-treated patients, the volume fraction of the T-tubular system was significantly increased, but the volume fraction of the sarcoplasmic reticulum remained unchanged. A complex surface structure in combination with high mechanical loads makes skeletal muscle plasma membranes susceptible to injury. Ca(2+)-dependent membrane repair proteins such as dysferlin and annexin A1 are deployed at T-tubular sites. The up-regulation of annexin A1 gene expression and protein points to this protein as a biomarker for T-tubular repair.

Statin therapy depresses fat metabolism in older individuals

OBJECTIVE

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG CoA] reductase inhibitors) reduce blood lipoproteins and reduce the risk of cardiovascular events. However, they may reduce fat metabolism. This study tested the hypothesis that total body fat oxidation is reduced by statins in older subjects and the reduction is not due to substrate availability.

METHODS

A total of 14 elderly patients (71 ± 6 years) on statin therapy were compared with 14 matched elderly controls (75 ± 7 years). Subjects were tested for respiratory exchange ratio (RER) during both maximal and submaximal sustained (70% Vo(2max)) exercise to voluntary exhaustion. Blood samples were drawn for lipoprotein analysis and substrate availability.

RESULTS

RER was significantly higher in subjects taking statins during both the max and submax tests, indicating reduced fat oxidation. Blood lipoprotein levels after a fast were not different between the statin and control groups. Levels of glucose, lactate, or triglyceride were not different between groups; however, free fatty acid levels were elevated by exercise in the statin group. Fat oxidation was significantly reduced in older subjects taking statin drugs that were not associated with diet, exercise, and fitness, which were matched between groups, nor availability of fat from the blood, which was higher in the statin group.

CONCLUSION

Although statin therapy normalizes blood lipoproteins, it reduced fat metabolism in older individuals, which cannot be a result of lower availability from blood.

Clinical response to statins: mechanism(s) of variable activity and adverse effects

Statins represent a major advance in the treatment of hypercholesterolemia, a significant risk factor for atherosclerosis. There is, however, notable interindividual variation in the cholesterolemic response to statins, and the origin of this variability is poorly understood; pharmacogenetics has attempted to determine the role of genetic factors. Myopathy, further, has been reported in a considerable percentage of patients, but the mechanisms underlying muscle injury have yet to be fully characterized. Most statins are the substrates of several cytochrome P450s (CYP). CYP polymorphisms may be responsible for variations in hypolipidemic activity; inhibitors of CYPs, e.g. of CYP3A4, can significantly raise plasma concentrations of several statins, but consequences in terms of clinical efficacy are not uniform. Pravastatin and rosuvastatin are not susceptible to CYP inhibition but are substrates of the organic anion-transporting polypeptide (OATP) 1B1, encoded by the SLCO1B1 gene. Essentially all statins are, in fact, substrates of membrane transporters: SLCO1B1 polymorphisms can decrease the liver uptake, as well as the therapeutic potential of these agents, and may be linked to their muscular side-effects. A better understanding of the mechanisms of statin handling will help to minimize adverse effects and interactions, as well as to improve their lipid-lowering efficiency.

Statin induced myotoxicity

Statins are an effective treatment for the prevention of cardiovascular diseases and used extensively worldwide. However, myotoxicity induced by statins is a common adverse event and a major barrier to maximising cardiovascular risk reduction. The clinical spectrum of statin induced myotoxicity includes asymptomatic rise in creatine kinase concentration, myalgia, myositis and rhabdomyolysis. In certain cases, the cessation of statin therapy does not result in the resolution of muscular symptoms or the normalization of creatine kinase, raising the possibility of necrotizing autoimmune myopathy. There is increasing understanding and recognition of the pathophysiology and risk factors of statin induced myotoxicity. Careful history and physical examination in conjunction with selected investigations such as creatine kinase measurement, electromyography and muscle biopsy in appropriate clinical scenario help diagnose the condition. The management of statin induced myotoxicity involves statin cessation, the use of alternative lipid lowering agents or treatment regimes, and in the case of necrotizing autoimmune myopathy, immunosuppression.

Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro.

Fluvastatin-induced alterations of skeletal muscle function in hypercholesterolaemic rats

Although statins, the most widely used drugs in the treatment of hyperlipidaemia, are generally accepted as efficient and safe drugs their side-effects on skeletal muscle have been reported with increasing frequency. The lack of an animal model in which these side effects would consistently be observed is one of the important drawbacks in studying statin associated myopathy. To overcome this and enable the studying of the effects of fluvastatin on skeletal muscles an animal model with high blood cholesterol levels was developed. In these animals cholesterol levels rose more than seven fold (from 1.5 ± 0.1 to 10.7 ± 2.0 mmol/l; n = 15 and 16) with a dramatic increase in low density lipoprotein/high density lipoprotein ratio (from 0.29 ± 0.02 to 1.56 ± 0.17). While the latter was reversed by statin treatment, an elevation in blood creatine kinase (CK) level indicated the presence of muscle wasting. Fibers from m. extensor digitorum longus (EDL) showed significant reduction in cross sectional area in the statin treated groups. Statin treatment also decreased the proliferation and fusion of skeletal myotubes in culture. In line with this, resting intracellular calcium concentration ([Ca(2+)](i)) was reduced in statin treated satellite cells and myotubes. On the other hand, in adult skeletal muscle fibers statin treatment increased resting [Ca(2+)](i) (116 ± 4 nM vs. 151 ± 5 nM; n = 33 and 34) and decreased both twitch and tetanic force both in EDL and m. soleus. In addition, in m. soleus the duration of twitch and tetanic force was shortened. These results clearly indicate that statin administration in these animals results in a myopathy characterized by decreased muscle force and elevated plasma CK level.

Association of common variants in the human eyes shut ortholog (EYS) with statin-induced myopathy: evidence for additional functions of EYS

INTRODUCTION

Of the nearly 38 million people in the USA who receive statin therapy, 0.1-0.5% experience severe or life-threatening myopathic side effects.

METHODS

We performed a genome-wide association study (GWAS) in a group of patients with severe statin myopathy versus a statin-tolerant group to identify genetic susceptibility loci.

RESULTS

Replication studies in independent groups of severe statin myopathy (n = 190) and statin-tolerant controls (n = 130) resulted in the identification of three single-nucleotide polymorphisms (SNPs), rs9342288, rs1337512, and rs3857532, in the eyes shut homolog (EYS) on chromosome 6 suggestive of an association with risk for severe statin myopathy (P = 0.0003-0.0008). Analysis of EYS cDNA demonstrated that EYS gene products are complex and expressed with relative abundance in the spinal cord as well as in the retina.

CONCLUSION

Structural similarities of these EYS gene products to members of the Notch signaling pathway and to agrin suggest a possible functional role in the maintenance and regeneration of the structural integrity of skeletal muscle.

Imaging of zebrafish in vivo with second-harmonic generation reveals shortened sarcomeres associated with myopathy induced by statin

We employed second-harmonic generation (SHG) imaging and the zebrafish model to investigate the myopathy caused by statin in vivo with emphasis on the altered microstructures of the muscle sarcomere, the fundamental contractile element of muscles. This approach derives an advantage of SHG imaging to observe the striated skeletal muscle of living zebrafish based on signals produced mainly from the thick myosin filament of sarcomeres without employing exogenous labels, and eliminates concern about the distortion of muscle structures caused by sample preparation in conventional histological examination. The treatment with statin caused a significantly shortened sarcomere relative to an untreated control (1.73±0.09 µm vs 1.91±0.08 µm, P<0.05) while the morphological integrity of the muscle fibers remained largely intact. Mechanistic tests indicated that this microstructural disorder was associated with the biosynthetic pathway of cholesterol, or, specifically, with the impaired production of mevalonate by statins. This microstructural disorder exhibited a strong dependence on both the dosage and the duration of treatment, indicating a possibility to assess the severity of muscle injury according to the altered length of the sarcomeres. In contrast to a conventional assessment of muscle injury using clinical biomarkers in blood, such as creatine kinase that is released from only disrupted myocytes, the ability to determine microstructural modification of sarcomeres allows diagnosis of muscle injury before an onset of conventional clinical symptoms. In light of the increasing prevalence of the incidence of muscle injuries caused by new therapies, our work consolidates the combined use of the zebrafish and SHG imaging as an effective and sensitive means to evaluate the safety profile of new therapeutic targets in vivo.

Vitamin D deficiency, myositis-myalgia, and reversible statin intolerance

OBJECTIVE

In 150 hypercholesterolemic patients, unable to tolerate ≥1 statin because of myositis-myalgia, selected by low (<32 ng/ml) serum 25 (OH) vitamin D, we prospectively assessed whether vitamin D supplementation with resolution of vitamin D deficiency would result in statin tolerance, free of myositis-myalgia.

RESEARCH DESIGN AND METHODS

We studied 74 men, 76 women, median age 60, 131 white, 17 black and 2 other. On no statins, 50,000 units of vitamin D was given twice a week for 3 weeks, and then continued once a week. After 3 weeks on vitamin D, statins were restarted. Patients were re-assessed on statins and vitamin D every 3 to 4 months, with serial measures of serum 25 (OH) vitamin D, creatine phosphokinase (CPK), LDL cholesterol (LDLC) and assessment of myositis-myalgia.

MAIN OUTCOME MEASURES

Percentage of patients myalgia-free on vitamin D plus reinstituted statins, serum 25 (OH) vitamin D, CPK, and LDLC on reinstituted statins and concurrent vitamin D supplementation.

RESULTS

On vitamin D supplementation plus re-instituted statins for a median of 8.1 months, 131 of the 150 patients (87%) were free of myositis-myalgia and tolerated the statins well. Serum 25 (OH) vitamin D increased from median 21 to 40 ng/ml (p < 0.001), and normalized (≥32 ng/ml) in 117 (78%) of 150 previously vitamin D deficient, statin-intolerant patients. Median LDLC decreased from 146 mg/dl to 95 mg/dl, p < 0.001.

CONCLUSION

Symptomatic myositis-myalgia in hypercholesterolemic statin-treated patients with concurrent serum 25 (OH) vitamin D deficiency may reflect a reversible interaction between vitamin D deficiency and statins on skeletal muscle causing myalgia.

Effects of myosin heavy chain (MHC) plasticity induced by HMGCoA-reductase inhibition on skeletal muscle functions

The rate-limiting step of cholesterol biosynthetic pathway is catalyzed by 3-hydroxy-3-methylglutaryl coenzyme reductase (HGMR), whose inhibitors, the statins, widely used in clinical practice to treat hypercholesterolemia, often cause myopathy, and rarely rhabdomyolysis. All studies to date are limited to the definition of statin-induced myotoxicity omitting to investigate whether and how HMGR inhibition influences muscle functions. To this end, 3-mo-old male rats (Rattus norvegicus) were treated for 3 wk with a daily intraperitoneal injection of simvastatin (1.5 mg/kg/d), and biochemical, morphological, mechanical, and functional analysis were performed on extensor digitorum longus (EDL) muscle. Our results show that EDL muscles from simvastatin-treated rats exhibited reduced HMGR activity; a 15% shift from the fastest myosin heavy-chain (MHC) isoform IIb to the slower IIa/x; and reduced power output and unloaded shortening velocity, by 41 and 23%, respectively, without any change in isometric force and endurance. Moreover, simvastatin-treated rats showed a decrease of maximum speed reached and the latency to fall off the rotaroad (∼-30%). These results indicate that the molecular mechanism of the impaired muscle function following statin treatment could be related to the plasticity of fast MHC isoform expression.

Mechanisms of statin-induced myalgia assessed by physiogenomic associations

OBJECTIVE

We investigated genetic variants predictive of muscular side effects in patients treated with statins. We utilized a physiogenomic approach to prototype a multi-gene panel correlated with statin-induced myalgia.

BACKGROUND

Statin-induced myalgia occurs in ∼10% of lipid clinic outpatients. Its clinical manifestation may depend in part upon gene variation from patient to patient.

METHODS

We genotyped 793 patients (377 with myalgia and 416 without) undergoing statin therapy at four U.S. outpatient clinic sites to evaluate 31 candidate genes from the literature for their association with statin-induced common myalgia.

RESULTS

Three previously hypothesized candidate genes were validated: COQ2 (rs4693570) encoding para-hydroxybenzoate-polyprenyltransferase, which participates in the biosynthesis of coenzyme Q10 (p<0.000041); ATP2B1 (rs17381194) which encodes a calcium transporting ATPase involved in calcium homeostasis (p<0.00079); and DMPK (rs672348) which encodes a protein kinase implicated in myotonic dystrophy (p<0.0016).

CONCLUSIONS

The candidate genes COQ2, ATP2B1, and DMPK, representing pathways involved in myocellular energy transfer, calcium homeostasis, and myotonic dystonia, respectively, were validated as markers for the common myalgia observed in patients receiving statin therapy. The three genes integrated into a physiogenomic predictive system could be relevant to myalgia diagnosis and prognosis in clinical practice.

Evaluation of skeletal muscle during calf exercise by 31-phosphorus magnetic resonance spectroscopy in patients on statin medications

Muscle pain is a common side effect of statin medications, but the cause is poorly understood. We characterized phosphocreatine (PCr) exercise recovery kinetics in 10 patients with hypercholesterolemia before and after a 4-week regimen of statin therapy using 31-phosphorus magnetic resonance spectroscopy ((31) P-MRS). (31) P spectra were obtained before, during, and after exercise on a calf flexion pedal ergometer. Creatine kinase (CK) serum levels were drawn before and after statin therapy. The mean metabolic recovery time constant in subjects increased from 28.1 s (SE = 6.5 s) to 55.4 s (SE = 7.4 s) after statin therapy. The unweighted mean of the pre/post-recovery time difference was -27.3 s (SE = 12.4 s; P = 0.02). Pre- and post-therapy CK levels were not significantly different (P = 0.50). Metabolic recovery time in the calf is prolonged in patients after statin use. This suggests that statins impair mitochondrial oxidative function, and (31) P MRS is a potential study model for statin-associated myopathy.

The relationship of vitamin D deficiency to statin myopathy

OBJECTIVE

Our goal was to examine the interaction between vitamin D and statins and the possible role of vitamin D deficiency in statin myopathy.

BACKGROUND

The vitamin D receptor is present in skeletal muscle and vitamin D deficiency can cause myopathy. Statins (3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitors) are generally well tolerated, but have been associated with a spectrum of skeletal muscle complaints, ranging from myalgia and asymptomatic mild elevations of creatine kinase (CK) to rhabdomyolysis. There has been recent interest in the possible interaction between statin myopathy and vitamin D deficiency. We performed a systematic medical literature review to examine this possible relationship.

METHODS

We identified English language articles relating statins, vitamin D and statin myopathy via a PubMed search through July 2010. Articles pertinent to the topic were reviewed in detail.

RESULTS/CONCLUSIONS

Our review suggests that some but not all statins increase 25(OH) D levels. Two cross sectional studies have associated vitamin D deficiency with statin-associated myalgias, and suggested that that increasing vitamin D levels can reverse the myalgia. Nevertheless, given the quality and paucity of studies examining this possibility, additional studies are needed to examine the potential role of vitamin D deficiency in statin myopathy. It is presently premature to recommend vitamin D supplementation as treatment for statin associated muscle complaints in the absence of low vitamin D levels although such supplementation could be tried in patients with deficient or reduced vitamin D levels.

The effects of statins on skeletal muscle strength and exercise performance

PURPOSE OF REVIEW

HMG-CoA reductase inhibitors or statins are associated with a variety of muscle side-effects but little is known about the effect of statins on skeletal muscle strength and exercise performance. We performed a literature search to examine these issues.

RECENT FINDINGS

We identified six studies examining the effect of statins on muscle strength and nine studies examining their effect on exercise tolerance. In general, studies examining both issues were small and used crude measures of strength and exercise performance.

SUMMARY

There is insufficient data to determine if statins affect muscle strength and exercise performance. There is suggestive evidence that these drugs may reduce muscle strength in older patients and alter energy metabolism during aerobic exercise, both possibilities require further study.

The use of statins potentiates the insulin-sensitizing effect of exercise training in obese males with and without Type 2 diabetes

Exercise training is advocated in insulin resistance and statins are used to treat hyperlipidaemia, two cardiometabolic risk factors often presenting concurrently. Statin intake may blunt mitochondrial function and the adaptive response to exercise training. Thus combining exercise training with statin administration may have adverse effects. We examined whether improvements in cardiometabolic risk factors, insulin sensitivity and mitochondrial function mediated by progressive exercise training are affected by statin use. A group of 14 obese elderly males on statins (ST) and 22 matched control subjects (C) were examined. Results on in vivo mitochondrial function [MRS (magnetic resonance spectroscopy)], mitochondrial density (Western blotting), insulin sensitivity (clamp) and metabolic flexibility (indirect calorimetry) were compared before and after a 12-week combined progressive exercise training programme (3 x per week; 45 min per session). Except for LDL (low-density lipoprotein) cholesterol, all pre-training values were comparable between statin users and control subjects. In vivo mitochondrial function and mitochondrial density improved by training in both groups. Interestingly, blood-lipid profile, insulin sensitivity (+72%), non-oxidative and oxidative glucose disposal (+38% and +112%) and insulin-mediated suppression of fat oxidation (-62%) improved only in the ST group. We conclude that statin treatment did not impede exercise performance or tolerance, mitochondrial function or mass. In addition, training-induced improvements in glucose homoeostasis were preserved in the ST group. Strikingly, the insulin-sensitizing effect of training was more prominent in the ST group than in the C group. The combined prescription of statins along with exercise training is safe and should be considered for subjects prone to develop insulin resistance.

Statin therapy and the expression of genes that regulate calcium homeostasis and membrane repair in skeletal muscle

In skeletal muscle of patients with clinically diagnosed statin-associated myopathy, discrete signs of structural damage predominantly localize to the T-tubular region and are suggestive of a calcium leak. The impact of statins on skeletal muscle of non-myopathic patients is not known. We analyzed the expression of selected genes implicated in the molecular regulation of calcium and membrane repair, in lipid homeostasis, myocyte remodeling and mitochondrial function. Microscopic and gene expression analyses were performed using validated TaqMan custom arrays on skeletal muscle biopsies of 72 age-matched subjects who were receiving statin therapy (n = 38), who had discontinued therapy due to statin-associated myopathy (n = 14), and who had never undergone statin treatment (n = 20). In skeletal muscle, obtained from statin-treated, non-myopathic patients, statins caused extensive changes in the expression of genes of the calcium regulatory and the membrane repair machinery, whereas the expression of genes responsible for mitochondrial function or myocyte remodeling was unaffected. Discontinuation of treatment due to myopathic symptoms led to a normalization of gene expression levels, the genes encoding the ryanodine receptor 3, calpain 3, and dystrophin being the most notable exceptions. Hence, even in clinically asymptomatic (non-myopathic) patients, statin therapy leads to an upregulation in the expression of genes that are concerned with skeletal muscle regulation and membrane repair.

Statin therapy decreases myocardial function as evaluated via strain imaging

OBJECTIVES

The purpose of this study was to evaluate the effects of statin therapy on myocardial function as measured with echocardiography with tissue Doppler imaging (TDI) and strain imaging (SI) independent of its lipid-lowering effect.

BACKGROUND

Statin use is known to improve outcomes in the primary and secondary prevention of ischemic heart disease, but their use is also associated with myopathy, muscle weakness and in rare cases, rhabdomyolysis. We sought to evaluate whether TDI and SI is able to identify changes in myocardial function associated with statin use.

METHODS

Myocardial function was evaluated in 28 patients via echocardiography with TDI and SI. We identified 12 patients (5 females) without overt cardiovascular disease (including hypertension, smoking, and diabetes) that were on statin therapy and compared their echocardiographic findings with 16 (12 females) age, sex, and cholesterol-profile-matched controls. Tissue Doppler imaging parameters of diastolic (E(')/A(') and E/E(')) and systolic (S') function were measured. Regional systolic function was obtained by SI in 4-chamber, 2-chamber, long axis, and average global views.

RESULTS

There was no significant difference in myocardial function as measured by Doppler and minor differences as measured via TDI among the 2 groups. There was significantly better function noted with SI in the control group vs the statin group in the 4-chamber (-19.05% +/- 2.45% vs -16.47% +/- 2.37% P = 0.009), 2-chamber (-20.30% +/- 2.66% vs -17.45% +/- 4.29% P = 0.03), long axis (-17.63% +/- 3.79% vs -13.83% +/- 3.74% P = 0.01), and average global (-19.0% +/- 2.07% vs -15.91% +/- 2.81% P = 0.004) views.

CONCLUSION

Statin therapy is associated with decreased myocardial function as evaluated with SI.

The genetics of statin-induced myopathy

OBJECTIVE

Our goal was to use genetic variants to identify factors contributing to the muscular side effects of statins.

BACKGROUND

Statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) are usually well tolerated medications, but muscle symptoms, ranging from mild myalgia to clinically important rhabdomyolysis are an important side effect of these drugs and a leading cause of noncompliance. Recent results suggest that genetic factors increase the risk of statin-related muscle complaints. We performed a systematic review of the medical literature to determine genetic factors associated with statin myopathy.

METHODS

We identified English language articles relating statin myopathy and genetic diseases and gene variants via a PubMed search. Articles pertinent to the topic were reviewed in detail.

RESULTS/CONCLUSIONS

Our review suggests that some patients are susceptible to statin myopathy because of pre-existing subclinical inherited muscular disorders, or genetic variation in statin uptake proteins encoded by SLCO1B1 or the cytochrome P enzyme system. Variations in genes affecting pain perception and polymorphism in vascular receptors may also contribute to statin myopathy. None of the variants identified in this review suggested novel metabolic mechanisms leading to statin myopathy.