Lovastatin increases exercise-induced skeletal muscle injury

Decoding the Intricacies of Statin-Associated Muscle Symptoms

PURPOSE OF REVIEW

Hyperlipidemia is the major cardiovascular morbidity and mortality risk factor. Statins are the first-line treatment for hyperlipidemia. Statin-associated muscle symptoms (SAMS) are the main reason for the discontinuation of statins among patients. The purpose of this review is to guide clinicians to recognize the difference between self-limited and autoimmune statin myopathy in addition to the factors that potentiate them. Finally, treatment strategies will be discussed. This review mostly focuses on new data in the past 3 years.

RECENT FINDINGS

Recent findings suggest that SAMS is a complex and multifactorial condition that involves mitochondrial dysfunction, oxidative stress, and immune-mediated mechanisms. Effective management of SAMS requires a thorough evaluation of the patient's symptoms, risk factors, and medication history, as well as consideration of alternative treatment options. While statins are effective in reducing the risk of cardiovascular events, their use is associated with a range of adverse effects, including SAMS.

The Role of Exercise in Statin-Associated Muscle Symptoms Outcomes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

To provide a synthesis of randomized controlled trials (RCTs) investigating statin-associated muscle symptoms (SAMS) in adults who underwent exercise training intervention.

Patients and Methods

We systematically searched 5 electronic databases for placebo-controlled RCTs through January 31, 2023. We included short-term and long-term exercise interventions that compared the efficacy and safety of exercise+statin vs exercise+placebo in healthy adults and reported SAMS preintervention and postintervention. Publication bias and methodological study quality assessments were performed.

Results

Five of 454 potentially qualifying RCTs met the inclusion criteria, all short-term exercise RCTs. Participants were predominantly physically inactive young to middle-aged (M=37.2 y) men (57%), 252 (49%) who were on statin therapy, and 271 (53%) on placebo. Of the 3 RCTs providing qualitative SAMS results, 19 (9%) out of 220 participants reported SAMS on exercise+statin and 10 (4%) out of 234 reported SAMS on exercise+placebo. There was no difference between exercise+statin vs exercise+placebo for maximal oxygen consumption (d=-0.18; 95% CI, -0.37 to 0.00; P=.06) or creatine kinase after short-term exercise (d=0.59; 95% CI, -0.06 to 1.25; P=.08). Participants in the exercise+statin group reduced low-density lipoprotein cholesterol vs exercise+placebo (d=-1.84; 95% CI, -2.28 to -1.39; P<.001). Most of the RCTs exhibited low levels of risk of bias (k=4, 80%) and achieved moderate methodological study quality (75.0%±5.2%).

Conclusion

Self-reported SAMs tended to be 5% greater after short-term exercise in statin users compared with placebo, although this difference did not achieve statistical significance. There remains an important need for placebo-controlled RCTs investigating the prevalence of statin-induced SAMS during exercise training.

Prolonged Moderate-Intensity Exercise Does Not Increase Muscle Injury Markers in Symptomatic or Asymptomatic Statin Users

BACKGROUND

Statin use may exacerbate exercise-induced skeletal muscle injury caused by reduced coenzyme Q10 (CoQ10) levels, which are postulated to produce mitochondrial dysfunction.

OBJECTIVES

We determined the effect of prolonged moderate-intensity exercise on markers of muscle injury in statin users with and without statin-associated muscle symptoms. We also examined the association between leukocyte CoQ10 levels and muscle markers, muscle performance, and reported muscle symptoms.

METHODS

Symptomatic (n = 35; age 62 ± 7 years) and asymptomatic statin users (n = 34; age 66 ± 7 years) and control subjects (n = 31; age 66 ± 5 years) walked 30, 40, or 50 km/d for 4 consecutive days. Muscle injury markers (lactate dehydrogenase, creatine kinase, myoglobin, cardiac troponin I, and N-terminal pro-brain natriuretic peptide), muscle performance, and reported muscle symptoms were assessed at baseline and after exercise. Leukocyte CoQ10 was measured at baseline.

RESULTS

All muscle injury markers were comparable at baseline (P > 0.05) and increased following exercise (P < 0.001), with no differences in the magnitude of exercise-induced elevations among groups (P > 0.05). Muscle pain scores were higher at baseline in symptomatic statin users (P < 0.001) and increased similarly in all groups following exercise (P < 0.001). Muscle relaxation time increased more in symptomatic statin users than in control subjects following exercise (P = 0.035). CoQ10 levels did not differ among symptomatic (2.3 nmol/U; IQR: 1.8-2.9 nmol/U), asymptomatic statin users (2.1 nmol/U; IQR: 1.8-2.5 nmol/U), and control subjects (2.1 nmol/U; IQR: 1.8-2.3 nmol/U; P = 0.20), and did not relate to muscle injury markers, fatigue resistance, or reported muscle symptoms.

CONCLUSIONS

Statin use and the presence of statin-associated muscle symptoms does not exacerbate exercise-induced muscle injury after moderate exercise. Muscle injury markers were not related to leukocyte CoQ10 levels. (Exercise-induced Muscle Damage in Statin Users; NCT05011643).

Mechanism of action and therapeutic use of bempedoic acid in atherosclerosis and metabolic syndrome

Bempedoic acid is a new cholesterol-lowering drug, which has recently received US FDA and EMA approval. This drug targets lipid and glucose metabolism as well as inflammation via downregulation of ATP-citrate lyase and upregulation of AMP-activated protein kinase (AMPK). The primary effect is the reduction of cholesterol synthesis in the liver and its administration is generally not associated to unwanted muscle effects. Suppression of hepatic fatty acid synthesis leads to decreased triglycerides and, possibly, improved non-alcoholic fatty liver disease. Bempedoic acid may decrease gluconeogenesis leading to improved insulin sensitivity, glucose metabolism, and metabolic syndrome. The anti-inflammatory action of bempedoic acid is mainly achieved via activation of AMPK pathway in the immune cells, leading to decreased plasma levels of C-reactive protein. Effects of bempedoic acid on atherosclerotic cardiovascular disease, type 2 diabetes and chronic liver disease have been assessed in randomized clinical trials but require further confirmation. Safety clinical trials in phase III indicate that bempedoic acid administration is generally well-tolerated in combination with statins, ezetimibe, or proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors to achieve low-density lipoprotein cholesterol targets. The aim of this narrative review on bempedoic acid is to explore the underlying mechanisms of action and potential clinical targets, present existing evidence from clinical trials, and describe practical management of patients.

Exercise-Pharmacology Interactions: Metformin, Statins, and Healthspan

There is an increased focus on treatments to extend the healthspan. There is solid evidence that exercise extends the healthspan, but other treatments, such as metformin and statins, are also gaining traction. If metformin and statins will be used to prolong healthspan, we must understand their effects in those free of disease and in combination with exercise.

Rationale for the use of metformin and exercise to counteract statin-associated side effects

INTRODUCTION

Statins are the most widely prescribed drugs for lowering low-density lipoprotein cholesterol (LDL-C) and reducing cardiovascular morbidity and mortality. They are usually well-tolerated, but have two main safety concerns: statin-associated muscle symptoms (SAMS) and new-onset type 2 diabetes (NOD).

METHODS

A PubMed search was carried out using the following key words were used: statins, statin-associated muscle symptoms, statin myalgia, statin-associated diabetes, metformin and statins, exercise and statins.

RESULTS

Mitochondrial damage and muscle atrophy are likely the central mechanisms producing SAMS, whereas decreased glucose transport, fatty acid oxidation and insulin secretion are likely involved in the development of NOD. Metformin and exercise training share many pathways that could potentially contrast SAMS and NOD. Clinical evidence also supports the combination of statins with metformin and exercise.

CONCLUSION

This combination appears attractive both from a clinical and an economical viewpoint, since all three therapies are highly cost-effective and their combination could result in diabetes and cardiovascular disease prevention.

Successful treatment of a patient with mitochondrial myopathy with alirocumab

A 48-year-old man presented to our lipid clinic with statin intolerance and elevated serum creatine kinase levels, being affected by mitochondrial myopathy because of heteroplasmic mitochondrial DNA missense mutation in MTCO1 gene (m.7671T>A). He had just been treated with a coronary artery bypass 4 years before because of acute coronary syndrome, and he had consistently high levels of both low-density lipoprotein cholesterol and triglycerides. Dyslipidemia was successfully treated using 75 mg of alirocumab subcutaneously every 2 weeks, 10 mg of ezetimibe daily, 2 g of marine omega-3 fatty acids daily, and 145 mg of micronized fenofibrate every 2 days. Although muscle weakness persisted, myalgia did not reoccur and serum creatine kinase levels remained almost stable over the time.

Exercise Training Protects against Atorvastatin-Induced Skeletal Muscle Dysfunction and Mitochondrial Dysfunction in the Skeletal Muscle of Rats

Statins are used to prevent and treat atherosclerotic cardiovascular disease, but they also induce myopathy and mitochondrial dysfunction. Here, we investigated whether exercise training prevents glucose intolerance, muscle impairment, and mitochondrial dysfunction in the skeletal muscles of Wistar rats treated with atorvastatin (5 mg kg-1 day-1) for 12 weeks. The rats were assigned to the following three groups: the control (CON), atorvastatin-treated (ATO), and ATO plus aerobic exercise training groups (ATO+EXE). The ATO+EXE group exhibited higher glucose tolerance and forelimb strength and lower creatine kinase levels than the other groups. Mitochondrial respiratory and Ca2+ retention capacity was significantly lower in the ATO group than in the other groups, but exercise training protected against atorvastatin-induced impairment in both the soleus and white gastrocnemius muscles. The mitochondrial H2O2 emission rate was relatively higher in the ATO group and lower in the ATO+EXE group, in both the soleus and white gastrocnemius muscles, than in the CON group. In the soleus muscle, the Bcl-2, SOD1, SOD2, Akt, and AMPK phosphorylation levels were significantly higher in the ATO+EXE group than in the ATO group. In the white gastrocnemius muscle, the SOD2, Akt, and AMPK phosphorylation levels were significantly higher in the ATO+EXE group than in the ATO group. Therefore, exercise training might regulate atorvastatin-induced muscle damage, muscle fatigue, and mitochondrial dysfunction in the skeletal muscles.

Statin therapy in athletes and patients performing regular intense exercise - Position paper from the International Lipid Expert Panel (ILEP)

Acute and chronic physical exercises may enhance the development of statin-related myopathy. In this context, the recent (2019) guidelines of the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS) for the management of dyslipidemias recommend that, although individuals with dyslipidemia should be advised to engage in regular moderate physical exercise (for at least 30 min daily), physicians should be alerted with regard to myopathy and creatine kinase (CK) elevation in statin-treated sport athletes. However it is worth emphasizing that abovementioned guidelines, previous and recent ESC/EAS consensus papers on adverse effects of statin therapy as well as other previous attempts on this issue, including the ones from the International Lipid Expert Panel (ILEP), give only general recommendations on how to manage patients requiring statin therapy on regular exercises. Therefore, these guidelines in the form of the Position Paper are the first such an attempt to summary existing, often scarce knowledge, and to present this important issue in the form of step-by-step practical recommendations. It is critically important as we might observe more and more individuals on regular exercises/athletes requiring statin therapy due to their cardiovascular risk.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Statin Safety and Associated Adverse Events: A Scientific Statement From the American Heart Association

One in 4 Americans >40 years of age takes a statin to reduce the risk of myocardial infarction, ischemic stroke, and other complications of atherosclerotic disease. The most effective statins produce a mean reduction in low-density lipoprotein cholesterol of 55% to 60% at the maximum dosage, and 6 of the 7 marketed statins are available in generic form, which makes them affordable for most patients. Primarily using data from randomized controlled trials, supplemented with observational data where necessary, this scientific statement provides a comprehensive review of statin safety and tolerability. The review covers the general patient population, as well as demographic subgroups, including the elderly, children, pregnant women, East Asians, and patients with specific conditions such as chronic disease of the kidney and liver, human immunodeficiency viral infection, and organ transplants. The risk of statin-induced serious muscle injury, including rhabdomyolysis, is <0.1%, and the risk of serious hepatotoxicity is ≈0.001%. The risk of statin-induced newly diagnosed diabetes mellitus is ≈0.2% per year of treatment, depending on the underlying risk of diabetes mellitus in the population studied. In patients with cerebrovascular disease, statins possibly increase the risk of hemorrhagic stroke; however, they clearly produce a greater reduction in the risk of atherothrombotic stroke and thus total stroke, as well as other cardiovascular events. There is no convincing evidence for a causal relationship between statins and cancer, cataracts, cognitive dysfunction, peripheral neuropathy, erectile dysfunction, or tendonitis. In US clinical practices, roughly 10% of patients stop taking a statin because of subjective complaints, most commonly muscle symptoms without raised creatine kinase. In contrast, in randomized clinical trials, the difference in the incidence of muscle symptoms without significantly raised creatinine kinase in statin-treated compared with placebo-treated participants is <1%, and it is even smaller (0.1%) for patients who discontinued treatment because of such muscle symptoms. This suggests that muscle symptoms are usually not caused by pharmacological effects of the statin. Restarting statin therapy in these patients can be challenging, but it is important, especially in patients at high risk of cardiovascular events, for whom prevention of these events is a priority. Overall, in patients for whom statin treatment is recommended by current guidelines, the benefits greatly outweigh the risks.

Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology

Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

The Effects of Statins on Physical Activity or Physical Fitness Among Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

This review examines the effects of statins on physical activity and/or fitness, as statins can have adverse muscle effects. A search was done of MEDLINE, Embase, and EBMR databases up to July 2018 for randomized controlled trials comparing statin with placebo or control, measuring physical activity and/or fitness in adults. Sixteen randomized controlled trials (total participants [N] = 2,944) were included, 6 randomized controlled trials contributed data for meta-analysis. Random effects meta-analysis examined differences in physical fitness, maximal exercise time (in seconds) in exercise testing, and maximal heart rate (in beats per minute) between statins and control. No significant difference between statin and control for maximal heart rate (mean difference = 2.8 beats per minute, 95% confidence interval [-7.4, 13.0]; p = .59) nor exercise time (mean difference = 82.8 s, 95% confidence interval [-31.9, 197.4]; p = .516) were seen. There were insufficient studies reporting habitual physical activity to perform a meta-analysis. This review found no evidence for an effect of statins on physical activity or fitness, but data availability is limited.

A Mechanism for Statin-Induced Susceptibility to Myopathy

This study aimed to identify a mechanism for statin-induced myopathy that explains its prevalence and selectivity for skeletal muscle, and to understand its interaction with moderate exercise. Statin-associated adverse muscle symptoms reduce adherence to statin therapy; this limits the effectiveness of statins in reducing cardiovascular risk. The issue is further compounded by perceived interactions between statin treatment and exercise. This study examined muscles from individuals taking statins and rats treated with statins for 4 weeks. In skeletal muscle, statin treatment caused dissociation of the stabilizing protein FK506 binding protein (FKBP12) from the sarcoplasmic reticulum (SR) calcium (Ca2+) release channel, the ryanodine receptor 1, which was associated with pro-apoptotic signaling and reactive nitrogen species/reactive oxygen species (RNS/ROS)-dependent spontaneous SR Ca2+ release events (Ca2+ sparks). Statin treatment had no effect on Ca2+ spark frequency in cardiac myocytes. Despite potentially deleterious effects of statins on skeletal muscle, there was no impact on force production or SR Ca2+ release in electrically stimulated muscle fibers. Statin-treated rats with access to a running wheel ran further than control rats; this exercise normalized FKBP12 binding to ryanodine receptor 1, preventing the increase in Ca2+ sparks and pro-apoptotic signaling. Statin-mediated RNS/ROS-dependent destabilization of SR Ca2+ handling has the potential to initiate skeletal (but not cardiac) myopathy in susceptible individuals. Importantly, although exercise increases RNS/ROS, it did not trigger deleterious statin effects on skeletal muscle. Indeed, our results indicate that moderate exercise might benefit individuals who take statins.

Muscle and statins: from toxicity to the nocebo effect

INTRODUCTION

Although statins have a satisfactory safety profile and are well tolerated, many statin-treated patients report muscle symptoms in clinical practice which contribute to drug discontinuation and, consequently, adverse cardiovascular outcomes.

AREAS COVERED

This narrative review will cover the definition and prevalence of statin intolerance, the clinical spectrum of statin-associated muscle symptoms (SAMS) with special focus on patients with only mild myalgias, the complexity of statin muscle intolerance diagnosis and provide an overview on the nocebo effect of particular importance for physicians.

EXPERT OPINION

Many patients are unable to tolerate statin therapy, with SAMS being the most common cause of statin intolerance. The reported incidence of SAMS was consistently lower in randomized placebo-controlled trials than in observational studies. These results strongly suggested that SAMS were not always due to by the pharmacologic effects of statin therapy. Convincing patients that their muscle symptoms might be due to causes other than statin treatment is sometimes difficult. Furthermore, clinicians should not prematurely discontinue statin therapy before considering other possible causes, including the nocebo effect.

Endurance exercise increases the protein levels of PGC-1α and respiratory chain complexes in mouse skeletal muscle during atorvastatin administration

Statins and exercise reduce cardiovascular disease incidence. We investigated whether endurance exercise in mice induces mitochondrial adaptation in skeletal muscle and muscle injury during administration of atorvastatin, a member of the statin medication class. Male C57BL mice were assigned to one of three groups: control (Con), statin (Statin), or statin and exercise (Statin + Ex). Atorvastatin was administered, and exercise performed on a treadmill for 8 weeks. The levels of mitochondria-associated proteins, PGC-1α, and respiratory chain complex, (COX) I-V, in the quadriceps femoris, and serum creatine kinase, a muscle injury marker, were measured. PGC-1α and COX I-V were upregulated in the Statin + Ex group compared to those in the Statin and Con groups; serum creatine kinase levels were similar. Endurance training in mice induced mitochondrial adaptation in skeletal muscle without causing muscle injury, during atorvastatin administration.

Association of Statin Use with Increased Risk of Musculoskeletal Conditions: A Retrospective Cohort Study

INTRODUCTION

Musculoskeletal conditions, including osteoarthritis (OA), result in tremendous disability and cost. Statins are among the most commonly prescribed medications and their use for primary prevention in many otherwise healthy individuals, including those who are physically active, is increasing. There is conflicting evidence regarding the relationship of statin use and musculoskeletal conditions. Given the rising disability associated with musculoskeletal conditions, understanding predisposing factors, including medication-related exposures, deserves further attention.

OBJECTIVES

We examined the association between statin use and the risk of being diagnosed with non-traumatic arthropathies, use-related injury, and undergoing rehabilitation in a cohort with longitudinal follow-up.

METHODS

Patients enrolled in a regional military healthcare system between 2003 and 2012 were evaluated in this retrospective cohort study. A propensity score was generated to match statin-users and nonusers using 115 baseline characteristics. Outcomes included ICD-9 diagnoses codes for Agency for Healthcare Research and Quality disease categories of: non-traumatic arthropathies, use-related injury and undergoing rehabilitation. Primary analysis examined the outcomes in statin-users and nonusers after propensity score matching using conditional logistic regression analysis.

RESULTS

Initially, 60,455 patients were identified. We propensity score-matched 6728 statin users with 6728 nonusers (52 years of age, ~ 47% women). In the propensity score-matched cohort, non-traumatic arthropathies occurred in 59.8% of statin users and 56.0% of nonusers [odds ratio (OR) 1.17, 95% confidence interval (95% CI) 1.09-1.25] and use related injury occurred in 31.9% of statin users and 29.8% of nonusers (OR 1.11, 95% CI 1.03-1.19). There was no difference between statin users and nonusers undergoing rehabilitation (22.6% among statin users, 21.9% among nonusers, OR 1.04, 95% CI 0.96-1.13).

CONCLUSION

Statin use was associated with a significant increased risk of non-traumatic arthropathies and use-related injury. Our results provide additional data that can inform patient and clinician conversations about the benefits and risks of statin use.

Statin-Associated Muscle Disease: Advances in Diagnosis and Management

Since the first approval of lovastatin in 1987, hydroxy-methyl-glutaryl CoA (HMG CoA) reductase inhibitors, or statins, have been effective and widely popular cholesterol-lowering agents with substantial benefits for the prevention and treatment of cardiovascular disease. Not all patients can tolerate these drugs, however, and statin intolerance is most frequently associated with a range of side effects directed toward skeletal muscle, termed statin-associated muscle symptoms or SAMS. SAMS are particularly difficult to treat because there are no validated biomarkers or tests that can be used to confirm patient self-reports of SAMS, and a number of patients who report SAMS have non-specific muscle pain not attributable to statin therapy. This review summarizes the most recent evidence related to diagnosis and management of SAMS. First, the range of skeletal muscle side effects associated with statin therapy is described. Second, data regarding the incidence and prevalence of SAMS, the most frequently experienced muscle side effect, are presented. Third, the most promising new techniques to confirm diagnosis of SAMS are explored. Finally, the most effective strategies for the clinical management of SAMS are summarized. Better diagnostic and treatment strategies for SAMS will increase the number of patients using these life-saving statins, thereby increasing statin adherence and reducing the costs of avoidable cardiovascular events.

Sources of Inter-individual Variability in the Therapeutic Response of Blood Glucose Control to Exercise in Type 2 Diabetes: Going Beyond Exercise Dose

In the context of type 2 diabetes, inter-individual variability in the therapeutic response of blood glucose control to exercise exists to the extent that some individuals, occasionally referred to as “non-responders,” may not experience therapeutic benefit to their blood glucose control. This narrative review examines the evidence and, more importantly, identifies the sources of such inter-individual variability. In doing so, this review highlights that no randomized controlled trial of exercise has yet prospectively measured inter-individual variability in blood glucose control in individuals with prediabetes or type 2 diabetes. Of the identified sources of inter-individual variability, neither has a prospective randomized controlled trial yet quantified the impact of exercise dose, exercise frequency, exercise type, behavioral/environmental barriers, exercise-meal timing, or anti-hyperglycemic drugs on changes in blood glucose control, in individuals with prediabetes or type 2 diabetes. In addition, there is also an urgent need for prospective trials to identify molecular or physiological predictors of inter-individual variability in the changes in blood glucose control following exercise. Therefore, the narrative identifies critical science gaps that must be filled if exercise scientists are to succeed in optimizing health care policy recommendations for type 2 diabetes, so that the therapeutic benefit of exercise may be maximized for all individuals with, or at risk of, diabetes.

Creatine supplementation does not alter the creatine kinase response to eccentric exercise in healthy adults on atorvastatin

BACKGROUND

Serum creatine kinase (CK) levels are higher after eccentric, muscle-damaging exercise in statin-treated patients. This could contribute to the increased statin-associated muscle symptoms reported in physically active individuals.

OBJECTIVE

We tested the hypothesis in this pilot study that creatine (Cr) monohydrate supplementation would reduce the CK response to eccentric exercise in patients using statins to determine if Cr supplementation could be a strategy to mitigate statin-associated muscle symptoms in physically active individuals.

METHODS

Healthy, nonsmoking men (n = 5) and women (n = 14) were randomized to Cr monohydrate = atorvastatin 80 mg + 10 g Cr monohydrate (n = 10, age = 60 ± 7 years) or to placebo (PL) = atorvastatin 80 mg + PL (n = 9, age = 52 ± 6 years). After 4 weeks of treatment, subjects performed 45 minutes of eccentric exercise (downhill walking at a -15% grade). Serum CK levels, muscle soreness (visual analog scale after two squats), and muscle pain severity and interference (using the brief pain inventory) were measured before and after 4 weeks of treatment, and then for 4 consecutive days after downhill walking. Vitamin D, or serum 25(OH)D, was also measured at baseline.

RESULTS

The PL group was younger (P = .01) but not otherwise different in blood lipids, vitamin D, CK, muscle visual analog scale, and pain scores before (all P > .21) or after (all P > .12) treatment. CK increased in all subjects after downhill walking (P < .01), but neither the relative peak change (expressed as group mean difference with 95% confidence intervals: 43.52% [-196.41, 283.45]) nor the absolute peak change (67.38 U/L [-121.55, 256.31]) relative to baseline was different between groups (P = .46 and .71, respectively). A similar lack of treatment effect was observed for muscle soreness (11.03 mm [-9.49, 31.55]), pain severity (0.77 pts [-0.95, 2.50]), and pain interference (1.02 pts [-1.25, 3.29]) with P-values for group comparisons = 0.27, 0.36, and 0.35, respectively. However, subjects with "insufficient" Vitamin D < 30 ng/mL (n = 10) had an ∼2-fold greater CK increase with eccentric exercise (nominal P-value = .04) than subjects with higher vitamin D levels.

CONCLUSION

Cr monohydrate did not reduce CK increases after exercise in statin-treated subjects. We did observe that low vitamin D levels are associated with a greater CK response to eccentric exercise in statin-treated subjects.

An update on the relationship between statins and physical activity

PURPOSE OF REVIEW

This review examined studies published within the last 16 months that investigated the relationship between statins and physical activity.

RECENT FINDINGS

These recent studies suggest that statins do not adversely affect cardiorespiratory fitness, muscle strength, athletic performance, or physical activity adherence. One recent study comparing patients with statin-associated myalgia and nonstatin-using controls did report that statins are associated with a slowing of time to peak power output, increased abdominal adiposity, and insulin resistance. Statin users also had different muscle gene expression than controls, but conclusions are limited by the design of that study.

SUMMARY

Previous reports suggest that statin-associated muscle symptoms such as myalgia, cramps, and weakness occur more frequently in physically active individuals, but the recent studies we reviewed do not provide additional support for this possibility. Well-designed clinical trials are needed to determine whether different statins or statin doses evoke statin-associated muscle symptoms or muscle damage that may reduce cardiorespiratory fitness and adherence to physical activity.

Does Coenzyme Q10 Supplementation Mitigate Statin-Associated Muscle Symptoms? Pharmacological and Methodological Considerations

Statin drugs markedly reduce low-density lipoprotein cholesterol and consequently the incidence of cardiac events. In approximately 5-10% of adults, these drugs are associated with a range of muscle side effects such as muscle pain, cramping and weakness. Reduction in mitochondrial coenzyme Q10 (CoQ10), or ubiquinone, has been proposed as a mechanism for these statin-associated muscle symptoms (SAMS), and thus various formulations of CoQ10 are marketed and consumed for the prevention and treatment of SAMS. However, data supporting the efficacy of CoQ10 are equivocal, with some studies showing that CoQ10 supplementation reduces the incidence and severity of SAMS and others finding no beneficial effects of supplementation. Methodological and pharmacological issues may confound interpretation of data on this topic. For example, many patients who report SAMS, such as those who have been enrolled in previous CoQ10 studies, may be experiencing non-specific (non-statin-associated) muscle pain. In addition, the effectiveness of oral CoQ10 supplementation to increase mitochondrial CoQ10 in human skeletal muscle is not well established. This manuscript will critically evaluate the published data on the efficacy of CoQ10 supplements in the prevention and treatment of SAMS.

Circulating myomiRs: a new class of biomarkers to monitor skeletal muscle in physiology and medicine

MicroRNAs (miRNA) are small non-coding RNAs that target mRNAs and are consequently involved in the post-transcriptional regulation of gene expression. Some miRNAs are ubiquitously expressed in tissue, while others are tissue-specific or tissue-enriched. miRNAs can be released by cells and are found in various biofluids, including serum and plasma. Thus, measuring miRNAs in the circulation may provide information on the originating tissue or cells. MyomiRs are described as striated muscle-specific or muscle-enriched miRNAs. Their circulating levels can be measured and have been proposed to be new biomarkers of physiological and pathological muscle processes. The aims of this review are to summarize the current knowledge of circulating myomiRs, to identify the types of information they can provide about skeletal muscle, and to determine how to apply that information in the fields of research and medicine.

The effects of statins on exercise and physical activity

OBJECTIVE

We sought to review studies examining the effect of statins on symptoms of exercise tolerance, markers of muscle injury and activity levels in physical active individuals.

BACKGROUND

Statin therapy reduces atherosclerotic cardiovascular disease (CVD) events. Regular physical activity is also associated with reduced CVD events, but statin therapy can produce muscle complaints, which may be more frequent in physically active individuals. We reviewed the literature to determine the effects of statins on symptoms, exercise performance and activity levels in physically active individuals.

METHODS

We performed a PubMed search to identify English language articles reporting on statins and their effect on athletic/exercise performance, and symptoms in active individuals.

RESULTS

We identified 65 articles, 32 of which provided sufficient information to be included in this review. Seventeen of the 32 studies examined the incidence of myalgia while exercising on statins, and showed that myalgia was increased in 8 of the 17 (47%) of these studies. Of the 17 studies examining the effects of statin therapy on muscle injury, 6 (35%) studies reported that statins augment the increase in creatine kinase (CK) produced by exercise. There were 10 studies that examined statin effects on aerobic exercise performance, only 3 of which (33%) concluded that statins decreased performance. Two (25%) of the 8 studies examined the effects of statins on muscular strength and suggested that statins decreased muscular strength, whereas 2 (25%) reported increased strength. Statins did not consistently affect physical activity levels since statins were associated with an increase in activity in 3 of the 5 studies examining habitual exercise. None of the studies showed a relationship between statins use and exercise and an increase in myalgia or a decrease in exercise performance. There was also no correlation between intensity of statin therapy and an effect on these variables.

CONCLUSION

Statins may increase the incidence of exercise-related muscle complaints and in some studies augment the exercise-induced rise in muscle enzymes, but statins do not consistently reduce muscle strength, endurance, overall exercise performance or physical activity.

Statin-Associated Side Effects

Hydroxy-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors or statins are well tolerated, but associated with various statin-associated symptoms (SAS), including statin-associated muscle symptoms (SAMS), diabetes mellitus (DM), and central nervous system complaints. These are "statin-associated symptoms" because they are rare in clinical trials, making their causative relationship to statins unclear. SAS are, nevertheless, important because they prompt dose reduction or discontinuation of these life-saving mediations. SAMS is the most frequent SAS, and mild myalgia may affect 5% to 10% of statin users. Clinically important muscle symptoms, including rhabdomyolysis and statin-induced necrotizing autoimmune myopathy (SINAM), are rare. Antibodies against HMG-CoA reductase apparently provoke SINAM. Good evidence links statins to DM, but evidence linking statins to other SAS is largely anecdotal. Management of SAS requires making the possible diagnosis, altering or discontinuing the statin treatment, and using alternative lipid-lowering therapy.

Efficacy and safety of statins and exercise combination therapy compared to statin monotherapy in patients with dyslipidaemia: A systematic review and meta-analysis

Background Statin treatment in association with physical exercise can substantially reduce mortality in dyslipidaemic individuals. However, the available data to compare the efficacy and safety of statins and exercise combination therapy with statin monotherapy are limited. Design Systematic review and meta-analysis. Methods We systematically searched PubMed, Embase and the Cochrane Library from database inception until December 2016. We included randomised and non-randomised studies that compared the efficacy and safety of statins and exercise combination therapy with statin monotherapy in patients with dyslipidaemia. Standardised mean differences were calculated and pooled by means of fixed effects models. The risk of bias and heterogeneity among trials was also assessed. Seven articles were assessed in terms of the efficacy of therapy and 13 from the viewpoint of therapeutic safety. Results In terms of efficacy, statins and exercise combination decreased the incidence of diabetes mellitus, improved insulin sensitivity and inflammation, but caused no change in lipid profile compared to statins alone. In terms of safety, statins and exercise combination increased peak oxygen uptake (standardised mean difference 1.01, 95% confidence interval 0.46 to 1.57) compared to statins alone. In contrast to statin-induced myopathy, chronic exercise training prior to statin treatment could counteract statin-induced adverse effects in skeletal muscle. Conclusion Statins and exercise combination therapy is more effective than statin monotherapy in terms of insulin sensitivity, inflammation and exercise capacity. The small number of studies warrants the need for more randomised controlled trials evaluating the efficacy and safety of combination therapy.

The Impact of Exercise on Statin-Associated Skeletal Muscle Myopathy

HMG-CoA reductase inhibitors (statins) are the most effective pharmacological means of reducing cardiovascular disease risk. The most common side effect of statin use is skeletal muscle myopathy, which may be exacerbated by exercise. Hypercholesterolemia and training status are factors that are rarely considered in the progression of myopathy. The purpose of this study was to determine the extent to which acute and chronic exercise can influence statin-induced myopathy in hypercholesterolemic (ApoE^-/-) mice. Mice either received daily injections of saline or simvastatin (20 mg/kg) while: 1) remaining sedentary (Sed), 2) engaging in daily exercise for two weeks (novel, Nov), or 3) engaging in daily exercise for two weeks after a brief period of training (accustomed, Acct) (2x3 design, n = 60). Cholesterol, activity, strength, and indices of myofiber damage and atrophy were assessed. Running wheel activity declined in both exercise groups receiving statins (statin x time interaction, p<0.05). Cholesterol, grip strength, and maximal isometric force were significantly lower in all groups following statin treatment (statin main effect, p<0.05). Mitochondrial content and myofiber size were increased and 4-HNE was decreased by exercise (statin x exercise interaction, p<0.05), and these beneficial effects were abrogated by statin treatment. Exercise (Acct and Nov) increased atrogin-1 mRNA in combination with statin treatment, yet enhanced fiber damage or atrophy was not observed. The results from this study suggest that exercise (Nov, Acct) does not exacerbate statin-induced myopathy in ApoE^-/- mice, yet statin treatment reduces activity in a manner that prevents muscle from mounting a beneficial adaptive response to training.

Effect of Statin Use on Mobility Disability and its Prevention in At-risk Older Adults: The LIFE Study

BACKGROUND

HMG-CoA reductase inhibitors (statins) are among the most commonly prescribed classes of medications. Although their cardiovascular benefits and myalgia risks are well documented, their effects on older adults initiating an exercise training program are less understood.

METHODS

1,635 sedentary men and women aged 70-89 years with Short Physical Performance Battery (SPPB) score of 9 or below and were able to walk 400 m were randomized to a structured, moderate-intensity physical activity (PA) program consisting of both center-based (twice/wk) and home-based (3-4 times/wk) aerobic, resistance, and flexibility training or to a health education (HE) program combined with upper extremity stretching.

RESULTS

Overall, the PA intervention was associated with lower risk of major mobility disability (hazard ratio [HR] = 0.82; 95% confidence interval [CI] = 0.69-0.98). The effect was similar (p value for interaction = .62) in both statin users (PA n = 415, HE n = 412; HR = 0.86, 95% CI = 0.67-1.1) and nonusers (PA n = 402, HE n = 404; HR = 0.78, 95% CI = 0.61-1.01). Attendance was similar for statin users (65%) and nonusers (63%). SPPB at 12 months was slightly greater for PA (8.35±0.10) than for HE (7.94±0.10) in statin users but not in nonusers (PA 8.25±0.10, HE 8.16±0.10), though the interaction effect was not statistically significant. Self-reported PA levels were not different between statin users and nonusers.

CONCLUSIONS

Although statins have been associated with adverse effects on muscle, data from the LIFE Study show that statin users and nonusers both benefit from PA interventions. Older adults who require statin medications to manage chronic medical conditions and are sedentary will be able to benefit from interventions to increase PA.

Short-term cessation of statin therapy does not alter aerobic exercise performance in physically active middle-aged adults

OBJECTIVES

Physically active adults may be especially vulnerable to the adverse muscular side effects of statins. We determined if short-term cessation of statin therapy would improve aerobic exercise performance in middle-aged adults engaged in regular aerobic exercise training.

METHODS

Physically active middle-aged adults on statin therapy ≥6 mo (n = 16; 58 ± 10 y) or not taking lipid-lowering medications (controls) (n = 19; 51 ± 9 y) completed a peak oxygen consumption (VO2peak) and time to exhaustion test on a cycle ergometer 2-7 d apart. Tests were repeated following 1 mo of statin cessation or a 1 mo period for controls. Questionnaires were administered to assess exercise history and muscle complaints.

RESULTS

Statin users reported little or no muscle complaints and participation in aerobic exercise was similar between groups (p≥0.13). The lower VO2peak (37.3 ± 9.0 vs. 43.1 ± 4.9 ml/kg/min; p = 0.02) and time to exhaustion (21.9 ± 4.4 vs. 26.0 ± 6.3 min; p = 0.04) in statin users versus controls did not persist after controlling for age (p≥0.08). Aerobic exercise performance did not change with 1 mo of statin cessation (p≥0.54). No changes were observed in controls when tests were repeated 1 mo later (p≥0.38).

CONCLUSION

Short-term cessation of statin therapy does not alter maximal aerobic capacity or aerobic endurance in physically active middle-aged adults with few or no statin muscle complaints.

Coming of Age: Considerations in the Prescription of Exercise for Older Adults

Older adults represent the fastest-growing age demographic of the population. Physiological changes associated with primary aging and concurrent chronic disease adversely impact functional capacity, health outcomes, and quality of life. For these reasons, there is a national emphasis for healthcare providers to improve the health, function, and quality of life of older adults to preserve independent living and psychological well-being. The benefits of regular physical activity or exercise with regard to aging and disease are indisputable, yet many clinicians do not prescribe exercise to older adults. This reluctance may be attributable to a lack of knowledge regarding appropriate exercise prescription for older adults in light of the potential risks and benefits of various doses and types of exercise. In addition, clinicians and patients may have concerns about potential health considerations relevant to older adults such as comprehensive pre-exercise screening and exercise-drug interactions. In light of this, the following review presents (1) guidelines for exercise prescription in older adults and modification of these guidelines for patients with the most common age-associated comorbidities; (2) recommendations for pre-exercise screening prior to initiating an exercise program in older adults; (3) considerations for older adults on one or more medications; and (4) common barriers to adopting and maintaining exercise in an older population. Our goal is to provide a framework that clinicians can follow when prescribing exercise in older adults while considering the unique characteristics and concerns present in this population.

Influence of statins on distinct circulating microRNAs during prolonged aerobic exercise

Statins exacerbate exercise-induced skeletal muscle injury. Muscle-specific microRNAs (myomiRs) increase in plasma after prolonged exercise, but the patterns of myomiRs release after statin-associated muscle injury have not been examined. We examined the relationships between statin exposure, in vitro and in vivo muscle contraction, and expression of candidate circulating myomiRs. We measured plasma levels of myomiRs, circulating microRNA-1 (c-miR-1), c-miR-133a, c-miR-206, and c-miR-499-5p from 28 statin-using and 28 nonstatin-using runners before (PRE), immediately after (FINISH), and 24 h after they ran a 42-km footrace (the 2011 Boston marathon) (POST-24). To examine these cellular-regulation myomiRs, we used contracting mouse C2C12 myotubes in culture with and without statin exposure to compare intracellular and extracellular expression of these molecules. In marathoners, c-miR-1, c-miR-133a, and c-miR-206 increased at FINISH, returned to baseline at POST-24, and were unaffected by statin use. In contrast, c-miR-499-5p was unchanged at FINISH but increased at POST-24 among statin users compared with PRE and runners who did not take statins. In cultured C2C12 myotubes, extracellular c-miR-1, c-miR-133a, and c-miR-206 were significantly increased by muscle contraction regardless of statin use. In contrast, extracellular miR-499-5p was unaffected by either isolated statin exposure or isolated carbachol exposure but it was increased when muscle contraction was combined with statin exposure. In summary, we found that statin-potentiated muscle injury during exercise is accompanied by augmented extracellular release of miR-499-5p. Thus c-miR-499-5p may serve as a biomarker of statin-potentiated muscle damage.

Treatment of dyslipidemia with statins and physical exercises: recent findings of skeletal muscle responses

Statin treatment in association with physical exercise practice can substantially reduce cardiovascular mortality risk of dyslipidemic individuals, but this practice is associated with myopathic event exacerbation. This study aimed to present the most recent results of specific literature about the effects of statins and its association with physical exercise on skeletal musculature. Thus, a literature review was performed using PubMed and SciELO databases, through the combination of the keywords "statin" AND "exercise" AND "muscle", restricting the selection to original studies published between January 1990 and November 2013. Sixteen studies evaluating the effects of statins in association with acute or chronic exercises on skeletal muscle were analyzed. Study results indicate that athletes using statins can experience deleterious effects on skeletal muscle, as the exacerbation of skeletal muscle injuries are more frequent with intense training or acute eccentric and strenuous exercises. Moderate physical training, in turn, when associated to statins does not increase creatine kinase levels or pain reports, but improves muscle and metabolic functions as a consequence of training. Therefore, it is suggested that dyslipidemic patients undergoing statin treatment should be exposed to moderate aerobic training in combination to resistance exercises three times a week, and the provision of physical training prior to drug administration is desirable, whenever possible.

Statin intolerance - an attempt at a unified definition. Position paper from an International Lipid Expert Panel

Statins are one of the most commonly prescribed drugs in clinical practice. They are usually well tolerated and effectively prevent cardiovascular events. Most adverse effects associated with statin therapy are muscle-related. The recent statement of the European Atherosclerosis Society (EAS) has focused on statin associated muscle symptoms (SAMS), and avoided the use of the term 'statin intolerance'. Although muscle syndromes are the most common adverse effects observed after statin therapy, excluding other side effects might underestimate the number of patients with statin intolerance, which might be observed in 10-15% of patients. In clinical practice, statin intolerance limits effective treatment of patients at risk of, or with, cardiovascular disease. Knowledge of the most common adverse effects of statin therapy that might cause statin intolerance and the clear definition of this phenomenon is crucial to effectively treat patients with lipid disorders. Therefore, the aim of this position paper was to suggest a unified definition of statin intolerance, and to complement the recent EAS statement on SAMS, where the pathophysiology, diagnosis and the management were comprehensively presented.

Statin myalgia is not associated with reduced muscle strength, mass or protein turnover in older male volunteers, but is allied with a slowing of time to peak power output, insulin resistance and differential muscle mRNA expression

Key points

Statins cause muscle‐specific side effects, most commonly muscle aches/weakness (myalgia), particularly in older people. Furthermore, evidence has linked statin use to increased risk of type 2 diabetes. However, the mechanisms involved are unknown.

This is the first study to measure muscle protein turnover rates and insulin sensitivity in statin myalgic volunteers and age‐matched, non‐statin users under controlled fasting and fed conditions using gold standard methods.

We demonstrate in older people that chronic statin myalgia is not associated with deficits in muscle strength and lean mass or the dysregulation of muscle protein turnover compared to non‐statin users. Furthermore, there were no between‐group differences in blood or muscle inflammatory markers.

Statin users did, however, show blunting of muscle power output at the onset of dynamic exercise, increased abdominal adiposity, whole body and leg insulin resistance, and clear differential expression of muscle genes linked to mitochondrial dysfunction and apoptosis, which warrant further investigation.

Abstract

Statins are associated with muscle myalgia and myopathy, which probably reduce habitual physical activity. This is particularly relevant to older people who are less active, sarcopaenic and at increased risk of statin myalgia. We hypothesised that statin myalgia would be allied to impaired strength and work capacity in older people, and determined whether differences aligned with divergences in lean mass, protein turnover, insulin sensitivity and the molecular regulation of these processes. Knee extensor strength and work output during 30 maximal isokinetic contractions were assessed in healthy male volunteers, nine with no statin use (control 70.4 ± 0.7 years) and nine with statin myalgia (71.5 ± 0.9 years). Whole body and leg glucose disposal, muscle myofibrillar protein synthesis (MPS) and leg protein breakdown (LPB) were measured during fasting (≈5 mU l⁻¹ insulin) and fed (≈40 mU l⁻¹ insulin + hyperaminoacidaemia) euglyceamic clamps. Muscle biopsies were taken before and after each clamp. Lean mass, MPS, LPB and strength were not different but work output during the initial three isokinetic contractions was 19% lower (P < 0.05) in statin myalgic subjects due to a delay in time to reach peak power output. Statin myalgic subjects had reduced whole body (P = 0.05) and leg (P < 0.01) glucose disposal, greater abdominal adiposity (P < 0.05) and differential expression of 33 muscle mRNAs (5% false discovery rate (FDR)), six of which, linked to mitochondrial dysfunction and apoptosis, increased at 1% FDR. Statin myalgia was associated with impaired muscle function, increased abdominal adiposity, whole body and leg insulin resistance, and evidence of mitochondrial dysfunction and apoptosis.

An assessment by the Statin Muscle Safety Task Force: 2014 update

The National Lipid Association's Muscle Safety Expert Panel was charged with the duty of examining the definitions for statin-associated muscle adverse events, development of a clinical index to assess myalgia, and the use of diagnostic neuromuscular studies to investigate muscle adverse events. We provide guidance as to when a patient should be considered for referral to neuromuscular specialists and indications for the performance of a skeletal muscle biopsy. Based on this review of evidence, we developed an algorithm for the evaluation and treatment of patients who may be intolerant to statins as the result of adverse muscle events. The panel was composed of clinical cardiologists, clinical lipidologists, an exercise physiologist, and a neuromuscular specialist.

A Neuromuscular Approach to Statin-Related Myotoxicity

Approximately 95% of statin-treated patients tolerate this form of cholesterol management without any adverse effects. However, given their efficacy in reducing low density lipoproteins and cardiovascular events large numbers of patients are selected for statin therapy. Therefore muscle complications are, in fact, quite common. Limited understanding of the underlying pathophysiology has hampered physicians' ability to identify patients at risk for developing statin myotoxicity. A growing number of published case reports/series have implicated statins in the exacerbation of both acquired and genetic myopathies. A clinical management algorithm is presented which outlines a variety of co-morbidities which can potentiate the adverse effects of statins on muscle. In addition, a rational approach to the selection of those patients most likely to benefit from skeletal muscle biopsy is discussed. Ongoing work will define the extent to which statin-intolerant patients represent carriers of recessive metabolic myopathies or pre-symptomatic acquired myopathies. The expanding importance of pharmacogenomics will undoubtedly be realized in the field of statin myopathy research within the next few years. Such critical information is needed to establish more definitive management and diagnostic strategies.

Antipsychotic-induced elevation of creatine kinase: a systematic review of the literature and recommendations for the clinical practice

RATIONALE

The primary antipsychotic-induced creatine kinase elevation (i.e., not due to neuroleptic malignant syndrome, extrapyramidal symptoms, etc.) is a poorly studied condition.

OBJECTIVES

The aims of the present study were to provide an overview of published cases with antipsychotic-induced creatine kinase elevation and give recommendations for the clinical practice.

METHODS

PubMed and EMBASE were searched for eligible trials, case series, and case reports. We set a threshold at ten times the upper normal limit of the creatine kinase value in order to define an elevation as significant.

RESULTS

The prevalence of significant creatine kinase elevation ranged between 2 and 7%. We found a total of 42 eligible cases. Men were overrepresented in our sample (81%). Patients with myoglobinuria were more likely to be symptomatic (Fisher's exact test, p = 0.006), whereas neither myoglobinuria (Mann-Whitney test, p > 0.10) nor symptoms (Mann-Whitney test, p = 0.64) were related to the magnitude of the creatine kinase (CK) elevation. In the majority of the cases, the antipsychotic medication was discontinued (86%). Forced diuresis was given in 36% of the patients. Eighty-three percent of the patients had no further complications. Only one case was found with a de novo acute renal failure.

CONCLUSIONS

The discontinuation of the antipsychotic medication was a sufficient measure for the CK elevation to subside in the majority of the cases. Cases with myoglobinuria should eventually be treated more aggressively. Further recommendations for the clinical practice are presented.

Statin-induced Myopathy in Skeletal Muscle: the Role of Exercise

Statins are widely used drugs to lower cholesterol levels and to reduce the risk of cardiovascular disease. However, it has been reported that statins are associated with adverse side effects of skeletal myopathy. Statin treatment can impair mitochondrial function and induce apoptosis in skeletal muscle in both human and animal models. Ubiquinone plays an essential role in transferring electrons in the mitochondrial electron transfer chain for oxidative phosphorylation. However, statin treatment reduces ubiquinone levels in the cholesterol synthesis pathway, which may be associated with mitochondrial dysfunction. In addition, reactive oxygen species (ROS) production and apoptosis induced by statins may provide cellular and molecular mechanisms in skeletal myopathy. Exercise is the most effective therapy to prevent metabolic and cardiovascular diseases. However, whether exercise provides a benefit to or exacerbation of statin-induced myopathy in skeletal muscle remains poorly investigated. This review will briefly provide a comprehensive summary regarding the effects of statins on skeletal myopathy, and discuss the potential mechanisms of statin-induced myopathy and the role of exercise in statin-induced myopathy in skeletal muscle.

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.