Clinical features related to statin-associated muscle symptoms.

INTRODUCTION: Statins reduce cardiovascular disease risk and are generally well tolerated, yet up to 0.5% of statin-treated patients develop incapacitating muscle symptoms including rhabdomyolysis. Our objective was to identify clinical factors related to statin-associated muscle symptoms (SAMS). METHODS: Clinical and laboratory characteristics were evaluated in 748 statin-treated Caucasians (634 with SAMS and 114 statin-tolerant controls). Information was collected on statin type, concomitant drug therapies, muscle symptom history, comorbidities, and family history. Logistic regression was used to identify associations. RESULTS: Individuals with SAMS were 3.6 times (odds ratio [OR] 3.60, 95% confidence interval [CI] 2.08-6.22) more likely than statin-tolerant controls to have a family history of heart disease. Additional associations included obesity (OR 3.08, 95% CI 1.18, 8.05), hypertension (OR 2.24, 95% CI 1.33, 3.77), smoking (OR 2.08, 95% CI 1.16, 3.74), and statin type. DISCUSSION: Careful medical monitoring of statin-treated patients with the associated coexisting conditions may ultimately reduce muscle symptoms and lead to improved compliance. Muscle Nerve 59:537-537, 2019.

The causes of drug-induced muscle toxicity.

PURPOSE OF REVIEW: Clinically identified myopathies are frequently a consequence of medication toxicities. However, recognizing drug-induced myopathies is sometimes difficult. Developing a greater understanding of the underlying mechanisms of drug-induced muscle toxicity will promote enhanced awareness and recognition, and improved management of these syndromes. RECENT FINDINGS: The adverse impact of certain drugs on muscle metabolism, muscle cell atrophy, and myocyte apoptosis is increasingly clear. Glucocorticoids impair glucose handling and directly promote protein catabolism. Statins impair mitochondrial function and alter intracellular signaling proteins, which can lead to myocyte apoptosis. Alternatively, statins can induce an autoimmune necrotizing myositis. Several medications impair autophagy, thus limiting access to the needed glycogen stores. SUMMARY: This review provides an overview of the main underlying mechanisms of drug-induced myopathies. These myopathies will most often be related to a drug's ability to alter metabolism and protein balance, induce necrosis, or impair autophagy.

Noninflammatory myopathies.

The noninflammatory myopathies are a diverse group of diseases, some of which may mimic the autoimmune-mediated idiopathic inflammatory myopathies in their clinical presentation. They include certain metabolic, toxic, and infectious myopathies, as well as muscular dystrophies. In addition to muscle weakness, these forms of myopathy may present with exercise intolerance and muscle pain. Special testing techniques are often required to establish the diagnosis. This review focuses on those noninflammatory myopathies that should be included in the differential diagnosis of idiopathic inflammatory myopathy.

The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy.

OBJECTIVE: It is generally believed that muscle weakness in patients with polymyositis and dermatomyositis is due to autoimmune and inflammatory processes. However, it has been observed that there is a poor correlation between the suppression of inflammation and a recovery of muscle function in these patients. This study was undertaken to examine whether nonimmune mechanisms also contribute to muscle weakness. In particular, it has been suggested that an acquired deficiency of AMP deaminase 1 (AMPD1) may be responsible for muscle weakness in myositis. METHODS: We performed comprehensive functional, behavioral, histologic, molecular, enzymatic, and metabolic assessments before and after the onset of inflammation in a class I major histocompatibility complex (MHC)-transgenic mouse model of autoimmune inflammatory myositis. RESULTS: Muscle weakness and metabolic disturbances were detectable in the mice prior to the appearance of infiltrating mononuclear cells. Force contraction analysis of muscle function revealed that weakness was correlated with AMPD1 expression and was myositis specific. Decreasing AMPD1 expression resulted in decreased muscle strength in healthy mice. Fiber typing suggested that fast-twitch muscles were converted to slow-twitch muscles as myositis progressed, and microarray results indicated that AMPD1 and other purine nucleotide pathway genes were suppressed, along with genes essential to glycolysis. CONCLUSION: These data suggest that an AMPD1 deficiency is acquired prior to overt muscle inflammation and is responsible, at least in part, for the muscle weakness that occurs in the mouse model of myositis. AMPD1 is therefore a potential therapeutic target in myositis.

Hyperuricemia and gout: new concepts in diagnosis and management.

Gout is a chronic, progressive condition for which hyperuricemia is the primary risk factor. The initial episodes of gout may be brief, only lasting for 3 to 5 days, and patients may experience pain-free intercritical periods that last from months to years. However, as the disease progresses, acute gout flares become more frequent and prolonged (typically lasting ≥ 5-10 days). Chronic gouty arthritis develops, with shorter pain-free intervals; tophi become visible and interarticular joint damage occurs. Patients with advanced gout experience chronic pain and a decreased quality of life. Gout prevalence has increased significantly over time. Despite the increase in the number of gout cases, the disease is often mismanaged, especially in primary care. Hyperuricemia is inadequately controlled as a result of suboptimal dosing with urate-lowering drugs, intolerance to therapy, or poor patient compliance. This review article provides a comprehensive discussion of gout pathophysiology, risk factors, and approaches to treatment that encourage the clinician to appreciate hyperuricemia as a multifaceted disorder and manage the condition optimally.

Latest evidence on gout management: what the clinician needs to know.

Until recently, the last drug approved for the treatment of gout by the United States Food and Drug Administration was allopurinol in 1966. Since 2008, two new drugs for the treatment of gout, febuxostat and pegloticase, have been approved in the US. Febuxostat has been approved in the EU and pegloticase approval is anticipated. A new single-ingredient colchicine preparation is available in the US, and the treatment recommendations for the use of colchicine in acute gout have evolved, now favoring a low-dose regimen. Several other exciting drugs are in development. Herein, we review some of basic principles in the diagnosis and staging of gout. We then examine current treatment principles, with particular attention to febuxostat and pegloticase, offering suggestions as to where they might fit into a modern therapeutic algorithm for gout treatment. We then present available data on several exciting new agents in development, including interleukin-1 inhibitors, and relate them to advances in our understanding of gout pathogenesis. We conclude with some important nonpharmacologic principles for optimal management of this ancient and eminently treatable disease. Dedicated gout research, going on quietly in the background of other breathtaking advances in rheumatology, is now paying off. This comes at a time when the number of patients affected by gout continues to rise, mainly due to an epidemic of obesity. An effort to improve lifestyle choices as a society and better management of the disease by clinicians should have a positive impact on gout incidence and outcome in our lifetimes.

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.

Genetic risk for malignant hyperthermia in non-anesthesia-induced myopathies.

Malignant hyperthermia (MH) is a pharmacogenetic, autosomal dominantly inherited disorder of skeletal muscle triggered by volatile anesthetics and infrequently by extreme exertion and heat exposure. MH has variable penetrance with an incidence ranging from 1 in 5000 to 1 in 50,000-100,000 anesthesias. Mutations in the ryanodine receptor gene, RYR1, are found in 50-70% of cases. We hypothesized that a portion of patients with drug-induced muscle diseases, unrelated to anesthesia, such as severe statin myopathy, have underlying genetic liability that may include RYR1 gene mutations. DNA samples were collected from 885 patients in 4 groups: severe statin myopathy (n=197), mild statin myopathy (n=163), statin-tolerant controls (n=133), and non-drug-induced myopathies of unknown etiology characterized by exercise-induced muscle pain and weakness (n=392). Samples were screened for 105 mutations and variants in 26 genes associated with 7 categories of muscle disease including 34 mutations and variants in the RYR1 gene. Disease-causing mutations or variants in RYR1 were present in 3 severe statin myopathy cases, 1 mild statin myopathy case, 8 patients with non-drug-induced myopathy, and none in controls. These results suggest that disease-causing mutations and certain variants in the RYR1 gene may contribute to underlying genetic risk for non-anesthesia-induced myopathies and should be included in genetic susceptibility screening in patients with severe statin myopathy and in patients with non-statin-induced myopathies of unknown etiology.

Drugs causing muscle disease.

Many drugs can cause myopathies, and such myopathies may range widely from asymptomatic elevations in the serum creatine phosphokinase levels to severe myalgias, cramps, exercise intolerance, muscle weakness, and even rhabdomyolysis. In this article, some of the commonly used drugs that may induce myopathies, as well as the clinical phenotypes, diagnosis, and management of these syndromes are reviewed.

Gout therapeutics: new drugs for an old disease.

The approval of febuxostat, a non-purine-analogue inhibitor of xanthine oxidase, by the European Medicines Agency and the US Food and Drug Administration heralds a new era in the treatment of gout. The use of modified uricases to rapidly reduce serum urate concentrations in patients with otherwise untreatable gout is progressing. Additionally, advances in our understanding of the transport of uric acid in the renal proximal tubule and the inflammatory response to monosodium urate crystals are translating into potential new treatments. In this Review, we focus on the clinical trials of febuxostat. We also review results from studies of pegloticase, a pegylated uricase in development, and we summarise data for several other pipeline drugs for gout, such as the selective uricosuric drug RDEA594 and various interleukin-1 inhibitors. Finally, we issue a word of caution about the proper use of the new drugs and the already available drugs for gout. At a time of important advances, we need to recommit ourselves to a rational approach to the treatment of gout.

Effect of prophylaxis on gout flares after the initiation of urate-lowering therapy: analysis of data from three phase III trials.

BACKGROUND: Use of urate-lowering therapy (ULT), such as febuxostat or allopurinol, is recommended for the long-term management of hyperuricemia in patients with gout to reduce the incidence of acute flares. Because of the paradoxical relationship between early use of ULT and the increased incidence of gout flares, prophylaxis with either low-dose colchicine or NSAIDs has been recommended, although there have been concerns about the long-term prophylactic use of these agents. OBJECTIVES: The present analysis examined flare rates during the 3 Phase III trials of febuxostat based on mean postbaseline serum urate (sUA) concentrations and duration of prophylaxis. Adverse events (AEs) were assessed by prophylaxis with colchicine or naproxen. METHODS: This investigator-initiated, post hoc reanalysis of data on gout flares from the 3 randomized, placebo-controlled, Phase III trials evaluated the proportion of patients requiring treatment for gout flares at 4-week intervals based on mean postbaseline sUA concentrations <6.0 and ≥ 6.0 mg/dL. The 3 trials enrolled males or females aged 18-85 years who had a diagnosis of gout and a baseline sUA concentration ≥ 8.0 mg/dL. Patients received ULT (febuxostat or allopurinol) or placebo for 6 months or 1 year and flare prophylaxis with colchicine 0.6 mg/d or naproxen 250 mg BID for 8 weeks or 6 months. The prophylactic regimen was chosen at the discretion of the investigator, based on renal function and known intolerance to either drug. Patients with an estimated creatinine clearance <50 mL/min were not to receive naproxen. AEs were summarized based on prophylaxis with colchicine or naproxen. RESULTS: The 3 trials enrolled a total of 4101 patients with gout. The majority were white (80.1%), male (94.5%), and obese (body mass index ≥ 30 kg/m(2)) (62.8%). The mean duration of gout ranged from 10.9-11.9 years, and the mean baseline sUA concentration ranged from 9.6-9.9 mg/dL. Flare rates increased sharply (up to 40%) at the end of 8 weeks of prophylaxis and then declined gradually, whereas flare rates were consistently low (range, 3%-5%) at the end of 6 months of prophylaxis. Mean postbaseline sUA concentrations were correlated with flare rates; by the end of each study, patients with a mean postbaseline sUA concentration <6.0 mg/dL had fewer flares than did those with a mean postbaseline sUA concentration ≥ 6.0 mg/dL. There were differences in rates of AEs between prophylaxis groups, but the rates did not increase with increased duration of prophylaxis. CONCLUSION: This analysis of gout flare data from the 3 Phase III trials of febuxostat found that flare prophylaxis for up to 6 months during the initiation of ULT appeared to provide greater benefit than flare prophylaxis for 8 weeks, with no increase in AEs.

Drug-induced myopathies.

The most common drugs currently in use that may cause myopathies were reviewed using the Medline database (U.S. National Library of Medicine, Bethesda, Maryland). Our review included results from epidemiologic and database surveys, clinical trials, and case reports. The clinical spectrum is wide, and presentations range from asymptomatic elevations in serum creatine phosphokinase levels to severe life-threatening rhabdomyolysis. Management of suspected drug-induced myopathy should include immediate discontinuation of the offending agent, as well as supportive care when needed. Earlier diagnosis and drug discontinuation raises the likelihood of resolution and recovery.

Malignancy is associated with dermatomyositis but not polymyositis in Northern New England, USA.

OBJECTIVE: To retrospectively evaluate the association of idiopathic inflammatory myopathy (IIM) and malignancy in patients seen at 1 academic center over a 23-year period. METHODS: Patients were identified using the International Classification of Diseases, 9th edition (ICD-9) codes and diagnoses, then confirmed by chart review. Population cancer statistics obtained from the US Centers for Disease Control for Vermont and New Hampshire were used for comparison. RESULTS: Chart review confirmed IIM in 198 of 483 patients initially identified by ICD-9 codes. Within 5 years of diagnosis with IIM, malignancy developed in 32 patients (16.2%), 24 of whom (75%) had dermatomyositis (DM). Malignancy and DM developed within 1 year in 75%. The cancer risk associated with DM was much greater than the risk associated with other IIM. The most frequent tumor types were breast, lung, pancreas, and colon. DM patients with cancer were more frequently male and >or= 45 years of age than those without cancer. There were no cases of interstitial lung disease among patients with cancer and any form of IIM. The incidence of cancer was increased in patients with DM compared to age- and sex-matched population controls, both over a 5-year interval surrounding the diagnosis of DM and over the lifetime interval following diagnosis. CONCLUSION: The risk of cancer in IIM is concentrated among patients with DM. The association between DM and cancer was enhanced by its temporal relationship (< 1 year) in 87.5% of these cases. Patients with malignancy-associated DM were more frequently male and over age 45 and less likely to have interstitial lung disease.

Effects of febuxostat versus allopurinol and placebo in reducing serum urate in subjects with hyperuricemia and gout: a 28-week, phase III, randomized, double-blind, parallel-group trial.

OBJECTIVE: To compare the urate-lowering efficacy and safety of febuxostat, allopurinol, and placebo in a large group of subjects with hyperuricemia and gout, including persons with impaired renal function. METHODS: Subjects (n = 1,072) with hyperuricemia (serum urate level > or = 8.0 mg/dl) and gout with normal or impaired (serum creatinine level >1.5 to < or = 2.0 mg/dl) renal function were randomized to receive once-daily febuxostat (80 mg, 120 mg, or 240 mg), allopurinol (300 or 100 mg, based on renal function), or placebo for 28 weeks. RESULTS: Significantly (P < or = 0.05) higher percentages of subjects treated with febuxostat 80 mg (48%), 120 mg (65%), and 240 mg (69%) attained the primary end point of last 3 monthly serum urate levels <6.0 mg/dl compared with allopurinol (22%) and placebo (0%). A significantly (P < 0.05) higher percentage of subjects with impaired renal function treated with febuxostat 80 mg (4 [44%] of 9), 120 mg (5 [45%] of 11), and 240 mg (3 [60%] of 5) achieved the primary end point compared with those treated with 100 mg of allopurinol (0 [0%] of 10). Proportions of subjects experiencing any adverse event or serious adverse event were similar across groups, although diarrhea and dizziness were more frequent in the febuxostat 240 mg group. The primary reasons for withdrawal were similar across groups except for gout flares, which were more frequent with febuxostat than with allopurinol. CONCLUSION: At all doses studied, febuxostat more effectively lowered and maintained serum urate levels <6.0 mg/dl than did allopurinol (300 or 100 mg) or placebo in subjects with hyperuricemia and gout, including those with mild to moderately impaired renal function.

Drug-induced arthritic and connective tissue disorders.

OBJECTIVES: All pharmacologic agents have the potential for both benefit and toxicity. Among the more interesting and important adverse consequences of drug therapy are a range of joint and connective tissue complaints that may mimic or reproduce primary rheumatologic diseases. In this article, we review the literature on commonly used drugs reported to induce arthritis and/or connective tissue-based diseases. We assess the strength of the reported associations, discuss diagnostic features and treatment implications, and consider possible mechanisms for drug-induced genesis of rheumatic conditions. METHODS: We reviewed the Medline database from 1987 to 2006 to identify drug-induced arthritic and connective-tissue disease syndromes, utilizing 48 search terms. A qualitative review was performed after the articles were abstracted and the relevant information was organized. RESULTS: Three hundred fifty-seven articles of possible relevance were identified. Two hundred eleven publications were included in the final analysis (case series and reports, clinical trials, and reviews). Many drugs were identified as mimicking existing rheumatic conditions, including both well-established small molecules (eg, sulfasalazine) and recently introduced biologic agents (eg, antitumor necrosis factor agents). The most commonly reported drug-induced rheumatic conditions were lupus-like syndromes. Arthritis and vasculitis were also often reported. CONCLUSIONS: Drug-induced rheumatic syndromes are manifold and offer the clinician an opportunity to define an illness that may remit with discontinuation of the offending agent. Early diagnosis and withdrawal of the drug may prevent unnecessary morbidity and disability.

Management of gout in older adults: barriers to optimal control.

Gout, a common inflammatory arthritis, can be diagnosed with absolute certainty. Gout results from the body's reaction to urate crystals deposited in tissues, and this pathophysiology is well understood. If used appropriately, available therapies can be entirely effective in not only treating the symptoms of gout, but also in eliminating the excess urate from the body, thereby eradicating the disease. Because of these facts, management of patients with gout should be successful. However, management of gout is particularly challenging in the elderly, even though the principles of management are the same for all age groups. The purpose of this article is to review these principles and discuss them as they pertain to the elderly. The classic gout attack is acute in onset, extremely painful and associated with marked swelling, warmth, erythema and tenderness of a single joint. However, the diagnosis of gout may be challenging in the elderly because atypical presentations are more common in this group. Treatment of acute gout involves the use of NSAIDs, colchicine, corticosteroids or corticotropin (adrenocorticotropic hormone). Unfortunately, co-morbid conditions such as chronic kidney disease, peptic ulcer disease and congestive heart failure may make the use of these agents dangerous or contraindicated. Thus, it is important to try to treat an acute flare of gout at the earliest sign, because the sooner treatment is initiated, the faster the inflammation will resolve. Urate-lowering agents include allopurinol and uricosuric agents. These also must be used judiciously in the elderly. However, if used at the lowest dose that maintains the serum urate level below 5.0-6.0 mg/dL, the excess urate in the body will be eliminated, acute flares will no longer occur and tophi will resolve. Gout is often seen in association with hypertension, excessive alcohol consumption, obesity and hypertriglyceridaemia. These conditions and the medications used to treat them may contribute to the hyperuricaemia. Treating these conditions and using medications that do not promote hyperuricaemia will aid in the management of gout. Despite the challenges that often complicate the management of gout in the elderly, an understanding of the pathophysiology of the disease and both the indications and limitations of the medications used should allow successful treatment.

Myotoxicity associated with lipid-lowering drugs.

PURPOSE OF REVIEW: Lipid-lowering drugs are associated with myotoxicity, which ranges in severity from myalgias to rhabdomyolysis resulting in renal failure and death. Although rhabdomyolysis is rare, muscle symptoms and serum creatine kinase elevations are sufficiently frequent during the course of lipid-lowering drug therapy to pose diagnostic challenges for the clinician. Progress in our understanding of this form of myotoxicity is reviewed. RECENT FINDINGS: Muscle pain and weakness are the cardinal symptoms and often interfere with vigorous exercise. These symptoms may occur with or without serum creatine kinase elevations. The risk of myotoxicity is increased by combination statin-fibrate therapy as well as by factors that elevate tissue levels of the lipid-lowering drug, including the dose, drug-drug interactions, and host factors. Underlying neuromuscular diseases may become clinically apparent during statin therapy and may predispose to myotoxicity. The pathophysiology of myotoxicity most probably involves metabolic effects of the statins on the isoprenoid pool and on mitochondrial function. SUMMARY: Management of myotoxicity requires an evaluation of risk factors prior to prescribing lipid-lowering drugs, attention to muscle symptoms, and withdrawal of drug in the event of significant abnormalities.