The role of cholesterol-lowering agents in drug-induced rhabdomyolysis and polymyositis

Role of genetics in the prediction of statin-associated muscle symptoms and optimization of statin use and adherence

Statin therapy reduces cardiovascular events in patients with, or at risk of, atherosclerotic cardiovascular disease. However, statins are underutilized in patients for whom they are indicated and are frequently discontinued. Discontinuation may be the result of statin-associated muscle symptoms (SAMS), which encompass a broad spectrum of clinical phenotypes from myalgia to severe myopathy. As with many adverse drug reactions (ADRs), inter-individual variability in susceptibility to SAMS is due, at least in part, to differences in host genetics. The genetic basis for SAMS has been investigated in candidate gene studies, genome-wide association studies, and, more recently, studies of multi-omic networks, including at the transcriptome level. In this article, we provide a systematic review of the pharmacogenetic basis of SAMS, focusing on how an understanding of the genetic and molecular determinants of SAMS can be considered in a personalized approach to reduce the incidence of this ADR, optimize statin adherence, and reduce the risk for cardiovascular events.

Biochemistry of Statins

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Elevated blood lipids may be a major risk factor for CVD. Due to consistent and robust association of higher low-density lipoprotein (LDL)-cholesterol levels with CVD across experimental and epidemiologic studies, therapeutic strategies to decrease risk have focused on LDL-cholesterol reduction as the primary goal. Current medication options for lipid-lowering therapy include statins, bile acid sequestrants, a cholesterol-absorption inhibitor, fibrates, nicotinic acid, and omega-3 fatty acids, which all have various mechanisms of action and pharmacokinetic properties. The most widely prescribed lipid-lowering agents are the HMG-CoA reductase inhibitors, or statins. Since their introduction in the 1980s, statins have emerged as the one of the best-selling medication classes to date, with numerous trials demonstrating powerful efficacy in preventing cardiovascular outcomes (Kapur and Musunuru, 2008 [1]). The statins are commonly used in the treatment of hypercholesterolemia and mixed hyperlipidemia. This chapter focuses on the biochemistry of statins including their structures, pharmacokinetics, and mechanism of actions as well as the potential adverse reactions linked to their clinical uses.

Dyslipidemia in patients with chronic and end-stage kidney disease

In this review, we discuss the physiology, diagnosis and treatment of dyslipidemia in patients with chronic and end-stage renal disease. The recent important clinical trials in patients with chronic kidney disease and dyslipidemia are reviewed. Because of the lack of evidence in treating lipid abnormalities in this specific patient population, we propose that future studies should focus on the pathophysiological mechanisms and treatment of dyslipidemia in this special patient population.

Persistent use of against-label statin-fibrate combinations from 2003-2009 despite United States Food and Drug Administration dose restrictions

STUDY OBJECTIVE

To describe the prevalence of prescribing against-label statin-fibrate combination therapy.

DESIGN

Retrospective cohort study.

DATA SOURCE

Medstat MarketScan Commercial Claims and Encounter database.

PATIENTS

Adults (aged 18-89 yrs) who were prescribed statin-fibrate combination therapy between January 1, 2003, and June 30, 2009, had pharmacy claims demonstrating two or more concurrently filled prescriptions for a statin and a fibrate, and had continuous insurance enrollment for at least 12 months.

MEASUREMENTS AND MAIN RESULTS

Claims data were used to identify patients with dyslipidemia based on International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. National Drug Codes were used to describe concurrent statin-fibrate combination therapy. The primary outcome was recent use of against-label statin-fibrate combination therapy, defined as use during the last 18 months (January 1, 2008-June 30, 2009) of the study period. Patients were stratified according to statin and dosage to identify against-label combination use (e.g., simvastatin > 10 mg/day with gemfibrozil). Within the recent-use period, 131,394 patients were prescribed concurrent statin-fibrate combination therapy; of these patients, 13,420 (10.2%) had against-label therapy. Simvastatin-gemfibrozil accounted for 8978 (66.9%) of all against-label combinations. Of all 9877 simvastatin-gemfibrozil combinations prescribed in the recent-use period (both on-label and against-label use), 8978 (90.9%) were against label. The secondary outcome was prevalence of against-label statin-fibrate combination therapy on an annual basis: 15.5% in 2003, 18.7% in 2004, 9.1% in 2005, 8.3% in 2006, 9.2% in 2007, and 9.8% in 2008.

CONCLUSION

Against-label statin-fibrate combination therapy continues to be prescribed despite established United States Food and Drug Administration (FDA) dose restrictions. Nearly every time the simvastatin-gemfibrozil combination was prescribed, it was against label because simvastatin exceeded the maximum dose restriction. Updated simvastatin labeling in June 2011 includes additional maximum dose restrictions and new contraindications, which include gemfibrozil. Different approaches in clinical practice are needed to ensure adherence with the revised FDA labeling.

Diagnosis, prevention, and management of statin adverse effects and intolerance: proceedings of a Canadian Working Group Consensus Conference

While the proportion of patients with significant statin-associated adverse effects or intolerance is very low, the increasing use and broadening indications have led to a significant absolute number of such patients commonly referred to tertiary care facilities and specialists. This report provides a comprehensive overview of the evidence pertaining to a broad variety of statin-associated adverse effects followed by a consensus approach for the prevention, assessment, diagnosis, and management. The overview is intended both to provide clarification of the untoward effects of statins and to impart confidence in managing the most common issues in a fashion that avoids excessive ancillary testing and/or subspecialty referral except when truly necessary. The ultimate goal is to ensure that patients who warrant cardiovascular risk reduction can be treated optimally, safely, and confidently with statin medications or alternatives when warranted.

Rhabdomyolysis: a review, with emphasis on the pediatric population

Rhabdomyolysis is a common clinical syndrome and accounts for 7% of all cases of acute kidney injury (AKI) in the USA. It can result from a wide variety of disorders, such as trauma, exercise, medications and infection, but in the pediatric population, infection and inherited disorders are the most common causes of rhabdomyolysis. Approximately half of patients with rhabdomyolysis present with the triad of myalgias, weakness and dark urine. The clinical suspicion, especially in the setting of trauma or drugs, is supported by elevated creatinine kinase levels and confirmed by the measurement of myoglobin levels in serum or urine. Muscle biopsy and genetic testing should be performed if rhabdomyolysis is recurrent or metabolic myopathy is suspected. Early recognition is important to prevent AKI through the use of aggressive hydration. Prevention is important in patients with inherited forms, but novel therapies may be developed with the better understanding of the pathophysiology and genetics of rhabdomyolysis.

Statins may aggravate myasthenia gravis

Statin-induced myopathy is well-known, but the effect of cholesterol-lowering agents on myasthenia gravis (MG) has not been studied in detail. We investigated statin use and its effects on MG among patients with this disease. Statin information was systemically obtained from 170 patients being treated at the Neuromuscular Disease Clinic at the University of Alabama at Birmingham. When a new myalgic syndrome or worsening of MG developed within 4 months after statin treatment, no other likely cause was found, and clinical improvement occurred either with or without discontinuation of the statin, we considered these symptoms to be statin-induced. Fifty-four patients (31%) were on statins. The statin group had proportionally more males, and older patients compared with the non-statin group. A myalgic syndrome was noted in 7 (13%) patients, but it resolved without any sequelae after withdrawal of the statin. MG worsening occurred in 6 (11%) patients without regard to type of MG or brand of statin. MG worsening occurred independently of myalgic syndrome and involved predominantly oculobulbar symptoms within 1-16 weeks of statin treatment. In 4 patients, additional treatment was needed to reverse MG worsening. Statins are safe in the majority of MG patients, but their use must be accompanied by close observation for possible MG worsening.

Dermatomyosite induite par la fluvastatine

BACKGROUND

Dermatomyositis is a rare inflammatory dermatosis for which an iatrogenic origin has been described in very few cases. We report a case of dermatomyositis occurring after fluvastatin intake.

CASE REPORT

A 76-year-old male patient sought medical attention for a photodistributed rash and considerable muscular weakness present for one month. Two months earlier, fluvastatin had been introduced following the discovery of dyslipidemia. Serum creatine phosphokinase levels were elevated. Histological examination of a muscle biopsy was consistent with a diagnosis of dermatomyositis. Investigation for neoplasia and associated autoimmune disease proved negative. All clinical and laboratory abnormalities diminished spontaneously without recourse to corticosteroids within one month of the final intake of fluvastatin. After a follow-up period of three years, no recurrence was observed and no signs of neoplasia or connectivitis were found.

DISCUSSION

Iatrogenic dermatomyositis has only been reported in rare cases. Certain drugs have been incriminated, notably D-penicillamine. Six cases of drug-induced dermatomyositis have been described with statins: simvastatin, atorvastatin, pravastatin and lovastatin. Of these cases, only one resolved spontaneously after withdrawal of the drug alone without use of corticosteroids. Our case concerns intake of fluvastatin, an HMG-CoA reductase inhibitor with rare though well-known muscular side effects: elevated serum CPK, myalgia and rhabdomyolysis. Six cases of polymyositis have also been reported. Ours is the first case of dermatomyositis described with this category of statins. It is also the second reported case showing improvement after withdrawal of the lipid-lowering agent and without corticosteroids. Thus in cases of dermatomyositis, this iatrogenic picture should be sought routinely.

Addressing cardiovascular risk beyond low-density lipoprotein cholesterol: the high-density lipoprotein cholesterol story

A large body of evidence from numerous, well-controlled, randomized trials demonstrates that treatment with statins reduce morbidity and mortality from cardiovascular disease (CVD). Although these observations are important and have resulted in the adoption of standard of care approaches to the management of CVD risk, they do not tell the whole story. When reviewing these landmark trials it is clear that on average two thirds of events are not prevented. This leads to the evaluation of risk beyond low-density lipoprotein cholesterol. This review focuses on the association of low high-density lipoprotein (HDL) cholesterol and increased CVD risk, the published trials that study the effect of raising HDL cholesterol on CVD outcomes, and the novel approaches toward HDL cholesterol raising that are on the horizon.

Genetic polymorphisms in cytochrome P450 enzymes: effect on efficacy and tolerability of HMG-CoA reductase inhibitors

Adverse drug reactions are common; they are responsible for a number of debilitating side effects and are a significant cause of death following drug therapy. It is now clear that a significant proportion of these adverse drug reactions, as well as therapeutic failures, are caused by genetic polymorphism, genetically based interindividual differences in drug absorption, disposition, metabolism, or excretion. HMG-CoA reductase inhibitors are generally very well tolerated and easy to administer with good patient acceptance. There are only two uncommon but potentially serious adverse effects related to HMG-CoA reductase inhibitor therapy: hepatotoxicity and myopathy. The occurrence of lethal rhabdomyolysis in patients treated with cerivastatin has prompted concern on the part of physicians and patients regarding the tolerability of HMG-CoA reductase inhibitors. Apart from pravastatin and rosuvastatin, HMG-CoA reductase inhibitors are metabolized by the phase I cytochrome P450 (CYP) superfamily of drug metabolizing enzymes. The best-characterized pharmacogenetic polymorphisms are those within this enzyme family. One of these enzymes, CYP2D6, plays an important role in the metabolism of simvastatin. It has been shown that the cholesterol-lowering effect as well as the efficacy and tolerability of simvastatin is influenced by CYP2D6 genetic polymorphism. Because the different HMG-CoA reductase inhibitors differ, with respect to the degree of metabolism by the different CYP enzymes, genotyping may help to select the appropriate HMG-CoA reductase inhibitor and the optimal dosage during the start of the treatment and will allow for more efficient individual therapy. A detailed knowledge of the genetic basis of individual drug response is potentially of major clinical and economic importance.

Effects of HMG-CoA reductase inhibitors on skeletal muscle: are all statins the same?

The 3-hydroxy-3-methyl coenzyme A (HMG-CoA) reductase inhibitors or statins, specifically inhibit the enzyme HMG-CoA in the liver, thereby inhibiting the rate limiting step in cholesterol biosynthesis and so reducing plasma cholesterol levels. Numerous studies have consistently demonstrated that cholesterol lowering with statin therapy reduces morbidity and mortality from coronary heart disease, whilst recent evidence has demonstrated that benefits of statin therapy may also extend into stroke prevention. Since hypercholesterolaemia is a chronic condition, the long-term safety and tolerability of these agents is an important issue. Numerous large-scale clinical trials have consistently demonstrated a positive safety and tolerability profile for statins. Hepatic, renal and muscular systems are rarely affected during statin therapy, with adverse reactions involving skeletal muscle being the most common, ranging from mild myopathy to myositis and occasionally to rhabdomyolysis and death. Postmarketing data supports the positive safety and tolerability profile of statins, with an overall adverse event frequency of less than 0.5% and a myotoxicity event rate of less than 0.1%. The recent withdrawal of cerivastatin from the world market due to deaths from rhabdomyolysis has, however, focused attention on the risk of adverse events and in particular myotoxicity associated with statins. Indeed, initial clinical trial data supports postmarketing data, demonstrating a higher incidence of myotoxicity associated with cerivastatin, particularly when used in combination with fibrates. The potential mechanisms underlying statin-induced myotoxicity are complex with no clear consensus of opinion. Candidate mechanisms include intracellular depletion of essential metabolites and destabilisation of cell membranes, resulting in increased cytotoxicity. Cytochrome P450 3A4 is the main isoenzyme involved in statin metabolism. Reduced activity of this enzyme due to either reduced expression or inhibition by other drugs prescribed concomitantly such as cyclosporin or itraconazole may increase drug bioavailability and the risk of myotoxicity. Such factors may partly account for the interindividual variability in susceptibility to statin-induced myotoxicity, although other as of yet unclarified, genetic factors may also be involved. The risk of rhabdomyolysis is increased with combination fibrate-statin therapy, with initial evidence suggesting that gemfibrozil-statin combination may particularly increase the risk of myotoxicity, with pharmacodynamic as well as pharmacokinetic mechanisms being involved.

Myopathy Associated With HMG-CoA Reductase Inhibitors (Statins): A Series of 10 Patients and Review of the Literature

OBJECTIVE

To examine the clinical profile of patients with myotoxicity due to HMG-CoA reductase inhibitors and the pathological features in the biopsies.

DESIGN

All patients receiving HMG-CoA reductase inhibitors who underwent muscle biopsy at the State Neuropathology Service, Melbourne, from October 2000 to September 2001 were identified, and clinical questionnaires were completed by the referring doctor.

RESULTS

Ten patients, including 4 males and 6 females, aged 50 to 76 years (median, 69.5 y), were identified. Six patients were diabetic and one was severely hypothyroid. Statins included simvastatin in 5, atorvastatin in 4, and cerivastatin in 1. Six patients had either a recent doubling in dosage of statin or change to another statin. Six patients were also taking one or more drugs with known interaction with HMG-CoA reductase inhibitors (gemfibrozil, ketoconazole, calcium channel antagonists, dothiepin, celecoxib, amiodarone). All patients had weakness, 8 had myalgias, and 3 had myoglobinuria. Peak creatine kinase (CK) elevation ranged from 1100 to 160,000 U/L (median, 16,000 U/L). Following cessation of statins, resolution of symptoms and normalization of CK levels were noted in all within a few months. All muscle biopsies showed necrotizing myopathy with minimal inflammation in 4 (40%). Histochemical studies did not suggest mitochondrial cytopathy.

CONCLUSION

Myotoxicity due to HMG-CoA reductase inhibitors commonly occurs in patients taking concomitant medication known to interact with metabolism of these agents, such as gemfibrozil or ketoconazole, or with an increase in dose. In addition, elderly patients with obesity, diabetes mellitus, and hypothyroidism appear to be at increased risk of developing myotoxicity.

Rhabdomyolysis and HMG-CoA reductase inhibitors

OBJECTIVE

To review rhabdomyolysis and discuss the role of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) and their interactions with other agents in precipitating this condition, and to present case reports of statin-induced rhabdomyolysis.

DATA SOURCE

Relevant clinical literature was accessed using MEDLINE (January 1985-October 2000). The following search terms were used: rhabdomyolysis, adverse events, drug interactions, statins, and HMG-CoA reductase inhibitors.

DISCUSSION

Rhabdomyolysis occurs when extensive muscle damage results in the release of cellular contents into systemic circulation. Major complications include acute renal failure, cardiac abnormalities, and compartment syndrome. Treatment of rhabdomyolysis is supportive, with the primary aim of preventing renal and cardiac complications. Statin monotherapy or combination therapy may result in myopathy, which rarely progresses to rhabdomyolysis. The mechanism for drug interactions with the statins involves their property of lipid or water solubility. This characteristic determines the degree of hepatoenteric or renal metabolism of the statins. All statins except pravastatin undergo metabolism via the cytochrome P450 enzyme system. Other pharmacologic agents that are also metabolized via this pathway may interact with the statins and cause rhabdomyolysis. The risk of statin-induced rhabdomyolysis is increased significantly when statins are used concomitantly with such drugs as fibrates, cyclosporine, macrolide antibiotics, and azole antifungals.

CONCLUSIONS

Rhabdomyolysis is a rare but clinically important adverse event of statin monotherapy or combination therapy. Thorough understanding of this condition may help prevent or minimize adverse health outcomes in patents receiving statin therapy.

Statin-fibrate combination therapy

BACKGROUND

Precautionary warnings for severe myopathy and rhabdomyolysis from the coadministration of statins and fibrates have been well publicized. However, a recent cerivastatin labeling change made the combined use with fibric acid derivatives a contraindication. Practical recommendations for clinicians who care for patients with refractory mixed hyperlipidemia are needed.

OBJECTIVE

To provide recommendations for clinicians in the treatment of refractory mixed hyperlipidemia.

DATA SOURCES

A comprehensive MEDLINE (1966-July 2000) and bibliographic search was performed.

DATA SYNTHESIS

Thirty-six published clinical trials and 29 case reports involving combination therapy with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors and fibric acid derivatives regarding the occurrence of rhabdomyolysis or myopathy were reviewed. The literature review demonstrated that combination therapy with a statin and fibrate increases the risk of muscle damage, with an incidence of 0.12%. Risk factors that predispose patients to myopathy caused by combination statin-fibrate therapy include increased age, female gender, renal or liver disease, diabetes, hypothyroidism, debilitated status, surgery, trauma, excessive alcohol intake, and heavy exercise.

CONCLUSIONS

Combination therapy with a statin and fibrate offers significant therapeutic advantage for the treatment of severe or refractory mixed hyperlipidemia. Although such a combination does increase the risk of myopathy, with an incidence of approximately 0.12%, this small risk of myopathy rarely outweighs the established morbidity and mortality benefits of achieving lipid goals. Nevertheless, a higher incidence of myopathy has been reported with statin monotherapy. When monotherapy with a statin fails to control mixed hyperlipidemia, combination therapy may be considered. Niacin may be added before a fibrate is considered, as it appears to have less risk of myopathy. Statin-fibrate combination therapy must be undertaken cautiously and only after careful risk-benefit analysis. Patient counseling on the risks and warning signs of myopathy is extremely important.

HMG-CoA reductase inhibitors and myotoxicity

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors specifically inhibit HMG-CoA reductase in the liver, thereby inhibiting the biosynthesis of cholesterol. These drugs significantly reduce plasma cholesterol level and long term treatment reduces morbidity and mortality associated with coronary heart disease. The tolerability of these drugs during long term administration is an important issue. Adverse reactions involving skeletal muscle are not uncommon, and sometimes serious adverse reactions involving skeletal muscle such as myopathy and rhabdomyolysis may occur, requiring discontinuation of the drug. Occasionally, arthralgia, alone or in association with myalgia, has been reported. In this article we review scientific data provided via Medline, adverse drug reaction case reports from the Swedish Drug Information System (SWEDIS) and the World Health Organization's International Drug Information System (INTDIS) database, focusing on HMG-CoA reductase inhibitor-related musculoskeletal system events. Cytochrome P450 (CYP) 3A4 is the main isoenzyme involved in the metabolic transformation of HMG-CoA reductase inhibitors. Individuals with both low hepatic and low gastrointestinal tract levels of CYP3A4 expression may be at in increased risk of myotoxicity due to potentially higher HMG-CoA reductase inhibitor plasma concentrations. The reported incidence of myotoxic reactions in patients treated with this drug class varies from 1 to 7% and varies between different agents. The risk of these serious adverse reactions is dose-dependent and may increase when HMG-CoA reductase inhibitors are prescribed concomitantly with drugs that inhibit their metabolism, such as itraconazole, cyclosporin, erythromycin and nefazodone. Electrolyte disturbances, infections, major trauma, hypoxia as well as drugs of abuse may increase the risk of myotoxicity. It is important that the potentially serious adverse reactions are recognised and correctly diagnosed so that the HMG-CoA reductase inhibitor may at once be withdrawn to prevent further muscular damage.

Rhabdomyolysis and acute renal failure due to combination therapy with simvastatin and warfarin

Simvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, is widely used to treat hyperlipidaemia. Although myalgias are recognized adverse effects, clinically significant elevations in serum creatine phosphokinase (CPK) levels are uncommon. We describe a case of rhabdomyolysis and acute renal failure associated with concomitant use of simvastatin and warfarin. Rhabdomyolysis and renal failure occurred 7 days after warfarin (5 mg day-1) was added to a chronic stable dose of simvastatin (20 mg day-1) and resolved abruptly after discontinuation of simvastatin. We recommend careful monitoring when warfarin is given to patients receiving simvastatin.

Metabolism and drug interactions of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in transplant patients: are the statins mechanistically similar?

3-Hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.88) inhibitors are the most effective drugs to lower cholesterol in transplant patients. However, immunosuppressants and several other drugs used after organ transplantation are cytochrome P4503A (CYP3A, EC 1.14.14.1) substrates. Pharmacokinetic interaction with some of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, specifically lovastatin and simvastatin, leads to an increased incidence of muscle skeletal toxicity in transplant patients. It is our objective to review the role of drug metabolism and drug interactions of lovastatin, simvastatin, pravastatin, fluvastatin, atorvastatin, and cerivastatin. In the treatment of transplant patients, from a drug interaction perspective, pravastatin, which is not significantly metabolized by CYP enzymes, and fluvastatin, presumably a CYP2C9 substrate, compare favorably with the other statins for which the major metabolic pathways are catalyzed by CYP3A.

Long-term efficacy and safety of fenofibrate and a statin in the treatment of combined hyperlipidemia

To assess the long-term efficacy and use of fenofibrate together with a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor ("statin") in the treatment of elevated levels of triglycerides and low-density lipoprotein (LDL) cholesterol, we conducted a study that compared a before- and after-case series. The study involved 80 patients with a diagnosis of combined hyperlipidemia and existing coronary artery disease (81% of patients) or outpatients with > or = 3 risk factors for coronary artery disease who had been receiving treatment at a tertiary care center. Fasting biochemical measures were obtained at baseline during monotherapy with a statin consisting of pravastatin 20 mg once daily or simvastatin 10 mg once daily (39 patients) or fenofibrate 300 mg once daily (41 patients), and during a 2-year period of combination therapy. This combination therapy comprised fenofibrate 300 mg once daily or micronized fenofibrate 200 mg once daily taken together with pravastatin 20 mg once daily (63 patients) or simvastatin 10 mg once daily (17 patients). The main outcome measures were: (1) absolute and percent change in total cholesterol, triglycerides, LDL cholesterol, and high-density lipoprotein (HDL) cholesterol; (2) percentage of patients with alanine aminotransferase > or = 2x the upper limits of normal on any occasion; (3) percentage of patients with creatinine kinase > or = 3 times the upper limits of normal on any occasion; (4) absolute changes in alanine aminotransferase and creatinine phosphokinase; and (5) months on combination therapy. Patients receiving combination therapy had a mean total cholesterol (+/- standard error of the mean [SEM]) that was significantly decreased by 26+/-1%, triglycerides by 41+/-3%, and LDL cholesterol by 28+/-2%, and mean HDL cholesterol that was significantly increased by 22+/-6%. These changes correspond to mean absolute changes of total cholesterol: -75+/-5 mg/dL; triglycerides: -94+/-13 mg/dL; LDL cholesterol: -52+/-5 mg/dL; and HDL cholesterol: 5+/-1 mg/dL. During combination treatment, alanine aminotransferase increased by 2+/-2 U/liter (not significant) and creatinine phosphokinase decreased by 4+/-13 U/liter (not significant). During treatment, 8 patients (10%) had transitory isolated elevations in alanine aminotransferase levels > or = 2 times the upper limits of normal and 2 patients (2.5%) had an isolated and transitory elevation of creatinine kinase (> or = 3x but < 6x upper limits of normal) without associated muscle symptoms. Patient-years on combination therapy equaled 220.6 (average 2.06 years per patient). The results demonstrated that combination treatment with fenofibrate and low-dose simvastatin or pravastatin is generally safe and effective for the treatment of combined hyperlipidemia in patients with normal hepatic and renal function.

Lovastatin-induced rhabdomyolysis possibly associated with clarithromycin and azithromycin

OBJECTIVE

To describe two cases of rhabdomyolysis in patients taking lovastatin that were precipitated by the use of the newer macrolide antibiotics clarithromycin and azithromycin.

CASE SUMMARIES

In each case, the patients were treated over 5 years with lovastatin and developed rhabdomyolysis that coincided with the completion of a prescribed regimen of a newer macrolide antibiotic. Following intravenous hydration and administration of bicarbonate, the patients' condition resolved without permanent' sequelae.

DISCUSSION

Rhabdomyolysis is a clinical syndrome resulting from the destruction of skeletal muscle that may progress to renal failure Several drugs have been associated with rhabdomyolysis, including lovastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor. Erythromycin is a macrolide antibiotic that may increase the risk of lovastatin-induced rhabdomyolysis. To our knowledge, these cases are the first published reports of lovastatin-induced rhabdomyolysis associated with azithromycin and clarithromycin.

CONCLUSIONS

The risk of drug-induced rhabdomyolysis due to the potential interaction between lovastatin and azithromycin or clarithromycin should be considered before the concomitant use of these agents.

Differential effects of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors on the development of myopathy in young rats

HMG-CoA reductase inhibitors (statins), cholesterol-lowering drugs that have not been approved for use in children and adolescents, may cause myopathy as a side effect. We compared the effects of three statins (simva-, prava- and lovastatin) in young rats to determine whether skeletal muscle of young animals is more susceptible than that of adults. We also evaluated whether the type of statin (lipophilic versus hydrophilic) determines the degree of muscle damage. Administration via chow of simvastatin (15 mg/kg of body weight/d) and lovastatin (43-55 mg/kg of body weight/d), both lipophilic, caused stunted growth, high creatine kinase (CK) activity in plasma, and severe myopathy. Statin doses that caused damage were much lower for young rats than for adults. Pravastatin (8-55 mg/kg of body weight/d), a hydrophilic drug, caused none of these symptoms. Histologic analysis of hind paw muscles of simvastatin-and lovastatin-treated rats showed abundant signs of damage (hypercontraction, fiber necrosis) in the extensor digitorum longus, correlating with the symptoms noted above. No cellular infiltrates were seen at the onset, pointing to a noninflammatory myopathy. Pravastatin-treated rats never showed signs of myopathy. Impaired DNA synthesis may explain why muscle toxicity is seen at lower doses in young, rapidly developing rats than in adult animals. The differences in muscle damage between the statins may be attributed to differences in lipophilicity and thus in tissue selectivity. Our results can be important when considering drug therapy in young patients with inherited lipoprotein disorders.

Drugs recently associated with lupus syndromes

A number of drugs have recently been implicated in a syndrome that resembles systemic lupus erythematosus. One of the difficulties in many of these patients is that the signs, symptoms and serological abnormalities reported in these patients may be a natural consequence of the primary diseases rather than the incriminated drug. A second problem with the studies is a lack of uniform reporting of the techniques used to detect autoantibodies. For example, a patient that has a highly positive ANA with a homogeneous pattern of staining or a positive LE cell test usually has antibodies directed against chromatin components (DNA, histones, high mobility group (HMG) proteins). The discrepancies in clinical criteria and the serological techniques in many of these reports, emphasize the importance of using guidelines for the diagnosis of drug-induced or drug-related lupus. In the future, it appears that the increased use of biological response modifiers such as interferon-alpha and other cytokines may prompt more reports of lupus syndromes associated with their use.

Effects of HMG-CoA reductase inhibitors on skeletal muscles of rabbits

This study was undertaken to evaluate the potential of HMG-CoA reductase inhibitors, pravastatin sodium (hereafter abbreviated to pravastatin) and simvastatin, for induction of myopathy and influence on the ubiquinone content of skeletal and cardiac muscles and other tissues in the rabbit. Both drugs were administered orally to New Zealand White rabbits (n = 5) at the dose of 50 mg/kg per day for 14 days. Serum cholesterol levels in the pravastatin- and simvastatin-treated groups were reduced significantly by 47% an 58% on day 14 (P < 0.05), respectively, as compared with the control group, but the difference between the two treatment groups was not significant. In animals of the simvastatin-treated group, abnormal elevations of creatine kinase (CK) and lactate dehydrogenase (LDH) levels were observed, in association with severe lesions in skeletal muscles, but not cardiac muscle. The ubiquinone content in skeletal muscle in this treatment group was not affected, even in the muscles that had severe lesions, whereas that in liver and cardiac muscle was significantly reduced compared with the control group. The results suggest that there is no direct correlation between myopathy and the decrease of ubiquinone content in skeletal muscles. In contrast, the animals in the pravastatin-treated group did not show any changes in CK and LDH levels, ubiquinone content in liver and muscles, or in histopathological features of muscle fibers. The difference between the adverse effects seen with the two drugs could be attributed to physicochemical properties: simvastatin permeates the plasma membrane because of its hydrophobic nature, whereas pravastatin does not, because it is hydrophilic.

Subacute toxicity of a halogenated pyrrole hydroxymethylglutaryl-coenzyme A reductase inhibitor in Wistar rats

Wistar rats received an hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, a halogenated pyrrole designated PD 123244-15, orally by gavage for 14 days at 10, 50, 150, 300, and 600 mg/kg. Doses of 150-600 mg/kg caused death and marked systemic toxicity involving stomach, esophagus, liver, gonads, lymphoid tissues, and skeletal muscle. Histopathologic findings included hyperkeratosis in esophagus and forestomach, increased hepatic mitotic activity, ovarian follicular necrosis, testicular atrophy and arrested spermatogenesis, and skeletal muscle necrosis and regeneration. Elevated serum aspartate aminotransferase correlated with muscle necrosis and hepatocellular damage. Marked systemic effects associated with high plasma concentrations were consistent with toxicity defined for other HMG-CoA reductase inhibitors, with the exception of pathologic alterations in the esophagus and ovaries. Direct mucosal irritation may have contributed to forestomach and esophageal lesions induced by this halogenated pyrrole.

Bezafibrate induced rhabdomyolysis

The case is presented of a 70 year old woman with mild hypercholesterolaemia and hypertension who was readmitted to hospital six months after a previous admission for angina pectoris. The patient was treated with verapamil, nifedipine, and aspirin, and had been receiving bezafibrate (400 mg every 12 hours) for the previous 40 days. Twenty four hours after admission she developed podagra, which was treated with indomethacin (100 mg daily). Eight days after admission myocardial infarction was suspected, and the next day she presented with symptoms of rhabdomyolysis, which was confirmed by laboratory tests. Bezafibrate was withdrawn and the patient became asymptomatic after seven days. It is recommended that doctors should be aware of the possibility of patients, especially those with impaired renal function, developing rhabdomyolysis while being treated with bezafibrate.

Lovastatin-induced rhabdomyolysis in the absence of concomitant drugs

OBJECTIVE

Presentation of a case of lovastatin-induced rhabdomyolysis in the absence of other medications known to potentiate this adverse effect.

METHODOLOGY

Case report.

RESULTS

A 60-year-old black man developed rhabdomyolysis after receiving lovastatin for 14 months. Rhabdomyolysis developed in the absence of other medications previously reported to cause this adverse effect when administered concomitantly with lovastatin. Adverse drug reaction causality algorithms categorized this reaction as either possible or probable.

CONCLUSIONS

Rhabdomyolysis is an uncommon adverse effect associated with lovastatin therapy. Although reported cases of lovastatin-induced rhabdomyolysis were associated with the coadministration of cyclosporine, erythromycin, gemfibrozil, or nicotinic acid, this adverse effect may occur in the absence of these agents.

[Rhabdomyolysis caused by simvastatinin a patient following heart transplantation and cyclosporine therapy]

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are cholesterol-lowering agents which may induce rhabdomyolysis. The authors present a case of rhabdomyolysis attributed to simvastatin in a heart-transplant recipient. They stress the probability of a dose-dependent muscular toxicity and the risk of overdosage in patients already under treatment with drugs that interfere with the pharmacokinetics of HMG-CoA reductase inhibitors, notably ciclosporine.

Effects of gemfibrozil and other fibric acid derivatives on blood lipids and lipoproteins

Fibric acid derivatives (FADs) are a class of drugs that have been shown to reduce the production of very low-density lipoprotein (VLDL) while enhancing VLDL clearance due to the stimulation of lipoprotein lipase activity. The drugs can reduce plasma triglyceride levels while raising high-density lipoprotein (HDL) cholesterol levels. Their effects on low-density lipoprotein (LDL) cholesterol levels are less marked and more variable. There is evidence that oral gemfibrozil (Lopid, Parke-Davis, Morris Plains, NJ) can reduce the risk of serious coronary events, specifically in those patients who had elevations of both LDL cholesterol levels and total plasma triglyceride levels with lower HDL cholesterol levels. Newer FADs (bezafibrate, ciprofibrate, fenofibrate) have been shown to have greater efficacy in reducing LDL cholesterol than gemfibrozil but, in general, these drugs are not as effective as the other primary drugs used to lower LDL levels. The FADs are also used to treat adult patients with very high levels of triglycerides who have pancreatitis and whose disease cannot be managed with dietary therapy. The FADs are well tolerated, with dyspepsia and abdominal pain the most common adverse effects. A small risk of cholelithiasis exists with these drugs, and caution should be used when combining these drugs with HMG-CoA reductase inhibitors because the combination increases the incidence of hyperlipidemic myositis and rhabdomyolysis.

[Fenofibrate induced polymyositis]

In a 65-year old man complaining of myalgias and loss of muscular strength, the creatine phosphokinase level was found to be 35 times higher than normal values. The electromyogram was of the diffuse myogenic type. Muscle biopsy showed necrotic lesions of the muscle fibres associated with perivascular infiltrates of mononuclear cells, leading to the diagnosis of polymyositis. This patient had been treated for 10 years with fenofibrate for hyperlipidaemia; during the last 32 months he had taken this drug in doses of 600 mg per day. Eight days after fenofibrate was discontinued, all clinical and laboratory abnormalities had disappeared. A reintroduction test performed 6 weeks later raised the creatine phosphokinase level up to 43 times the normal value. Withdrawal of fenofibrate therapy resulted in rapid and lasting recovery. This case shows that fenofibrate should be added to the list of drugs that are responsible for iatrogenic polymyositis.

Lovastatin-induced acute rhabdomyolysis

Severe rhabdomyolysis complicated by respiratory and renal failure developed three weeks after initiation of low dose lovastatin therapy in a 79 year old, non-immunocompromised patient. The concomitant use of gemfibrozil may increase the risk of this complication.