Rhabdomyolysis in Association with Simvastatin and Amiodarone

Amiodarone-Induced Multi-Systemic Toxicity Involving the Liver, Lungs, Thyroid, and Eyes: A Case Report

Objectives

Amiodarone is widely used to treat arrhythmia. However, amiodarone is known for its severe toxicity to the liver, lungs, and thyroid. Amiodarone causes liver damage ranging from asymptomatic serum aminotransferase elevation to hepatic failure requiring liver transplantation. Although amiodarone toxicity has been reported, its simultaneous multi-organ toxicity is not well-known. Here, we introduce a novel case of multi-systemic amiodarone toxicity involving the liver, lungs, thyroid, and eyes.

Case Presentation

A 61-year-old woman visited the emergency room due to general weakness, nausea, visual disturbance, heat intolerance, and a non-productive cough. The patient had been using clopidogrel and amiodarone due to underlying atrial fibrillation. The total level of bilirubin was 0.71 mg/dL, aspartate aminotransferase was 358 U/L, alanine aminotransferase was 177 U/L, and prothrombin time was 27.1 s. Computed tomography showed diffuse increased liver intensity and scattered hyperattenuated nodular consolidations in both lungs. Transthoracic needle lung biopsy revealed fibrinoid interstitial inflammation with atypical change of type II pneumocytes and intra-alveolar foamy macrophages. In addition, the thyroid-stimulating hormone level was <0.008 μIU/mL, and free thyroxine was 4.67 ng/dL. The thyroid scan showed diffuse homogenous intake of technetium-99 m pertechnetate in both thyroid lobes. The ophthalmologic exam detected bilateral symmetrical corneal deposits in a vortex pattern. With these findings, we could diagnose amiodarone-induced hepatic, pulmonary, thyroid, and ophthalmologic toxicity. Liver function was restored after cessation of amiodarone, and thyroid function was normalized with methimazole administration. However, due to aggravated lung consolidations, systemic steroid treatment was administered, and improvement was seen 1 week after, at the follow-up exam. As her symptoms improved, she was discharged with a plan of steroid administration for 3 to 6 months.

Conclusions

This case implies the possibility of multi-systemic amiodarone toxicity. Thus, the toxicity of amiodarone to multiple organs must be monitored. Prompt cessation of the drug should be considered upon diagnosis.

Statin-Associated Myopathy: Emphasis on Mechanisms and Targeted Therapy

Hyperlipidemia is a major risk factor for cardiovascular morbidity and mortality. Statins are the first-choice therapy for dyslipidemias and are considered the cornerstone of atherosclerotic cardiovascular disease (ASCVD) in both primary and secondary prevention. Despite the statin-therapy-mediated positive effects on cardiovascular events, patient compliance is often poor. Statin-associated muscle symptoms (SAMS) are the most common side effect associated with treatment discontinuation. SAMS, which range from mild-to-moderate muscle pain, weakness, or fatigue to potentially life-threatening rhabdomyolysis, are reported by 10% to 25% of patients receiving statin therapy. There are many risk factors associated with patient features and hypolipidemic agents that seem to increase the risk of developing SAMS. Due to the lack of a "gold standard", the diagnostic test for SAMS is based on a clinical criteria score, which is independent of creatine kinase (CK) elevation. Mechanisms that underlie the pathogenesis of SAMS remain almost unclear, though a high number of risk factors may increase the probability of myotoxicity induced by statin therapy. Some of these, related to pharmacokinetic properties of statins and to concomitant therapies or patient characteristics, may affect statin bioavailability and increase vulnerability to high-dose statins.

Investigating the clinical factors and comedications associated with circulating levels of atorvastatin and its major metabolites in secondary prevention

Aims The lipid-lowering drug, atorvastatin (ATV), is 1 of the most commonly prescribed medications worldwide. The aim of this study was to comprehensively investigate and characterise the clinical factors and comedications associated with circulating levels of ATV and its metabolites in secondary prevention clinical practice. Methods The plasma concentrations of ATV, 2-hydroxy (2-OH) ATV, ATV lactone (ATV L) and 2-OH ATV L were determined in patients 1 month after hospitalisation for a non-ST elevation acute coronary syndrome. Factors were identified using all subsets multivariable regression and model averaging with the Bayesian information criterion. Exploratory genotype-stratified analyses were conducted using ABCG2 rs2231142 (Q141K) and CYP2C19 metaboliser status to further investigate novel associations. Results A total of 571 patients were included; 534 and 37 were taking ATV 80 mg and 40 mg daily, respectively. Clinical factors associated with ATV and/or its metabolite levels included age, sex, body mass index and CYP3A inhibiting comedications. Smoking was newly associated with increased ATV lactonisation and reduced hydroxylation. Proton pump inhibitors (PPIs) and loop diuretics were newly associated with modestly increased levels of ATV (14% and 38%, respectively) and its metabolites. An interaction between PPIs and CYP2C19 metaboliser status on exposure to specific ATV analytes (e.g. interaction P = .0071 for 2-OH ATV L) was observed. Overall model R² values were 0.14-0.24.ConclusionMultiple factors were associated with circulating ATV and metabolite levels, including novel associations with smoking and drug-drug(-gene) interactions involving PPIs and loop diuretics. Further investigations are needed to identify additional factors that influence ATV exposure.

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.

Drug-drug interactions involving CYP3A4 and p-glycoprotein in hospitalized elderly patients

Polypharmacy is very common in older patients and may be associated with drug-drug interactions. Hepatic cytochrome P450 (notably 3A4 subtype, CYP3A4) is a key enzyme which metabolizes most drugs; P-glycoprotein (P-gp) is a transporter which significantly influences distribution and bioavailability of many drugs. In this study, we assess the prevalence and patterns of potential interactions observed in an hospitalized older cohort (Registro Politerapia Società Italiana di Medicina Interna) exposed to at least two interacting drugs involving CYP3A4 and P-gp at admission, during hospitalization and at discharge. Individuals aged 65 and older (N-4039; mean age 79.2; male 48.1%), hospitalized between 2010 and 2016, were selected. The most common combinations of interacting drugs (relative frequency > 5%) and socio-demographic and clinical factors associated with the interactions were reported. The prevalence of interactions for CYP3A4 was 7.9% on admission, 10.3% during the stay and 10.7% at discharge; the corresponding figures for P-gp interactions were 2.2%, 3.8% and 3.8%. The most frequent interactions were amiodarone-statin for CYP3A4 and atorvastatin-verapamil-diltiazem for P-gp. The prevalence of some interactions, mainly those involving cardiovascular drugs, decreased at discharge, whereas that of others, e.g. those involving neuropsychiatric drugs, increased. The strongest factor associated with interactions was polypharmacy (OR 6.7, 95% CI 5.0-9.2). In conclusion, hospital admission is associated with an increased prevalence, but also a changing pattern of interactions concerning CYP3A4 and P-gp in elderly. Educational strategies and appropriate use of dedicated software seem desirable to limit drug interactions and the inherent risk of adverse events in older patients.

Insulin prevents and reverts simvastatin-induced toxicity in C2C12 skeletal muscle cells

Simvastatin is an inhibitor of the 3-hydroxy-3-methylglutaryl-CoA reductase used for decreasing low density lipoprotein (LDL)-cholesterol in patients. It is well-tolerated but can cause myopathy. Our aims were to enlarge our knowledge regarding mechanisms and effects of insulin on simvastatin-associated myotoxicity in C2C12 myotubes. Simvastatin (10 µM) reduced membrane integrity and ATP content in myotubes treated for 24 hours, which could be prevented and partially reversed concentration- and time-dependently by insulin. Furthermore, simvastatin impaired the phosphorylation of Akt (Protein Kinase B) mainly at Ser473 and less at Thr308, indicating impaired activity of the mammalian Target of Rapamycin Complex 2 (mTORC2). Impaired activation of Akt increased mRNA expression of the muscle atrophy F-Box (MAFbx), decreased activation of the mammalian Target of Rapamycin Complex 1 (mTORC1) and stimulated apoptosis by impairing the Ser9 phosphorylation of glycogen synthase kinase 3β. Decreased phosphorylation of Akt at both phosphorylation sites and of downstream substrates as well as apoptosis were prevented concentration-dependently by insulin. In addition, simvastatin caused accumulation of the insulin receptor β-chain in the endoplasmic reticulum (ER) and increased cleavage of procaspase-12, indicating ER stress. Insulin reduced the expression of the insulin receptor β-chain but increased procaspase-12 activation in the presence of simvastatin. In conclusion, simvastatin impaired activation of Akt Ser473 most likely as a consequence of reduced activity of mTORC2. Insulin could prevent the effects of simvastatin on the insulin signaling pathway and on apoptosis, but not on the endoplasmic reticulum (ER) stress induction.

Mechanisms of statin-associated skeletal muscle-associated symptoms

Statins lower the serum low-density lipoprotein cholesterol and prevent cardiovascular events by inhibiting 3-hydroxy-3-methyl-glutaryl-CoA reductase. Although the safety of statins is documented, many patients ingesting statins may suffer from skeletal muscle-associated symptoms (SAMS). Importantly, SAMS are a common reason for stopping the treatment with statins. Statin-associated muscular symptoms include fatigue, weakness and pain, possibly accompanied by elevated serum creatine kinase activity. The most severe muscular adverse reaction is the potentially fatal rhabdomyolysis. The frequency of SAMS is variable but in up to 30% of the patients ingesting statins, depending on the population treated and the statin used. The mechanisms leading to SAMS are currently not completely clarified. Over the last 15 years, several research articles focused on statin-induced mitochondrial dysfunction as a reason for SAMS. Statins can impair the function of the mitochondrial respiratory chain, thereby reducing ATP and increasing ROS production. This can induce mitochondrial membrane permeability transition, release of cytochrome c into the cytosol and induce apoptosis. In parallel, statins inhibit activation of Akt, mainly due to reduced function of mTORC2, which may be related to mitochondrial dysfunction. Mitochondrial dysfunction by statins is also responsible for activation of AMPK, which is associated with impaired activation of mTORC1. Reduced activation of mTORC1 leads to increased skeletal muscle protein degradation, impaired protein synthesis and stimulation of apoptosis. In this paper, we discuss some of the different hypotheses how statins affect skeletal muscle in more detail, focusing particularly on those related to mitochondrial dysfunction and the impairment of the Akt/mTOR pathway.

Unmet Needs in LDL-C Lowering: When Statins Won't Do!

The use of low-density lipoprotein cholesterol (LDL-C)-lowering medications has led to a significant reduction of cardiovascular risk in both primary and secondary prevention. Statin therapy, one of the cornerstones for the prevention and treatment of cardiovascular disease (CVD), has been demonstrated to be effective in lowering LDL-C levels and in reducing the risk for CVD and is generally well-tolerated. However, compliance with statins remains suboptimal. One of the main reasons is limitations by adverse events, notably myopathies, which can lead to non-compliance with the prescribed statin regimen. Reducing the burden of elevated LDL-C levels is critical in patients with CVD as well as in patients with very high baseline levels of LDL-C (e.g. patients with familial hypercholesterolaemia), as statin therapy is insufficient for optimally reducing LDL-C below target values. In this review, we discuss alternative treatment options after maximally tolerated doses of statin therapy, including ezetimibe, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and cholesteryl ester transfer protein (CETP) inhibitors. Difficult-to-treat patients may benefit from combination therapy with ezetimibe or a PCSK9 inhibitor (evolocumab or alirocumab, which are now available). Updates of treatment guidelines are needed to guide the management of patients who will best benefit from these new treatments.

IGF-1 prevents simvastatin-induced myotoxicity in C2C12 myotubes

Statins are generally well tolerated, but treatment with these drugs may be associated with myopathy. The mechanisms of statin-associated myopathy are not completely understood. Statins inhibit AKT phosphorylation by an unclear mechanism, whereas insulin-like growth factor (IGF-1) activates the IGF-1/AKT signaling pathway and promotes muscle growth. The aims of the study were to investigate mechanisms of impaired AKT phosphorylation by simvastatin and to assess effects of IGF-1 on simvastatin-induced myotoxicity in C2C12 myotubes. C2C12 mouse myotubes were exposed to 10 μM simvastatin and/or 10 ng/mL IGF-1 for 18 h. Simvastatin inhibited the IGF-1/AKT signaling pathway, resulting in increased breakdown of myofibrillar proteins, impaired protein synthesis and increased apoptosis. Simvastatin inhibited AKT S473 phosphorylation, indicating reduced activity of mTORC2. In addition, simvastatin impaired stimulation of AKT T308 phosphorylation by IGF-1, indicating reduced activation of the IGF-1R/PI3K pathway by IGF-1. Nevertheless, simvastatin-induced myotoxicity could be at least partially prevented by IGF-1. The protective effects of IGF-1 were mediated by activation of the IGF-1R/AKT signaling cascade. Treatment with IGF-1 also suppressed muscle atrophy markers, restored protein synthesis and inhibited apoptosis. These results were confirmed by normalization of myotube morphology and protein content of C2C12 cells exposed to simvastatin and treated with IGF-1. In conclusion, impaired activity of AKT can be explained by reduced function of mTORC2 and of the IGF-1R/PI3K pathway. IGF-1 can prevent simvastatin-associated cytotoxicity and metabolic effects on C2C12 cells. The study gives insight into mechanisms of simvastatin-associated myotoxicity and provides potential targets for therapeutic intervention.

Co-administration of paroxetine increased the systemic exposure of pravastatin in diabetic rats due to the decrease in liver distribution

1. Liver distribution and systemic exposure of pravastatin were the determinant factors of efficacy and toxicity of pravastatin. Aim of the present study was to investigate the effect of paroxetine on the liver distribution and systemic exposure of pravastatin in diabetic rats induced by combining high fat diet (HFD) and low-dose streptozotocin (STZ). 2. Plasma concentrations and liver distribution of pravastatin were measured in the presence of paroxetine. Effect of paroxetine on pravastatin excretion via bile, intestine, feces and urine, as well as pravastatin absorption via intestine was documented. Freshly isolated hepatocytes and Caco-2 cells were used to investigate the effect of paroxetine on pravastatin transport. 3. Paroxetine increased the systemic exposure of pravastatin and decreased hepatic distribution of pravastatin in diabetic rats. In vitro, paroxetine inhibited the hepatic uptake of pravastatin and promoted the efflux of pravastatin in freshly isolated hepatocytes, which may partly explain the decreased hepatic distribution of pravastatin by paroxetine. It was also observed that paroxetine promoted the absorption of pravastatin via jejunum and the uptake of pravastatin in Caco-2 cells. 4. We concluded that paroxetine increased the systemic exposure of pravastatin partly via promoting absorption via jejunum and inhibiting hepatic uptake of pravastatin.

The AKT/mTOR signaling pathway plays a key role in statin-induced myotoxicity

Statins are drugs that lower blood cholesterol levels and reduce cardiovascular morbidity and mortality. They are generally well-tolerated, but myopathy is a potentially severe adverse reaction of these compounds. The mechanisms by which statins induce myotoxicity are not completely understood, but may be related to inhibition of the AKT signaling pathway. The current studies were performed to explore the down-stream effects of the statin-associated inhibition of AKT within the AKT signaling pathway and on myocyte biology and morphology in C2C12 myotubes and in mice in vivo. We exposed C2C12 myotubes to 10 μM or 50 μM simvastatin, atorvastatin or rosuvastatin for 24 h. Simvastatin and atorvastatin inhibited AKT phosphorylation and were cytotoxic starting at 10 μM, whereas similar effects were observed for rosuvastatin at 50 μM. Inhibition of AKT phosphorylation was associated with impaired phosphorylation of S6 kinase, ribosomal protein S6, 4E-binding protein 1 and FoxO3a, resulting in reduced protein synthesis, accelerated myofibrillar degradation and atrophy of C2C12 myotubes. Furthermore, impaired AKT phosphorylation was associated with activation of caspases and PARP, reflecting induction of apoptosis. Similar findings were detected in skeletal muscle of mice treated orally with 5 mg/kg/day simvastatin for 3 weeks. In conclusion, this study highlights the importance of the AKT/mTOR signaling pathway in statin-induced myotoxicity and reveals potential drug targets for treatment of patients with statin-associated myopathies.

Rhabdomyolysis in association with simvastatin and dosage increment in clarithromycin

Clarithromycin is the most documented cytochrome P450 3A4 (CYP3A4) inhibitor to cause an adverse interaction with simvastatin. This particular case is of interest as rhabdomyolysis only occurred after an increase in the dose of clarithromycin. The patient developed raised cardiac biomarkers without any obvious cardiac issues, a phenomenon that has been linked to rhabdomyolysis previously. To date, there has been no reported effect of rhabdomyolysis on the structure and function of cardiac muscle. Clinicians need to be aware of prescribing concomitant medications that increase the risk of myopathy or inhibit the CYP3A4 enzyme. Our case suggests that troponin elevation could be associated with statin induced rhabdomyolysis, which may warrant further studies.

Potential drug interactions with statins: Estonian register-based study

In Estonia, HMG-CoA reductase inhibitors are widely used to modify lipid levels but there are no current data on additional medicines prescribed alongside the statins. The aim of this study was to identify the frequency of potential clinically relevant interactions at a national level among an outpatient population treated with statins between January and June 2008, based on the prescription database of the Estonian Health Insurance Fund. This retrospective prevalence study included 203,646 outpatients aged 50 years or older, of whom 29,367 received statin therapy. The study analysed individuals who had used at least one prescription medicine for a minimum of 7 days concomitantly with statins. Potential drug interactions were analysed using Epocrates online, Stockley's Drug Interactions, and the drug interaction database developed in Estonia. Statins metabolised by the CYP3A4 isoenzyme were prescribed to 64% of all statin users. Medicines known to have potentially clinically significant interactions with statins were prescribed to 4.6% of patients. The drugs prescribed concomitantly most often with simvastatin were warfarin (5.7%) and amiodarone (3.9%), whereas digoxin (1.2%) and ethinylestradiol (2%) were prescribed with atorvastatin. Potential interactions were not detected in the treatment regimens of rosuvastatin, pravastatin, and fluvastatin users.

Simvastatin induces mitochondrial dysfunction and increased atrogin-1 expression in H9c2 cardiomyocytes and mice in vivo

Simvastatin is effective and well tolerated, with adverse reactions mainly affecting skeletal muscle. Important mechanisms for skeletal muscle toxicity include mitochondrial impairment and increased expression of atrogin-1. The aim was to study the mechanisms of toxicity of simvastatin on H9c2 cells (a rodent cardiomyocyte cell line) and on the heart of male C57BL/6 mice. After, exposure to 10 μmol/L simvastatin for 24 h, H9c2 cells showed impaired oxygen consumption, a reduction in the mitochondrial membrane potential and a decreased activity of several enzyme complexes of the mitochondrial electron transport chain (ETC). The cellular ATP level was also decreased, which was associated with phosphorylation of AMPK, dephosphorylation and nuclear translocation of FoxO3a as well as increased mRNA expression of atrogin-1. Markers of apoptosis were increased in simvastatin-treated H9c2 cells. Treatment of mice with 5 mg/kg/day simvastatin for 21 days was associated with a 5 % drop in heart weight as well as impaired activity of several enzyme complexes of the ETC and increased mRNA expression of atrogin-1 and of markers of apoptosis in cardiac tissue. Cardiomyocytes exposed to simvastatin in vitro or in vivo sustain mitochondrial damage, which causes AMPK activation, dephosphorylation and nuclear transformation of FoxO3a as well as increased expression of atrogin-1. Mitochondrial damage and increased atrogin-1 expression are associated with apoptosis and increased protein breakdown, which may cause myocardial atrophy.

Musculoskeletal safety outcomes of patients receiving daptomycin with HMG-CoA reductase inhibitors

Daptomycin, a cyclic lipopeptide antibiotic, and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are commonly administered in the inpatient setting and are associated with creatine phosphokinase (CPK) elevations, myalgias, and muscle weakness. Safety data for coadministration of daptomycin with statins are limited. To determine the safety of coadministration of daptomycin with statin therapy, a multicenter, retrospective, observational study was performed at 13 institutions in the Southeastern United States. Forty-nine adult patients receiving statins concurrently with daptomycin were compared with 171 patients receiving daptomycin without statin therapy. Detailed information, including treatment indication and duration, infecting pathogen, baseline and subsequent CPK levels, and presence of myalgias or muscle complaints, was collected. Myalgias were noted in 3/49 (6.1%) patients receiving combination therapy compared with 5/171 (2.9%) of patients receiving daptomycin alone (P = 0.38). CPK elevations of >1,000 U/liter occurred in 5/49 (10.2%) patients receiving combination therapy compared to 9/171 (5.3%) patients receiving daptomycin alone (P = 0.32). Two of five patients experiencing CPK elevations of >1,000 U/liter in the combination group had symptoms of myopathy. Three patients (6.1%) discontinued therapy due to CPK elevations with concurrent myalgias in the combination group versus 6 patients (3.5%) in the daptomycin-alone group (P = 0.42). CPK levels and myalgias reversed upon discontinuation of daptomycin therapy. Overall musculoskeletal toxicity was numerically higher in the combination group but this result was not statistically significant. Further prospective study is warranted in a larger population.

Potential statin-drug interactions: prevalence and clinical significance

Background

Statins are cholesterol-lowering drugs widely used for cardiovascular prevention. Although safe when used alone, in combination with other drugs the likelihood of adverse drug reactions increases significantly. The exposure of the Bulgarian population to coprescriptions leading to potential statin-drug interactions is currently unknown.

Objective

The aim of this study was to investigate the incidence of coprescriptions involving statins and to compare the exposure of outpatients and inpatients to potential statin-drug interactions.

Setting

A cardiology clinic of the teaching University hospital in Varna, Bulgaria.

Method

This observational retrospective study examined the medical records of hospitalized patients prescribed a statin in combination with potentially interacting drugs. Patients who entered the hospital with a statin coprescription (considered outpatients) were compared with those coprescribed a statin at discharge from hospital (considered inpatients). Potentially interacting drugs included inhibitors and inducers of cytochrome P450 (CYP) enzymes and drugs of narrow safety margin (coumarin anticoagulants, digitalis).

Main outcome measure

The proportion of patients exposed to statin coprescriptions with potentially interacting drugs at hospital admission and discharge. Secondary outcome measures: laboratory evidence supporting possible statin-drug interactions.

Results

Out of 1641 hospitalized patients examined, 572 were prescribed a statin, either at hospital admission or discharge. Simvastatin was most commonly prescribed and simvastatin-drug coprescription predominated, especially at discharge. The exposure to all potential statin-drug interactions was similar at hospital admission (26.1%) and discharge (24.4%), as was the exposure to statin combinations with CYP inhibitors, 6.4% and 4%, correspondingly. Overall, more coprescriptions were generated, than were eliminated by hospital physicians. Amiodarone was the CYP inhibitor most frequently coprescribed. Of all interacting drugs acenocoumarol was the most commonly found, the proportions of statin-acenocoumarol coprescriptions being roughly the same at hospital entry (11.5%) and discharge (12.4%). In 7 patients out of 69 exposed to the combination, INR was found to be higher than 3, indicating a risk of over-anticoagulation.

Conclusions

Potential statin-drug interactions are common. Although they do not differ between outpatient and inpatient settings, new hazardous coprescriptions are more frequently generated in hospital. Caution is required when acenocoumarol is coprescribed with statins, especially simvastatin.

Cytochrome P450 and ischemic heart disease: current concepts and future directions

INTRODUCTION

The P450 enzymes (P450s) mediate the biotransformation of several drugs, steroid hormones, eicosanoids, cholesterol, vitamins, fatty acids and bile acids, many of which affect cardiovascular homeostasis. Experimental studies have demonstrated that several P450s modulate important steps in the pathogenesis of ischemic heart disease (IHD).

AREAS COVERED

This article discusses the current knowledge on i) the expression of P450s in cardiovascular and renal tissues; ii) the role of P450s in the pathophysiology of IHD, in particular the modulation of blood pressure and cardiac hypertrophy, coronary arterial tone, ischemia-reperfusion injury and the metabolism of cardiovascular drugs; iii) the available evidence from observational studies on the association between P450 gene polymorphisms and risk of myocardial infarction (MI); and iv) suggestions for further research in this area.

EXPERT OPINION

P450s exert important modulatory effects in experimental models of IHD and MI. However, observational studies have provided conflicting results on the association between P450 genetic polymorphisms and MI. Further, adequately powered studies are required to ascertain the biological and clinical impact of P450s on clinical IHD end-points, that is, fatal and nonfatal MI, revascularization and long-term outcomes post MI. Pharmacogenetic substudies of recently completed cardiovascular clinical trials might represent an alternative strategy in this context.

Population-Based Assessments of Clinical Drug-Drug Interactions: Qualitative Indices or Quantitative Measures?

Population-based assessments of drug-drug interactions have become more common since the introduction and acceptance of the population pharmacokinetic approach. Unlike traditional methods, population-based studies provide clinically relevant results that can be applied directly to a target patient population. Furthermore, population-based studies do not demand the traditional requirements of intensive pharmacokinetic sampling, rigorous inpatient stays, or stringent assessment schedules. As such, the population-based approach can effectively be used to confirm known drug-drug interactions and further characterize anticipated interactions. A prospectively designed analysis can also reveal drug-drug interactions that might otherwise have gone undetected with traditional methods. Ultimately, these results could help to alleviate clinicians' concerns about using widely marketed drugs in combination therapies and also reduce patients' risk of experiencing unacceptable side effects. This article intends to provide a balanced overview of the population-based approach and its merits, drawbacks, and potential utility in the assessment of drug-drug interactions during clinical drug development.

Current understanding of hepatic and intestinal OATP-mediated drug-drug interactions

At present, many patients are medicated with various drugs, which are, at the same time, associated with an increased risk of drug-drug interactions (DDIs). Detailed analysis of mechanisms underlying DDIs is the basis of a better prediction of adverse drug events caused by drug interactions. In the last few decades, an involvement of transporters in such processes has been more and more recognized. Indeed, uptake transporters belonging to the organic anion-transporting polypeptide (OATP) family have been shown to interact with a variety of drugs in clinical use. Particularly, the subfamily of OATP1B transporters has been extensively studied, identifying several clinical significant DDIs based on those hepatic uptake transporters. By contrast, the role of OATP2B1 in this context is rather underestimated. Therefore, in addition to known interactions based on OATP1B transporters, we have focused on DDIs probably based on OATP2B1 inhibition in the liver and those possibly owing to the inhibition of OATP2B1-mediated drug absorption in the intestine.

[Specific considerations on the prescription and therapeutic interchange of statins]

OBJECTIVE

The pharmaceutical industry currently offers six different statins in Spain and there is one more soon to be available. Choosing the most appropriate drug and dose is determined by the therapeutic target (reduction in LDL-C levels). Statin doses that decrease LDL-C at the same percentage are considered equivalent. Evaluating the pharmacokinetic characteristics of each statin can be useful when setting selection criteria, helping to determine which statin may be more appropriate for a patient based on their individual characteristics and on the other co-administered drugs.

METHODS

We reviewed the pharmacokinetics properties of each statin and its possible involvement in drug interactions.

RESULTS

CYP3A4 was responsible for the metabolism of lovastatin, simvastatin and atorvastatin; fluvastatin depends on CYP2C9; P-glycoprotein is responsible for decreased atorvastatin, pravastatin, simvastatin and lovastatin concentrations. The OATPA1B1 transporter involved in all statins' access to the hepatocyte, except for fluvastatin, is essential for rosuvastatin and pravastatin. These circumstances cause those drugs inhibiting or inducing isoenzymes or transporters' activity not to have the same effect on the different statins.

CONCLUSION

The pharmacokinetics is important when choosing the best statin and could be a limitation in the use of interchange therapeutic programmes when other drugs are present.

Potential drug-drug interactions in prescriptions dispensed in community pharmacies in Greece

OBJECTIVES

To evaluate the nature, type and prevalence of potential drug-drug interactions (DDIs) in prescriptions dispensed in community pharmacies in Thessaloniki, Greece. Secondary objectives included the classification of DDIs as per pharmacotherapeutic class of the medications and the investigation of the relationship between medical specialties and the frequency of potential DDIs, as well as the relationship between DDIs and prescription size. Setting DDIs are a common cause of adverse drug reactions (ADRs) among patients using multiple drug therapy. In Greece a reliable computerized surveillance system for monitoring potential DDIs is not yet fully established. As a result, the prevalence of such DDIs in prescriptions dispensed by community pharmacies in Greece is unknown.

METHODS

We conducted a prospective, descriptive study. Over a 3-month period (November 2007-January 2008), a total of 1,553 handwritten prescriptions were collected from three community pharmacies in Thessaloniki, Greece. The prescriptions were processed using the Drug Interactions Checker within the www.drugs.com database. The identified potential DDIs were categorized into two classes, major and moderate, according to their level of clinical significance.

MAIN OUTCOME MEASURES

Overall 213 prescriptions had one or more potential DDIs and a total of 287 major and moderate DDIs were identified. Potential DDIs were identified in 18.5% of all prescriptions. Major DDIs were identified in 1.9% of all prescriptions and represented 10.5% of all DDIs detected, whereas moderate DDIs were identified in 16.6% of all prescriptions and represented 89.5% of all DDIs detected. The rate of DDIs increased with prescription size. The most common drug involved in major DDIs was amiodarone which interacts with potassium-wasting diuretics, digoxin, simvastatin and acenocoumarol.

CONCLUSIONS

Our results indicate that patients in Greece are at risk of ADRs caused by medications due to potential DDIs. An appropriate surveillance system for monitoring such interactions should be implemented and physicians should be more aware of potentially harmful DDIs. Pharmacists can contribute to the detection and prevention of drug-related injuries, especially of clinically meaningful DDIs that pose a potential risk to patient safety.

Does Simvastatin Cause More Myotoxicity Compared with Other Statins?

Objective:

To review the literature regarding statins and myotoxicity and evaluate these data to determine whether incidence rates are higher with simvastatin.

Data Sources:

Literature was identified from a search of MEDLINE (1966–August 2009) and International Pharmaceutical Abstracts (1970–August 2009), as well as references of selected articles. Key search terms included the names of individual statins, rhabdomyolysis, myopathy, myalgia, myotoxicity, statins, and drug interactions.

Study Selection and Data Extraction:

All English-language articles discussing statin-related myotoxicity and relevant drug interactions that involved human subjects were examined.

Data Synthesis:

Simvastatin is a commonly prescribed, moderately potent statin. Recent evidence suggests that the risk of severe muscle toxicity with simvastatin may be higher than that with other statins, particularly when used in combination with cytochrome P450 isoenzyme inhibitors. However, the lack of direct comparative clinical trials assessing the risk of myotoxicity among the statins in equivalent doses precludes definitive conclusions. Data sources examining low-to-mode rate doses of simvastatin suggest that myotoxicity with this agent is infrequent, with rates similar to those seen with other statins. Conversely, findings from clinical trials using the maximum daily dose (80 mg) and a clinical trials database of varying doses of simvastatin suggest a possible increase in rates of myotoxicity with the 80-mg dose compared with lower doses and a higher incidence rate when compared with maximum doses of other statins.

Conclusions:

Overall, the rates of severe myotoxicity with all statins are low, especially with low-to-moderate doses. However, recent trials for those using simvastatin 80 mg daily suggest a higher incidence of myotoxicity compared with maximum approved doses of other statins. Practitioners should be aware of these possible risks and individualize therapy to limit myotoxicity.

Simvastatin and Amiodarone: Emergence of a Potentially Toxic Interaction

This continuing feature updates readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number 1 killer in the United States, and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, if pharmacists stay current with developments in drug therapy, they can have a significant impact on prevention and treatment.

Risk management of simvastatin or atorvastatin interactions with CYP3A4 inhibitors

BACKGROUND

Co-administration of cytochrome P450 (CYP) 3A4 inhibitors with simvastatin or atorvastatin is associated with increased risk of developing myopathy or rhabdomyolysis.

OBJECTIVE

To detect co-prescriptions of CYP3A4 inhibitors with simvastatin or atorvastatin in community pharmacies and assess the risk-preventive actions taken by the prescribing physicians who were alerted about the co-prescription by the pharmacist.

METHODS

This naturalistic study was performed during four separate 6-week periods in 2004 and 2005, and involved 110 Norwegian community pharmacists (25-30 in each period). Co-prescription of the selected CYP3A4 inhibitors diltiazem, verapamil, clarithromycin, erythromycin, fluconazole, itraconazole and ketoconazole with either simvastatin or atorvastatin was detected with the aid of a simple computer programme. In instances where the pharmacist alerted the prescribing physician about the co-prescription, information on possible strategies to minimize the risk associated with the interaction was also provided. Odds ratios (ORs) were estimated to describe the associations between prescription variables and frequencies of physician information and prescription change, respectively.

RESULTS

In total, 245 co-prescriptions of CYP3A4 inhibitors with simvastatin (134 events) or atorvastatin (111) were detected. Diltiazem (86 events), verapamil (72), erythromycin (48) and clarithromycin (29) were the most commonly co-prescribed CYP3A4 inhibitors. Physicians were informed in 168 out of 245 cases (68.6%). The prescription was subsequently changed in 100 out of 168 cases (59.5%). Another 50 physicians (29.8%) responded that they would consult the patient and monitor potential adverse effects, while only 18 physicians (10.7%) replied that they had already managed the interactions or considered the issue as irrelevant. The adjusted OR for the informing of the physician was 1.89 (95% CI 0.98, 3.63) in patients receiving a daily HMG-CoA reductase inhibitor ('statin') dose of >or=40 mg compared with patients receiving a statin dose of <40 mg/day. The adjusted OR for prescription change was 4.98 (95% CI 2.36, 10.52) if co-prescription was detected prior to the initiation of concurrent use compared with if it was detected during concurrent use.

CONCLUSION

Nine out of ten physicians changed prescriptions or monitored potential adverse effects when informed by community pharmacists about the risk associated with co-prescription of CYP3A4 inhibitors with simvastatin or atorvastatin. This suggests that an important risk factor for myotoxicity due to these statins could be minimized through interdisciplinary co-operation.

Recent developments in the treatment of atherosclerosis

Atherosclerosis is one of the most frequent causes of cardiac arrest. The major cause of this disease is high concentrations of lipid in the blood. Medicinal agents so far have been quite successful in the management of hyperlipidemia. Among the several widely used drugs, (fibrates, statins and niacin) statins are the most frequently prescribed in many forms of hyperlipidemia. Recently, statins have been found to produce serious toxicities, which are rare but can be potentially harmful and are noise concern for the immediate need to develop some new chemical entities in this category. This review is primarily concerned with recent developments in atherosclerotic drug discovery including novel inhibitors of cholesterol biosynthesis, cholesterol absorption inhibitors and antioxidants. The review also focuses on possible future targets including gene therapy.

Prevalence of drug-drug interactions at hospital entry and during hospital stay of patients in internal medicine

OBJECTIVE

The aim of this study was to assess potential drug-drug interactions (pDDIs) at hospital admission, during hospitalization and at discharge and to evaluate the number of pDDIs created during hospitalization.

METHODS

The medication of 851 patients was screened for pDDIs (major and moderate severity) using the screening program Pharmavista. The frequency of pDDIs per patient, per number of drugs and drug pairs was estimated.

RESULTS

During hospitalization, the frequency of major and moderate pDDIs per patient was 1.11, which was higher compared to hospital admission (0.59) or to hospital discharge (0.60). The frequency of major and moderate pDDIs per drug prescribed (13.7% vs. 9.1%) or per drug pairs analyzed (4.5% vs. 2.3%) was higher at hospital admission compared to hospital discharge. 47% of all major and moderate pDDIs at discharge were due to a medication change during hospitalization.

CONCLUSIONS

Although the number of major and moderate pDDIs per patient did not increase from hospital admission to discharge, it is important to realize that 47% of all major and moderate DDIs at hospital discharge were created during hospitalization. Prescribing drugs with a low risk for pDDIs as well as careful monitoring for adverse drug reactions are important measures to minimize harm associated with DDIs.

Simvastatin: present and future perspectives

Simvastatin is lipophilic statin with a short half-life that is primarily metabolized by CYP450 3A4. At doses of 5 - 80 mg, simvastatin lowers LDL cholesterol by 25 - 50%. Simvastatin has been shown to reduce the risk of cardiovascular disease by 35% and overall mortality by up to 30% over 5 years. The recommended starting dose of simvastatin 40 mg is approved as a lipid-lowering agent and for all high-risk patients, including those with cardiovascular disease and diabetes, regardless of the baseline LDL level. Simvastatin dose should be adjusted in those receiving CYP3A4 inhibitors, gemfibrozil, or ciclosporin, amiodarone, or in those with severe renal insufficiency. Coformulation of simvastatin with ezetimibe is now available, and coformulation with extended release niacin is under development.

Which statin should be used together with colchicine? Clinical experience in three patients with nephrotic syndrome due to AA type amyloidosis

Colchicine and statins are well known drugs that cause myopathy and neuropathy. Co-administration of certain drugs with statins may increase myotoxic effect, causing myopathy and varying degrees of rhabdomyolysis. Therefore, it is very crucial to know which statin should be used during a combination therapy including colchicine and other drugs. We present three cases with AA amyloidosis secondary to familial Mediterranean fever, who developed neuromyopathy while receiving the combination of colchicine and statin. We also briefly discussed the different metabolic pathways of statins and colchicine when used together.

Age-related differences in the prevalence of potential drug-drug interactions in ambulatory dyslipidaemic patients treated with statins

BACKGROUND AND OBJECTIVE

Elderly patients may be at higher risk of drug-drug interactions (DDIs) because of polypharmacy. This study evaluated age-specific differences in the prevalence of clinically relevant potential DDIs (pDDIs) in ambulatory dyslipidaemic patients treated with an HMG-CoA reductase inhibitor (statin). We hypothesised that elderly patients are at higher risk for pDDIs because of the presence of more drugs and drugs with a higher potential for DDIs in this age group.

METHODS

A total of 2742 dyslipidaemic ambulatory patients treated with a statin were included in this cross-sectional study. Drug treatment was screened for clinically relevant pDDIs using an electronic drug interaction program (DRUG-REAX System).

RESULTS

The study sample consisted of 483 (17.6%) patients aged < or = 54 years, 732 (26.7%) aged 55-64 years, 924 (33.7%) aged 65-74 years and 603 (22.0%) patients aged > or = 75 years. Patients > or =75 years had significantly more pharmacologically active substances prescribed than patients aged < or =54 years (mean 5.8 vs 3.8, respectively; p < 0.001). Cardiovascular diseases such as coronary heart disease, heart failure or arrhythmias were also significantly more prevalent in patients aged > or = 75 years than in younger patients. The overall prevalence of pDDIs increased significantly from 7.9% in those aged < or = 54 years to 18.4% in patients aged > or = 75 years (p < 0.001). The frequency of both pDDIs associated with statins and non-statin pDDIs increased with age. Risk factors for pDDIs in patients aged > or = 75 years were arrhythmias, heart failure and the number of pharmacologically active substances prescribed. The more frequent prescription of cardiovascular drugs with a high potential for pDDIs (e.g. amiodarone and digoxin) in patients aged > or = 75 years was mainly responsible for the observed increases in statin and non-statin pDDIs in this age group.

CONCLUSIONS

Compared with younger patients, elderly dyslipidaemic patients are at a higher risk for clinically relevant pDDIs, mainly because of a higher number of drugs prescribed. In addition, patients aged > or = 75 years were prescribed more drugs with a high potential for DDIs, especially drugs used for the treatment of arrhythmias and heart failure. The risk for adverse reactions associated with pDDIs may often be reduced by dose adjustment, close monitoring or selection of an alternative drug.

Amiodarone Interacts with Simvastatin but not with Pravastatin Disposition Kinetics

The aim of this study was to determine the influence of amiodarone on the pharmacokinetics of simvastatin and pravastatin in humans. This was a prospective, crossover, randomized, open-label study performed in 12 healthy volunteers comparing the pharmacokinetics of a single oral dose of simvastatin (40 mg) or pravastatin (40 mg) taken alone and after 3 days of amiodarone (400 mg/day). Amiodarone increased simvastatin acid AUC (area under the plasma concentration-time curve)0-24 h, peak plasma concentration (Cmax), and t1/2 by 73% (P=0.02), 100% (P=0.02), and 48% (P=0.06), respectively, whereas it did not significantly alter pravastatin pharmacokinetics. Point estimates and 90% confidence intervals for simvastatin acid, simvastatin lactone, and pravastatin AUC0-24 h were 154% (109-216%), 155% (109-227%), and 86% (63-118%), respectively. If amiodarone and a statin have to be simultaneously prescribed, pravastatin should be preferred to simvastatin in order to avoid a drug interaction.

[Medically induced myopathia]

Muscular side effects of various anesthetics, analgetics, antibiotics, antihistaminic drugs, antiretrovirals, cardiotropics, immunosuppressants, lipid-lowering drugs, psychotropic drugs, anticancer drugs, and other substances are more frequent than assumed and are easily overlooked. Clinically, muscular side effects manifest as fatigue, myalgias, persistent or transient weakness, stiffness, intolerance to exercise, psychomotor slowing, muscle cramps, wasting, dyspnea, dysphagia, fasciculations, reduced tendon reflexes, impaired consciousness, myoglobinuria, renal failure, or hyperthermia. Diagnosis of these drug-induced myopathies is based on history, clinical neurologic examination, blood work, urine analysis, repetitive stimulation, electromyography, and muscle biopsy. A drug which induces muscular side effects should never be given again. Particularly in patients suffering from primary myopathy, myotoxic drugs should be applied with caution. The drugs which most frequently induce muscular side effects are steroids, statins, fibrates, antiretrovirals, immunosuppressants, colchicine, amiodarone, and anticancer drugs. Many drugs exhibit their myotoxic potential only in combination with other drugs or premorbid pathologic myogenic conditions.

Review article: The role of statins in reducing perioperative cardiac risk: physiologic and clinical perspectives

PURPOSE

To review the pathobiology and clinical implications of coronary vulnerable atherosclerotic plaques (VAPs), to discuss the role of statin therapy in VAP stabilization, and the potential benefits of perioperative statin therapy (PST) in reducing perioperative risk of acute coronary syndromes (ACSs).

SOURCE

MEDLINE search using "perioperative", "cardiac morbidity", "atherosclerosis", "vulnerable plaque", "statins" and combinations of these terms as keywords. The reference lists of relevant articles were further reviewed to identify additional citations.

PRINCIPAL FINDINGS

The nonstenotic, yet rupture-prone VAP causes most myocardial infarctions (MIs) and other ACSs, both in the nonsurgical and surgical patients. Large clinical trials in both primary and secondary prevention and in patients with ACSs have demonstrated that statin therapy will reduce cardiovascular morbidity and mortality across a broad spectrum of patient subgroups. These trials also suggest, and laboratory investigations establish, that statins possess favourable vascular effects independent of cholesterol reduction. Statins appear to interfere specifically with the pathophysiologic mechanisms implicated in atherothrombotic disease. Statins reduce vascular inflammation, improve endothelial function, stabilize VAPs, and reduce platelet aggregability and thrombus formation. Recent studies have shown that PST is associated with a reduced incidence of perioperative and long-term cardiovascular complications in high-risk patients. Combined therapy with statins and ss-blockers is a conceptually valid strategy targeting critical steps in the pathogenesis of an ACS.

CONCLUSION

Emerging evidence for the efficacy and safety of PST is promising, especially when combined with ss-blocker therapy in patients at highest risk. Confirmation of this early evidence awaits the results of ongoing and future prospective randomized controlled trials.

Statins and myotoxicity: a therapeutic limitation

Hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors represent the most successful class of drugs for the treatment of hypercholesterolaemia and dyslipidaemia implicated in the pathogenesis of coronary heart disease and atherosclerosis. However, the popular profile of statins in terms of efficacy has been maligned by its adverse events. The myotoxicity, ranging from mild myopathy to serious rhabdomyolysis, associated with HMG-CoA reductase inhibitors, during treatment of hypercholesterolaemia is of paramount importance. Rhabdomyolysis is a rare but idiosyncratic muscle wasting disorder of different etiologies. Statin-associated rhabdomyolysis causes skeletal muscle injury by self-perpetuating events leading to fatal irreversible renal damage through a series of biochemical reactions. Preferential distribution and action of statins in liver could be the key to minimise myotoxicity concerns. Hepato-specific distribution of statins is governed by various factors such as physicochemical properties, pharmacokinetic properties and selective transporter-mediated uptake in liver rather in extrahepatic cells. The interactions of statins with concomitant drugs of different classes merit attention for their safety profile. Although pharmacokinetic as well as pharmacodynamic interactions have been implicated in pathophysiology of statin-induced muscle wasting, the underlying mechanism is not clearly understood. Besides, pharmacokinetic and phramcodynamic factors, statin-associated myotoxcity may also implicate pharmacogenomic factors. The pharmacogenomics characterised by CYP polymorphism and other genetic factors is responsible for inter-individual variations to efficacy and tolerability of statins. The pathophysiological mechanisms may include statin-induced differences in cholesterol:phospholipid ratio, isoprenoid levels, small GTP binding proteins and apoptosis. However, the present understanding of pathophysiological mechanisms, does not offer a reliable approach to address the same at preclinical level. Although statin-associated myotoxicity affects compliance, quality of life of patient and discontinuation rate, yet the low incidence of myotoxicty including rhabdomyolysis and less severity of commonly occurring myopathy and myalgia do not raise doubts about the clinical efficacy and tolerability of statins. Medical management of myotoxicity seems to be pivotal for the proper compliance of patients with statin treatment. The appropriate and judicious use of drugs would substantially reduce the likelihood of developing clinically important myopathy.

Treating dyslipidaemia in the setting of diabetes mellitus and cardiovascular disease: a less commonly perceived therapeutic perspective in clinical practice

Diabetes mellitus and cardiovascular disease are being managed more belligerently in recent times, with multifactorial cardiovascular risk reduction being the focus of therapeutic interventions. We review some of the caveats to be exercised in the treatment of these patients that are pertinent to clinicians in daily clinical practice.

Simvastatin-amiodarone interaction resulting in rhabdomyolysis, azotemia, and possible hepatotoxicity

OBJECTIVE

To describe the fifth reported instance, as of February 15, 2006, of a severe interaction between simvastatin and amiodarone and hypothesize inhibition of CYP3A4 as the major mechanism.

CASE SUMMARY

A 72-year-old white man (178 cm, 77.2 kg) with diabetes mellitus, hyperlipidemia, hypertension, and mild azotemia was hospitalized on September 21, 2004, with thigh weakness, achiness, and dark urine for 7 days. Coronary artery bypass had been performed on July 7, 2004. Amiodarone 200 mg/day was started on July 10, and simvastatin 80 mg/day was initiated on August 13. Laboratory testing on the present admission included creatine kinase (CK) 19,620 U/L (reference range 60-224), blood urea nitrogen 50 mg/dL, creatinine 2.6 mg/dL, aspartate aminotransferase (AST) 912 U/L (30-60), alanine aminotransferase (ALT) 748 U/L (30-60), urine myoglobin 71,100 microg/L (<50), and serum myoglobin 13,877 microg/L (<110). Simvastatin and amiodarone were discontinued, and the patient was hydrated with forced alkaline diuresis. Thirteen days later, his CK was 323 U/L, creatinine 1.7 mg/dL, ALT 145 U/L, and AST 37 U/L.

DISCUSSION

Simvastatin is metabolized primarily by CYP3A4, and amiodarone is a recognized inhibitor of this enzyme. This may, therefore, account for the presumed drug interaction.

CONCLUSIONS

An objective causal assessment suggests that rhabdomyolysis, renal failure, and possibly hepatotoxicity were probably related to an amiodarone-simvastatin interaction.

Rhabdomyolysis from Simvastatin Triggered by Infection and Muscle Exertion

A 42-year-old woman received a 6-month course of simvastatin (20 mg/d) for hypercholesterolemia. Despite an infection with fever, fatigue, myalgias, and lumbar pain, she continued to perform her regular sports activities. Neurologic examination revealed bilateral ptosis and slight upper limb weakness. Serum creatine kinase was 41,000 U/L. Needle electromyography was nonspecifically abnormal. Discontinuation of simvastatin and reduction of the sports activities was followed by a prompt continual lowering of the elevated muscle enzymes to normal values over a 2-week period. The patient's infection, regular sports activity despite the infection, and a suspected mitochondrial defect were regarded as triggers of rhabdomyolysis.

Rosuvastatin safety: lessons from the FDA review and post-approval surveillance

Rosuvastatin is the first statin approved by the regulatory authorities since the withdrawal of cerivastatin. Although highly efficacious, this new statin has generated considerable controversy regarding its safety. Rosuvastatin was approved for clinical use based on the largest pre-approval database for all statins prior to commercial use. In this database, rosuvastatin had a similar safety profile to other approved statins up to the highest approval dose of 40 mg. As with all statins, there is a marked increase in adverse effects when the dose is titrated from 40 to 80 mg, and rosuvastatin demonstrates a similar dose/toxicity relationship. In the pre-approval data trials on 80 mg, there was a 1.0% (n = 16) incidence of myopathy and 7 patients developed rhabdomyolysis. However the <or= 40 mg doses had a myopathy rate similar to other statins. In the post-marketing surveillance for rosuvastatin, there have been reports of rhabdomyolysis, but the incidence rate, when corrected for prescription utilisation, is similar to other statins following initial approval.