Rhabdomyolysis due to warfarin and atorvastatin combination therapy in a patient with ischemic heart disease: (A drug interaction)

Introduction

Although atorvastatin has serious adverse effects, including hepatotoxicity and myopathy, it can cause drug interactions and side effects such as rhabdomyolysis and acute kidney injury, especially when combined with warfarin, which uses the same enzyme pathway for metabolism.

Case presentation

We describe a 66-year-old man with a history of ischemic heart disease who developed renal complications and rhabdomyolysis after concomitant use of atorvastatin and warfarin.

Discussion

Statins reduce serum LDL cholesterol levels significantly. It is a safe and cost-effective medicine used in the treatment of DLP as well as the primary and secondary prevention of CAD, atherosclerosis, myocardial infarction, and stroke. Despite their benefits, statins can cause side effects in various organs of the body, including the gastrointestinal tract, CNS, liver, and kidneys.

Conclusion

Statins are widely prescribed to patients with cardiovascular problems. Therefore, clinicians should pay attention to the patient's medical history, current prescribed doses, and drug interactions when adding new drugs or adjusting existing drugs.

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Rhabdomyolysis due to warfarin and atorvastatin combination therapy.

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Renal complications and rhabdomyolysis after concomitant use of atorvastatin and warfarin.

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Rhabdomyolysis is a life-threatening disease that begins with myalgia and progresses to myocyte necrosis, hyperkalemia.

Statins: Pharmacokinetics, Pharmacodynamics and Cost-Effectiveness Analysis

Cardiovascular diseases secondary to atherosclerosis are the primary causes of early death and disability worldwide and dyslipidaemia represents one of the most important modifiable risk factors. Among lipid abnormalities that define it, low-density lipoprotein cholesterol (LDL-C) is the primary target of therapy, since multiple randomized controlled trials have shown the positive impact of its reduction on atherosclerosis development. For their ability to lower LDL-C levels, statins are the most studied drugs in cardiovascular disease prevention, of proven utility in slowing the progression or even determining regression of atherosclerosis. In addition, they have ancillary proprieties, with positive effects on the mechanisms involved in the development of atherosclerosis and cardiovascular morbidity and mortality, the so-called "pleiotropic mechanisms". Although sharing the same mechanism of action, the different chemical and pharmacological characteristics of each kind of statins affect their absorption, bioavailability, plasma protein binding properties, excretion and solubility. In this overview, we analysed pharmacokinetic and pharmacodynamic mechanisms of this class of drugs, specifying the differences among the molecules, along with the economic aspects. Detailed knowledge of characteristics and differences of each kind of available statin could help the physician in the correct choice, based also on patient's clinical profile, of this essential tool with a demonstrated high cost-effectiveness both in primary than in the secondary prevention of cardiovascular disease.

Mechanism of Drug-Drug Interactions Between Warfarin and Statins

The anticoagulant drug warfarin and the lipid-lowering statin drugs are commonly co-administered to patients with cardiovascular diseases. Clinically significant drug-drug interactions (DDIs) between these drugs have been recognized through case studies for many years, but the biochemical mechanisms causing these interactions have not been explained fully. Previous theories include kinetic alterations in cytochrome P-450-mediated drug metabolism or disturbances of drug-protein binding, leading to anticoagulant activity of warfarin; however, neither the enantioselective effects on warfarin metabolism nor the potential disruption of drug transporter function have been well investigated. This study investigated the etiology of the DDIs between warfarin and statins. Liquid chromatography-mass spectrometry methods were developed and validated to quantify racemic warfarin, 6 of its hydroxylated metabolites, and pure enantiomers of warfarin; these methods were applied to study the role of different absorption, distribution, metabolism, and excretion properties, leading to DDIs. Plasma protein binding displacement of warfarin was performed in the presence of statins using equilibrium dialysis method. Substrate kinetics of warfarin and pure enantiomers were performed with human liver microsomes to determine the kinetic parameters (Km and Vmax) for the formation of all 6 hydroxywarfarin metabolites, inhibition of warfarin metabolism in the presence of statins, was determined. Uptake transport studies of warfarin were performed using overexpressing HEK cell lines and efflux transport using human adenocarcinoma colonic cell line cells. Fluvastatin significantly displaced plasma protein binding of warfarin and pure enantiomers; no other statin resulted in significant displacement of warfarin. All the statins that inhibited the formation of 10-hydroxywarfarin, atorvastatin, pitavastatin, and simvastatin were highly potent compared to other statins; in contrast, only fluvastatin was found to be a potent inhibitor of formation of 7-hydroxy warfarin. Uptake and efflux drug transporters do not play any role in these DDIs. The results showed that DDIs between warfarin and statins are primarily caused by cytochrome P-450 inhibition.

Diagnosis, prevention, and management of statin adverse effects and intolerance: Canadian Working Group Consensus update

The Proceedings of a Canadian Working Group Consensus Conference, first published in 2011, provided a summary of statin-associated adverse effects and intolerance and management suggestions. In this update, new clinical studies identified since then that provide further insight into effects on muscle, cognition, cataracts, diabetes, kidney disease, and cancer are discussed. Of these, the arenas of greatest controversy pertain to purported effects on cognition and the emergence of diabetes during long-term therapy. Regarding cognition, the available evidence is not strongly supportive of a major adverse effect of statins. In contrast, the linkage between statin therapy and incident diabetes is more firm. However, this risk is more strongly associated with traditional risk factors for new-onset diabetes than with statin itself and any possible negative effect of new-onset diabetes during statin treatment is far outweighed by the cardiovascular risk reduction benefits. Additional studies are also discussed, which support the principle that systematic statin rechallenge, and lower or intermittent statin dosing strategies are the main methods for dealing with suspected statin intolerance at this time.

Rhabdomyolysis developing secondary to atorvastatin therapy in a patient with liver cirrhosis

Atorvastatin is a lipid lowering agent that is widely used worldwide. Rhabdomyolysis is a rare but serious side effect that may lead to renal failure and dangerous electrolyte abnormalities in patients with decreased hepatic clearance of atorvastatin. We herein report the case of a patient with liver cirrhosis receiving atorvastatin therapy for ischemic heart disease and hyperlipidemia who developed rhabdomyolysis and acute renal failure.

Statin drug interactions and related adverse reactions

INTRODUCTION

Statin monotherapy is generally well tolerated, with a low frequency of adverse events. The most important adverse effects associated with statins are myopathy and an asymptomatic increase in hepatic transaminases, both of which occur infrequently. Because statins are prescribed on a long-term basis, their possible interactions with other drugs deserve particular attention, as many patients will typically receive pharmacological therapy for concomitant conditions during the course of statin treatment.

AREAS COVERED

This review summarizes the pharmacokinetic properties of statins and emphasizes their clinically relevant drug interactions and related adverse reactions.

EXPERT OPINION

Avoiding drug-drug interactions and consequent adverse drug reactions is essential in order to optimize compliance, and thus improve the treatment of patients at high cardiovascular risk. The different pharmacokinetic profiles among statins should be carefully considered, in order to understand the possible spectrum of drug interactions. The growing trend toward earlier statin treatment for the prevention of cardiovascular disease means that physicians must anticipate future polypharmacy when their patients require additional medications for comorbid conditions.