Statin safety and chronic liver disease

Statins, Muscle Disease and Mitochondria

Cardiovascular disease (CVD) accounts for >17 million deaths globally every year, and this figure is predicted to rise to >23 million by 2030. Numerous studies have explored the relationship between cholesterol and CVD and there is now consensus that dyslipidaemia is a causal factor in the pathogenesis of atherosclerosis. Statins have become the cornerstone of the management of dyslipidaemia. Statins have proved to have a very good safety profile. The risk of adverse events is small compared to the benefits. Nevertheless, the potential risk of an adverse event occurring must be considered when prescribing and monitoring statin therapy to individual patients. Statin-associated muscle disease (SAMS) is by far the most studied and the most common reason for discontinuation of therapy. The reported incidence varies greatly, ranging between 5% and 29%. Milder disease is common and the more serious form, rhabdomyolysis is far rarer with an incidence of approximately 1 in 10,000. The pathophysiology of, and mechanisms leading to SAMS, are yet to be fully understood. Literature points towards statin-induced mitochondrial dysfunction as the most likely cause of SAMS. However, the exact processes leading to mitochondrial dysfunction are not yet fully understood. This paper details some of the different aetiological hypotheses put forward, focussing particularly on those related to mitochondrial dysfunction.

Treating statin-intolerant patients

Statins are effective in reducing cardiovascular events and are safe for almost all patients. Nevertheless, intolerance to statins is frequently faced in clinical practice. This is mostly due to muscular symptoms (myalgia with or without increase of plasma creatinine kinase) and/or elevation of hepatic aminotransferases, which overall constitutes approximately two-thirds of reported adverse events during statin therapy. These side effects raise concerns in patients as well as in doctors and are likely to reduce patients' adherence and, as a consequence, the cardiovascular benefit. Therefore, it is mandatory that clinicians improve their knowledge on the clinical aspects of muscular and hepatic side effects of statin therapy as well as their ability to manage patients with statin intolerance. Besides briefly examining the clinical aspects and the mechanisms that are proposed to be responsible for the most common statin-associated side effects, the main purpose of this article is to review the available approaches to manage statin-intolerant patients. The first step is to determine whether the adverse events are indeed related to statin therapy. If so, lowering the dosage or changing statin, alternate dosing options, or the use of nonstatin compounds may be practical strategies. The cholesterol-lowering potency as well as the usefulness of these different approaches in treating statin-intolerant patients will be examined based on currently available data. However, the cardiovascular benefit of these strategies has not been well established, so their use has to be guided by a careful clinical assessment of each patient.

Towards companion diagnostics for the management of statin therapy

BACKGROUND

Statins are the most commonly prescribed drugs in the world and are established first-line therapy for cardiovascular disease. Statin toxicity is related to dose, age, gender, ethnicity, body mass, renal and endocrine function and also to concomitant medications - particularly those that inhibit cytochrome P450 3A4.

OBJECTIVE/METHOD

This review describes the tests used before initiation of statin therapy, to establish their efficacy and to monitor their principal side effects. Lipids and apolipoproteins are used to measure efficacy and compliance, whereas transaminases and creatine kinase are used to measure toxicity. Guidelines agree in general, but differ in the details of measurement of baseline levels, action limits and management strategies for statin toxicity. Genetic factors are relevant to both the efficacy and the toxicity of statin therapy, with efficacy being associated with polymorphisms in lipid-related genes, whereas a function-related polymorphism in the organic anion transporting polypeptide 1B1 (OATP1B1; SLCO1B1) is associated with 60% of the cases of myopathy with high-dose simvastatin.

CONCLUSIONS

Although basic efficacy and safety panels for the initiation and monitoring of statin therapy are well established, controversy remains about the need for ancillary diagnostics in patients and to which patient groups these should be applied.