Statins for renal patients: a fiddler on the roof?

Drug-drug interactions between HMG-CoA reductase inhibitors (statins) and antiviral protease inhibitors

The HMG-CoA reductase inhibitors are a class of drugs also known as statins. These drugs are effective and widely prescribed for the treatment of hypercholesterolemia and prevention of cardiovascular morbidity and mortality. Seven statins are currently available: atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin and simvastatin. Although these drugs are generally well tolerated, skeletal muscle abnormalities from myalgia to severe lethal rhabdomyolysis can occur. Factors that increase statin concentrations such as drug-drug interactions can increase the risk of these adverse events. Drug-drug interactions are dependent on statins' pharmacokinetic profile: simvastatin, lovastatin and atorvastatin are metabolized through cytochrome P450 (CYP) 3A, while the metabolism of the other statins is independent of this CYP. All statins are substrate of organic anion transporter polypeptide 1B1, an uptake transporter expressed in hepatocyte membrane that may also explain some drug-drug interactions. Many HIV-infected patients have dyslipidemia and comorbidities that may require statin treatment. HIV-protease inhibitors (HIV PIs) are part of recommended antiretroviral treatment in combination with two reverse transcriptase inhibitors. All HIV PIs except nelfinavir are coadministered with a low dose of ritonavir, a potent CYP3A inhibitor to improve their pharmacokinetic properties. Cobicistat is a new potent CYP3A inhibitor that is combined with elvitegravir and will be combined with HIV-PIs in the future. The HCV-PIs boceprevir and telaprevir are both, to different extents, inhibitors of CYP3A. This review summarizes the pharmacokinetic properties of statins and PIs with emphasis on their metabolic pathways explaining clinically important drug-drug interactions. Simvastatin and lovastatin metabolized through CYP3A have the highest potency for drug-drug interaction with potent CYP3A inhibitors such as ritonavir- or cobicistat-boosted HIV-PI or the hepatitis C virus (HCV) PI, telaprevir or boceprevir, and therefore their coadministration is contraindicated. Atorvastatin is also a CYP3A substrate, but less potent drug-drug interactions have been reported with CYP3A inhibitors. Non-CYP3A-dependent statin concentrations are also affected although to a lesser extent when coadministered with HIV or HCV PIs, mainly through interaction with OATP1B1, and treatment should start with the lowest available statin dose. Effectiveness and occurrence of adverse effects should be monitored at regular time intervals.

Trends in statin therapy initiation during the period 2000-2010 in Israel

PURPOSE

The aim of this population-based study is to describe trends in the characteristics and treatment patterns of statin initiators over the first decade of the 21st century.

METHODS

New statin use was studied retrospectively using the database of Maccabi Healthcare Services (MHS), a large Israeli health maintenance organization. Statin initiators were defined as MHS members aged ≥ 30 years who first purchased statins between 2000 and 2010. The starting dose was calculated in simvastatin equivalents based on the World Health Organization's daily defined dose index. Persistence was calculated as the percentage of days covered (PDC) with statins during the first year of therapy.

RESULTS

Statin initiation peaked in 2005 and decreased from 38.6 to 18.6 per 1,000 in the period 2005-2010. The average age at therapy initiation decreased from 58.9 (± 12.0) to 54.5 (± 11.7) years, and the average (SD) baseline low-density lipoprotein cholesterol (LDL-C) decreased from 4.2 (± 1.1) to 4.0 (± 0.9) mmol/l during the study period. Women were on average 3 years older than men at treatment initiation, with a higher baseline LDL-C. Among statin initiators, the prevalence of ischemic heart disease (IHD) decreased from 17.8 to 6.7 %, and diabetes prevalence increased from 8.6 to 15.7 %, peaking in 2008 (18.0 %). The PDC with statins ranged between 52.9 and 57.7 %. Simvastatin use at initiation increased from 27.5 % in 2000 to >90 % since 2002. Starting dose increased from 18.5 (± 8.9) to 24.3 (± 13.7) mg simvastatin equivalent.

CONCLUSIONS

Among the study population, statin initiators were increasingly characterized by a lower cardiovascular risk-namely, younger individuals without IHD and with a lower baseline LDL-C. These trends underscore the important shift towards statin initiation for primary prevention, as well as the need to balance between benefits and the potential side effect of statins.