levated low-density lipoprotein (LDL) cholesterol has been identified as a primary risk-reduction target in patients at risk for coronary heart disease (CHD). Numerous epidemiological studies have demonstrated a relationship between elevated LDL and the incidence of CHD. Use of LDL-lowering therapy, including hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors, also known as statins (atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin, and simvastatin), has been shown to significantly reduce risk for major coronary events and coronary deaths. Statins are recommended as standard treatment for elevated LDL and are widely used in clinical practice. 1 Results from clinical trials with statins show a decrease in CHD and total mortality, revascularization procedures, and stroke. 2-6 A meta-analysis demonstrates a decrease of 31% in major coronary events and 21% in total mortality with use of statins compared with placebo. 7 Statins are generally well tolerated, with elevated liver enzymes and myopathy reported as the most common adverse effects. 8,9 Myopathy is a general term for muscle disease and includes myalgia, myositis, and rhabdomyolysis ( Figure 1). The prevalence of statin rhabdomyolysis is rare. A review of adverse drug events reported to the U.S. Food and Drug Administration (FDA) showed an overall reporting rate of 0.15 cases of fatal rhabdomyolysis per 1 million statin prescriptions. 10 However, the true incidence of statin rhabdomyolysis is unknown because of the underreporting of adverse drug reactions during the postmarketing period of medications. All statins seem to have a potential for causing rhabdomyolysis. The risk of myopathy is dose related and increases with statin serum concentration. 9,11 Most myopathy associated with statins occurs in patients of older age, small body frame, multisystem disease (including chronic renal insufficiency), multiple medications, perioperative periods, or specific drug-drug interactions. 8,12,13 Several medications have been identified that increase the risk of myopathy when administered concurrently with statins, primarily by decreasing the metabolism of the statin (Figure 2). 8,[14][15][16][17][18] Although these drug-drug interactions are well documented as increasing risk for myopathy, published studies documenting the frequency of prescribing interacting drugs are lacking. Einarson and colleagues 19 studied the extent of drug interactions and health care utilization in patients receiving statins. However, Einarson focused on concomitant drugs whose levels increased from the statin therapy and short-term concomitant therapy, which could increase statin serum concentrations.The primary objective of this review is to quantify the proportion of patients in a primary care setting on simvastatin, the ABSTRACT OBJECTIVE: The primary objective of this review is to quantify the proportion of patients on simvastatin, an HMG-CoA reductase inhibitor (commonly known as statin), who received concurrent prescriptions for potentially interacting c...