Statin-macrolide interaction risk: a population-based study throughout a general practice database.

Introduction: The myopathy risk associated with statin use increases in case of concomitant prescription of certain drugs, such as cytochrome P(450) (CYP) system inhibitors (i.e., macrolides). The aim of this study was to assess whether concurrent statin/macrolide prescriptions at high interaction risk are commonly written in a general practice setting.

Methods: For this study, 156 general practitioners (GPs) with a patient population of almost 200,000 individuals, and participating in the Arianna database set up by "Caserta-1" Local health-Service Agency (ASL), were recruited. Within such a study sample, subjects receiving at least one statin/macrolide concomitant prescription during the year 2003 were identified. Sensitivity analysis was performed to assess the time distribution of high-risk macrolide prescriptions written within +/-10 days from the statin prescription date.

Results: Among 190,124 patients included in the study, 7,176 (3.8%) received at least one statin prescription during the observation period. Of these, 228 (3.2%) were occasionally co-prescribed with any macrolide on the same date, in 153 cases (2.1% of statin users) the macrolide being of high interaction risk. In particular, 2.1% (55) of simvastatin users and 2.2% (64) of patients on atorvastatin were prescribed with high-risk macrolide on the same date versus 0.6% and 1.8% of patients prescribed with fluvastatin and pravastatin, respectively. Concerning GPs, 99 (63.5%) co-administered statin and macrolide at high interaction risk at least once.

Conclusions: Most GPs occasionally prescribed statin/macrolide at high interaction risk on the same date, despite the availability of therapeutic alternatives. Prevention strategies targeted to increase awareness of health professionals about the interaction risks of widely prescribed drugs are needed.