[Prevalence of potential drug-drug interactions in ambulatory patients with statin therapy].

Aim: To asses the prevalence of potentially critical drug-drug interactions (DDIs) in outpatients treated with a statin.

Patients/methods: Data of patients (e.g. age, sex, comorbidities, individual statin, number of drugs, number of diagnoses) were collected from 242 Swiss practitioners. The medication was screened electronically for potentially critical DDIs.

Results: We included 2742 statin-treated patients (mean age 65.1 +/- 11.2 [SD] years, 3.2 +/- 1.6 diagnoses, 4.9 +/- 2.4 drugs prescribed) from the German (53.3%), French (36%) or Italian speaking (10.7%) part of Switzerland. Of those, 401 (14.6%) had a total of 591 potentially severe DDIs; 190 patients (6.9%) had potential statin DDIs, 288 (10.5%) potential non-statin DDIs, mainly due to pharmacodynamic mechanisms. The prevalence of potential DDIs was similar between regions, except for a trend for a higher prevalence of drug-statin interactions in the French-speaking part. The number of drugs per patient and a diagnosis of arrhythmia or heart failure were identified as risk factors for DDIs.

Conclusions: Drug combinations with potentially severe DDIs are common in patients treated with statins due to pharmacotherapy of their co-morbidities. Special attention in this specific population should be drawn on patients with polypharmacy and those with drug treatments for arrhythmia or heart failure.