Abstract
Background and objective:
Rosuvastatin is a lipid-lowering drug, the newest of a class of drugs called HMG-CoA reductase inhibitors, or ‘statins’, launched in the UK in March 2003. Our objective was to monitor the post-marketing safety of this drug, prescribed in primary care in England, using prescription-event monitoring.

Methods:
An observational cohort study in which patients were identified from dispensed prescriptions issued by primary care physicians/general practitioners (GPs) between August and December 2003. Demographic and clinical-event data were collected from questionnaires posted to GPs at least 6 months after the date of first prescription for each patient. Stratified analysis of specific events by starting dose of rosuvastatin was conducted. Follow-up and causality assessment of medically significant events was undertaken.

Results:
The cohort comprised 11 680 patients (median age 64 years); 50.3% were males (5880 of 11 680). The median period of treatment was 9.8 months. Of these patients, 72.7% (n=8494) were started on rosuvastatin 10mg/day. A total of 17.5% (n=2047) of the patients were reported to have stopped treatment with rosuvastatin. Myalgia was the most frequent reason for stopping rosuvastatin and the most frequently reported clinical event. A 2.5-fold increase in the rate of abnormal liver-function tests (LFTs) was observed for patients started on rosuvastatin 40mg/day compared with those started on 10mg/day (2.71; 95% CI 1.53, 4.53). No case of rhabdomyolysis was reported in the cohort.

Conclusion:
Rosuvastatin was considered to be a reasonably well tolerated drug. In the majority of patients, rosuvastatin was prescribed in line with recommendations. Abnormality of LFTs was found to be more frequent with the 40mg/day dosage of rosuvastatin. Results from this study should be taken into account together with those of other clinical and pharmacoepidemiological studies of rosuvastatin.