The pharmacovigilance of tamsulosin: event data on 12484 patients

To determine drug effectiveness and adverse effects in a noninterventional observational cohort study of over 10 000 patients treated with tamsulosin in general medical practice.

Using prescription-event monitoring, data were collected of all prescriptions for tamsulosin issued nationally during June 1996 to January 1998. For each patient entered into the cohort a computerized longitudinal record of exposure was constructed. The outcome data, patient information and an opinion about the effectiveness of the drug were provided by the prescriber, using a standard questionnaire sent 6 months after the initial prescription for tamsulosin. The incidence of each of almost 2000 events listed in the Drug Safety Research Unit computerized dictionary was calculated and scrutinized by medical assessors for possible adverse reactions, and any difference determined between the incidence of each event in the first month and subsequent months of exposure. All deaths were followed up to detect possibly drug-related causes.

Event data were obtained on 12484 patients, from the 52.9% of questionnaires returned and that contained valid event data. Tamsulosin was reported to have been effective in 7428 (78.3%) of the 9487 patients in whom the general practitioners expressed an opinion about effectiveness. Suspected adverse drug reactions were reported in only 171 (1.4%) of the cohort. Dizziness, headache, malaise and hypotension were common to the reported adverse reactions, reasons for stopping the drug and events of greatest incidence density. None of the 282 deaths that occurred in this elderly cohort were attributed to the drug.

This study suggests that tamsulosin has a highly acceptable benefit-to-risk ratio. No untoward features not already mentioned in the prescribing guidance were identified.