Contraindicated use of cisapride - Impact of food and drug administration regulatory action

Context Cisapride, a gastrointestinal tract promotility agent, can cause li fe-threatening cardiac arrhythmias in patients susceptible either because o f concurrent use of medications that interfere with cisapride metabolism or prolong the QT interval or because of the presence of other diseases that predispose to such arrhythmias. In June 1998, the US Food and Drug Administ ration (FDA) determined that use of cisapride was contraindicated in such p atients and informed practitioners through additions to the boxed warning i n the label and a "Dear Health Care Professional" letter sent by the drug's manufacturer. Objective To evaluate the impact of the FDA's 1998 regulatory action regard ing contraindicated use of cisapride. Design and Setting Analysis of data for the 1-year periods before (July 199 7-June 1998) and after (July 1998-June 1999) the regulatory action from the population-based, pharmacoepidemiology research databases of 2 managed car e organizations (sites A and B) and a state Medicaid program (site C). Participants Patients with at least 180 days of prior enrollment in 1 of th e 3 sites who were prescribed cisapride at least once in the period before (n = 24840) or after (n = 22459) regulatory action. Patients could be inclu ded in both cohorts. Main Outcome Measures Proportion of cisapride users in each period for whom cisapride use was contraindicated by the product label, based on computeri zed patient medical encounter records. Results In the year prior to regulatory action, cisapride use was contraind icated for 26%, 30%, and 60% of users in study sites A, B, and C, respectiv ely. In the year after regulatory action, use was contraindicated for 24%, 28%, and 58% of users, a reduction in contraindicated use of approximately 2 per 100 cisapride users at each site. When the analysis was restricted to new users of cisapride after regulatory action, only minor reductions in c ontraindicated use were found. Conclusion The FDA's 1998 regulatory action regarding cisapride use had no material effect on contraindicated cisapride use. More effective ways to co mmunicate new information about drug safety are needed.