The heartburn drug, cisapride, continues to be inappropriately prescribed for patients with medical conditions that contraindicate its use. This is in spite of June 1998 regulatory action by the U.S. Food and Drug Administration (FDA) outlining contraindications to cisapride. Even letters to physicians and drug label warnings were not sufficient to spark more appropriate prescribing a year later, according to a recent study led by Walter Smalley, M.D., M.P.H., of the Vanderbilt University School of Medicine.
After marketing of cisapride began in the United States in 1993, it soon became clear that the drug could cause life-threatening cardiac arrhythmia in susceptible patients. The reasons for this susceptibility, outlined in 1998 by the FDA, included current use of medications that interfere with cisapride metabolism (for example, the antibiotic erythromycin) or prolong a heart rhythm interval (for example, cyclic antidepressants), as well as the presence of other diseases that predispose patients to such arrhythmias.
The FDA informed health care practitioners of these contraindications to cisapride via additions to the boxed warning label on cisapride and a "Dear health care professional" letter sent by the drug's manufacturer. Unfortunately, these actions only reduced contraindicated prescribing of the drug by about 2 percent (two patients per 100 cisapride users).
Dr. Smalley and his colleagues analyzed data for the 1-year period before (July 1997 to June 1998) and after (July 1998 to June 1999) the FDA regulatory action from the population-based pharmacoepidemiology research databases of two managed care organizations (sites A and B) and a State Medicaid program site (site C). In the year prior to regulatory action, cisapride use was contraindicated for 26 percent, 30 percent, and 60 percent of users in study sites A, B, and C, respectively. In the year after regulatory action, use was contraindicated for 24 percent, 28 percent, and 58 percent of users. The researchers cite the need for more effective ways to communicate with clinicians about drug safety.
This study was supported by the FDA and the Agency for Healthcare Research and Quality through a Centers for Education and Research in Therapeutics cooperative agreement (HS10384).
For more details, see "Contraindicated use of cisapride: Impact of Food and Drug Administration action," by Dr. Smalley, Deborah Shatin, Ph.D., Diane K. Wysowski, Ph.D., and others, in the December 20, 2000, Journal of the American Medical Association 284(23), pp. 3036-3039.
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