The instructions in the package lists a number of drugs that should never be given with cisapride, a medication formerly prescribed for nighttime heartburn. Yet, dangers cisapride combinations are often dispensed to patients and neither their doctors nor their pharmacists notice the error.

Researchers reporting in the Oct. 3, 2001 issue of the Journal of the American Medical Association studied 131,485 prescriptions for cisapride that were dispensed after warnings were issued about dispensing cisapride along with certain medications.

The authors found a total of 4,414 (3.4%) of cisapride prescriptions dispensed overlapped with at least one contraindicated drug. Half (2,190) of the overlapping prescriptions were prescribed by the same physicians for the same patients while 89% (3,908) were dispensed by the same pharmacies for the same patients, and 765 (17%) were dispensed on the same day.

Cisapride was approved for use in the United States in 1993 and voluntarily removed from the market in 2000 after more than 270 cases of seriously irregular heartbeat (70 of which resulted in death) were reported among U.S. patients. Most of these cases involved concurrent use of cisapride with drugs that interact with it. Four label changes and physician notifications about the potential adverse reactions were issued between 1995 and 1999.

"Throughout the study period, most patients with overlapping contraindicated dispensings had obtained both drugs from the same pharmacy," the authors noted. "This suggests that a pharmacy-based intervention to prevent codispensing of contraindicated medication pairs could be accomplished without involving complicated communications among different pharmacies."

The authors stated that even the computer-based warning systems used by many pharmacists today are often not successful in catching these potentially deadly drug errors.