Pharmacies and Prevention of Potentially Fatal Drug Interactions

To the Editor. —Dr Bates and colleagues1reported that 28% of adverse drug events in a hospital setting were preventable, and Dr Leape and colleagues2identified failure in the dissemination of drug knowledge as being the most common cause of these errors. Outside the hospital, the pharmacist is the last line of defense to protect the patient from prescribing errors. We examined how successful pharmacies are in detecting and correcting physician errors. The Food and Drug Administration determined that concomitant use of terfenadine with drugs known to inhibit hepatic metabolism, such as ketoconazole and erythromycin, was a risk factor for ventricular arrhythmias, syncope, and cardiac arrest.3This information is included in the product labeling of terfenadine, erythromycin, and ketoconazole. In July 1992, Marion Merrell Dow, Inc, distributed "Dear Doctor" and "Dear Pharmacist" letters, warning about the above drug interactions (oral communication, Marion Merrell Dow, Inc). To assess