Torsades de pointes occurring in association with terfenadine use

Article Abstract:

Torsades de pointes is a characteristic pattern on the electrocardiogram (the recording of the heart's electrical activity) that can appear after the administration of certain drugs. It is a type of ventricular tachycardia (rapid heart beat), but should be distinguished from other types of tachycardia that require different treatments. The case of a 39-year-old woman who developed lightheadedness and fainting after 10 days' consumption of terfenadine, an antihistamine, is described. After admission to the hospital, abnormalities in the electrocardiogram were noted, and another episode of palpitations, difficulty in breathing, and near-fainting took place. Torsades de pointes was seen. The patient stopped taking all medications and the symptoms, including the abnormal electrocardiogram, resolved. Blood tests revealed that the patient had much higher blood levels of terfenadine and its metabolite than are usual. It is likely that another drug taken at the same time for suspected vaginal candidiasis, ketoconazole (an antifungal agent), affected metabolic pathways (the P-450 system) so that terfenadine could not be properly metabolized. Physicians should be aware of this possible complication in patients who use both drugs or who are taking terfenadine with other drugs that inhibit the P-450 system, such as cimetidine or erythromycin. Any information regarding such interactions should be reported to the Food and Drug Administration. (Consumer Summary produced by Reliance Medical Information, Inc.)

Case studies, Causes of, Heart, Ventricular tachycardia, Torsade de pointes, Ketoconazole

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Use of terfenadine and contraindicated drugs

Article Abstract:

The prescribing of the antihistamine terfenadine (Seldane) concurrently with a class of antibiotics called macrolides or the antifungal drug ketoconazole still occurs despite published accounts of serious interactions between these drugs. Researchers used a large health insurer's pharmacy claims database to track the simultaneous or overlapping prescription of these drugs since the FDA first announced a serious drug interaction in 1990. This was followed in 1992 by a Mailgram sent to all pharmacists and many reports in the medical literature. The claims database revealed that the simultaneous dispensing of terfenadine and macrolide antibiotics or ketoconazole dropped 84% between Jan 1990 and June 1994. The dispensing of one drug or the other during the time a contraindicated drug was being used dropped 57% in that time. However, in the first half of 1994, 2% to 3% of all claims for terfenadine were prescribed to people who were already taking the contraindicated drugs.

Usage, Drugs, Media coverage, Prescriptions (Drugs)

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Coprescribing and Codispensing of Cisapride and Contraindicated Drugs

Article Abstract:

Over 4,000 prescriptions of cisapride were given between 1993 and 1998 to patients who were also taking a drug that could interact with it even though the FDA issued a series of warnings against this practice during that time period. Cisapride was approved in 1993 for treating gastroesophageal reflux but was withdrawn in 1999 after drug interactions caused 270 cardiac arrhythmias and 70 deaths.

Health aspects, Drug therapy, Gastroesophageal reflux, Cisapride

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