THE ROLE OF KETOCONAZOLE IN THE QTC INTERVAL PROLONGING EFFECTS OF H-1-ANTIHISTAMINES IN A GUINEA-PIG MODEL OF ARRHYTHMOGENICITY

We have carried out experiments to re-evaluate the influence of ketoco nazole (400 mg kg(-1),p.o.) on the effects of ebastine, terfenadine an d loratadine on the QTc interval in conscious guinea-pigs. Following a previously described protocol of oral drug administration, but using telemetric recording of the ECG, we have found that the prolongation o f the QTc interval attributed to ebastine and terfenadine is in fact e ntirely due to ketoconazole, and that neither terfenadine, ebastine no r loratadine produce any additional effects on subsequent administrati on.