Diprafenone for treatment of Wolff-Parkinson-White syndrome.

The effect of intravenous (1.5 to 2.0 mg/kg body weight) and oral (300 to 375 mg/d) diprafenone was studied in 15 patients with the Wolff-Parkinson-White syndrome and symptomatic supraventricular tachycardia. Intravenous application of diprafenone significantly increased atrioventricular nodal conduction time as well as the effective refractory periods of the right ventricle and the accessory pathway in both the antegrade and retrograde directions. Antegrade conduction block in the accessory pathway occurred in two patients after the dose was increased to 2.0 mg/kg body weight. Intravenous diprafenone suppressed the inducibility of supraventricular tachycardia in two patients, but the tachycardia cycle length was significantly increased in all other patients. Fourteen patients were treated with oral diprafenone, and 11 were asymptomatic during a 17-month follow-up, two of these after the dose had been increased to 375 mg/d. Oral therapy had to be withdrawn in two patients because of adverse gastrointestinal side effects and in one because of recurring bronchospasm.