The electrophysiological effects of flosequinan

We have evaluated the acute electrophysiological effects of flosequinan in 18 patients with normal ventricular function. Following intravenous infusion of flosequinan 100 mg over 1 h, mean (SD) systolic blood pressure fell from 131 +/- 19 to 120 +/- 22 mmHg (P less than 0.02) and there was significant shortening of sinus cycle length (732 +/- 151 to 575 +/- 93 ms, P less than 0.001), AH interval (110 +/- 45 to 71 +/- 19 ms, P less than 0.01), QRS duration (98 +/- 28 to 91 +/- 26 ms, P less than 0.02) and QT interval (373 +/- 47 to 337 +/- 35 ms, P less than 0.001), but no change in sinus node recovery time, intra-atrial conduction time, HV interval or the corrected QTc interval. There was a reduction in both anterograde atrioventricular Wenckebach cycle length (299 +/- 53 to 259 +/- 52 ms, P less than 0.01) and retrograde ventriculoatrial Wenckebach cycle length (375 +/- 77 to 300 +/- 56 ms, P less than 0.01). There was no change in atrial or ventricular effective refractory period (ERP) but atrial functional refractory period (FRP) shortened (233 +/- 31 to 212 +/- 24 ms, P = 0.07) as did ventricular FRP (249 +/- 24 to 234 +/- 21 ms, P less than 0.01). Patients received an oral dose of flosequinan 50 mg 12 h later. By 24 h, sinus cycle length, QRS duration and the QT interval had all returned towards baseline values, but ventricular ERP had lengthened (199 +/- 22 to 215 +/- 26 ms, P less than 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)