Kinetics of fenoximone, a new cardiotonic, in healthy subjects.

Fenoximone, a new cardiotonic, was given to six healthy men as a single intravenous dose of 1 mg/kg and a single oral dose of 3 mg/kg as solution in a crossover study. Plasma concentrations were monitored for 8 hr and urine was collected for 24 hr. Peak plasma concentrations (Cmax) were reached 30 min after the oral dose. Decay of plasma concentrations was fitted to a mean (+/- SD) elimination t1/2 (t1/2 beta) of 60 +/- 14 min after intravenous injection and 78 +/- 26 min after oral dosing. Mean total body clearance for intravenous dosing was 2062 +/- 846 ml/min, renal clearance (ClR) was 5.3 +/- 2.4 ml/min, and extrapolated volume of distribution was 0.37 +/- 0.26 l/kg. The sulfoxide derivative was detected as the main metabolite. Cmax of the sulfoxide metabolite occurred 10 min after the end of the intravenous infusion and 20 to 60 min after oral dosing. From the decay of the plasma concentrations of the sulfoxide, the t1/2 beta s were calculated as 132 +/- 15 min after intravenous injection and 140 +/- 27 min after oral dosing of fenoximone. ClR of the sulfoxide was 499 +/- 106 ml/min after intravenous injection; 24-hr urinary recovery of the sulfoxide was 75.7% +/- 5.7% after intravenous injection and 64.3% +/- 10.4% after oral dosing. Mean oral bioavailability of fenoximone was 53% (range 44% to 69%).