Stereoselective halofantrine disposition and effect:concentration‐related QTc prolongation

Abstract

Mean accumulation half-times (days) for halofantrine were: 7.0 +/- 4.8 [(+)-halofantrine] and 7.3 +/- 4.8 [(-)-halofantrine]. Mean steady-state concentrations were: 97.6 +/- 52.0 ng ml(-1) [(+)-halofantrine] and 48.5 +/- 20.8 [(-)-halofantrine]. Steady-state oral clearance was: 139 +/- 73 l h(-1) [(+)-halofantrine] and 265 +/- 135 l h(-1) [(-)-halofantrine]. Peak plasma concentrations of both (+)- and (-)-halofantrine were attained at 6 h and maximal ECG QTc prolongation was at 4-8 h following drug administration. Fourteen of 16 subjects who received active drug had ECG QTc prolongation that was positively correlated with both (+)- and (-)-halofantrine concentration. The five subjects who received placebo had no demonstrable change in ECG QTc throughout the study. Conclusions Halofantrine accumulates extensively and shows high intersubject pharmacokinetic variability, is associated with concentration-related ECG QTc prolongation in healthy subjects, and is clinically well tolerated in this subject group.