Stereoselectivity in the disposition of chloroquine and desethylchloroquine in rabbits.

Stereoselective pharmacokinetic properties of chloroquine (CAS 54-05-7) and desethylchloroquine were investigated in rabbits by administration of the separate enantiomers according to a cross-over design. The terminal half-life was longer for (R)-chloroquine than for (S)-chloroquine. A striking difference was revealed in the concentrations of metabolites. The levels of (R)-desethylchloroquine were higher than those of (S)-desethylchloroquine, resulting in a statistically significant higher AUC for the (R)-metabolite than for the (S)-metabolite.