The reproducibility of quinine bioavailability.

Plasma concentrations of quinine were measured in six healthy volunteers after a duplicate administration of 15 mg kg-1 of quinine hydrochloride orally and the administration of 15 mg kg-1 of quinine dihydrochloride as an infusion over 6 h. Quinine absorption rate devised by deconvolution was shown to be complete in less than 2 h. The mean (+/- s.d.) fraction available (F) was 0.76 (0.11) after both oral doses and maximum plasma drug concentrations occurred at 1.90 (0.83) h and 2.00 (0.30) h, respectively. The reproducibility of absorption was high, with a within-subject coefficient of variation of less than 10% for Cmax, AUC and F. Thus, quinine absorption is extensive, fast and reproducible in healthy volunteers.