Bioavailability of sulphate and dihydrochloride salts of quinine

A comparative bioavailability of three formulations of quinine was performed in 6 healthy male adult Africans after intravenous infusion of 600mg quinine hydrochloride in 0.9% saline over 4 hours and after single oral doses of 600mg quinine sulphate capsule, 600mg quinine dihydrochloride plain tablet and 600mg quinine sulphate sugar coated tablet. The drugs were given according to a randomised cross-over design. The quinine sulphate coated tablet was found to contain no quinine. There was no statistical significant difference (P > 0.05) in the plasma Cmax, tmax, AUC and Ka values between the quinine sulphate capsule and quinine dihydrochloride plain tablet, although a considerable degree of inter- and intra-individual variability in the pharmacokinetic parameters was observed. The absolute bioavailability was 64.5 and 64.3% for the quinine sulphate capsule and the quinine dihydrochloride plain tablet respectively. The non-detection of quinine in the sugar coated tablet (obtained from Nigeria) confirms the presence of fake circulating antimalarial drugs in the country.