Oral quinine pharmacokinetics and dietary salt intake.
The objective was to determine whether or not dietary salt intake affects the relative bioavailability of oral quinine. Salt intake has been shown to alter quinidine bioavailability. The pharmacokinetic properties of oral quinine sulphate (600 mg salt) were investigated in seven healthy Caucasian volunteers, in a randomised, crossover study, on low- and high-salt diets. Plasma quinine concentrations were measured by high-performance liquid chromatography (HPLC) and the 24-h urinary sodium excretion was assayed. Although the 24-h urine sodium excretion was significantly higher when the volunteers were on a high-salt diet, there were no significant differences in quinine AUC0-infinity, tmax, and Cmax after the two diets. The median (range) quinine elimination half-life was significantly shorter after a high-salt diet [8.5 (4.3-10.2) h] than after a low-salt diet [10.0 (7.6-14.8) h] (P = 0.04). Dietary salt does not affect the relative oral bioavailability of quinine sulphate.