Pharmacokinetics of quinine in obesity

Obesity can modify the pharmacokinetics of lipophilic drugs. As quinine is a lipophilic drug, this study was conducted to determine whether the pharma cokinetics of quinine is altered in obese subjects. Nine obese Thai men wer e compared with 8 age-matched lean men. After an oral dose of quinine had b een given to the men, plasma quinine concentrations were measured up to 48 h after the dosing. Mean peak plasma quinine concentration in the obese gro up was significantly lower than that observed in the controls (4.0 +/- 0.8 vs 5.0 +/- 0.3 mgn, P< 0.01). There were no significant differences in time to reach the peak plasma concentration, half-life and total clearance of q uinine between the 2 groups. The mean clearances of quinine normalized to t he ideal bodyweight (IBW) in the obese and the control groups were not sign ificantly different (0.091 +/- 0.018 vs 0.091 +/- 0024 L/h/kg IBW, P > 0.05 ). As there are similarities in the total clearance and the clearance of qu inine based on IBW, the maintenance dose of quinine should be given to obes e patients on the basis of ideal bodyweight, not on total bodyweight.