The effect of rifampicin and isoniazid pretreatment on the pharmacokinetics of quinine after a single oral dose (600 mg quinine sulphate) was studied in nine healthy young Thai male volunteers using a three-way randomized crossover design. Subjects were studied over three 2 day periods, during which they received no pretreatment, or pretreatment with daily 600 mg p.o. rifampicin for 2 weeks, or isoniazid 300 mg p.o. daily for 1 week, prior to quinine administration. The mean (+ s.d.) clearance (CL/F) of quinine coadministered with rifampicin (0.87 ± 0.35 1 h-1 kg-') was significantly greater than that of quinine alone (0.14 ± 0.05 1 h-1 kg-'). The mean difference in clearance from the control treatment was 0.73 1 h-1 kg-', with 95% confidence interval (C.I.) of 0.48 to 0.98. The unbound clearance (CLu/F) of quinine, which reflects the activity of the drug-metabolizing enzymes, was considerably greater (6.9-fold) in subjects when rifampicin was coadministered with quinine than that of quinine alone (6.9 ± 3.6 vs 1.0 ± 0.5 1 h-1 kg-'; the 95% C.I. for the mean difference was 3.3 to 8.5). The mean elimination half-life of quinine when coadministered with rifampicin (5.5 ± 3.0 h) was significantly shorter than when quinine was given alone (11.1 ± 3.0 h; the 95% C.I. for the mean difference was -8.6 to -2.6). In contrast to rifampicin, pretreatment for 1 week with 300 mg oral isoniazid had no significant effects on the pharmacokinetics of quinine. These results indicate that rifampicin pretreatment caused a marked increase (6.2-fold) in the clearance of quinine, possibly due to enzyme induction. The extent to which the elimination of quinine is enhanced by the concomitant administration of rifampicin is likely to have important clinical consequences. Although the clinical significance of these findings is unknown, they indicate the need for caution in the administration of quinine to patients who are concurrently taking rifampicin as an anti-tuberculosis medication.

The pharmacokinetics of a single dose (600 mg) of quinine sulphate were examined in a group of non-smokers (n = 10) and in heavy cigarette smokers (n = 10). The mean (± s.d.) oral clearance of quinine in smokers (0.189 ± 0.075 1 h-1 kg-1) was significantly greater than in non-smokers (0.107 ± 0.045 1 h-1 kg-, P < 0.01). The unbound clearance of quinine which reflects activity of the drug-metabolizing enzyme, was considerably greater (1.5-fold) in the smokers than in the non-smoker subjects. The mean elimination half-life of quinine in smokers was 7.5 ± 1.4 (s.d.) h, significantly shorter (P < 0.005) than the mean value in non-smokers (12.0 ± 3.1 h). These results suggest that cigarette smoking enhances the elimination of quinine. The clinical significance of these findings is unknown but they indicate the need for caution in the administration of quinine to patients who are heavy cigarette smokers.

Hendersonula toruloidea infection is present in Thailand, where the clinical picture of tinea pedis is scales 61%, erythema 22%, maceration 10.8%, and hyperkeratosis 9%. The diagnosis was confirmed by repeated isolation of H. toruloidea. The slow-growing type was found more often than the fast-growing in the ratio of 2.8:1. In patients with H. toruloidea infection, skin test with Hs antigen of 1:10 was positive. Griseofulvin sensitivity test revealed that the MIC of 20 cultures was more than 100 micrograms/ml. Only 2 out of 93 cases (0.02%) were cured with half-strength Whitfield ointment for 4 months. Pathomechanism of the infection is being studied.

7 out of 534 South Vietnamese males showed erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, giving a 1.31% incidence of G-6-PD deficiency. Partially purified erythrocyte enzyme was studied in 6 of the 7 G-6-PD deficient males. Three variants were found: G-6-PD Mahidol (3), Canton (2), and Long Xuyen (1).

Obesity can modify the pharmacokinetics of lipophilic drugs. As quinine is a lipophilic drug, this study was conducted to determine whether the pharmacokinetics of quinine is altered in obese subjects. Nine obese Thai men were compared with 8 age-matched lean men. After an oral dose of quinine had been given to the men, plasma quinine concentrations were measured up to 48 h after the dosing. Mean peak plasma quinine concentration in the obese group was significantly lower than that observed in the controls (4.0 +/- 0.8 vs 5.0 +/- 0.3 mg/L, P < 0.01). There were no significant differences in time to reach the peak plasma concentration, half-life and total clearance of quinine between the 2 groups. The mean clearances of quinine normalized to the ideal bodyweight (IBW) in the obese and the control groups were not significantly different (0.091 +/- 0.018 vs 0.091 +/- 0.024 L/h/kg IBW, P > 0.05). As there are similarities in the total clearance and the clearance of quinine based on IBW, the maintenance dose of quinine should be given to obese patients on the basis of ideal bodyweight, not on total bodyweight.