Primaquine is used for relapses caused by
vivax malaria hypnozoites. No studies on the pharmacokinetics of
primaquine (PMQ) has been reported in Korean patients. In our study, thirty
vivax malaria patients were given 15 mg
primaquine daily for 14 days after 3 days of
chloroquine treatment. Plasma samples were taken at intervals after each daily dose of PMQ for 3 days. Plasma concentrations of PMQ and
carboxyprimaquine (CPMQ), the major metabolite of
primaquine, were measured by HPLC. The PMQ concentrations reached a maximum of 0.28+/-0.18 microg/mL at 1.5 h after the first dose. The maximum concentration of CPMQ was 0.32+/-0.13 microg/mL at 4 h. Higher
drug concentrations with repeated dosing were observed for CPMQ, but not for the parent
drug, PMQ. The elimination half-life was 3.76+/-1.8 h and 15.7+/-12.2 h, for PMQ and CPMQ, respectively. Large variation in the plasma concentrations of both drugs was observed. Overall, PMQ is absorbed and metabolized rapidly after
oral administration. It was noted that the mean peak plasma concentration of PMQ was significantly higher and that of CPMQ was lower in our patients compared to other studies. This suggests a potential difference of inter-ethnic groups, which warrants further investigations.