HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF PRIMAQUINE AND CARBOXYPRIMAQUINE CONCENTRATIONS IN PLASMA AND BLOOD-CELLS IN PLASMODIUM-VIVAX MALARIA CASES FOLLOWING CHRONIC DOSAGE WITH PRIMAQUINE

A reversed-phase HPLC method using acetonitrile-methanol-1 M perchlori c acid-water (30:9:1:95, v/v) at a how-rate of 1.5 ml/min on a mu-Bond apak C-18 column with UV detection at 254 nm was developed for the sep aration of primaquine, its major metabolite carboxyprimaquine and othe r metabolites such as N-acetyl-primaquine, 4-hydroxyprimaquine, 5-hydr oxyprimaquine, 5-hydroxy-6-methoxyprimaquine, demethylprimaquine and 6 -methoxyprimaquine, and also other antimalarials. The calibration grap hs were linear in the range 0.025-100 mu g/ml for primaquine and 4-100 0 mu g/ml for carboxyprimaquine. The within-day and day-to-day coeffic ients of variation averaged 3.65 and 6.95%, respectively, for primaqui ne and 3.0 and 7.52%, respectively, for carboxyprimaquine in plasma. T he extraction recoveries for primaquine and carboxyprimaquine were 89 and 83%, respectively. The mean carboxyprimaquine concentration was mu ch higher in plasma and blood cells of Plasmodium vivax patients than that in plasma from healthy subjects. The carboxyprimaquine level was also higher in blood cells than plasma whereas the primaquine concentr ation was the same in both cases.