The clinical efficacy of the monotherapy involving the administration of a high dose of dihydroartemisinin (DHA 900 mg) for 5 days was compared with that of the combination regimen (DHA 600 mg + mefloquine [MQ] 750 mg) in an open randomized study in 90 patients with uncomplicated falciparum malaria in the southern part of Viet Nam. Patients were randomly treated with the DHA-5 day monotherapy regimen (300, 300, 100, 100, and 100 mg given at 0, 24, 48, 72, and 96 h) or the DHA-MQ combination

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... men (300 mg DHA at 0 h, then 300 mg DHA plus 750 mg MQ at 24 h). The end points for comparison were the parasite and fever clearance times (PCT and FCT) and recrudescence rates (by day 28 for DHA-5 days and day 42 for DHA-MQ). Eighty-nine patients completed the trial per protocol, including 45 cases receiving DHA-5 day and 44 receiving DHA-MQ. There was no difference in clinical manifestations, parasitemia density or other laboratory tests between the two patient groups. The PCTs were 35.3 +/- 17.4 h (mean +/- SD; range, 12-96) and 37.8 +/- 19.2 h (range, 12-96), respectively for the DHA-5 day and DHA-MQ regimens (P > 0.05). Twelve patients receiving the DHA-5 day regimen relapsed with falciparum malaria by day 28 (26.7%) and 5 patients receiving the DHA-MQ regimen relapsed by day 42 (11.4%) (P=0.07). Survival analysis showed that the DHA-5 day regimen had a radical cure rate significantly lower than that of the DHA-MQ regimen (P=0.003). The high dose of DHA in the monotherapy regimen did not increase the efficacy of the treatment of patients with uncomplicated Plasmodium falciparum malaria. The DHA combination regimens are suggested to be the better regimens for DHA.