Trials of mefloquine in vivax and of mefloquine plus 'fansidar' in falciparum malaria.

Two randomised double-blind trials were conducted to examine the activity and tolerability of mefloquine alone and in combination with sulfadoxine/pyrimethamine (MSP). In one trial mefloquine was compared with chloroquine in 40 patients with Plasmodium vivax malaria and in the other one mefloquine was compared with MSP in 40 patients with P falciparum malaria. The former trial showed that both a single oral dose of 250 mg mefloquine and a single oral dose of 450 mg chloroquine (base) were highly effective in relieving symptoms of malaria and in clearing P vivax parasitaemia. No side-effects and no changes in laboratory variables attributable to the test drugs were observed. The other trial showed that a single oral dose of 750 mg mefloquine and a single oral dose of MSP (750 mg mefloquine plus 3 tablets of 'Fansidar', were equally effective in the treatment of falciparum malaria. 2/4 treatment failures in the mefloquine group and 2/3 treatment failures in the MSP group were due to low plasma drug levels resulting from vomiting soon after ingestion of the tablets. Gametocytes of P falciparum were unaffected by either mefloquine or MSP. 5 patients in each group had side-effects such as vomiting, skin rash, diarrhoea, and transient mental confusion. Mefloquine was well tolerated by patients with glucose-6-phosphate dehydrogenase deficiency or heterozygous haemoglobin E.