IN-VITRO BLOOD SCHIZONTICIDAL ACTIVITY OF SERA CONTAINING MEFLOQUINE-QUININE AGAINST PLASMODIUM-FALCIPARUM

Serum samples collected at intervals from healthy volunteers, after th e administration of 3 drug regimens (quinine (QN) 600 mg, mefloquine ( MQ) 750 mg, and MQ 750 mg plus QN 600 mg) were investigated for their blood schizonticidal activities against K-x strain Plasmodium falcipar um in vitro. Superiority of activity was shown in the sera collected a fter the combination regimen. In the diluted sera of the QN regimen, a complete inhibitory effect was observed for only 24 hours, whereas th e effect was sustained for 72 hours in the sera collected after MQ in either regimen (MQ alone or MQ/QN). The pattern of minimum inhibitory concentrations (MICs) of QNEq of the sera from QN alone was constant t hroughout a 24-hour period, with significantly higher concentrations t han that from the combination regimen (118-150 vs 21.25-73.5 mu g/l) I n sera collected after the combination regimen, however, the MIC gradu ally decreased from 0.5 until 2.5 and 4 h, and thereafter gradually re turned to the same levels again during a period of 6-24 hours. The MIC s of MQEq when given as MQ alone or in combination appeared constant, with a significantly higher value in the former regimen (24.4-26.8 vs 17-19.2 mu g/l).