IVERMECTIN PLUS DIETHYLCARBAMAZINE - AN ADDITIVE EFFECT ON EARLY MICROFILARIAL CLEARANCE

The effects of ivermectin, diethylcarbamazine (DEC), and the combinati on of both drugs on levels of microfilaremia (mf) were studied in 30 m ale Polynesian Wuchereria bancrofti carriers. Microfilarial densities were measured 30 min (H1/2), I hr (HI), and 2, 4, 8, 24, and 96 hr (H2 , H4, H8, H24, and H96) after supervised single doses of ivermectin pl us DEC (400 mu g/kg plus 1 mg/kg, respectively, 400 mu g/kg plus 3 mg/ kg, respectively, and 400 mu g/kg plus 6 mg/kg, respectively), DEC (6 mg/kg) alone, and ivermectin (400 mu g/kg and 100 mu g/kg, respectivel y) alone given to six groups of five patients each. The results showed that 1) DEC alone or combined with ivermectin induced a rapid clearan ce of mf after drug intake; at H1/2, the number of circulating microfi lariae was reduced to 16%, 8%, 28%, and 31%, respectively, of pretreat ment values in the groups receiving ivermectin plus DEC (400 mu g/kg p lus 1 mg/kg, 400 mu g/kg plus 3 mg/kg, and 400 mu g/kg plus 6 mg/kg) a nd DEC (6 mg/kg) alone; 2) ivermectin alone induced a rapid increase o f mf densities during the first 2 hr, followed by a sharp decrease fro m H4 to H96; and 3) between H8 and H96, mf clearance was almost comple te with the combination of ivermectin and DEC. A comparison among grou ps did not show any synergistic interaction between ivermectin and DEC on the clearance of microfilaria, with the effect of each drug being additive to each another.