Ivermectin (MK-933) has been compared with
diethylcarbamazine (DEC) and placebo in a double-blind study in 30 adult male Senegalese patients with Onchocerca volvulus
infection. 10 patients were randomly assigned to each treatment group.
Ivermectin was administered as a single oral dose of 12 mg and DEC as 50 mg daily for two days and 100 mg twice daily for the following six days, total 1.3 g in eight days. Skin O.
volvulus microfilaria densities remained near pre-study values in the placebo patients, but decreased rapidly with both active drugs to mean values about 2% of pretreatment (Day 8) and then increased slowly, reaching in 12 months about 4% of pre-treatment (
ivermectin) and 18% (DEC). This difference is statistically significant. Clinical adverse reactions were recorded in four
ivermectin, ten DEC and three placebo patients. One
ivermectin and six DEC patients received
steroid treatment for relief of these reactions. Serious adverse ocular changes were not seen in any patients, possibly because of the
steroid therapy in the DEC patients. Adult O.
volvulus from onchocercal nodules one and six months
after treatment showed no effect of either
drug on viability. Intra-uterine developing forms of the microfilariae appeared normal in all three treatment groups at the one month examination but deformed and degenerated forms were evident at six months in the
ivermectin group but not in the DEC and placebo patients.
Ivermectin as a single oral dose appears to be a safer and more effective microfilaricidal
drug in human
onchocerciasis than DEC in the standard multi-dose regimen.