An improved dosing schedule for ivermectin as a microfilaricidal agent against onchocerciasis

The introduction of ivermectin therapy has proved to be the most important advance in the management and control of onchocerciaisis. By using the standard dosing schedule (150 micrograms/kg) in a mass chemotherapy campaign in Awhum, Nigeria, 128 (14.6%) of 875 eligible subjects used in this study were underdosed while 696 (79.6%) and 51 (5.8%) were overdosed and correctly dosed, respectively. Since underdosing is more serious than overdosing, an improved dosing schedule (300 micrograms/kg) is hereby suggested, bearing in mind that ivermectin is safe at doses well in excess of the standard dose. 824 (94.2%) And 51 (5.8%) of these eligible subjects would be overdosed and correctly dosed respectively, if this improved dosing schedule (< 15 kg, 0 mg (0 tablet); 15-20 kg, 6 mg (1 tablet); 21-40 kg, 12 mg (2 tablets); 41-60 kg, 18 mg (3 tablets); > 60 kg, 24 mg (4 tablets)) were to be employed. This dosing schedule is worth adopting and an investigation of the effects of these high single doses of ivermectin on adult Onchocerca volvolus worms is advocated. Furthermore 'non-responders' may be investigated for doses administered.