IVERMECTIN AND ONCHOCERCAL OPTIC NEURITIS - SHORT-TERM EFFECTS

In 1982 the macrocyclic lactone, ivermectin, was first tested in human patients with onchocerciasis. It has since undergone phase I to IV tr ials and is now being widely distributed in onchocercal areas. The pre vious microfilaricide, diethylcarbamazine citrate (DEC), is known to p recipitate or exacerbate active optic neuritis in some onchocercal pat ients, as part of a wider inflammatory response (the Mazzotti reaction ). Ivermectin may also cause a mild reaction, especially in people wit h high microfilarial loads. Few data are available concerning the effe ct of ivermectin on active optic neuritis. A large, randomised, double -masked, phase IV trial is reported. Individuals were screened for evi dence of optic nerve disease (OND), and those identified as possible c ases of OND underwent detailed ophthalmic examination, including fluor escein angiography, before being dosed with ivermectin or placebo. A t otal of 6831 persons were screened of whom 856 (13%) underwent angiogr aphy prior to dosing. At 7-14 days after dosing an attempt was made to reexamine 50% of adults over the age of 20 years, including all those with OND. Six hundred and eighty-eight repeat or new angiograms were performed. During this period, 5 new cases of active optic neuritis an d one case of exacerbation of existing optic neuritis were identified. Five of these individuals had received placebo and one ivermectin. Tw o individuals with optic neuritis before dosing had improved after 7-1 4 days. One had received placebo, the other ivermectin. Ivermectin doe s not appear to precipitate or exacerbate optic neuritis at a period o f 7-14 days.