The role of pigmentation on the development of chloroquine retinopathy in rabbits

In a prospective study using sex-matched pigmented and non-pigmented rabbits, the role of pigmentation or melanin on chloroquine-induced retinal or ocular toxicity was determined. Results showed that chloroquine produced a series of ocular toxicity ranging from loss of pupillary and corneal reflex to severe retinopathy. The minimal dose at which these ocular toxicities develop on pigmented rabbits was found to be 5 mg/kg daily for 30 days or a cumulative dose of 225 mg of chloroquine. Furthermore, the cumulative effect of the drug depends on the body weight of the animal, total dose administered and duration of therapy. It is concluded that the effect of chloroquine on pigmentation depends on total amount of drug used, which would predispose to retinal pathology. Keywords : Chloroquine, pigmentation, melanin, retinopathy, retinotoxic West African Journal of Pharmacology and Drug Research Vol. 21 (1&2) 2005: pp. 55-59