DAPSONE-INDUCED AND PRIMAQUINE-INDUCED METHEMOGLOBINEMIA IN HIV-INFECTED INDIVIDUALS

Clinically significant methemoglobinemia can develop as a result of me dications. Although dapsone and primaquine are known to produce methem oglobinemia in susceptible individuals, methemoglobinemia has been rep orted only rarely in the human immunodeficiency virus (HIV) population . We describe five cases of methemoglobinemia caused by either primaqu ine or dapsone alone or in combination. The initial methemoglobin leve l ranged from 15.3% in the patient whose methemoglobinemia was caused by primaquine alone to 33.1%. Five patients developed symptomatic meth emoglobinemia requiring hospitalization for 1 to 12 days. Two cases re sulted from intentional overdoses of dapsone, and three developed with in several days of commencing primaquine while dapsone remained presen t in the bloodstream. The four severe cases required intravenous methy lene blue, supplemental oxygen, plus erythrocyte transfusions, whereas the mild case responded to oxygen therapy plus discontinuation of the precipitating drugs. Blood gases and pulse oximetry do not aid in the diagnosis, which requires cooximetry. Our study indicates that dapson e and primaquine alone or in combination can produce clinically signif icant methemoglobinemia in HIV-infected individuals, either in the set ting of an overdose or when primaquine is instituted before dapsone ha s been cleared from the bloodstream.