Efficacy of atovaquone in treatment of toxoplasmosis in patients with AIDS. The NIAID-Clinical Center Intramural AIDS Program.

Atovaquone (formerly 566C80) is a hydroxynaphthoquinone with potent activity against Toxoplasma in vitro and in laboratory animals. Eight patients with AIDS and presumed or biopsy confirmed toxoplasmosis who were intolerant of or had not responded to standard therapies were treated with oral atovaquone 750 mg four times a day. Seven patients showed radiographic improvement; the other remained radiographically stable. Six patients died 6-60 weeks after enrollment with no clinical (six) or necropsy (three) evidence of recurrent toxoplasmosis; two patients relapsed at 10 and 32 weeks. Toxicity was mild: only one patient required temporary discontinuation of drug due to a rash. Atovaquone is a well-tolerated drug that appears to be an effective alternative for patients with toxoplasmosis who are intolerant of standard therapies.