Atovaquone for salvage treatment and suppression of toxoplasmic encephalitis in patients with AIDS. Atovaquone/Toxoplasmic Encephalitis Study Group.

To examine the efficacy of atovaquone as salvage therapy in patients with AIDS-related toxoplasmic encephalitis, 93 patients with AIDS and toxoplasmic encephalitis who were intolerant of standard therapy (pyrimethamine plus sulfadiazine or clindamycin) or for whom such therapy was failing were treated with atovaquone tablets (750 mg four times daily) for 18 weeks. Plasma levels of atovaquone were measured with high-pressure liquid chromatography, and the clinical and radiological responses and survival were compared according to median plasma concentration groups. During the acute-therapy phase (the first 6 weeks), the conditions of 52% and 37% of the patients, respectively, were clinically or radiologically improved; the conditions of 26% and 15% remained clinically or radiologically improved by week 18. Median survival for all patients was 189 days (Kaplan-Meier estimate). A post-hoc analysis revealed a positive relationship between clinical and radiological responses and median atovaquone plasma concentrations. Survival time among patients with high or medium median steady-state plasma concentrations (319 and 289 days) was significantly better than that among those with low plasma concentrations (114 days; P = .003 and P = .006, respectively).