Activity of roxithromycin (RU 28965), a macrolide, against Toxoplasma gondii infection in mice.

Roxithromycin (RU 28965), an ether oxime derivative of erythromycin, protected mice against a lethal infection with the virulent RH strain of Toxoplasma gondii. Therapy begun 24 h before, 2 h after, and 24 h after infection with 2 X 10(3) tachyzoites protected 90, 80, and 50% of the mice, compared with 0% of untreated controls (P less than 0.05 to 0.001). Toxoplasma was isolated in less than 20% of surviving roxithromycin-treated mice.