Pneumocystis carinii pneumonia therapy with 9-deazainosine in rats.

An inosine analog, 9-deazainosine, has previously been demonstrated to inhibit Pneumocystis carinii in culture with WI-38 cells. The present study shows that it is also effective against Pneumocystis carinii in immunosuppressed Sprague-Dawley rats with Pneumocystis carinii pneumonia. After 8 wk of immunosuppression, rats that developed severe Pneumocystis carinii pneumonia were treated with either 9-deazainosine or served as controls. After 15 days of therapy, animals were sacrificed and severity of infection determined by morphologic examination of lungs for numbers of Pneumocystis carinii. Treated animals had greatly reduced numbers of Pneumocystis carinii trophozoites and cysts, compared with controls. This drug shows promise for therapy of Pneumocystis carinii pneumonia and should be studied further.