New developments in the treatment of Pneumocystis carinii pneumonia.

Pneumocystis carinii pneumonia and therapies to treat this infection are associated with frequent and severe morbidity in patients with acquired immunodeficiency syndrome (AIDS). Mortality rates remain in the 20 to 40 percent range for severe episodes. Thus, less toxic and more effective therapies are needed. For mild-to-moderately severe episodes (PaO2 greater than 70 mm Hg or [A-a]DO2 less than 35 mm Hg), studies suggest that trimethoprim-dapsone, clindamycin-primaquine, and BW 566C80 may cause less toxicity than conventional therapy with trimethoprim-sulfamethoxazole or parenteral pentamidine. However, prospective, controlled trials are needed to establish whether the newer therapies are as effective as the existing licensed treatments. Aerosolized pentamidine is another new therapy that is better tolerated than trimethoprim-sulfamethoxazole but may not be as effective as parenteral treatment when there is extensive airspace consolidation. For severe episodes (PaO2 less than 70 mm Hg or [A-a]DO2 greater than 35 mm Hg), recent studies have established that adjunctive therapy with corticosteroids reduces mortality approximately twofold. For patients who have failed conventional treatments and are unable to ingest oral medications, trimetrexate may be tried. Other compounds being tested may further expand the therapeutic armamentarium with safer and more effective drugs.