Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome: pathophysiology, therapy, and prevention.

The continuing growth of the acquired immunodeficiency syndrome (AIDS) epidemic has caused a parallel increase in patients with Pneumocystis carinii pneumonia (PCP). PCP has a wide spectrum of severity, from mild disease to severe parenchymal lung damage. Outcome is determined by severity of lung injury, the underlying physical condition of the patient, and concomitant infections. Both trimethoprim-sulfamethoxazole (TMP-SMX) and pentamidine are effective therapeutic agents; however, both cause a high incidence of adverse reactions. TMP-SMX therapy can be made safer by careful monitoring and dose adjustment. Pentamidine toxicity, especially hypoglycemia, appears to be cumulative dose-dependent. Experimental therapies, including TMP-dapsone and aerosolized pentamidine, appear promising in mild to moderate disease, while trimetrexate may be more effective in severe disease. Corticosteroids are unproven in decreasing mortality. Prophylaxis of PCP is possible with TMP-SMX but the high rate of adverse reactions make long-term therapy difficult. Other oral therapies such as dapsone, pyrimethamine/sulfadoxine are also promising but not yet tested. Aerosolized pentamidine is effective and safe for prophylaxis regimen when administered correctly. Airway irritation as manifested by cough and/or wheezing is a common adverse effect of aerosolized pentamidine.