Prevention of Pneumocystis carinii pneumonia by inhaled pentamidine

The efficacy and toxicity of pentamidine inhaled once a month to prevent Pneumocystis carinii pneumonia (PCP) was investigated in 102 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). The cohort was compared with historical controls after a mean duration of prophylaxis of 6.38 months. 86% and 15% of the patients had AIDS or ARC, respectively. 50% of patients had had one previous episode of PCP, 9% had had two episodes, and 3% had had three. 11 patients acquired PCP. Among these 51 patients with one prior episode of PCP, the PCP-free survival after 3.03, 4.7, and 6.38 months of prophylaxis was 98%, 92%, and 82%, respectively. Compared with those for historical controls, the data suggest that inhaled pentamidine can delay relapse by 6 months and reduce the rate of relapse by 50%. PCP acquired while patients were inhaling pentamidine prophylactically was mild and had a case-fatality rate of only 9%. Further investigation of the prophylactic value of inhaled pentamidine is warranted.