Good outcome with trimethoprim 10 mg/kg/day-sulfamethoxazole 50 mg/kg/day for Pneumocystis jirovecii pneumonia in HIV infected patients

Pneumocystis jirovecii pneumonia (PCP) in human immunodeficiency virus (HIV)-infected patients is usually treated with trimethoprim (TMP)-sulfamethoxazole (SMX) 1920 mg 3 times daily (approximately equivalent to TMP 15 mg/kg/day-SMX 75 mg/kg/day) for 21 days. Pharmacokinetic data suggest that lower doses would be equally efficacious and might be associated with a lower incidence of adverse effects. We conducted a retrospective review of case notes for the first episode of laboratory-confirmed PCP in HIV-infected patients treated at Auckland City Hospital, from January 1991 through December 2007. Seventy-three of 84 (87%) patients were treated with TMP-SMX 960 mg 4 times daily or 3 times daily (approximately TMP 10 mg/kg/day-SMX 50 mg/kg/day). The overall mortality was 5/73 (7%). The mortality in patients with severe disease (transcutaneous oxygen saturation on admission <= 84%) was 3/16 (19%) and in patients admitted to the intensive care unit was 5/9 (56%). Fifteen of 73 (21%) patients required a change to an alternative treatment regimen because of adverse effects (rash in 10, rash plus fever in 3, neutropenia in 1, fever plus headache in 1). Treatment of PCP in adult HIV-infected patients with TMP-SMX 960 mg QID or TID appears to have comparable efficacy to treatment with higher doses and to be associated with a lower rate of treatment limiting adverse effects.