Trimethoprim-Sulfamethoxazole Compared with Pentamidine for Treatment of Pneumocystis carinii Pneumonia in the Acquired Immunodeficiency Syndrome: A Prospective, Noncrossover Study

Study Objective: To ascertain the efficacy and toxicity of trimethoprim-sulfamethoxazole or pentamidine when either is given alone during the entire treatment period for Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome (AIDS).

Design: Prospective, randomized, noncrossover comparison of trimethoprim-sulfamethoxazole with pentamidine. Trimethoprim-sulfamethoxazole dosage was adjusted to maintain serum trimethoprim at 5 to 8 µg/mL. Pentamidine dosage was reduced by 30% to 50% for an absolute rise in serum creatinine of more than 88 µmol/L (1 mg/dL).

Setting: Tertiary care hospital and AIDS clinic.

Patients: Thirty-six patients were treated with trimethoprim-sulfamethoxazole and 34 with pentamidine. Pretreatment clinical features and laboratory test results were similar in the two groups.

Measurements and Main Results: Thirty-six recipients of trimethoprim-sulfamethoxazole and 33 recipients of pentamidine completed therapy without crossover. Trimethoprim-sulfamethoxazole caused a rash (44%) and anemia (39%) more frequently (P ≤ 0.03, whereas pentamidine caused nephrotoxicity (64%), hypotension (27%), or hypoglycemia (21%) more frequently (P ≤ 0.01). The (A - a)Do₂ improved by greater than 1.3 kPa (10 mm Hg) 8 days earlier for trimethoprim-sulfamethoxazole recipients (95% CI for the difference in response, -1 to 17; P = 0.04). Thirty-one (86%) patients treated with trimethoprim-sulfamethoxazole and 20 (61%) with pentamidine survived and were without respiratory support at completion of treatment (95% CI for the difference in response, 5% to 45%; P = 0.03).

Conclusions: For most patients with AIDS and P. carinii pneumonia, successful treatment with a single agent is possible. Toxicity associated with the two standard treatments is rarely life-threatening and may be diminished if the trimethoprim-sulfamethoxazole dosage is modified by pharmacokinetic monitoring and the pentamidine dosage is reduced for nephrotoxicity. Oxygenation improved more quickly and survival was better with trimethoprim-sulfamethoxazole.