Trimethoprim-sulfamethoxazole desensitization in AIDS.

Trimethoprim-sulfamethoxazole (TMS) desensitization was carried out in three patients with AIDS and Pneumocystis carinii pneumonia (PCP) in whom treatment with TMS had to be discontinued after 8 to 12 days due to an allergic reaction. Although the pneumonia was under control we decided for a desensitization to TMS because of the frequent reinfection and the high mortality rate particularly if treatment is incomplete. On the first day the patients took 0.4 mg/2 mg trimethoprim/sulfamethoxazole orally. The dose was increased during 9 successive days to 80 mg/400 mg trimethoprim/sulfamethoxazole. From the 10th to the 16th day 160 mg/800 mg trimethoprim/sulfamethoxazole was given daily and subsequently twice daily which is the recommended dose for prophylaxis of PCP. The desensitization was successful in two patients and a PCP prophylaxis was possible.