Safety of dapsone as Pneumocystis carinii pneumonia prophylaxis in human immunodeficiency virus-infected patients with allergy to trimethoprim/sulfamethoxazole

Abstract

Objective: To assess the safety of dapsone prophylaxis of Pneumocystis carinii pneumonia (PCP) in patients with prior intolerance to trimethoprim/sulfamethoxazole (TMP/SMX).

Methods: We conducted a retrospective study in the categorical human immunodeficiency virus out-patient program of a university hospital. Patients who had filled prescriptions for dapsone at our pharmacy between January 1991 and April 1994 were evaluated and 75 patients were found eligible for analysis.

Results: The overall incidence of adverse events (AE) in our study cohort was 39%. The most common AEs were anemia (23%) and rash (16%). However, after critical evaluation of each case, only 3 cases of anemia (4%) and 2 cases of rash (3%) were judged to be "likely related" to dapsone. Only 5/75 patients (7%) developed the same intolerance to dapsone as previously experienced on TMP/SMX, and none of these cases was viewed as "likely related" to dapsone. A dapsone regimen of 100 mg qd and a prior episode of PCP were associated with a higher incidence of AEs. Eight cases of PCP occurred in spite of dapsone prophylaxis for an incidence of 7 cases per 1,000 patient-months. Seven of the cases of PCP occurred in patients who were receiving secondary prophylaxis.

Conclusions: Given the low incidence of AEs judged to be "likely related" to dapsone, this drug is a reasonable choice for PCP prophylaxis in patients with prior AEs to TMP/SMX.