Successful desensitization to dapsone for Pneumocystis carinii prophylaxis in an HIV-positive patient

OBJECTIVE: To report a case of successful desensitization to dapsone for Pneumocystis carinii pneumonia (PCP) prophylaxis in a patient unable to tolerate trimethoprim/sulfamethoxazole (TMP/SMX) desensitization or dapsone at standard doses. CASE SUMMARY: A 37-year-old HIV-positive African-American man was treated for pneumonia with TMP/SMX and then continued on the drug for PCP prophylaxis. After experiencing a pruritic maculopapular rash with TMP/SMX, both at standard doses and after attempting a desensitization regimen to the drug, he was started on dapsone for PCP prophylaxis. He experienced a rash and fever after taking dapsone at standard PCP prophylactic doses. At this time, an 18-day oral dapsone rechallenge by dose escalation was attempted, and it was well tolerated. CONCLUSIONS: This case suggests that utilization of a dapsone desensitization regimen may permit a viable treatment option in patients previously thought to be intolerant to the agent. More regimens of this type should be attempted and the results published using both dapsone and TMP/SMX, so that standard desensitization treatment guidelines may eventually be adopted.