A randomized, pilot trial comparing full versus escalating dose regimens for the desensitization of AIDS patients allergic to sulfonamides.

UNLABELLED Sulfonamides are drugs extensively used in the management of AIDS patients. However, the use of sulfonamides is often associated with the development of allergic reactions, provoking the substitution of the drug (by another that may be less effective); alternatively attempts are made to desensitize the patient. OBJECTIVE Compare two drug regimens (full vs. escalating doses) for the oral desensitization of AIDS patients allergic to sulfonamides. MATERIAL AND METHODS AIDS patients with previous allergic reactions to sulfonamides and requiring prophylaxis against Pneumocistis carinii, central nervous system toxoplasmosis and diarrhea caused by Isospora belli were randomly assigned to a group receiving a routine dose of cothrimoxazole, or another that received escalating doses of an oral suspension of the same drug, initiating with 75 mg/day of sulfamethoxazole that was doubled every 48 hours till the full dose was reached, if no allergic reaction occurred. Patients were monitored for at least 6 months after enrollment in the trial. The major end-point was the ability to maintain prophylactic treatment after that period of time. Plasma viral load (PVL) and CD(4)/CD(8) counts were measured at baseline. Liver enzymes and hematological parameters were measured at baseline and after 1, 3 and 6 months. RESULTS Eighteen patients were enrolled in the study (15 men and 3 women), with ages ranging from 30 to 57 years (mean 39.9). The mean CD(4) counts were slightly higher for patients receiving a full dose; there was also a trend towards higher baseline CD(8) counts among patients developing new reactions. The mean PVL was similar among the patients in both desensitization groups. The incidence of new allergic reactions was identical (40%) in the two groups. All adverse reactions were mild and no significant increase in liver enzymes were observed. CONCLUSION Dose regimen is not a predictor of the development of new allergic reactions amongst patients challenged with sulfonamides after an initial allergic reaction.