Lack of cross-reactive allergic response to brimonidine in patients with known apraclonidine allergy.

PURPOSE

To assess the allergenic potential of topical brimonidine 0.2% in patients shown to be allergic to apraclonidine 0.5%.

METHODS

Eighteen glaucoma patients who developed allergy to apraclonidine were enrolled. Allergy was graded and documented photographically. Apraclonidine was then discontinued until the allergy resolved. Grading and photography were repeated, following which treatment with brimonidine was initiated. Patients were examined 1 h after the initial drop of brimonidine, twice weekly for 6 weeks, and at 3 monthly intervals thereafter. All other anti-glaucoma medications were continued.

RESULTS

Mean patient age was 66.3 +/- 14.9 years (range 33.5-89.3 years). The mean time to apraclonidine allergy from initial exposure was 12.9 +/- 12.9 months (range 2.1-46.8 months). For the 10 patients rechallenged with apraclonidine, the mean time to allergy was 13.6 +/- 10.2 days (range 3-32 days). Mean duration of brimonidine therapy was 140.7 +/- 66.2 days (range 14-286 days), with 11 patients reaching at least 150 days of follow-up. Two patients developed symptomatic brimonidine allergy at 138 and 201 days respectively. For those patients who did not develop symptoms of allergy to brimonidine, there was no significant change in any of the parameters by which allergy was graded throughout the study.

CONCLUSIONS

Patients with known apraclonidine allergy do not develop an early allergic response to brimonidine. These data rule against a cross-reactive allergic response between these two alpha 2-adrenoreceptor agonists.