Alphagan allergy may increase the propensity for multiple eye-drop allergy.
OBJECTIVE
Since its introduction in 1996, brimonidine tartrate 0.2% ophthalmic solution (Alphagan, Allergan) twice daily has become established as an effective intra ocular pressure-lowering treatment. While the efficacy of Alphagan cannot be questioned, we gained the clinical impression that the drug has an unacceptably high rate of allergy. Of greater concern, we suspected that patients suffering from local Alphagan allergy had a higher rate of allergy to subsequently used topical preparations. We analysed data from a large scale study of glaucoma patients to establish whether our suspicions were correct.


METHODS
We have created a database of the entire glaucoma treatment histories for consecutive patients attending a single consultant's clinics (DMIM) at Glasgow Royal Infirmary between May 1999 and September 2001. All have undergone medical treatment for primary open angle glaucoma, ocular hypertension, or normal tension glaucoma. Patients with any other form of glaucoma, and patients in whom a full record of treatment was not available were excluded from the study.


RESULTS
Alphagan was discontinued due to allergy on 73 per 100,000 patient treatment days. This was a far higher frequency than for other preparations. In patients allergic to both Alphagan and another preparation (Timoptol, Trusopt and Xalatan), the mean interval between the first and second allergy was shorter when Alphagan allergy occurred first. This was statistically significant in Timoptol and Trusopt cross-reactivity.


CONCLUSIONS
Alphagan has high allergenicity, and may increase the likelihood of allergy to subsequently used preparations.
Osborne
S A
SA
North Glasgow University Hospitals, NHS Trust, UK. stuartosborne@doctors.org.uk
Montgomery
D M I
DM
Morris
D
D
McKay
I C
IC
D000316:Adrenergic alpha-Agonists / Q000009:adverse effects; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000009:adverse effects*; D000068438:Brimonidine Tartrate; D003429:Cross Reactions; D004334:Drug Administration Schedule; D004342:Drug Hypersensitivity / Q000209:etiology*; D005260:Female; D005901:Glaucoma / Q000188:drug therapy / Q000601:surgery; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000601:surgery; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000009:adverse effects; D011810:Quinoxalines / Q000009:adverse effects*; D012189:Retrospective Studies; D013449:Sulfonamides / Q000009:adverse effects; D013876:Thiophenes / Q000009:adverse effects; D013999:Timolol / Q000009:adverse effects
D000316:Adrenergic alpha-Agonists; D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions; D011810:Quinoxalines; D013449:Sulfonamides; D013876:Thiophenes; D000068438:Brimonidine Tartrate; D013999:Timolol; C062765:dorzolamide