Alphagan allergy may increase the propensity for multiple eye-drop allergy

Area of Science:

• Ophthalmology
• Allergology
• Pharmacovigilance

Background:

• Brimonidine tartrate 0.2% ophthalmic solution (Alphagan) is a widely used treatment for lowering intraocular pressure in glaucoma.
• Clinical observations suggest a high incidence of allergic reactions to Alphagan.
• Concerns exist regarding potential cross-reactivity and increased allergy rates to subsequent topical medications in patients allergic to Alphagan.

Purpose of the Study:

• To determine the frequency of allergy-related discontinuation of brimonidine tartrate (Alphagan).
• To investigate whether patients experiencing allergy to Alphagan have a higher rate of allergy to other topical glaucoma preparations.
• To assess the potential for cross-reactivity between Alphagan and other commonly used glaucoma medications.

Main Methods:

• A retrospective analysis of glaucoma patient treatment histories was conducted.
• Data from consecutive patients treated for primary open angle glaucoma, ocular hypertension, or normal tension glaucoma between May 1999 and September 2001 were included.
• Patients with incomplete treatment records or other forms of glaucoma were excluded.

Main Results:

• The rate of Alphagan discontinuation due to allergy was 73 per 100,000 patient treatment days, significantly higher than other preparations.
• In patients allergic to both Alphagan and other medications (Timoptol, Trusopt, Xalatan), the interval between the first and second allergic reaction was shorter when Alphagan allergy occurred first.
• Statistically significant cross-reactivity was observed with Timoptol and Trusopt.

Conclusions:

• Brimonidine tartrate (Alphagan) exhibits high allergenicity.
• Prior allergy to Alphagan may increase the risk of developing allergies to subsequently prescribed topical glaucoma treatments.
• Clinicians should consider the potential for increased allergic sensitivity when prescribing alternative medications after Alphagan discontinuation.