Brimonidine reduces the amount of fluid in the eye, which decreases pressure inside the eye. Brimonidine ophthalmic (for the eyes) is used to treat open-angle glaucoma or ocular hypertension (high pressure inside the eye). Brimonidine is an alpha adrenergic receptor agonist (primarily alpha-2). Fluorophotometric studies in animals and humans suggest that Brimonidine has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow. Adverse reactions occurring in approximately 10­20% of the subjects receiving brimonidine ophthalmic solution (0.1-0.2%) included: allergic conjunctivitis, conjunctival hyperemia, and eye pruritus. Because Brimonidine may reduce blood pressure, caution in using drugs such as antihypertensives and/or cardiac glycosides with Brimonidine is advised.

Brinzolamide reduces the amount of fluid in the eye, which decreases pressure inside the eye. Brinzolamide is a carbonic anhydrase inhibitor that is FDA approved for the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma. Common adverse reactions include abnormal taste in mouth and blurred vision. The concomitant administration of brinzolamide and oral carbonic anhydrase inhibitors is not recommended. Plus, in patients treated with oral carbonic anhydrase inhibitors, rare instances of acid-base alterations have occurred with high-dose salicylate therapy.