Brimonidine 2 mg, Brinzolamide 10 mg Eye drops

Brimonidine tartrate ophthalmic solution is a relatively selective alpha-2 adrenergic receptor agonist with a peak ocular hypotensive effect occurring at two hours post-dosing.

Fluorophotometric studies in animals and humans suggest that brimonidine tartrate has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow.

Absorption — After ocular administration of either a 0.1% or 0.2% solution, plasma concentrations peaked within 0.5 to 2.5 hours and declined with a systemic half-life of approximately 2 hours.

Distribution — Brimonidine was approximately 29% bound to plasma proteins in healthy subjects.

Metabolism — In humans, brimonidine is extensively metabolized by the liver.

Excretion — Urinary excretion is the major route of elimination of brimonidine and its metabolites. Approximately 87% of an orally-administered radioactive dose of brimonidine was eliminated within 120 hours, with 74% found in the urine.

SIMBRINZA is comprised of two components: brinzolamide (carbonic anhydrase inhibitor) and brimonidine tartrate (alpha 2 adrenergic receptor agonist). Each of these two components decreases elevated IOP. Elevated IOP is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. The higher the level of IOP, the greater the likelihood of glaucomatous field loss and optic nerve damage.

Brinzolamide inhibits carbonic anhydrase in the ciliary processes of the eye to decrease aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport. Brinzolamide has a peak ocular hypotensive effect occurring at 2 to 3 hours post-dosing. Fluorophotometric studies in animals and humans suggest that brimonidine tartrate has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow. Brimonidine tartrate has a peak ocular hypotensive effect occurring at two hours post-dosing. The result is a reduction in intraocular pressure (IOP).

Following topical ocular administration, brinzolamide is absorbed into the systemic circulation. Due to its affinity for CA-II, brinzolamide distributes extensively into the Red Blood Cells (RBC) and exhibits a long half-life in whole blood (approximately 111 days). In humans, the metabolite N-desethyl brinzolamide is formed, which also binds to CA and accumulates in RBCs. This metabolite binds mainly to CA-I in the presence of brinzolamide. In plasma, both parent brinzolamide and N-desethyl brinzolamide concentrations are <10 ng/mL. Binding to plasma proteins is approximately 60%. Brinzolamide is eliminated predominantly in the urine as unchanged drug. N-Desethyl brinzolamide is also found in the urine along with lower concentrations of the N-desmethoxypropyl and O-desmethyl metabolites.

After ocular administration of a 0.2% solution of brimonidine tartrate, plasma concentrations peaked within 1 to 4 hours and declined with a systemic half-life of approximately 3 hours. In humans, systemic metabolism of brimonidine is extensive. It is metabolized primarily by the liver. Urinary excretion is the major route of elimination of the drug and its metabolites. Approximately 87% of an orally-administered radioactive dose was eliminated within 120 hours, with 74% found in the urine.

In humans, a study was conducted to evaluate the pharmacokinetics of the fixed combination of brinzolamide/brimonidine tartrate 1%/0.2% ophthalmic suspension. Healthy volunteers were randomly assigned to receive twice or three times a day either the fixed combination, or either of its individual components, brinzolamide or brimonidine. Subjects who were assigned to the brinzolamide alone or combination arms were administered oral brinzolamide capsules for two weeks prior to beginning dosing with the topical ocular suspension. The results demonstrate that the systemic plasma exposure (AUC and Cmax) to brinzolamide and brimonidine in humans is similar after dosing with the fixed combination to that observed following dosing with the individual components.