therapeutic focus

Relieving Pressure

Fixed-dose combination medication helps lower patients' IOP.

LEO SEMES, O.D.

Each day I see a number of patients suffering from glaucoma. Many of them are elderly and, therefore, need additional lowering of their intraocular pressure (IOP) as increasing age is a risk factor for disease progression.

I use Simbrinza Suspension (brinzolamide/brimonidine tartrate ophthalmic suspension, Alcon) as an adjunctive therapy to other IOP-lowering drugs — typically prostaglandin analogues (PGAs) — in open-angle glaucoma patients. It can also be used as a replacement therapy for patients using other fixed combinations of IOP-lowering drugs, and for patients already taking a PGA and showing disease progression or not achieving target IOP.

Alcon's Simbrinza Suspension received FDA approval in April.

Background

Simbrinza combines a carbonic anhydrase inhibitor (brinzolamide 1.0%) with an alpha 2 adrenergic receptor agonist (brimonidine tartrate 0.2%) in one bottle. The fixed-dose combination medication decreases elevated IOP by 21% to 35% percent.^1,2

Also, Simbrinza does not include a beta blocker. This is especially important for my elderly patients who often suffer from high blood pressure, high cholesterol, heart disease and diabetes. Beta blockers to lower systemic blood pressure are commonly prescribed to the elderly, and patients on systemic beta blockers usually do not show additional IOP lowering.

Additionally, the systemic absorption may lower blood pressure at night, which may have harmful implications to perfusion pressure at the optic nerve.

Mechanism of action

Both components of Simbrinza have complimentary mechanisms of action. Brimonidine tartrate works to reduce aqueous production, as well as increase aqueous outflow, and brinzolamide also reduces aqueous production, providing a “one-two punch.” While these compounds both have similar mechanism of action, they have different durations of action and onset. Additionally, brimonidine tartrate does not lower IOP at night.

The recommended dose for Simbrinza is one drop in the affected eye(s) t.i.d. If the patient uses a topical ophthalmic drug, have them administer the drops at least five minutes apart.

Side effects

The most frequently reported adverse reactions occurring in 3% to 5% of patients in clinical trials included blurred vision, eye irritation, dysgeusia (distortion of taste), dry mouth and eye allergy. Individually, brimonidine tartrate has a relatively high prevalence of ocular sensitivity, so some patients may develop allergic responses or reactions. Meanwhile, brinzolamide is contraindicated in patients who have a systemic sulfur sensitivity, as it's a sulfonamide.

Clinical studies

Through two Phase III clinical trials comprised of approximately 1,300 patients, Simbrinza provided 5mmHg to 9mmHg IOP reduction from baseline to month three, and patients' mean IOP at baseline from 22mmHg to 36mmHg.

An efficient treatment

I have about half a dozen patients currently on Simbrinza and find it effective in producing additional IOP-lowering effects. Also, its lack of beta blockers made it a great choice for my older patient base. OM

References are available in the online version of this article at optometricman agement.com.

DR. SEMES IS AN ASSOCIATE PROFESSOR AND DIRECTOR OF CONTINUING EDUCATION AT THE UNIVERSITY OF ALABAMA BIRMINGHAM SCHOOL OF OPTOMETRY. HE IS A FOUNDING MEMBER OF THE OPTOMETRIC GLAUCOMA SOCIETY. SEND COMMENTS TO OPTOMETRICMANAGEMENT@GMAIL.COM.