Brinzolamide (Azopt)

Brinzolamide (brand name Azopt) is a topical carbonic anhydrase inhibitor eye drop used to lower intraocular pressure in open-angle glaucoma and ocular hypertension. It is similar in mechanism and effect to dorzolamide but is formulated as a milky-white suspension rather than a solution. The two main practical differences from dorzolamide are that brinzolamide stings less on instillation but must be shaken before use.

How It Works

Brinzolamide blocks carbonic anhydrase II in the ciliary body, reducing aqueous humor production and lowering intraocular pressure. Effect begins within 1-2 hours and lasts approximately 8-12 hours.

Common Uses

• Primary open-angle glaucoma
• Ocular hypertension
• Adjunctive therapy when prostaglandin alone is inadequate

Combinations:

• Simbrinza - brinzolamide + brimonidine

How to Use

• Shake well before each use
• Monotherapy: One drop in affected eye(s) three times daily
• Simbrinza combination: One drop three times daily in the U.S.; follow the exact label used in your country
• Punctal occlusion for 1-2 minutes after instillation
• Separate other eye drops as directed; the U.S. Azopt/generic label says to wait at least 10 minutes
• Remove contact lenses before use; reinsert after 15 minutes

Side Effects

Local

• Mild blurring transiently after instillation (the suspension temporarily clouds the tear film) - the most common side effect
• Bitter taste from drainage into the throat
• Eye dryness, foreign body sensation, itching, redness, or discomfort with chronic use
• Ocular keratitis or punctate staining
• Allergic blepharoconjunctivitis (uncommon)
• Corneal edema - uncommon overall, but more likely with reduced corneal endothelial cell counts

Systemic

• Much lower systemic exposure than oral CAIs, but topical brinzolamide can still be absorbed systemically
• The systemic side effects of oral CAIs (acetazolamide) - fatigue, paresthesias, kidney stones - are uncommon with topical brinzolamide

Precautions

• Sulfa allergy - brinzolamide is a sulfonamide. The FDA label carries a class warning that rare severe sulfonamide-type reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, can occur. Immunologic cross-reactivity with sulfonamide antibiotics appears uncommon, but severe prior reactions warrant extra caution and clinician review.
• Severe renal impairment - not recommended if creatinine clearance is below 30 mL/min
• Corneal endothelial disease - caution; may worsen edema, especially in Fuchs dystrophy or after multiple intraocular surgeries
• Pregnancy and breastfeeding - alternative agents are usually preferred during pregnancy when clinically feasible. Brinzolamide showed teratogenic effects in animal studies at high systemic doses; ophthalmic exposure is much lower but the safety margin in pregnancy has not been established in humans. It is not known whether brinzolamide is excreted in human breast milk; topical dosing produces low systemic levels, and punctal occlusion further reduces systemic transfer. Discuss with your obstetrician and ophthalmologist

Brinzolamide vs. Dorzolamide

Patients who do not tolerate one CAI sometimes do well on the other. Brinzolamide is preferred when stinging is a major issue; dorzolamide is preferred when blur after instillation is a problem.

Frequently Asked Questions

Why does my vision blur after using the drop?

Brinzolamide is a suspension - small particles that temporarily cloud the tear film. The blur clears within minutes to half an hour. Many patients dose at times when brief blur is not a problem.

Why do I have to shake the bottle?

The suspension settles between uses. Shaking redistributes the particles so each drop has the correct concentration. Failing to shake reduces effectiveness.

Can I use it with my prostaglandin?

Yes. Brinzolamide works by reducing fluid production and is additive with prostaglandins (which increase outflow). Separate drops by the interval on your label or as directed by your clinician.

References