Brinzolamide – Uses, Dosage, Side Effects, Interactions

Brinzolamide is a sulfonamide and carbonic anhydrase inhibitor with a specific affinity for carbonic anhydrase II. Following topical ocular administration, brinzolamide inhibits carbonic anhydrase II, an enzyme that is responsible for the movement of sodium and fluid transport in the eye. This inhibition leads to a decrease in aqueous humor secretion, probably by slowing the formation of bicarbonate ions and results in a reduction in intraocular pressure. Brinzolamide is used to treat increased pressure in the eye caused by open-angle glaucoma.

Brinzolamide is a sulfonamide and a thienothiazine. It has a role as an antiglaucoma drug and an EC 4.2.1.1 (carbonic anhydrase) inhibitor.

Brinzolamide is a highly specific, non-competitive, reversible carbonic anhydrase inhibitor. Carbonic anhydrase (CA) is an enzyme found in many tissues of the body including the eye. It catalyzes the reversible reaction involving the hydration of carbon dioxide and the dehydration of carbonic acid. In humans, carbonic anhydrase exists as a number of isoenzymes, the most active being carbonic anhydrase II (CA-II). Inhibition of carbonic anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport. The result is a reduction in intraocular pressure. Brinzolamide is indicated in the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.

Mechanism of Action

Brinzolamide is a highly specific inhibitor of CA-II, which is the main CA isoenzyme involved in the secretion of aqueous humor. Inhibition of CA in the ciliary process of the eye slows the formation of bicarbonate and reduces sodium and fluid transport. This results in a reduction in the rate of aqueous humor secretion and intraocular pressure. Brinzolamide is absorbed systemically following topical ocular administration. Since it has a high affinity for CA-II, brinzolamide binds extensively to red blood cells, where CA-II is primarily found. As sufficient CA-II activity remains, adverse effects resulting from the systemic inhibition of CA by brinzolamide are not observed. The metabolite N-desmethyl brinzolamide is also formed. This metabolite binds to CA and accumulates in red blood cells as well. In the presence of brinzolamide, the metabolite binds mainly to carbonic anhydrase I (CA-I).

Indications of Brinzolamide

  • For the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.
  • Decrease of elevated intraocular pressure (IOP) in adult patients with open-angle glaucoma or ocular hypertension for whom monotherapy provides insufficient IOP reduction.
  • Glaucoma, Open-Angle
  • Intraocular Hypertension
  • Treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma
  • Used in the treatment of glaucoma, brinzolamide inhibits aqueous humor formation and reduces elevated intraocular pressure. Elevated intraocular pressure is a major risk factor in the pathogenesis of optic nerve damage and glaucomatous visual field loss. Brinzolamide can decrease intraocular pressure by approximately 16-19% in patients with elevated intraocular pressure.

Contraindications of Brinzolamide

  • depression
  • a disorder of the blood vessels of the brain
  • Raynaud’s phenomenon, a condition where blood vessels constrict too much with coldness or stress
  • Buerger’s disease
  • orthostatic hypotension, a form of low blood pressure
  • severe renal impairment

Dosage of Brinzolamide

Strengths: 1%

Intraocular Hypertension
  • One drop in the affected eye(s) three times a day
Glaucoma (Open Angle)
  • One drop in the affected eye(s) three times a day

MAXIMUM DOSAGE

Adults
  • 3 drops/day ophthalmic solution in each affected eye.
Elderly
  • 3 drops/day ophthalmic solution in each affected eye.
Adolescents
  • Safety and efficacy have not been established.
Children
  • Safety and efficacy have not been established.

Side Effects 0f Brinzolamide

More common

  • Blurred vision
  • Discharge from the eye
  • dry eyes
  • redness, soreness, irritation, or pain of the eye or eyelid
  • skin rash
  • eye pain, redness, or swelling;
  • sensitivity to light;
  • the feeling of something is in your eye;
  • stomach pain (upper right side);
  • jaundice (yellowing of your skin or eyes); or
  • signs of eye infection–swelling, redness, severe discomfort, crusting or drainage.

Common

  • Chest pain
  • cough
  • crusting in the corner of the eye
  • difficulty with swallowing
  • dizziness
  • double vision
  • excessive muscle tone
  • eye redness, irritation, or pain
  • fast heartbeat
  • hives
  • itching, swelling, or other signs of eye or eyelid irritation
  • kidney pain
  • muscle stiffness
  • muscle tension or tightness
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • seeing double
  • shortness of breath
  • sore throat
  • tightness in the chest
  • unusual tiredness or weakness
  • wheezing

Rare

  • Abdominal or stomach pain
  • blistering, peeling, or loosening of the skin
  • chills
  • clay-colored stools
  • dark urine
  • diarrhea
  • fever with or without chills
  • a general feeling of tiredness or weakness
  • headache
  • hoarseness
  • joint or muscle pain
  • loss of appetite
  • lower back or side pain
  • nausea
  • painful or difficult urination
  • red or irritated eyes
  • red skin lesions, often with a purple center
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen or painful glands
  • unpleasant breath odor
  • unusual bleeding or bruising
  • vomiting of blood
  • yellow eyes or skin
  • Confusion
  • irregular heartbeat
  • muscle cramps or pain
  • numbness, tingling, pain, or weakness in the hands or feet
  • seizures
  • trembling
  • weakness and heaviness of the legs

Drug Interactions of Brinzolamide

  • acetazolamide
  • aspirin
  • bismuth subsalicylate
  • choline salicylate
  • dichlorphenamide
  • diflunisal
  • magnesium salicylate
  • methazolamide
  • salsalate
  • sodium salicylate
  • sodium thiosalicylate
  • topiramate
  • zonisamide

Pregnancy Category

  • AU TGA pregnancy category – B3
  • US FDA pregnancy category – C
Pregnancy
  • Brinzolamide is classified in FDA pregnancy category C. There are no adequate and well-controlled studies in pregnant women. According to the manufacturer, brinzolamide should be used during pregnancy only if the potential benefit to the mother outweighs the potential risk to the fetus.
  • Drugs have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
Breast-feeding
  • According to the manufacturer, a decision should be made whether to discontinue nursing or to discontinue brinzolamide. It is not known whether this drug is excreted in human milk. It may be prudent to consider an alternative glaucoma therapy in a woman who is breastfeeding, such as dorzolamide and acetazolamide (see individual monographs). Consider the benefits of breastfeeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breastfeeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
  • Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant the use of the drug in pregnant women despite potential risks.

How should this medicine be used?

Ophthalmic brinzolamide comes as a solution (liquid) to instill in the eyes. It is usually instilled three times a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Use brinzolamide eye drops exactly as directed. Do not use more or less of it or use it more often than prescribed by your doctor.

Brinzolamide eye drops to control glaucoma but does not cure it. Continue to use brinzolamide eye drops even if you feel well. Do not stop using brinzolamide eye drops without talking to your doctor.

To instill the eye drops, follow these steps

  • Wash your hands thoroughly with soap and water.
  • Check the dropper tip to make sure that it is not chipped or cracked.
  • Avoid touching the dropper tip against your eye or anything else; eye drops and droppers must be kept clean.
  • While tilting your head back, pull down the lower lid of your eye with your index finger to form a pocket.
  • Hold the dropper (tip down) with the other hand, as close to the eye as possible without touching it.
  • Brace the remaining fingers of that hand against your face.
  • While looking up, gently squeeze the dropper so that a single drop falls into the pocket made by the lower eyelid. Remove your index finger from the lower eyelid.
  • Close your eye for 2 to 3 minutes and tip your head down as though looking at the floor. Try not to blink or squeeze your eyelids.
  • Place a finger on the tear duct and apply gentle pressure.
  • Wipe any excess liquid from your face with a tissue.
  • If you are to use more than one drop in the same eye, wait at least 5 minutes before instilling the next drop.
  • Replace and tighten the cap on the dropper bottle. Do not wipe or rinse the dropper tip.
  • Wash your hands to remove any medication.

Before using brinzolamide eye drops,

  • tell your doctor and pharmacist if you are allergic to brinzolamide eye drops, other antibiotics, sulfa drugs, or any other medications.
  • tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially acetazolamide (Diamox), dichlorphenamide (Daranide), eye medications, methazolamide (Neptazane), products that contain aspirin, and vitamins and herbal products.
  • if you are using another topical eye medication, instill it 10 minutes before or 10 minutes after you instill brinzolamide eye drops.
  • tell your doctor if you have or have ever had kidney or liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are using brinzolamide eye drops.
  • if you get an eye injury or infection, call your doctor to see if you should still use the same eye drop bottle.
  • tell your doctor if you wear soft contact lenses. Wait at least 15 minutes after using the medicine to put in soft contact lenses.
  • use caution when driving or operating machinery because vision may be blurred after inserting the drops.

What should I do if I forget a dose?

Instill the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not instill a double dose to make up for a missed one.

What side effects can this medication cause?

Brinzolamide eye drops may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • blurred vision
  • bitter, sour, or unusual taste after instilling the drops
  • dry eyes
  • feeling that something is in your eye
  • headache
  • runny nose
If you experience any of the following symptoms, stop using brinzolamide eye drops and call your doctor immediately
  • itching eyes or skin
  • redness or swelling of eyes, lips, tongue, or skin
  • watery eyes
  • eye pain
  • skin rash, hives, or skin changes
  • difficulty breathing or swallowing
  • sore throat
  • fever
  • chest pain

References

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