How Do Antiglaucoma Combos Work?
Antiglaucoma combos are combinations of medications that work in different ways to reduce the pressure inside the eye (intraocular pressure). Each medication works on different protein molecules, enzymes, or other mechanisms in the eye. Antiglaucoma medications reduce intraocular pressure in two ways:
Aqueous humor is a clear fluid that fills the space between the lens and the cornea in the eyes. A part of the eye known as the ciliary body produces aqueous humor, which supplies oxygen and nutrients to the lens and cornea, and removes waste products.
Aqueous humor drains out of the eyes into the ocular veins through two pathways:
- Trabecular meshwork: Trabecular meshwork is specialized porous tissue in the eyes that enables drainage
- Uveoscleral pathway: Uvea and sclera are layers in the eyes through which part of the aqueous humor seeps through
Balancing the inflow and outflow of aqueous humor helps maintain optimum pressure in the eye and it is this pressure that keeps the eyeball roughly in a spherical shape. Antiglaucoma combos are used as a two-pronged strategy to address both aqueous humor, production, and drainage elements, which contribute to elevated intraocular pressure.
The types of medications used in antiglaucoma combos include:
- Antiglaucoma alpha agonists: Reduce production of aqueous humor and increase its outflow through the uveoscleral pathway by blocking the activity of protein molecules known as alpha receptors in the eyes.
- Antiglaucoma beta-blockers: Reduce production of aqueous humor by blocking the activity of beta receptors in the ciliary body.
- Antiglaucoma carbonic anhydrase inhibitors: Decrease production of aqueous humor by blocking carbonic anhydrase, an enzyme in the ciliary body involved in aqueous humor secretion in the eyes.
- Antiglaucoma prostaglandin agonists: Increase outflow of aqueous humor through both pathways by relaxing the ciliary muscle and modifying the extracellular matrix, a network of structural support for cells to adhere and form tissue.
- Antiglaucoma rho kinase inhibitors: Reduce aqueous humor production, increase its outflow and reduce venous pressure in the sclera (episcleral venous pressure), by blocking the activity of an enzyme known as rho kinase.
How Are Antiglaucoma Alpha Agonists Used?
Antiglaucoma combos are ophthalmic solutions and suspensions topically administered in the eyes. Antiglaucoma combos are used to treat eye conditions with elevated intraocular pressure such as:
- Open-angle glaucoma: Glaucoma is a degenerative disease that damages the optic nerve and can lead to vision loss if left untreated. Open-angle glaucoma is the most common type of glaucoma in which the drainage angle through which the aqueous humor drains remains open, but the drainage channels are partially blocked.
- Ocular hypertension: Elevated intraocular pressure due to imbalance in the production and drainage of aqueous humor.
What Are Side Effects of Antiglaucoma Alpha Agonists?
Side effects of antiglaucoma combos may include the following:
Ocular side effects:
- Hyperemia (dilation of blood vessels)
- Pain, burning, and stinging
- Tearing and/or discharge
- Blurred vision
- Double vision (diplopia)
- Abnormal or reduced vision
- Irritation, discomfort, and foreign body sensation
- Conjunctival follicles (round collections of lymphocytes in the conjunctiva, the membrane that lines the eye and inner surface of eyelids)
- Allergic reactions and itching
- Blepharitis (inflammation of the eyelids)
- Tearing and/or discharge
- Eye fatigue
- Corneal inflammation (keratitis)
- Corneal erosion
- Light sensitivity
- Redness of eyelid
- Eyelid edema
- Eyelid margin crusting
- Conjunctival edema
- Conjunctival blanching
- Conjunctival hemorrhage
- Conjunctivitis (inflammation of the conjunctiva)
- Keratoconjunctivitis (inflammation of cornea and conjunctiva)
- Degeneration of cornea (keratopathy)
- Corneal deposits (cornea verticillata)
- Increased iris pigmentation
Systemic side effects:
- Dry mouth (xerostomia)
- Rhinitis (inflammation of mucous membrane in the nose)
- Drowsiness, particularly in children
- Fatigue and weakness
- Taste disorder (dysgeusia)
- Nasal dryness
- Pharyngitis (inflammation of the pharynx)
- Upper respiratory infection, influenza
- Rattling or clicking sounds in lungs (rales)
- Bronchospasm and shortness of breath (dyspnea)
- Reduced exercise tolerance
- Abnormal skin sensation (paresthesia)
- Raynaud’s phenomenon (discoloration and numbness in fingers and toes due to cold temperature or stress)
- Gastrointestinal symptoms such as:
- Anxiety and depression
- Chest pain
- Palpitations and irregular heartbeat (arrhythmia)
- Fainting (syncope)
- Allergic reactions such as:
- Muscle stiffness (hypertonia)
- Muscle pain (myalgia)
- Joint pain (arthralgia)
- Kidney pain
The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.
What Are Names of Some Antiglaucoma Alpha Agonists?
Generic and brand names of some antiglaucoma combos include:
- Carbonic anhydrase inhibitor/alpha agonist:
- Brinzolamide/brimonidine (Simbrinza)
- Prostaglandin agonist/Rho kinase inhibitor:
- Beta blocker/alpha agonist:
- Beta blocker/carbonic anhydrase inhibitor:
- Timolol/dorzolamide (Cosopt, Cosopt PF)
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