Medication Summary
The goals of pharmacotherapy are to reduce IOP and morbidity and to prevent complications. The goal of therapy with IOP-lowering medications is for a reduction of at least 30%. Nonselective beta-blockers (eg, timolol maleate, levobunolol) are controversial because as visual-field progression is possibly due to secondary aggravated nocturnal arterial hypotension. [18, 19] A systematic review and meta-analysis of 15 randomized clinical trials studying IOP-lowering agents for treatment of normal-tension glaucoma determined that latanoprost, bimatoprost, and timolol were most effective. [20]
Medications for neuroprotection are as follows:
-
Calcium channel blockers - Less progression [21]
-
Betaxolol - Improved choroidal flow, better visual-field preservation
-
Dorzolamide - Increased retinal blood flow velocity in humans
-
Brimonidine - Increased retinal ganglion cell survival in rat optic nerve crush injury
Future medications include the following:
-
N -methyl-D-aspartate (NMDA) receptor antagonist (Memantine) - Prevents binding of glutamate and resultant calcium influx; blocks rat ganglion cells from glutamate toxicity in rats and blocks toxic level of glutamate in vitreous
-
Serotonin S2 receptor antagonist (Naftidrofuryl) - Arteriolar vasodilation, improved blood flow in Raynaud syndrome
-
Glutamate antagonists
-
Monoamine oxidase inhibitors (Deprenyl) - Neuroprotection in rat crush model
-
Neurotrophic factors (Neurotrophins) - Retard apoptosis in cell culture
-
Free radical scavengers - Ginkgo biloba extract scavenges free radicals and nitric oxide, improves blood flow (60-120 mg bid)
-
Cannabinoids (marijuana) - Reduces IOP with NMDA antagonist and antioxidant activity
Alpha2-adrenergic agonists
Class Summary
Decrease IOP pressure by reducing aqueous humor production.
Brimonidine (Alphagan)
Selective alpha2-receptor that reduces aqueous humor formation and may increase uveoscleral outflow or inhibit inflow.
Carbonic anhydrase inhibitors
Class Summary
By slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport, may inhibit carbonic anhydrase in the ciliary processes of the eye. This effect may decrease aqueous humor secretion, reducing IOP.
Dorzolamide (Trusopt)
Used concomitantly with other topical ophthalmic drug products to lower IOP. If more than 1 ophthalmic drug is being used, administer the drugs at least 10 min apart. Reversibly inhibits carbonic anhydrase, reducing hydrogen ion secretion at renal tubule and increasing renal excretion of sodium, potassium bicarbonate, and water to decrease production of aqueous humor.
Beta-adrenergic blockers
Class Summary
The exact mechanism of ocular antihypertensive action is not established, but it appears to be a reduction of aqueous humor production or inhibition of inflow.
Timolol ophthalmic (Timoptic XE, Timoptic, Blocadren)
May reduce elevated and normal IOP with or without glaucoma by inhibiting inflow.
Levobunolol (AKBeta, Betagan)
Nonselective beta-adrenergic blocking agent that lowers IOP by reducing aqueous humor production and possibly increasing outflow of aqueous humor.
Betaxolol ophthalmic (Betoptic)
Indicated for glaucoma. Selectively blocks beta1-adrenergic receptors with little or no effect on beta2-receptors. Reduces IOP by reducing production of aqueous humor.
Prostaglandin agonists
Class Summary
For reduction of IOP in patients intolerant to other IOP-lowering medications or who do not respond optimally to other IOP-lowering medications.
Travoprost ophthalmic solution (Travatan)
Prostaglandin F2-alpha analog. Selective FP prostanoid receptor agonist believed to reduce IOP by increasing uveoscleral outflow. Used to treat open-angle glaucoma or ocular hypertension.
Unoprostone ophthalmic solution (Rescula)
Prostaglandin F2-alpha analog. Selective FP prostanoid receptor agonist believed to reduce IOP by increasing uveoscleral outflow. Used to treat open-angle glaucoma or ocular hypertension.
Bimatoprost ophthalmic solution (Lumigan)
A prostamide analogue with ocular hypotensive activity. Mimics the IOP-lowering activity of prostamides via the prostamide pathway. Used to reduce IOP in open-angle glaucoma or ocular hypertension.
Latanoprost (Xalatan, Xelpros)
May decrease IOP by increasing outflow of aqueous humor.
