Drug-Induced Glaucoma Medication

The goal of pharmacotherapy is to reduce morbidity and to prevent complications.

Bimatoprost (Lumigan) and travoprost (Travatan) are ophthalmic prostaglandin analogs approved for use in the United States. Bimatoprost is a prostamide analog with ocular hypotensive activity. It mimics the IOP-lowering activity of prostamides via the prostamide pathway. Travoprost and bimatoprost are prostaglandin F2-alpha (ie, dinoprost) analogs similar to latanoprost. They are selective FP prostanoid receptor agonists believed to reduce IOP by increasing uveoscleral outflow. They are indicated for the lowering of IOP in patients with open-angle glaucoma or ocular hypertension who are intolerant of other IOP-lowering medications or insufficiently responsive (failed to achieve target IOP determined after multiple measurements over time) to another IOP-lowering medication.

Bimatoprost and travoprost are each administered once daily at bedtime (ie, 1 gtt in affected eye[s] hs); they have not been studied in pediatric patients.

They are contraindicated if hypersensitivity has been documented. No drug interactions have been reported. All are classified as pregnancy category C (ie, fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus).

Like latanoprost, all demonstrate the unusual adverse effect of permanent increase in pigment of the iris (ie, increases brown pigment) and eyelid, and they may increase eyelash growth. Bacterial keratitis may occur. Use is cautioned in uveitis or macular edema. They should not be used if inflammation is present.

Class Summary

Topical agents (sympathomimetics) decrease aqueous production and reduce resistance to aqueous outflow. Often used with cholinergic agonists like pilocarpine. Adverse effects include dry mouth and allergenicity.

Brimonidine (Alphagan)

Selective alpha2-receptor agonist that reduces aqueous humor formation and possibly increases uveoscleral outflow.

Apraclonidine (Iopidine) 0.5%, 1%

Reduces IOP whether or not accompanied by glaucoma. Selective alpha-adrenergic agonist without significant local anesthetic activity. Has minimal cardiovascular effect.

Class Summary

Topical beta-adrenergic receptor antagonists decrease aqueous humor production by the ciliary body. Adverse effects are due to systemic absorption of the drug, decreased cardiac output, and bronchoconstriction. In susceptible patients, this may cause bronchospasm, bradycardia, heart block, or hypotension. Monitor the patient's pulse rate and blood pressure; patients may be instructed to perform punctal occlusion after administering the drops. Depression or anxiety may be experienced in some patients, and sexual dysfunction may be initiated or exacerbated.

Levobunolol (Betagan) 0.25%, 0.5%

Nonselective beta-adrenergic blocking agent that lowers IOP by reducing aqueous humor production.

Timolol ophthalmic (Betimol, Timoptic)

May reduce elevated and normal IOP, with or without glaucoma, by reducing production of aqueous humor.

Betaxolol ophthalmic (Betoptic)

Relatively selective in blocking beta1-adrenergic receptors. Reduces IOP by reducing production of aqueous humor.

Carteolol ophthalmic (Cartrol, Ocupress)

Blocks beta1- and beta2-receptors and has mild intrinsic sympathomimetic effects.

Metipranolol ophthalmic (OptiPranolol)

Beta-adrenergic blocker that has little or no intrinsic sympathomimetic effects and membrane stabilizing activity. Has little local anesthetic activity. Reduces IOP by reducing production of aqueous humor.

Class Summary

Increase outflow of aqueous humor through trabecular meshwork and possibly through uveoscleral outflow pathway, probably by a beta2-agonist action. Up to one third of patients will not respond to these drugs.

Epinephrine (Epifrin) 0.5%, 1%, 2%

Lower IOP by increasing outflow and reducing production of aqueous humor. Used as adjunct to miotic or beta-blocker therapy. Combination of miotic and sympathomimetic will have additive effects in lowering IOP.

Dipivefrin (AKPro, Propine)

Converted to epinephrine in eye by enzymatic hydrolysis. Appears to act by decreasing aqueous production and enhancing outflow facility. Has same therapeutic effect as epinephrine with fewer local and systemic adverse effects. May be used as an initial therapy or as an adjunct with other antiglaucoma agents for the control of IOP.

Class Summary

Reduce secretion of aqueous humor by inhibiting carbonic anhydrase in the ciliary body. In acute angle-closure glaucoma, administer systemically; apply topically in patients with open-angle glaucoma. These drugs are less effective, and their duration of action is shorter than many other classes of drugs. Adverse effects are relatively rare but include superficial punctate keratitis, acidosis, paresthesias, nausea, depression, and lassitude.

Dorzolamide (Trusopt)

Used concomitantly with other topical ophthalmic drug products to lower IOP. If more than one ophthalmic drug is being used, administer the drugs at least 10 min apart.

Dorzolamide is a reversible carbonic anhydrase inhibitor that may decrease aqueous humor secretion, causing a decrease in IOP. Presumably, it slows bicarbonate ion formation with subsequent reduction in sodium and fluid transport.

Systemic absorption can affect carbonic anhydrase in the kidney, reducing hydrogen ion secretion at renal tubule, and increases renal excretion of sodium, potassium bicarbonate, and water.

Brinzolamide (Azopt) 1%

Catalyzes reversible reaction involving hydration of carbon dioxide and dehydration of carbonic acid. May use concomitantly with other topical ophthalmic drug products to lower IOP. If more than one topical ophthalmic drug is used, administer drugs at least 10 min apart.

Dorzolamide HCl/timolol maleate (Cosopt)

Carbonic anhydrase inhibitor that may decrease aqueous humor secretion, causing a decrease in IOP. Presumably slows bicarbonate ion formation with subsequent reduction in sodium and fluid transport.

Timolol is nonselective beta-adrenergic receptor blocker that decreases IOP by decreasing aqueous humor secretion.

Both agents administered together bid may result in additional IOP reduction compared with either component administered alone, but reduction is not as much as when dorzolamide tid and timolol bid are administered concomitantly.

Class Summary

Contract the ciliary muscle, tightening the trabecular meshwork and allowing increased outflow of aqueous. Miosis results from the action of these drugs on pupillary sphincter. Adverse effects include brow ache, induced myopia, and decreased vision in low light.

Pilocarpine ophthalmic (Pilocar, Pilagan, Pilogel)

Directly stimulates cholinergic receptors in the eye, decreasing resistance to aqueous humor outflow.

Instillation frequency and concentration are determined by patient's response. Individuals with heavily pigmented irides may require higher strengths.

If other glaucoma medication also is being used, at bedtime, use drops at least 5 min before gel.

Class Summary

Increase uveoscleral outflow of aqueous. One mechanism of action may be through induction of metalloproteinases in the ciliary body, which breakdown the extracellular matrix, reducing resistance to outflow through the ciliary body. They can be used in conjunction with beta-blockers, alpha-agonists, or topical carbonic anhydrase inhibitors. Many patients respond well to these agents; others do not respond at all. Adverse effects include iris pigmentation, cystoid macular edema, and uveitis.

Latanoprost (Xalatan) 0.005%

Decreases IOP by increasing outflow of aqueous humor.