Glaucoma drug mechanisms

These drugp are contraindicated in patients with known hypersensitivity to die drugs, asthma, peptic ulcer disease, coronary artery disease, and hyperthyroidism. Bethanecol is contraindicated in those with mechanical obstruction of die gastrointestinal or genitourinary tracts. Fhtients with secondary glaucoma, iritis, corneal abrasion, or any acute inflammatory disease of the eye should not use die ophtiialmic cholinergic preparations. 

Tripathi RC, Tripathi BJ, Haggerty C. Drug-induced glaucomas mechanism and management. Drug Saf 2003 26 749-767. Weinreb RN, Khaw PT. Primary open-angle glaucoma. Lancet 2004 363 1711-1720. 

Blockers can be used topically to reduce intraocular pressure in patients with chronic open-angle glaucoma and ocular hypertension. The mechanism by which ocular pressure is reduced appears to depend on decreased production of aqueous humor. Timolol has a somewhat greater ocular hypotensive effect than do the available cholinomimetic or adrenomimetic drugs. The 3-blockers also are beneficial in the treatment of acute angle-closure glaucoma. 

Systemic administration of 3-blocking drugs for other indications was found serendipitously to reduce intraocular pressure in patients with glaucoma. Subsequently, it was found that topical administration also reduces intraocular pressure. The mechanism appears to involve reduced production of aqueous humor by the ciliary body, which is physiologically activated by... 

Q9 Comment on the drug treatments for glaucoma by explaining their mechanism of action. Your answer should include some examples of the drugs used. 

The drug can also be used concomitantly with echo-thiophate to prevent the formation of miotic cysts during treatment of open-angle glaucoma or accommodative esotropia. Addition of the 2.5% concentration to the echothiophate regimen is recommended. The mechanism whereby phenylephrine prevents cyst formation is not known. However, inhibition of the intense miosis may account, at least in part, for the beneficial effect. 

Table II-4-2. Mechanism of Action of Drugs Used to Treat Glaucoma...

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