Glaucoma cholinesterase inhibitors

L The answer is b. (Hardman, pp 166-167.) Echothiophate iodide is a long-acting (irreversible) cholinesterase inhibitor. It is used topically in the eye for the treatment of various types of glaucoma. Maximum reduction of intraocular pressure occurs within 24 h, and the effect may persist for several days. The drug is a water-soluble compound, which affords it a practical advantage over the lip id-soluble isofluorphate (another cholinesterase inhibitor used to treat glaucoma). 

Hypersensitivity to cholinesterase inhibitors or any component of the formulation active uveal inflammation or any inflammatory disease of the iris or ciliary body glaucoma associated with iridocyclitis. 

Because anticholinesterase agents also inhibit plasma pseudo-ChE, they will potentiate the effects of succinylcholine by inhibiting its breakdown. This is important, for example, when succinylcholine is to be employed in patients who have previously received cholinesterase inhibitors for the treatment of myasthenia gravis or glaucoma. 

The major therapeutic uses of the cholinomimetics are for diseases of the eye (glaucoma, accommodative esotropia), the gastrointestinal and urinary tracts (postoperative atony, neurogenic bladder), the neuromuscular junction (myasthenia gravis, curare-induced neuromuscular paralysis), and very rarely, the heart (certain atrial arrhythmias). Cholinesterase inhibitors are occasionally used in the treatment of atropine overdosage. Several newer cholinesterase inhibitors are being used to treat patients with Alzheimer s disease. 

Echothiophate Iodine (Phospholine Ophthalmic) [Cholinesterase Inhibitor/Glaucoma Agent] Uses Glaucoma ... 

Action Cholinesterase inhibitor Dose 1 gtt eye(s) bid w/ 1 dose hs Caution [C, ] Contra Active uveal inflammation, inflammatory Dz of iris /ciliary body, glaucoma... 

Muscarinic cholinomimetics mediate contraction of the circular pupillary constrictor muscle and of the ciliary muscle. Contraction of the pupillary constrictor muscle causes miosis, a reduction in pupil size. Miosis is usually present in patients exposed to large systemic or small topical doses of cholinomimetics, especially organophosphate cholinesterase inhibitors. Ciliary muscle contraction causes accommodation of focus for near vision. Marked contraction of the ciliary muscle, which often occurs with cholinesterase inhibitor intoxication, is called cyclospasm. Ciliary muscle contraction also puts tension on the trabecular meshwork, opening its pores and facilitating outflow of the aqueous humor into the canal of Schlemm. Increased outflow reduces intraocular pressure, a very useful result in patients with glaucoma. All of these effects are prevented or reversed by muscarinic blocking drugs such as atropine. 

Glaucoma is a disease characterized by increased intraocular pressure. Muscarinic stimulants and cholinesterase inhibitors reduce intraocular pressure by causing contraction of the ciliary body so as to facilitate outflow of aqueous humor and perhaps also by diminishing the rate of its secretion (see Figure 6-9). In the past, glaucoma was treated with either direct agonists (pilocarpine,... 

Reversible cholinesterase inhibitors find their greatest clinical use in the treatment of open-angle glaucoma. Relief is achieved by enhancing the contraction of the ciliary muscle and the iris sphincter. This contracture pulls the iris off the lens and facilitates fluid movement through the canal of Schlemm. The result is decreased pressure with reduced distortion of the lens and increased movement of aqueous humor out of the anterior chamber of the eye. 

Echothiophate iodide is a long-lasting cholinesterase inhibitor of the irreversible type, as is isofluorphate. Unlike the latter, however, it is a quaternary salt, and when applied locally, its distribution in tissues is limited, which can be very de.sirablc. It is used as a long-acting anticholinesterase agent in the treatment of glaucoma. 

Echothiophate is a cholinesterase inhibitor that causes miosis, increase in facility of outflow of aqueous humor, a fall in lOP, and potentiation of accommodation by enhancing the effect of endogenously liberated acetylchohne in the iris, ciliary muscle, and other parasympathetic innervated structures of the eye. It is indicated in the treatment of chronic open-angle glaucoma and treatment of accommodative esotropia (see also Figure 12). 

Physostigmine sulfate and physostigmine salicylate (Antilirium) are cholinesterase inhibitors that are indicated as antidotes to poisoning from substances possessing anticholinergic properties such as imipramine, a tricyclic antidepressant. In addition, it has been used in open-angle glaucoma. 

The long-acting cholinesterase inhibitors are associated with an increased incidence of cataracts in patients who receive them for long periods for glaucoma. The answer is (E). 

Organophosphate cholinesterase inhibitor less lipid-soluble than most organophosphates used topically in glaucoma. 

Cholinesterase inhibitors are used to treat glaucoma and myasthenia gravis. In glaucoma, aqueous humor production exceeds outflow, resulting in increased intraocular pressure. In the presence of cholinesterase inhibitor eye drops, acetylcholine causes constriction of the sphincter muscle which surrounds the iris. The iris is drawn away from the canal of Schlemm, enhancing outflow of aqueous humor. 

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