Pilocarpine, miosis caused

The adverse effects of pilocarpine are caused by the induction of miosis. The contraction of the ciliary muscle causes the lens to displace forward, which can lead to accommodation spasm, myopia, and brow ache. Pupillary constriction can also affect night vision. Pilocarpine should be avoided in patients with severe myopia, as it increases the risk of developing retinal detachment. Systemic effects may occur at higher concentrations and include, nausea, vomiting, diarrhea, and bradycardia. 

Miosis caused by physostigmine, pilocarpine, acetylcholine and morphine... 

Pilocarpine is classified as a tertiary amine that has parasympathomimetic activity. When administered as eye drops, it causes pupillary constriction or miosis and is therefore indicated in the treatment of glaucoma. In glaucoma, multiple-drug therapy may be necessary to achieve the desired intraocular control. Pilocarpine may be used in combination with topical beta-blockers such as timolol. 

Parasympathomimetics such as physostigmine sulfate increase the level of acetylcholine, which contracts the ciliary muscle and opens the fluid pathway which leads to reduction in IOP. They are usually used with pilocarpine hydrochloride or pilocarpine nitrate, which acts on cholinoceptors. Parasympathomimetics cause poor night vision because of miosis. 

Pilocarpine, in contrast to muscarine, is being used therapeutically - mostly for local application to the eye. It will cause both miosis (by action on the sphincter or constrictor muscle of the iris) and accommodation of the eye lens for seeing close, by acting on another (ciliary) muscle. These muscle movements will decongest a tiny canal which is located right behind the ciliary muscle and thereby facilitate the efflux of fluid from the eye. Pilocarpine is thus used in glaucoma, a disease that is caused by pathologically increased pressure within the eye. 

Because of its activity at muscarinic receptor sites on the iris sphincter and ciliary muscles, pilocarpine causes pupillary constriction and varying degrees of accommodative spasm, depending on the patient s age. Longterm therapy with pilocarpine or other miotics alters iris muscle activity and may cause permanent miosis resulting from loss of iris radial muscle tone and from fibrosis of the sphincter muscle. 

FIGURE 78 Pilocarpine is a naturally occurring cholinomimetic agent possessing both muscarinic and nicotinic properties. It causes miosis, reduces intraocular pressure, and is used in the treatment of wide-angle glaucoma. In addition, it may be applied topically in the eye in the form of a dmg reservoir. 

Antimuscarinics (homatropine, tropicamide) are mydriatic and cycloplegic alpha-sympathomimetic agonists are only mydriatic. Pilocarpine causes miosis. The answer is (C). 

Pilocarpine nitrate is a parasympathomimetic agent possessing muscarinic effects of acetylcholine. It is mostly used as a solution (1 to 5%) to exert an action on the eye to cause miosis and retard intraocular tension in the treatment of open-angle glaucoma. Pilocarpine nitrate being less hygroscopic than its corresponding hydrochloride and hence it is more easy to handle. 

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