1/21/2024 0 Comments Miotic pupil definitionIn Sjogren syndrome, dosing is commonly four times per day. The typical daily dosing is initially 5 mg three times per day and can be titrated depending on patient response. In the treatment of xerostomia, pilocarpine is available in the form of oral tablets. With excessive dosing, it can propagate a cholinergic crisis. Pilocarpine will also cause constriction of the pupillary sphincter muscle, resulting in miosis. This conformational change is helpful to decrease intraocular pressure in glaucoma. Contraction of the ciliary body will relax the zonular fibers, resulting in a more spherical shape of the lens and allowing aqueous outflow to occur. The ciliary body connects to the zonular fibers that control the accommodation of the lens. This dose form will result in ciliary contraction (a contraction of the iris), which will increase aqueous humor outflow, miosis, and accommodation. When used as a miotic agent, pilocarpine is available in the form of ophthalmologic eye drops. It also is capable of stimulating salivary gland function. Therefore, M3 cholinergic agonists result in the upregulation of calcium and ultimately smooth muscle contraction, such as in the pupillary sphincter muscle. This leads to the creation of the second messenger’s inositol triphosphate and diacylglycerol and calcium and protein kinase. By stimulating the Gq receptor, the M3 receptor can activate phospholipase C. The M3 receptor is an excitatory receptor expressed in gastric glands, salivary glands, and smooth muscle cells, such as those present in the pupillary sphincter and ciliary bodies. However, it is important to note that pilocarpine may affect the M1-M3 receptor subtypes, which causes parasympathetic side effects later discussed in this paper. There are five subtypes of the muscarinic acetylcholine receptor, the detail of which is beyond the scope of this paper. Its mechanism of action includes both full and partial agonism of the muscarinic M3 receptor, which is an acetylcholine receptor. Pilocarpine is an alkaloid pharmacologic used in treating xerostomia resulting from radiation exposure, Sjogren syndrome, and glaucoma.
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