Also Known As: Pilocarpine, Salagen
Pilocarpine is a parasympathomimetic alkaloid obtained from the leaves of tropical American shrubs from the genus Pilocarpus. It is a non-selective muscarinic receptor agonist in the parasympathetic nervous system, which acts therapeutically at the muscarinic acetylcholine receptor M3 due to its topical application, e.g., in glaucoma and xerostomia.
Pilocarpine has been used in the treatment of chronic open-angle glaucoma and acute angle-closure glaucoma for over 100 years. It acts on a subtype of muscarinic receptor (M3) found on the iris sphincter muscle, causing the muscle to contract and engage in miosis. Pilocarpine also acts on the ciliary muscle and causes it to contract. When the ciliary muscle contracts, it opens the trabecular meshwork through increased tension on the scleral spur. This action facilitates the rate that aqueous humor leaves the eye to decrease intraocular pressure.
In ophthalmology pilocarpine is also used to reduce the possibility of glare at night from lights if the patient underwent implantation of phakic intraocular lenses; the use of pilocarpine would reduce the size of the pupils, relieving these symptoms. The most common concentration for this use is pilocarpine 1%, the weakest concentration.
Pilocarpine is also used to treat dry mouth (xerostomia) which can occur, for example, as a side effect of radiation therapy for head and neck cancers. Pilocarpine stimulates the secretion of large amounts of saliva and sweat.