Directly acting cholinomimetic drugs
Cholinomimetic agents also called acetylcholinomimetic, reproduce the effects of acetylcholine, by direct or indirect action.
Drugs which penetrate easily into the brain have predominantly central effects. Drugs which do not cross easily the blood-brain barrier have predominantly peripheral effects. Their therapeutic uses depend on this penetration.
Directly acting cholinomimetic drugs are agonists of acetylcholine receptors. Whereas acetylcholine activates all types of acetylcholine receptors, the other cholinomimetic agents act preferentially on a given type of receptor, either muscarinic or nicotinic receptors.
Direcly acting cholinomimetics used in therapeutics are, in addition to acetylcholine, carbaminoylcholine, pilocarpine, aceclidine and nicotine.
Acetylcholine
Acetylcholine is not used by general route but only in intraocular solution for obtaining miosis during ocular surgery.
Carbachol
Carbachol, also called carbaminoylcholine, is obtained by replacement of acetic acid of acetylcholine molecule by carbamic acid. This chemical modification makes it resistant to cholinesterases and imore active but also more toxic than acetylcholine. It has muscarinic and nicotinic actions. It was used by local route, as an ophthalmic solution, for treatment of glaucoma but, because of its toxicity, it is not used any more.
Bethanechol
Bethanechol or carbamylmethylcholine has primarily muscarinic effects and stimulates gastrointestinal and vesical motricity. It is used in treatment of gastroesophagal reflux in infants and of vesical atonicity for facilitating micturition.
Pilocarpine
Pilocarpine, alkaloid of vegetable origin, with primarily muscarinic properties, elicits sweat and salivary hypersecretion. Currently, pilocarpine is especially used in the form of ophthalmic solutions for treatment of glaucoma where, by reducing iris diameter, it facilitates the flow of aqueous humor by trabeculum and canal of Schlemm . It is also used by general route in the treatment of hyposialy. It is present in several proprietary formulations.
Aceclidine
Aceclidine is a cholinomimetic obtained by chemical synthesis, used in the form of ophthalmic solution in the treatment of glaucoma.
Cevimeline
Cevimeline is a cholinergic agonist with muscarinic effect. It is used for the treatment of symptoms of dry mouth with Sjögren's Syndrome.
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