Lecture: 4 Cholinergic and anti cholinergic drugs Dr. Mohammed Daoud. PhD in pharmacology Note: tertiary amine can enter the CNS, quaternary amine can not enter. Note: competitive mean depending on concerntration. Note: agonist=activator=mimetic antagonist= blocker= inhibitor=plegic 1- The cholinergic agonists (Cholinomimetic drugs): are drugs that mimic acetylcholine by directly or indirectly activating the receptors with which acetylcholine interacts. Sites of action : : Represent the sites of action of Cholinomimetics. So most Cholinomimetics will augment both the sympathetic and parasympathetic systems. So they lack selectivity and not considered parasympathomimetics only, except those which selectively bind and activate the muscarinic receptors (considered parasympathomimetics). However, in some drugs, chemical modifications made some selectivity as will be discussed below with some drugs. DIRECT-ACTING CHOLINERGIC AGONISTS: In general as a group, the direct-acting agonists show little specificity in their actions, which limits their clinical usefulness. Classified into two groups: 1-Ach and choline esters : @ Ach: Non selective act on M & N receptors. @Carbachol: Non selective act on M & N receptors. @Bethanechol: selective act on M receptors (parasympathomimetic) and called muscarinic agonist. 2- Alkaloids; Pilocarpine: selective act on M receptors (parasympathomimetic) and called muscarinic agonist.
Lecture: 4 Cholinergic and anti cholinergic drugs Dr. Mohammed Daoud. PhD in pharmacology Note: tertiary amine can enter the CNS, quaternary amine can not enter. Note: competitive mean depending on concerntration. Note: agonist=activator=mimetic antagonist= blocker= inhibitor=plegic 1- The cholinergic agonists (Cholinomimetic drugs): are drugs that mimic acetylcholine by directly or indirectly activating the receptors with which acetylcholine interacts. Sites of action : : Represent the sites of action of Cholinomimetics. So most Cholinomimetics will augment both the sympathetic and parasympathetic systems. So they lack selectivity and not considered parasympathomimetics only, except those which selectively bind and activate the muscarinic receptors (considered parasympathomimetics). However, in some drugs, chemical modifications made some selectivity as will be discussed below with some drugs. DIRECT-ACTING CHOLINERGIC AGONISTS: In general as a group, the direct-acting agonists show little specificity in their actions, which limits their clinical usefulness. Classified into two groups: 1-Ach and choline esters : @ Ach: Non selective act on M & N receptors. @Carbachol: Non selective act on M & N receptors. @Bethanechol: selective act on M receptors (parasympathomimetic) and called muscarinic agonist. 2- Alkaloids; Pilocarpine: selective act on M receptors (parasympathomimetic) and called muscarinic agonist.