Cholinergic Pharmacology

Flashcards for review of Cholinergic Pharmacology including Cholinomimetics and Antimuscarinics.

Choline acetyltransferase (CHAT)

Enzyme responsible for the synthesis of Acetylcholine (ACh) from Acetyl CoA and Choline.

Vesicular Acetylcholine Transporter (VACHT)

Transporter responsible for moving Acetylcholine into vesicles for storage and release.

Acetylcholine esterase

Enzyme responsible for the breakdown of Acetylcholine into Choline and Acetate.

True Cholinesterase

Present in synapse, specific for Ach and essential for life

Pseudo Cholinesterase

Synthesized in liver, present in plasma and non specific.

Muscarinic receptors

Cholinergic receptors, M1-M5 subtypes, located in CNS, heart, smooth muscle, glands.

Nicotinic receptors

Cholinergic receptors, Nn (neuronal) and Nm (muscle) subtypes, located in CNS, autonomic ganglia, adrenal medulla, and skeletal muscle.

M1 Receptors

Excitatory receptors in the CNS involved in arousal, learning and short-term memory.

M2 Receptors

Located in Presynaptic neurons, Heart, and CNS→ inhibit ACh release and Slowing of heart rate

M3 receptors

Located in Smooth muscles and Exocrine glands involved in contraction and ↑ All secretions (except milk).

Bethanechol

Choline ester with marked muscarinic effects, particularly on GIT & bladder. Used for megacolon & urinary retention

Pilocarpine

Natural alkaloid, selective M3 agonist. Miotic used for Glaucoma & increase secretion used in dryness of eye & mouth (Sjogren Syndrome)

Edrophonium

Cholinesterase inhibitor, ultra short acting (4ry).

Neostigmine

Synthetic carbamate, cholinesterase inhibitor (4ry). Muscarinic and Nicotinic effects

Physostigmine

Natural carbamate, cholinesterase inhibitor (3ry). Muscarinic effects

Pyridostigmine

Neostigmine analogue, cholinesterase inhibitor. ↑duration, fewer visceral side effects

Organophosphates

Irreversible cholinesterase inhibitors used as insecticides and nerve gases.

Atropine

3ry Amine Competitive Antagonist of Ach at M receptors.

Hyoscine

Mydriatic (briefer than atropine). More Safe in thyrotoxicosis & cardiac patients and More CNS depressant action

Ipratropium

Bronchial Atropine Substitutes given by inhalation with No systemic Effect and Not dry Secretion

Glycopyrrolate

Antisecretory antispasmodics

Oxybutynin

Urinary atropine substitutes: •Used in nocturnal enuresis & in urge incontinence and overactive bladder.