Cholinergic Agents Flashcards
Hexamethonium, Mecamylamine, Trimethaphan
Antinicotinic Agents
Competitively inhibit Nn postsynaptic receptors of ANS gangia. Block outflow to sympathetic and parasympathetic NS. Decreased PVR and CO leads to hypotension (sympathetic-mediated).
Former Rx of hypertensive crisis. SE: sedation, cycloplegia, loss of accommodation, hypotensuon, tachycardia, constipation, urinary retention.
__chol__
Direct Muscarinic Agonist
Directly binds to and activates M2 and M3 receptors, the postsynaptic receptors in the Parasympathetic NS and sweat glands. Myosis (constriction), bradycardia, bronchoconstriction, increased GI/GU motility and secretions, sweating, vasodilation.
Rx for narrow and wide angle glaucoma, dry mouth, urinary retention, GI paralysis. Overdose: SLUDGE.
Ex: Bethanechol, Methacholine, Pilocarpine (topical, BEST glaucoma Rx), Carbachol (miosis, Rx of wide angle glaucoma and constriction in eye surgery).
__stigmine
Indirect Muscarinic Agonist. ACh Esterase Inhibitors.
Prolongs ACh life by reversibly inhibiting enzyme that breaks ACh down, acetylcholine esterase. Complex actions b/c affects all ACh receptors, increases stimulation of both N and M. This indirectly activates M receptors, the postsynaptic receptors in the Parasympathetic NS and sweat glands. Myosis (constriction), bradycardia, bronchoconstriction, increased GI/GU motility and secretions, sweating, NO vasodilation (no ACh to prolong), flushing, nausea.
Rx for Myasthenia Gravis, post-op intestinal/bladder atony, overcome nondepolarizing neuromuscular blockade. Physo: antidote to anticholinergic poisoning (Atropine), glaucoma via miosis. Overdose: SLUDGE, organophosphates do this irreversibly. Can overmedicate MG and make worse, Tensilon tells.
Ex: Physostigmine (CNS), Neostigmine (MG), Pyridostigmine (MG), Edrophonium (MG diagnosis, Tensilon Test).
Donepezil, Tacrine
Indirect Muscarinic Agonist. ACh Esterase Inhibitors.
Prolongs ACh life by reversibly inhibiting enzyme that breaks ACh down, acetylcholine esterase. Complex actions b/c affects all ACh receptors, increases stimulation of both N and M. This indirectly activates M receptors, the postsynaptic receptors in the Parasympathetic NS and sweat glands.
Rx for Alzheimer disease by stimulating neurons previously lost. SE: nausea, hepatotoxicity. Slows progression by 6 months, no memory loss improvement.
__ophate
Indirect Muscarinic Agonist. ACh Esterase Inhibitors.
Prolongs ACh life by inhibiting enzyme that breaks ACh down, acetylcholine esterase. Complex actions b/c affects all ACh receptors, increases stimulation of both N and M. This indirectly activates M receptors, the postsynaptic receptors in the Parasympathetic NS and sweat glands.
Topical Rx of wide-angle glaucoma via miosis. Systemic SE: sizures, psychosis, GI upset, salivation, blurry vision, bradycardia. Eventually leads to neuromuscular blockade and flaccid paralysis.
Ex: Echothiophate, Isoflurophate.
Pralidoxime
Reactivates Acetylcholinesterase.
Antidote for AChEI poisoning, Parathion and Malathion exposures. Atropine also useful in nerve gas poisoning.
Atropine, Scopolamine
Muscarinic Antagonist
Competitively blocks M1-3 receptors from activation, the postsynaptic receptors in the Parasympathetic NS and sweat glands. Mydriasis (dilation), tachycardia, bronchodilation, decreased GI/GU motility/urge and secretions, LESS sweating (leads to mild vasodilation, no direct effect because nothing to antagonize).
Rx for cholinesterase inhibitor poisoning (nerve gas, AChEIs), bradycardia in cardiac emergencies, urinary incontinence, eye exams. SE: sedation, psychosis. Overdose: Can’t see/pee, no shit/spit, HYPERthermia leads to flushing, hot blind dry red mad. Treat with Physostigmine or Pralidoxime.
Ex: Atropine (M2), Scopolamine (CNS, prevents motion sickness and excessive respiratory secretions), Homatropine and Tropicamide (eye exams).
Benzotropine
Muscarinic Antagonist
Blocks M1-3 receptors from activation, the postsynaptic receptors in the Parasympathetic NS and sweat glands. Crosses BBB, hits receptors in corpus striatum where DA inhibits GABAnergic outflow and ACh stimulates it; form a balance. Parkinsons is a loss of DA neurons, so GABA neurons have unopposed excitation. Decreasing ACh activity restores the balance.
Adjuvant Rx for Parkinson disease. Improves tremor and rigidity, no effect on bradykinesia. SE: dry mouth, irritability, confusion, constipation, mydriasis, burry vision, urinary retention, hyperthermia, sedation. Contraindicated in narrow-angle glaucoma.
Ex: Benztropine, Biperiden, Trihexyphenidyl.
__tropium
Muscarinic Antagonist. Inhaled.
Blocks M3 in lungs, relaxing smooth muscle around bronchi and leading to bronchodilation.
Rx of COPD and Asthma, especially in patients unable to take adrenergic agents. SE: some dry mouth and sedation
Ex: Ipratropium, Tiotropium.
Propantheline
Muscarinic Antagonist.
Blocks M3, increasing bladder sphincter tone and reducing GI motility and secretions, such as Gastrin. Rx for urinary incontinence and duodenal ulcers.
Other: Oxybutynin also increases bladder sphincter tone and decreases spasm to treat urinary incontinence.
Selegiline, Levodopa, Bromocriptine, Amantadine
Anti-Parkinsonium Agents.
Dopamine agonists. Ex: Levodopa, Bromocriptine (partial, adjunct, also hyperprolactinemia), Amantadine.
MAO type B Inhibitors. Selectively increases DA in the presynaptic neuron. Ex: Selegiline.
