FINISHED Cholinergic drugs Flashcards
Why does acetylcholine have virtually no therapeutic applications?
Actions are diffuse, hydrolysis is rapid
What are cholinomimetics?
Cholinergic agonists - acetylcholine derivatives that are more selective and have prolonged actions
Bethanechol, methacholine, and pilocarpine belong to which class of cholinergic drugs?
Muscarinic agonists
What are the three primary therapeutic uses of bethanechol?
Post operative abdominal distension, gastric atony, non-obstructive urinary retention
What is the primary therapeutic use of methacholine?
Diagnosis of asthma
What are the two primary therapeutic uses of pilocarpine?
Xerostomia, initial treatment of glaucoma
Why are bethanechol and pilocarpine therapeutically useful muscarinic agonists?
Resistant to cholinesterases, limited or no nicotinic activity
How does bethanechol treat post-operative abdominal distension and gastric atony?
Increases contractile force in smooth muscle throughout the GI tract
How does bethanechol treat non-obstructive urinary retention?
Increases smooth muscle contractions of the bladder body
How does pilocarpine treat xerostomia?
Facilitates lacrimal and salivary secretions
How does pilocarpine treat acute glaucoma attacks?
Contraction of ciliary muscle relaxes of suspensory ligaments of the lens, allowing it to become more convex and shift forward slightly; decrease intraocular pressure by widening the Canal of Schlemm, which increases drainage of aqueous humor
What are the two contraindications to therapeutic uses of muscarinic agonists?
Asthma (increase bronchial secretion and stimulate bronchial smooth muscle constriction) and peptic ulcer disease (increase acid secretion)
What are some potential side effects of muscarinic agonists?
Sweating, abdominal cramps, difficulty in visual accommodation, excess salivation
Atropine, scopolamine, ipratropium, prienzipine, and oxybutynin are examples of which class of cholinergic drugs?
Muscarinic receptor antagonists
How does atropine affect heart rate at high and low doses?
Slight cardiac slowing at low doses, increased heart rate at higher doses
What is atropine’s action on pupillary response?
Blocks muscarinic acetylcholine receptors on the sphincter pupillae causing relaxation and pupillary dilation
What is the major difference between pirenzipine and other muscarinic receptor antagonists?
Pirenzipine has some selectivity for M1, while all other muscarinic receptor antagonists have no selectivity for specific receptor subtypes
What was pirenzipine historically used to treat?
Peptic ulcers
What are the therapeutic uses of atropine?
Irritable bowel syndrome (reduce GI tract tone and motility), inducing mydriasis for ophthalmologic exams, treatment of organophosphate poisoning
What are the therapeutic uses of oxybutynin?
Mild cystitis (in conjunction with antibiotics), bladder spasm
What are the therapeutic uses of ipratropium?
COPD and asthma (minimal inhibition of mucociliary clearance, inefficient absorption from GI tract minimizes systemic effects
What are the therapeutic uses of scopolamine?
Motion sickness prophylaxis
What effects does nicotine have on the autonomic nervous system at high and low doses?
Stimulation of ANS at low doses, initial stimulation followed by longer-lasting transmission blockade at higher doses
What effects does nicotine have on skeletal neuromuscular junctions at high and low doses?
Stimulation of NMJ at low doses, initial stimulation followed by rapidly developing paralysis at higher doses
