Cholinergic Antagonist Flashcards
What is the cause of Atropine fever?
Hyperthermia induced by antimuscarinic drugs; caused mainly by inhibition of sweating. Can be lethal in children and infants.
Describe Atropine flush:
Marked cutaneous vasodilation of the arms and upper torso and head by toxic doses of antimuscarinic drugs, especially atropine; mechanisms unknown
Describe the effects of anti-muscarinic drugs on: CNS, Eye, Bconchi, GI tract, Genitourinary tract, Heart, blood vessels, glands and skeletal muscle.
Describe the effects of ganglion-blocking drugs on: CNS, Eye, Bconchi, GI tract, Genitourinary tract, Heart, blood vessels, glands and skeletal muscle.
T or F: Antimuscarinic agents block exogenously administered cholinergic agonist more effectively than endogenously released acetylcholine?
TRUE
Muscarinic receptors are constitutively active, and drugs that block the actions of Ach are inverse agonists. Examples of muscarinic blockers which are inverse agonist include atropine, pirenzepine, trihexypenidyl, and methyl derivative of scopolamine. What result does inverse agonists have on the activation of active vss. inactive receptors?
Inverse agonist favor the inactive receptor state, thus decreasing effects of the agonist.
How long will atropine persist in the eye?
Greater than 72 hours.
List the drugs that are derived from plants and are known as Belladonna Alkaloids:
Atropine
Homoatropine
Scopolamine
I-Hyoscyamine
(all are non-selective)
What are typical antimuscarinic drugs used in opthalmolgy? Note their duration of action.
Also, what eye conditions can be treated with antimuscarinic drugs?
- promote mydriasis (shouldn’t be used for mydriasis unles cycloplegia, or prolonged action is required.
- Prevent synechia (adhesion) in uveitis (inflammation of ciliary muscles) and iritis (inflammation of iris) Atropine and homoatropine
What are the CVS (cardiovascular system) use for antimuscarinic drugs?
Why does low doses of atropine initially cause bradycardia? Why will moderate to high doses of atropine cause tachycardia?
Describe the MOA regarding the administration of atropine and its relation to the receptor occupancy. Note the differences between the heart rate and salivary flow. Note the importance of M1 autoreceptors on the presynaptic cell in elucidating these responses.
Compare the two drugs Tioptropium and Ipratropium in the treatment of COPD and asthma. Which drug is preferred?
Tioptropium has longer bronchodilator action and can thus be given once a day. Howver, Ipratropium is useful as an inhalational drug in asthma.
Describe the clinical use of antimuscarinic agents in the GI track, include:
Antispasmodia, irritable bowel syndrome, inhibit excessive salivation and mucus secretion during surgery, antidiarrheal, peptic ulcers.
Irritable bowel syndrome (antispasmodic)- Dicyclomine, Hyoscyamine (longer duration of action), glycopyrrolate, propantheline
Inhibit excessive salivation and mucus secretion during surgery - Atropine
Antidiarrheal purposes (Dicyclomine, hyocyamine, glycopyrrolate)
Peptic ulcers: Pirenzipine -M1 selective- and glycopyrrolate
List common drugs that are antimuscarinic and useful for treating urinary urgency.
Describe the effects of the SNS and PNS on the bladder. Detail what neurotransmitters are being released and to what types of receptors they respond to.
Antimuscarinic drugs used for the CNS include usees for motion sickness, treatment after exposure to cholinesterase inhibitors (overdose) or sarin, and to mushroom poisoning. Indicate the drugs that can be used that are antimuscarinic in these scenarios.
List commonly used ganglion receptor blockers.
Describe the differences between non-depolarizing and depolarizing skeletal muscle blockers.
Describe the use of d-tubocurarine (curariform drugs) for its use as a non-depolarizing skeletal muscle blocker.
Non-depolarizing blocking drugs are usually determined by their duration of action. List other drugs that may be used opposed to d-tubocurarine and state the reasoning.
List common spasmolytic agents and their mechanism of action.
Dantrolene, Baclofen, Benzodiazepines
