Cholinergic Agents Flashcards
What is selectivity?
The degree to which a drug preferentially binds to a receptor subtype
At recommended doses, which drug is relatively selected for muscarinic receptors in the detrusor muscle of the urinary bladder and intestinal wall?
Bethanechol (Urecholine)
The internal urethral sphincter is under which type of control
Sympathetic
What type of receptor is found the internal urethral sphincter
Alpha-1
Which nerve innervates the external urethral sphincter? Sympathetic nerve? PS nerve?
Pudendal external
Symp hypogastric n.
PS pelvic n.
What types of receptors are found on the detrusor muscle
Beta-2 and muscarinic
Carbamylcholine
Mostly used uterine contractions pigs. Selective intestinal wall. Not a lot small animal. Gi atony.
Pilocarpine
Primary indication is to stimulate gland secretions. Decreases IOP. GIVE LOW dose because worry SLUD effects
Metaclopramide
Anti emetic. Promotes gastric motility. KCS
Edrophonium drug class, trade name, function
Tensilon, competitive reversible indirect acting cholinergic agent.
Bind to ACHE so that ACH can’t bind and get broken down
Prevent ach degradation, allows increased ACH bind to the few receptors left. Dx myasthenia gravis
Pyridostigmine trade and purpose
Mestinon, tx myasthenia gravis, maintenance
Physostigmine indications and drug class and toxic effects
Anticholinesterase or indirect acting cholinergic agent
Decrease IOP by causing miosis
Breakdown posterior synechia in horses
Treat gi atony in cattle subq
Can cross BBB since it’s non-ionized
Resp paralysis, vomiting, CNS depression, PS effects basically
How do you irreversible indirect acting cholinergic agents work
They covalently bonded to acetylcholinesterase permanently inactivating it
Organophosphates
Talk about major factors of organophosphate toxicities
Can cross blood brain barrier. Bronco constriction, airway secretions increased, abdominal cramping because of motility overdrive. Muscle tremors through the neuromuscular junction eventually lead to flaccid paralysis. This includes skeletal muscle needed to breathr. This leads to respiratory failure.
Name two agents to counteract irreversible ACHesterases. Talk about their mechanism of action
Pralidoxime tradename 2Pam it breaks the bonds between acetylcholinesterase and organophosphate. It binds to the organophosphate so that the body can eliminate it.This frees up ACHE to work again. Atropine is palliative care counters the intense parasympathetic affects
Atropine drug class and mechanism of action in treating ____ toxicity
Muscarinic receptor antagonist. @rec doses, It binds to cholinergic receptors until the body can eliminate organophosphates causing excess ACH
Anti-cholinergic effects usually referred to which type of agents?
Cholinergic receptor antagonists
Talk about atropine’s affects on the eye
It is often used for its cycloplegic effect. It relaxes the ciliary muscle. It inhibits parasympathetic innervation and there is unopposed sympathetic effect.
What are the parasympathetic affects on the ciliary muscle?
Causes the ciliary muscle to contract. The ciliary muscle is attached to the lens.It makes the lens into a CONE shape and puts the focal point in the near field.
What happens as a result of muscarinic antagonist at the ciliary muscle?
It relaxes the ciliary muscle. Lens flatten, and the focal point is in the distance. Common side effect is it blurry near vision
Does atropine cause the mydriasis or miosis? What does muscle does it affect?
It causes pupil dilation. unopposed sympathetic stimulation at the dilator muscle
Which cranial nerve carries parasympathetic innervation to the cranial organs
10
What is the effect at the AV node mediated by cholinergic and adrenergic receptors? What types of receptors?
Speed of conduction. Muscarinic and beta-1
What types of receptors are found on the heart? What is the effect at the SA node?
Muscarinic and beta-1. Heart rate
