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NURS 572A 13-cc
Chapter 13-16 Cholinergic drugs
| Question | Answer |
|---|---|
| What catagory of drugs influence cholinergic receptors indirectly? | Cholinesterase inhibitors bwo preventing breakdown of ACh |
| Examples of toxic cholinergic drugs | *nicotine *insecticides *chemical warfare |
| Six categories of cholinergic drugs | 1-muscarinic agonists 2-muscarinic antagonists 3-ganglionic stimulating agents 4-ganglionic blocking agents 5-neuromuscular blocking agents 6-cholinesterase inhibitors |
| What category of cholinergic drug behaves like a muscarinic agonist? | cholinesterase inhibitors behave like this |
| Example of muscarinic agonist | bethanechol (pilocarpine) |
| example of muscarinic antagonist | atropine |
| example of ganglionic stimulant | nicotine |
| example of ganglionic blocking agent | mecamylamine |
| example (2) of cholinesterase inhibitors | neostigmine, physostigimine |
| example (2) of neuromuscular blocking agents | d-tubocurarine, succinylcholine |
| Location of Muscarinic receptors (broad-3) | 1-sweat glands 2-blood vessels 3-all organs of psymp |
| Primary effects of activating muscarinic receptors (broad-3) | 1-glandular secretions 2-dec HR 3-sm musc contraction (except bv dilation) |
| Bethanechol pharm actions - GI,Ur, CV, Bronch,eye | 1 - GI - inc secretions, peristalsis, emptying 2 - CV - dec HR, BP 3 - Bronchioconstriction 4 - miosis, accomodaton |
| Bethanechol therapeuitic uses (4) | 1- tx urinary retention, nonobstructed 2- tx ileus, GI retention, post-ob ab dist 3-GERD, more effective agents now avail |
| Bethanechol pharmacokinetics | * quaternary ammonium passes mem poorly, only small fraction absorbed *oral dose, SQ withdrawn *onset 30-60min, duration 1h |
| Bethanechol s/e | s/e include 1- GI: sal, n/v/d, abd cramps 2- CV: brady, HTN 3- Pulm: bronchoconst, worse asthmatics |
| Muscarinic poisoning results from | 1-ingestion of certain mushrooms 2-OD musc. ag. bethanechol, pilocarpine 3- OD cholinesterase inhib (neostigimine, physostigmine) |
| muscarinic poisoning s/s | *SLUDV, S(w)LUDGE(rect *brady, bronchospasm *miosis, visual disturbances |
| Tx of muscarinic poising | admin atropine to treat toxicity |
| Synonyms for muscarinic antagonists | parasympatholytic, anticholinergics, antimuscarinics, muscarinic blockers are all synonyms for this category |
| sources of atropine | *atropa belladonna (deadly nightshade) *datura stramonium (jimsonweed, stinkweed) |
| MOA of atropine | MOA is to prevent muscarinic receptor activation |
| Primary targets of atropine - 4 | 1- heart 2- exocrine glands 3-smooth muscle 4-eye (mydriasis, vis disturb) |
| Pharm effects of atropine | 1- inc HR 2-dec secretions, thick resp secretions 3 - bronchod 4-dec GI/bladder tone, motility 5-pupil dilation 6-crosses BBB, CNS excitation |
| low doses of atropine effect | decreased secretions sal, sweat, bronch glands |
| int doses of atropine effect | heart, eye, urinary, intestine |
| High doses of atropine | bronchod stom acid sec dec |
| tx uses of atropine | 1-preanesthetic prevents brady 2-rx brady 3-eye disorders (need to dilate) 4-cramps/dia (int. hypertonicity, hypermotility) 5-muscarinic agonist poisoning 6- asthma (opens bronchi) 7 - biliary colic, peptic ulcer disease (rare) |
| s/e atropine | 1-xerostomia 2-blurred vision (accomodation) 3- photophobia (mydriasis) 4 - inc intraocular pressure (bwo iris sphincter paralysis) 5- urinary retention, constipation 6- tachy 7- anhydrosis (not sweating) 8-aggravation of asthma (drying secretions) |
| what class of drug is used to treat OAB = overactive bladder | anticholinergic drugs AKA muscarinic antagonists are used to treat this disorder |
| Since cholinesterase inhibitors intensify transmission at all cholinergic junctions (Nn, Nm, M), are they selective? | No, thise catagory is not selective and has limited therapeutic application |
| another name for cholinesterase inhibitors | anticholinesterase agents |
| 2 catagories of cholinesterase inhibitors | 1-reversible inhibitors (moderate duration) 2-irreversible inhibitors (long lasting) |
| reaction of anticholinesterases | ACh --> choline + acetic acid |
| Prototype of reversible anticholinesterase and its principal indication | neostigmine used for myesthania gravis |
| chemical class of neostigmine | this anticholinesterase is a quaternary ammonium whose oral form is poorly absorbed with little CNS/placental passage |
| MOA reversible anticholinesterase reversible neostigmine | It takes AChesterase a long time to degrade this drug, temporarily inactivating enz and availing more ACh in synapse |
| duration of action of neostigmine | 2-4 hours is the duration of this reversible anticholinesterase drug |
| Expected Muscarinic effects of neostigmine | muscarinic effects of this drug are 1- GI: inc sec, peristals, poss v/d 2- CV: brady, hypoTN 3- GU: inc urination, erection 4-pulm: bronchoc, inc secretions 5-NM: tx dose --> increase sk mus contr toxic does --> dec contr forc |
| Actual effects of neostigmine (general) | *Muscarinic + Nm actions *little/no action at Nn, CNS |
| 4 drugs of reversible cholinesterase inhibitors used to tx myesthania gravis | 1- neostigmine 2- physostigmine 3- ambenonium 4- pyridostigimine |
| What other disease state does reversible cholinesterase inhibitors treat? | Alzheimer's disease is treated by this class of drugs, in addition to myesthenia gravis |
| irreversible cholinesterase inhibitors have a phosphorus, tx ONE disease and are also found in . . . | 1-used to tx glaucoma (echothiophate) 2-found in nerve gas, insecticides |
| echothiophate - class and tx | irreversible anticholinesterase to tx glaucoma |
| myesthania gravis pathophys | autoimmune process where antibodies attack Nm receptors |
| organophosphate agents in the category of irreversible cholinesterase inhibitors, with the exception of echothiophate are . . .lipid or water soluble | this class of drugs are highly lipid soluble and move thorughout the body with ease (nerve gas, insecticides) |
| Side effects of reversible anticholinesterases | mostly muscarinic due to too much drug |
| common symptoms of myasthenia gravis | *ptosis (drooping eyelid) *facial muscle weakness *difficulting swallowing |
| se of cholinesterase inhibitors | can cause ACh to accumulate an NMJ as well as muscarinic junctions (can give atropine to supress symptoms) |
| what are we trying to accomplish by using neuromuscular (NM) blocking agents | we want to paralyze the pt by preventing ACh from binding with Nm receptors |
| what type of pt would benefit from Nm blocking agents | *surgical pts for sk muscle relaxation *endotracheal intubation *mechanical ventilation *other medical procedures |
| 2 ways to classify NM blocking agents | 1- MOA (depolarizing agents, nondepolarizing agents) 2 - time course (long, int, short, ultrashort acting) |
| prototype drug of nondepolarizing NM blocking agents | tubocurarine is prototype for this class (no longer used in US, replaced by newer drugs) |
| Chemistry of tubocurarine & other NM blockers | *has quaternary N, can't cross mem. Can't be admin, po. Must be admin parentarelly (IV) *can't cross placenta |
| MOA of NM blockers (tubocurarine) | this class competes with ACh to bind Nm receptors *has no agonist action in and of itself |
| Examples of non-depolarizing Intermediate acting NM blockers | 1-atracurium 2-cisatracurium 3- pancuronium 4- rocuromium 5- vecuronium |
| Only ONE depolarizing NM blocker is | succinylcholine is in this category |
| MOA of succinylcholine | this drug creates sustained depol at NMJ |
| therapeutic class of succinylcholine | this drug is a NMJ blocker, ultra-short acting |
| succinylcholine is metabolized by what enz | pseudocholinesterase metabolizes succinylcholine and is NOT reversed by neostigmine |
| why is succinylcholine ultra short acting | this drug is ultra short acting because it is rapidly degraded by pseudocholinesterase, which is abundant in plasma and is highly active, thereby eliminating succinycholine in minutes |
| s/e of nondepolarizing NM blockers | s/e include 1- respiratory arrest bwo resp muscle paralysis 2-HTN bwo histamine release 3 - HTN bwo ganglionic blockage 4 - tachy (depends on which drug) |
| why does the s/e tachycardia vary in various nondepolarizing NM blockers? | because some drugs, esp pancuronium, have antimuscarinic action (bwo muscarinic antagonist or vagolytic) *dysrhythmias and cardiac arrest are possible |
Created by:
lorrelaws
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