Anti Muscarinics Flashcards
semi synthetic tertiary antimuscurinic drug used for intestinal spasm
Dycycloverin ( dycyclomine)
list all the centrally actin antimuscarinic drugs
Biperiden, benztropine, diphenhydramine (for more dramatic response), trihexyphenidyl
drugs that selectively block M3 receptors and are used for the treatment of overactive bladder
Darifenacin, solifenacin, imidafenacin
true or false. Tiotropium, oxytropium, aclidinium, and ipratropium are used for treating COPD and asthma
false. Aclidium is not used as treatment for asthma. Ipratropium, tiotropium, oxytropium- for asthma
fuction of glycopyrolate
used for respiratory disorders
Name the centrally acting antimuscarinic drugs
Biperiden, benztropine, diphenhydramine (for more dramatic response), trihexyphenidyl
Name a tertiary antimuscarinic drug with the same function as trospium and homatropine methylbromide
Oxybutinin which is used for urinary incontenence. Trospium and Homatropine methylbromide are also used for urinatry incontinence
what type of inhibition does and antimuscarinic drug exhibit?
COMPETITIVE INHIBITION. Reversible, equilibrium, surmountable - bind to receptor but no intrinsic activity of its own
True or False. Heteroreceptors are found at the presynapticc muscarinic receptors.
False. At Presynaptic muscarinic receptors: autoreceptors | At sympathetic nerve fibers: heteroreceptors
Explain the mechanism of action upon blocking presynaptic M2 receptors
Blockade of M2 can augment transmitter release. Presynaptic M2 modulates release of Ach - decreases of Ach - decrease Ach effect. With an antimuscarinic drug blocking the M2 receptor, there is an increase of Ach release.
Explain the paradoxical response occuring upon blocking the M3 receptor
antimuscarinic blocks M3 receptors, which result to brochodilation. However, M2 receptor blockade (wherein its function as a modulator of Ach is reduced - inc Ach) can counteract the effect of blocking M3. Blocking M3 results to a paradoxical response of increased levels of Ach - bronchoconstiction
name 4 drugs that possess inverse agonism
Atropine, ipratropium glycopyrrolate, trihexyphenidyl
Between atropine and scopolamine, which drug can easily penetrate the blood brain barrier?
scopolamine has a greter permeation across BBB than atropin
compare Atropine and Scopolamine in terms of their predilection
Atropine - heart, GI,bronsial smooth muscle. Scopolamine: iris sphincter, ciliary muscle, exocrine glands
which drug has a prominent central effects at therapeutic dose? (atropine/scopolamine)
Scolpolamine
true or false. Scopolamine exhibits both depression and excitation central effects at a therapeutic dose.
True. Excitation is occasionally in presence of severe pain
side effect of using scopolamine as an antiemetic
dry mouth
Why use first generation H1 receptor blockers as antiemetic?
first genereation H1 receptor blockers have antimuscarinic/atropine like effect
Antimuscarnic drugs that are used for parkinsons disease.
centrally acting/ tertiary antimuscarinic drugs ( biperiden, benztropine, diphenhydramine, trihexyphenidyl)
why are the ventricle less affected by the effects of the antimuscarinic drugs?
ventricles are less affected due to less vagal parasympathetic control
explain how atropine causes a paradoxical bradycardia at very low dosed given by slow IV.
There is a blockade of your prejunctional M1 receptors on the vagal postganglionic fibers that limit Ach release in SA node - Removal of autoinhibition - increased Ach release - bradycardia (but once peripheral effects from atropine takes place, tachycardia occurs)
effects of atropine to the circulation when given alone in clinical doses
Atropin counteracts peripheral vasodilation and sharp fall in bp induced by choline esters. M3 in vascular endothelium are not innervated by the parasympathetic system. However, M3 responds to muscarinic agonist. By blocking M3 heteroreceptors antimuscarinic can then counteract vasodilation effects - vasoconstriction
effects of atropine to the circulation when given alone in toxic doses
atropine flush
effects of large doses of atropine to the gastrointestinal tract
completely abolish Ach on GI motility and secretion only; Decrease amplitude and frequency of propulsive movements means more relaxed walls, Basal secretion is blocked more effectively than that stimulated by food, alcohol, or nicotine
selective M1 antimuscarinic drugs that selectively inhibit gastric acid secretion only
pirizepine and telenzepine
which is more selective in blocking M1 receptors? (Telenzepine/pirenzepine)
Telenzepine
why is diphenoxylate more effective when taken with atropine in treating traveller’s diarrhea?
diphynoxylate can cause dryness of mouth. To prevent this, very low dose of atropin is take.
True or false. Effects of endogenous muscarinics are more effectively blocked than those exogenously administered muscarinics.
False. Exogenously administered muscarinic stimulants are more effectively blocked than those following vagal impulsive activity/ Parasympathetic nerve activity (edogenous ach)
Usage of dicyclomine
reduces intestinal spasm
nonselective drugs for treating overactive bladder/OAB
Tolterodine, oxybutynin, trospium, propiverine
selective M3 blockers that are effective in treating overactive bladder
Solifenacin, Darifenacin, imidafenacin
compare effects of muscarinic agonist and antimuscarinic to the ciliary muscles.
muscarinic agonist: cyclopasm; antimuscarinis: cycloplegia
effects of antimuscarinis to the ocular system
mydriasis, cycloplegia, sandy eyes
true or false. Antimuscarinics dilates the eye by acting on the radial muscles
False. Antimuscarinics do not stimulate redial muscles
explain how antimuscarinics cause mydriasis.
recall that Blocking the more dominant division (parasympathetic) - see more effect of the sympathetic system (submissive division. Antimuscarinic inhibits the parasymathetic effect of colinergics (pupillary constriction) making it possible for the sympathetic effect (vasodilation) to be observed
which of the following drugs can be used for fundoscopy requiring cycloplegic effects? (Tropicamide/cyclopentylate/Scopolamine/atopine)
atropine
arrange the following antimuscarinics bsased on their duration of effect in decreasing order. scopolamine, atropine, cyclopentylate, tropicamide, homatropine,
Tropicamide: 15-60 mins | Cyclopentylate: 3-6 hrs | Homatropine: 12-24 hrs | Scopolamine: 3-7 days | Atropine: 5-6 days blocked more effectively
effect of atropine to the respiratory tract
brochodilation. However, it decreases mucociliary clearance and can form a mucous plug (can be a site for bacterial proliferation)
what is the advantage of using Ipratropium, oxitropium, and tiotropium over atropine?
Less inhibitory effect on mucociliary clearance as compared to atropine. sideeffect: dry mouth
how does ipratropium counteract the blockade of m3 receptor-mediated brochoconstriction
Ipratropium ounteracts blockade of M3 mediated bronchoconstriction due to removal of autoinhibition by blockin M2 receptor. Ipratropium blocks all muscarinic receptors including presynaptic M2 leading to removal autoinhibition - increase Ach - bronchodilation.
compare and contrast therapeutic usage of tiotropim and aclidinium.
tiotropium: used for both COPD and asthma; aclidinium: only used for COPD and not for asthma
effect of atropine to the exocrine gland
xerostomia, anhydrosis, atropine fever (due to the suppression of thermoregulatory sweatin
effects of scopolamine to the CNS
CNS Depressant (drowsiness, amnesia, fatigue, dremless sleep, decrease REM, suphoria) and anti-emetic
centrally acting antimuscarinic drugs
Benztropine, biperiden, trihexyphenidyl, procyclidine, diphenhydramine
toxic effects of antimuscarinics
xerostomia, cycloplegia, atropine flush, atropine fever, cns excitation
treatment for atropine taken orally
gastric lavage with activated charcoal slurry without delay
drugs used for atropine poisoning that can also cross BBB
physostigmine
Antimuscarinic that is given through IV for sedation and seizures
benzodiazepines
drugs used for treating antimuscarinic poisoining due to quarternary compounds
neostigmine and sympathomimetic
list 5 contraindication of antimuscarinics
narrow angle glaucoma, benign prostativ hyperplasia, bstructive conditions: urinary tract, GIT, Gastric ulcer, intestinal atony
when can anti-muscarinic be used for opthalmologic diagnosis?
if cycloplegic or prolonged action is required in fundoscopy
what drugs can be used for opthalmologic diagnosis that only require myadriasis?
sympathomimetic drugs and alpha adrenoreceptor stimulant (phenylephrine)
List some opthalmologic diseases wherein antimuscarinics are used for treatment.
anterior uveitis, acute irits, iridocyclitis, keratitis, prevent synechia formation
List 4 gastrointestinal disorders that can be treated by antimuscarinics
acid peptic disease, common traveller’s diarrhea, intestinal spasm, reflux esophagitis
drug used for traveller’s diarrhea that does not have diphynolate
lomotil
antimuscarinic drug that enhances the gastric emptying time and prevents reflux by increasing the lower esophageal pressure
metoclopramide
antimuscarinics used for reflux esophagitis
metoclopramide and betanechol preferred drug
antimuscarinic drugs used for acid peptic disease
pirizepine and telenzepine
List the therapeutic uses of antimuscarinics in the genitourinary tract
urolithiasis, enuresis in childre, urniary incontinence, overactive bladder
antimuscarinic drug used to decrease urinary spasm in ureter
hyoscine
used to relieve bladder spasm after urologic surgery and in reducing involuntary voiding in patinets with neurologic disease
oxybutinin
antimuscarinic nonselective antagonists with greater selectivity for M3 receptors than oxybutinin or trospium
darifenacin and solifenacin
a tricyclic antidepressant drugs that is used to reduce incontinence in institutionalized elderly patients
impramine
antimuscarinic drug used for COPD and has a longer bronchodilation action thatn ipratropium
tiotropium.
antimuscarinic drug given to patients with mycetism
atropine
