Antimuscarinics Flashcards
Atropine
- -structure
- -derived from
- -what receptors does it effect?
an ester between tropanol and tropic acid
leaves of atropa belladonna
blocks the muscarinic not nicotinic receptors
What effects are seen when atropine is given at 0.5 mg?
some dryness of mouth
inhibition of sweating
What effects are seen when atropine is given at 2 mg?
marked dryness of mouth
rapid HR
dilated pupils
What effects are seen when atropine is given at 10 mg?
Symptoms from 0.5 mg and 2 mg are more marked
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ataxia
restlessness
excitement
hallucination
delirium
^CNS effects
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What is atropine used for in the eye?
- -general
- -specific
- -example drugs
–mydriatic (dilates the pupil)
so used
- -to dilate pupil in eye exam
- -when torn iris (b/c iris is an active mm that is constantly altering to the amount of light)
- -to break synechiae that occur with herpes infections in the eye
cyclopentolate
tropicamide
What are the advantages of cyclopentolate and tropicamide?
They have a quicker onset and a shorter duration than atropine itself
cyclopentolate - 45 min onset, 15 hr duration
tropicamide - 30 min onset, 4 hr duration
What is atropine used for in the respiratory system?
antimuscarinic to decrease respiratory secretions
- -preanesthetic mediation
- -decrease accumulation of fluid in lungs
- -block excess vagal activity in anesthesia and surgery
What is atropine used for in the GI system?
- -antispasmodic effect
- -IBS
- –common problem
- –spastic constipation or diarrhea
- -may contain small amounts of atropine or scopolamine and mild sedative
What is atropine used for in the urinary system?
antimuscarinics in urinary incontinence (enuresis)
- -increasingly common in elderly and also occurs in children (30% of 4 yo)
- -durgs are competitive blockers of muscarinic receptors)
- -drugs effective but dryness of mouth and eyes limit tolerability
What atropine analogues are used for enuresis?
- oxybutinin
- tolterodine
- solifenacin
oxybutinin
7x stronger than atropine as antispamoid but only 20% of dry mouth problems
Skin patch even more tolerable
tolterodine
more tolerable than oxybutinin
solifenacin
reduced xerostomia and constipation
Lasts 24 hr
Has specificity for M3, so don’t see any effects on the heart – its the best selling antimuscarinic on the market
What are antimuscarinics used for in the respiratory system?
Examples - their use, advantage, etc.
Treatment of bronchoconstriction
decreases hyperactive vagal reflex
Ipratropium inhaler
Tiotropium lasts 24 hours
^^ both quaternary, not absorbed
–no decreases ciliary activity; little drying
What is the cardiovascular use for antimuscarinics?
For sinus bradycardia after MI
Used to block excess vagal activity
Use it cautiously to restore cardiac output
Receptor specificity of atropine
Relatively non-specific
Good for M2 and M3, but less effective on M1
Can antimuscarinics effect the CNS?
Yes. Tertiary amine antimuscrinics can enter the CNS
–includes atropine, scopolamine, mydriatics, and drugs for enuresis
Cause restlessness, ataxia, hallucinations
In high doses, cause psychosis
Children and elderly esp susceptible
What is the antidote for excess antimuscarinics effecting the CNS?
physostimgine
What antimuscarinics are used for IBS?
Methoscopolamine
- -quaternary amine
- -no CNS effects
Dicyclomine
–“direct” effect on smooth mm
What precautions should be taken when using antimuscarinics? AKA when should you not use it?/what should you be aware of as side effects?
- Bad heart
- -atropine can increase HR
- -vagal activity less in infancy and old age
- Intestinal atony
- Eye infection
- Lung infection
- Blurred vision
- Glaucoma
- Prostatic hypertrophy
- Block sweating
Mnemonic for remembering atropine/antimuscarinic side effects
Dry as a bone, blind as a bat, red as a beet, mad as a hatter
