3 Antimuscarinic Agents

Front 1

What are antimuscarinics?
Mechanism of action

Back 1

1. Decrease ACh action
2. Bind post-synaptic muscarinic receptors competitively inhibiting ACh. Antiparasympathetic or parasympatholytic(competitive antagonist)

Front 2

What are the effects of antimuscarics?

Back 2

Opposite of PSNS stimulation, & depend on cholinergic tone.

Front 3

Atropine & Scopolamine

Which receptors are they selective for?
Which crosses the BBB?
Side effects?

Back 3

Selective for muscarinic vs. nicotinic but NOT subtypes
-Multiple side effects
Selectivity by local administration
Scopolamine crosses BBB easily & Atropine only at high doses.
CNS effects: depression, amnesia, excitation, & hallucination.(more with scopalamine due to BBB)

Front 4

Therapeutic Uses for Antimuscarinics
-Use for the mouth?
-Use for the eye? Which drugs?Which muscles?
-Pre & Post surgery use?

Back 4

-Reduces saliva production:Atropine
-Dilates pupil for opthalmological exam:Tropicamide relaxes sphincter muscle, short acting. Tropicamide+phenylephrine = an alpha-adrenergic agonist to contract radial muscle for complete dilation.
-Prior: Block parasympathetic impulse to the heart(vagal slowing) preventing cardiac shutdown(NOT for patients risking cardiac slowing such as Down's synd)/Post: prevents muscarinic side effects of ChE-Inhibitor & used to reverse muscle block.

Front 5

Cholinesterase Inhibitor Intoxication

-Effects of Organophosphate poisoning?
-Therapeutic goal?
-Drugs?

Back 5

-Muscarinic, Nicotinic, CNS effects
-M: miosis, salivation sweating bronchial constriction & secretions
-N: weakness, twitching, muscle weakness & paralysis
-C: convulsions, coma, respiratory paralysis

-Block all Muscarinic receptors & reactivate ChE
-HIGH DOSE atropine/ChE reactivator = Pralidoxime: breaks bond holding cholinesterase to ChE BEFORE aging (w/in 24 hrs)

Front 6

Urinary urgency & frequency

-Drugs?
-Used for which populations?

Back 6

-Tolterodine: selective for detrusor muscle relaxation & internal sphincter tightening.
-SOLIFENACIN: M3 agonist, more effective than tolterodine, less dry mouth problem
-Incontinence in adults, bed wetting in kids
-Few side effects

Front 7

Motion Sickness

Drugs?
Side effets?

Back 7

-Scopolamine: given prophylactically as a path or oral.
-Dry mouth, drowsiness, sometimes blurred vision.

Front 8

Bronchospasm(Asthma, COPD)

Drugs?
Effect?

Back 8

-IPRATROPIUM: non-selective muscarinis antagonist for inhale.
TIOTROPIUM: receptor antagonist, 24 hr duration, selective for M1 & M3
-Bronchodilation & reduced secretion, local effect via direct inhalation.

Front 9

Parkinsonism

Cause?
Drugs?Side effects?
Contraindications?

Back 9

-LOSS of dopaminergic neurons
-Net increase in ACh excitation
-Antimuscarinics play a secondary role now.
-LEVODOPA & CARBIDOPA
-CNS effects increase w/ age
-Any condition with impaired PSNS function

Front 10

Antimuscarinic toxicity
-Sources of toxicity?
-Symptoms?
-Treatment?

Back 10

-Plants: eat common weeds, Drugs w/ atropine-like agents: antihistamines, phenothiazine, tricyclic's. Ingestion of antidiarrheal drug = lomotin in chilren
-Blind as a bat, dry as a bone, red as a beet, hot as a hare, mad as a hatter.
-Remove drug source, gastric lavage, PHYSOSTIGMINE via IV reverses delerium & coma. DIAZEPAM IV used for CNS convulsions.