Anti-Cholinergics Flashcards
What is the Mechanism of action of Atropine?
blocks muscarinic ACh receptors
what are the main clinical uses of atropine? (there are a lot ~ 5)
1) EYES: Used to dilate pupils (mydriasis), to paralyze accommodation reflex (cycloplegia)
2) GI: antispasmodic
3) Urinary Retention
4) HEART: Bradycardia, 2nd degree heart block (mobitz I)
5) organophosphate poisoning
Can atropine cross BBB?
yes
MOA of Antimuscarinics in the Cardiovascular system
May block pre-synaptic sites first and increase release of Ach and lower HR. then is works at POST-SYNAPTIC M2 sites on SA node and increases HR
MOA of anti-muscarinics on secretions?
work at M3 receptors- blocks salivary glands.
produces dry mouth, dry eye (blocks lacrimal and sweat glands)
MOA of anti-muscarinics on eyes? 2 main effects.
M3- topical:
1) Mydriatic (blocks pupillae sphincter muscle)
2) cycloplegic effects (blocks ciliary muscle, loss of accommodation)
If you wanted to block secretions for surgery, which receptor would you want the anti-muscarinic to work at?
M3
In which cases can anti-muscarinics (like atropine) be used as antidote?
cholinergic agonists, esterase inhibitors and some mushroom poisonings
What is the therapeutic use for Homatropine?
EYE: cycloplegic (to temporarily paralyze accommodation), and as a mydriatic (to dilate the pupil)
GI: reduce motility of GI tract (given with histamine H2 receptor antagonist to treat peptic ulcers)
What are the 6 antimuscarinics that are tertiary amines?
1) atropine
2) scopolamine
3) homatropine
4) tropicamide
5) benztropine
6) darifenacin
what are the 2 antimuscarincs that are quaternary ammonium compounds?
1) glycopyrrolate
2) ipratropium
what are the 4 ganglionic blocking drugs?
1) nicotine
2) meccamylamine
3) glycopyrrolate
4) ipratopium
What is the therapeutic use of tropicamide?
used in eye exams: cycloplegic (to temporarily paralyze accommodation), and as a mydriatic (to dilate the pupil). short acting when applied as eye drops. It is used to allow better examination of the lens, vitreous humor, and retina.
may also be used before or after eye surgery.
Adverse effects of antimuscarinics
dry mouth blurred vision tachycardia constipation inhibition of sweating
larger doses:
restlessness, confusion, hallucinations, delerium
children more susceptible to delirum and hallucination (CNS side affects)
patch not approved in children
what drug should you give to reverse serious overdose of antimuscarinics?
Physostigmine
What are the therapeutic uses of Scopolamine?
similar to atropine– acts more in CNS and has longer duration of action.
Anti-nausea for motion sickness.
Block memory for surgery
higher doses of scopolamine produce what?
excitement
side effect of scopolamine?
blockage of memory formation
What are the therapeutic uses of ipratropium?
inhalation– used to treat asthma or COPD
nasal spray– rhinitis
What are the therapeutic uses of Benztropine?
used to reduce the side effects of antipsychotic treatment. No longer recommended to reverse tumors in Parkinsons because it alters balance.
What drug can reverse the effects of Donepezil (CNS cholinesterase inhibitor for Alzheim’ers)?
Benztropine
What are the 5 NT receptors sites important in the vomiting reflex?
M1 D2 H1 5-HT3- serotonin NK1- Substance P
What tract in the brain do anti-emetics work on?
nucleus tractus solitarius
What is the specific MOA of Darifenacin?
competitive muscarinic blocker selective at M3 sites
What are the therapeutic uses of Darifenacin?
used for overactive bladders
what is another drug that can be used to help an overactive bladder aside from darifenacin?
Mirabegon (Beta-3 agonist)
Cholinergics do what to the detrusor muscle of bladder?
contraction– void urine
adrenergics (beta-3) do what to the detrusor muscle of bladder?
relaxed- urine storage
What are the therapeutic uses of Glycopyrrolate?
1) blocks vagal reflees during intubation
2) blocks drooling in cerebral palsy
3) blocks secretions in stomach to help with peptic ulcers
doesnt cross BBB
ganglionic blockers act where?
work on nicotinic receptors on ganglia
no selectivity to SNS or PNS and are not physiologically effective as neuromuscular junction antagonists.
Nicotine
- when inhaled is absorbed 90% by lungs
Has higher affinity for CNS receptors and at high concentrations will work on ganglia. Ganglionic blockade occurs later (? don’t think I really get whats going on here– sorry)
Ganglionic blockers
peripheral muscarinic effects on sweat glands
diaphoresis
Ganglionic blockers
peripheral muscarinic effects on heart, exocrine glands and smooth muscle
bradycardia ventricular dysrythrmias torsades des poins AV blocks Cardiac arrest miosis blurred vision lacrimation etc.
mecamylamine MOA
competitive ganglionic blocker
prevents stimulation of postynaptic receptors by ACh released from presynaptic nerve endings.
clinical use of mecamylamine?
used for severe hypertension and uncomplicated cases of malignant HTN. Long duration
what is the route of administration of mecamylamine and can it cross BBB?
orally active and can cross BBB and cause CNS sedation, tremor, abnormal movements and mental changes
Big picture effects of ganglion blockers on
1) CNS
2) EYE
3) CV
4) GI
5) GU
1) CNS –> sedation, tremor, abnormal mvmt
2) LOss of accomodation, some dilation or mydriasis
3) CV: drop in BP, moderate tachy
4) GI: GI motility reduced, marked constipation
5) GU: urinary retention, impaired sexual function
Major (BIG PIC) therapeutic uses for anticholinergics:
1) CNS (3)
2) EYE (3)
3) GI (2)
4) GU (1)
5) Secretions (2)
6) Respiratory (1)
7) CV (1)
1) CNS:
atropine vs. poisons (muscarinic agonist poisonis, cholinesterase inhibitors)
benztropine (used in parkinsons to prevent tremors)
scopolamine (motion sickness prevention)
2) homatropin, atropine and tropicamide for eye exams (mydriasis and cycloplegia)
3) atropine, glycopyrrolate (diarrhea)
4) Darifenacin (M3, urge incontinence)
5) atropine, glycopyrrolate (decreased salivation, bronchial secretions for surgery, rhinorrhea, sweating, acids in stomach)
6) ipratropium (bronchial asthma and copd)
7) Atropine (CPR, bradycarida, second degree heart block)
