Cholinoceptor-Blocking Drugs Flashcards
M1 receptor subtype is located in?
M2?
M3?
M1 - CNS neurons, sympathetic postganglionic cell bodies, many presynaptic sites
M2 - Myocardium, smooth muscle organs
M3 - Effector cell membrane
Muscarinic Antagonist a.k.a
- Parasympathetic
- Antimuscarinic
What drug is derived from plant atropa belladonna that are often use on their effects on the eye and CNS
Atropine (Hyosctamine)
Tissues most sensitive to atropine?
Salivary
Brochial
Sweat Glands
Which antimuscarinic drug has more marked central effects?
In your answer above, it produces what in recommended dose?
In toxic doses, produce what?
- Scopolamine > Atropine
- Drowsiness (Amnesia in sensitive individuals)
- Excitement, agitation, hallucinations, and coma
- Antimuscarinic effect on pupillary constrictor muscle.
- unopposed sympthetic dilator activity and mydriasis
Additional effects:
- weaken the contraction of the ciliary muscle or cycloplegia (loss of the ability to accommodate)
- reduce lacrimal secretion(large doses)
SA node is very sensitive to muscarinic receptor blockade.
Moderate to high therapeutic doses of atropine causes what?
- Tachycardia
True or False.
Ventricles are highly affected by anti-muscarinic drugs at therapeutic levels.
False.
Ventricles are less affected by anti-muscarinic drugs at therapeutic levels because of lesser degree of vagal control.
Certain vestibular disorders respond to anti-muscarinic drugs (and to antihistamine with anti-muscarinic effects). True or False. Name one example.
True. Scopolamine.
Antimuscarinic agents are administered topically as eye drops or ointment are not helpful in doing complete examination. True or false.
False
Atropine became part of routine preoperative medication when anesthetics such as ether were used. This would lead to what?
How to prevent?
Increased airway secretion and frequent laryngospasm.
Pre-anesthetic injection of atropine or scopolamine could prevent this hazardous effects.
This is a synthetic analog atropine used as inhalation drug for asthma or COPD.
How does is work?
Ipatropium.
Aerosol route has the advantage of maximal concentration At bronchial target tissue with reduced systemic effects.
(Also used in COPD.)
In the situation of marked reflex vagal discharge that sometimes accompanies the pain in MI, what is the drug of choice?
Parenteral Atropine
A person infected with trypanosoma cruzi has what disease?
It affects what receptor in the heart? And exert what action? This is prevented by what drug?
Chagas’ Disease.
M2 muscarinic receptors.
Parasympathomimetic action.
Atropine.
What muscarinic receptors are expressed predominantly in the human urinary bladder?
M3 and M2.
With M3 mediating direct activation of contraction.
