Pharm: Muscarinic antagonists Flashcards
What two plants contain atropine?
Atropa belladonna (used to be used to dilate women’s eyes to make them more beautiful) and Jimson weeds
(Think of atropine alice holding a flower)
What is the technical name for dilated pupils?
Mydriasis
What is cycloplegia?
Inability to control the ciliary muscle, leading to far-sightedness; antimuscarinics can cause this, because the parasympathetic response is needed to focus on objects up cloase (think of the walrus with the scope- scopalamine is an antimuscarinic)
Which antimuscarinic can be applied transdermally?
Scopolamine (the eyepatch on the walrus)
Why is atropine used to treat bradycardia?
Because M2 receptors on the heart cause relaxation and decreased HR; blocking this input stimulates tachycardia
___________ (an antimuscarinic) can be used to treat bradycardia and heart block by inhibiting M2 receptors at the SA and AV node.
Atropine (think of the Queen of Hearts standing right by atropine Alice with two jeweled nodes on her staff and the rabbit pushing aside the heart shield)
What antimuscarinics are used to treat COPD and asthma?
Ipratropium and tiotropium, which block the M3 receptor (think of the caterpillar inhaling smoke: cat-IPRA-TIO-TROPillar)
What two antimuscarinics that block M3 receptors are used to treat overactive bladder?
Oxybutynin and tolterodine (think of the OX butler and the TurTle shutting off the bladder-shaped vessel at the table)
In the CNS, antimuscarinics can be used to treat __________.
Parkinson’s (think of the parking sign)
What two antimuscarinics distribute best to the CNS?
Benztropine (think of the Benz parked at the M1 spot) and trihexiphenidyle (think of the tri-hexi car)
Parkinson’s results from decreased ______ and increased ______ activity.
dopamine; cholinergic
Why do antimuscarinics make you hot?
Because they suppress the sweating response (sympathetic input, but uses acetylcholine)
What are some side effects of antimuscarinic overdose?
Parasympatholytic side effects:
“Mad as a hatter (from blocking M1 in the CNS leading to sedation, agitation, hallucination and coma especially in elderly).
Blind as a bat (cycloplegia).
Dry as a cracker (decreased salivation and eye moisture).
Hot as a hare (suppressed sweating from blocking M3)
High pressure as a kettle (acute angle closure glaucoma from mydriasis and decrease aqueous humor outflow).”
Which M receptors does atropine inhibit?
M1, M2, M3
What is transdermal scopolamine used to treat?
Sea sickness- by blocking M1 receptors in the CNS
