ANS Antagonists Flashcards
This medication binds covalently to alpha receptors
Phenoxybenzamine
What happens when you give a large dose of a selective drug?
It loses its selectivity
Beta agonists are a derivative of ____ and therefore have _______
Isoproterenol
Sympathomimetic effects
Why is beta blocker action hard to predict / hard to dose?
Because everyone has genetic differences in receptor density, susceptibility, level of basal tone, etc.
We have to use trial and error to get the dose just right
M1,3,5 all follow this GPCR pathway
G-alpha-q (same pathway as alpha 1!)
M2 & 4 follow this GPCR pathway
G-alpha-i
An anticholinergic basically blocks this
The PSNS
Where the cholinergic receptors are located
M1: CNS and stomach
M2: CNS, cardiac muscle, and airway smooth muscle
M3: Airway smooth muscle and glandular tissue
M4: CNS
M5: CNS
Nm: NMJ of skeletal muscle (vec and roc work here)
Nn: Autonomic ganglia, adrenal medulla, CNA (not many meds work here)
How do antimuscarinics work?
Competitively antagonize ACh at muscarinic receptors by binding to ACh’s binding site on the receptor. This allows the SNS to predominate.
How can antimuscarinics be reversed?
By increasing ACh (remember that the block is competitive!)
These antimuscarinics are tertiary amines (can cross the BBB) and are alkaloids of the belladonna plant
Atropine and scopolamine
This antimuscarinic has quaternary structure and can not cross the BBB
Glycopyrrolate (Robinal)
Also Ipratropium
S/S of central anticholinergic syndrome
Caused by atropine and scopolamine
Restlessness, hallucinations (extra craziness with atropine)
Somnolence and unconsciousness
Delayed emergence / delayed recovery in PACU
Treatment of central anticholinergic syndrome
Physostigmine 15-60 mcg/kg Q1-2 as needed
