ANS: Pharmacology & Pathophysiology Flashcards
What is the postganglionic parasympathetic neurotransmitter?
ACh (cholinergic)
What is the postganglionic sympathetic neurotransmitter?
NE (adrenergic)
What are 3 alpha-selective drugs?
- Phenylephrine: alpha 1 selective
- Clonidine: alpha 2 selective
- Dexmedetomidine : alpha 2 selective
Is Renal Blood Flow (RBF) deceased or increased when using phenylephrine?
Decreased
What is a potential side effect of administering phenylephrine to a hypotensive CAD patient? What is the cause of the CO
Increase in BP and decrease in CO (worsening the ischemic that may be present)
The CO results from barorecptor reflex-induced bradycardia and increase in afterload.
Why are Beta-receptors antagonist contraindicated in hypertensive crisis?
They can induce pulmonary edema and catastrophic, irreversible cardiac collapse.
What enzyme metabolizes phenylephrine?
MAO
Which adrenergic agonist is NOT arrhythmogenic
Phenylephrine
What percentage of clonidine is metabolized by the liver and kidneys?
50% Liver
50% Kidney
What are the 3 locations classifications for alpha-2 receptors?
-Presynaptic: NE-releasing neurons in the CNS and PNS (negative feedback mechaism reduces NE release)
-Posynaptic: Smooth muscle and several organs
-Nonsynaptic: Platelets
Where does clonidine act in the body? MOA?
Acts an a alpha 2 agonist at central presynaptic receptors (medulla and locus coeruleus)
It inhibits norepinephrine release causing vasodilation
A patient abruptly stops taking her clonidine. You know that this could cause what in the patient?
Rebound hypertension
What is the MOA of dexmedetomidine?
Stimulates alpha 2 receptors in the brain and the spinal cord leading to the inhibition of neuronal firing.
Is a presynaptic alpha 2 agonist at central receptors.
Dexmedetomidine decreases SNSand results in what?
Hypotension
Bradycardia
Sedation
Analgesia
Which selective alpha-2 agonist is more highly protein-bound?
Dexmedetomidine
