Clonidine

Question 1

action

Answer 1

• centrally acting alpha 2 agonist
• decreased sympathetic outflow from CNS
• Dec in BP, HR< CO

Question 2

indication

Answer 2

• essential hypertension
• diagnose pheochromcytoma–dec plasma concentrations of catecholamines in nl pts, but not those with pheo
• supresses sxs of narcotic withdrawal
• dec MAC, fent requirement–c/w dec in sympathetic outflow
• intrathecal when tolerance to morphine has developed
• epidurally

Question 3

side effect

Answer 3

-rebound hypertension–assoc with large inc in catecholamines

Question 4

receptors affected

Answer 4

• descending medullospinal noradrenergic pathway modulating spinal nociceptive processing
• receptors are from dorsal horn, where they inhibit neurotransmitters like substance P

Question 5

epidural clonidine

Answer 5

• epidural clonidine–better, longer analgesia compared to subQ morphine
• does not reduce sensory or motor block
• associated with hypotension, bradycardia–inhibition of preganglionic sympathetic fibers

Question 6

methyldopa

Answer 6

• a2 agonist

- stimulates a2 receptors in hypothalamus–decreasing sympathetic outflow from brain

Question 7

clonidine

Answer 7

• stimulates a2 neurons in medullary vasomotor center

- decreases sympathetic outflow from CNS

Question 8

Reserveres

Answer 8

• interferes with NE reuptake into nerve terminal storage vesicles
• depletion of NE

Question 9

guanethidine

Answer 9

• enters storage granules and interferes with NE release from storage vesicles
• TCA and ephedrine block this, decreasing effectiveness of the drugs