ANS Cholinomimetics

Question 1

Methacholine

Answer 1

choline ester, direct agonist, more resistant to hydrolysis, longer duration. selective for cardiovascular receptors

Question 2

Bethanechol

Answer 2

choline ester, direct agonist, even more resistant to hydrolysis, longer duration. stimulate GI, relatively selective for bladder

Question 3

Tertiary Alkaloids (pilocarpine, nicotine)

Answer 3

direct agonist, well absorbed, increased E in acid urine. pilocarpine selective for mAChR (sweat glands). nicotine selective for nAChR, absorbed across skin, desensitizes R, CNS stimulant. TX: hypertension, nausea, bladder voiding. insecticide

Question 4

Quaternary alkaloid (muscarine)

Answer 4

direct agonist, poorly absorbed GI, toxic enters CNS. potent diaphoretic, not used clinically

Question 5

Edrophonium

Answer 5

indirect agonist, alcohol, reversibly binds cholinesterase, acts peripherally, short duration

Question 6

Carbamates (synthetic: neostigmine + pyridostigmine, natural: physostigmine)

Answer 6

indirect agonist, more resistant to hydrolysis, intermediate duration, low lipid solubility. Physostigmine access to CNS is toxic. Neostigmine binds/activates nAChR. Pyridostigmine prophylactic chemical warfare.

Question 7

Organophosphates (parathion + malathion, soman + sarin)

Answer 7

indirect agonist, undergoes aging, essentially irreversible. well absorbed from skin/lung/GI/eyes. Toxic, access to CNS. insecticides and nerve gases. Malathion safest for public use