Cholinergic Pharmacology II

Question 1

cholinoreceptor blocking drugs divided into

Answer 1

muscarinic antagonists and nicotinic antagnosts

Question 2

antimuscarinic drugs come in two types

Answer 2

tertiary amines (effects in eye or CNS) and quaternary amines (peripheral effects, cannot penetrate lipid)

prototypical drug is atropine

Question 3

atropine

Answer 3

causes reversible (competitive blockage)
and is not selective between M1, M2, and M3 subtypes

Question 4

Nicotinic antagonists are

Answer 4

ganglion blockers, nmj blockers (paralytics)

Question 5

Cholinoreceptor blocking drugs- organ system effects: CNS

Answer 5

profound effects at higher, toxic doses
agitation, hallucinations, coma

often used with dopamine precursor in parkinson’s

Question 6

cholinoreceptor blocking drugs- organ system effects: eye

Answer 6

activation constricts pupil
-blockade results in dilation and blurry vision (blockade by topical atropine) by causing paralysis of ciliary muscle (used in ophthalmic exam- cyclopegia)

-contraindicated in acute glaucoma, especially in pts with narrow anterior chamber angle

Question 7

cholinoreceptor blocking drugs- organ system effects: CV

Answer 7

SA node is under PNS tone- sensitive to muscarinic blockade

• atropine produces tachycardia
• antimuscarinics can cause cutaneous vasodilation

Question 8

cholinoreceptor blocking drugs- organ system effects: respiration, GI, GU, sweat

Answer 8

respiratory- bronchodilation and reduction of secretion (more important), used in asthma or allergies but not first line

gi tract- predominant tone is parasympathetic, reduces motility and secretion; useful as preop adjuvant before abd surgery

gu tract- urinary retention, esp with BPH

sweat glands- suppresses thermoregulatory sweating (under sympathetic control but cholinergic), body temp elevation

Question 9

therapeutic applications for cholinoreceptor blocking drugs

Answer 9

parkinson’s, motion sickness, preop meds, relieves bronchoconstriction (ipratropium plus beta2 agonists in asthma and copd), relief of vagal syncope, traveler’s diarrhea, urinary urgency and incontinence, reversal of cholinergic poisoning (w/ tertiary drug), hyperhidrosis

Question 10

atropine poisoning

Answer 10

dry mouth, mydriasis, tachycardia, flushed skin, delirium- “dry as a bone, blind as a bat, red as a beet, mad as a hatter”
-can be treated with physostigmine (cholinesterase inhibitor) or symptom management

Question 11

contraindications of cholinoreceptor blocking drugs

Answer 11

glaucoma (closed angle)

and prostatic hyperplasia because you can promote urinary retention

Question 12

ganglion blocking drugs

Answer 12

• block actions of ADh and other agonists at nicotinic receptors
• receptors on both PNS and SNS autonomic ganglia (post ganglionic neurons that leave from paravertebral chains of SNS or peripheral ganglia for PNS)
• non selective produces limited side effect profiles
• all synthetic amines

-wherever the blockade is, blocking sympathetic reflex will result in orthostatic hypotension

Question 13

first ganglion blocking drug developed was

Answer 13

tetraethylammonium (TEA)- short doa

• developed for management of htn and effective
• block sympathetic outflow to peripheral vasculature- specific because tone of peripheral vasculature is sympathetic
• however, vessels won’t be able to adapt to change (no vasoconstriction to maintain perfusion to brain after standing up)

Question 14

ganglionic blockers organ system effects

Answer 14

-depend on predominant ANS tone at specific end organ

Question 15

mecamylamine

Answer 15

a ganglion blocking drug which can enter the CNS- can cause sedation, tremor, choreiform movements, mental aberrations

Question 16

ganglion blocking drug effects on eye

Answer 16

ciliary muscle- mostly PNS- cyclopegia (paralysis of ciliary muscle)

pupil- both PNS and SNS but PNS dominates slightly, moderate dilation of pupil

Question 17

ganglion blocking drug effects on CV

Answer 17

blood vessels have SNS tone (no PNS)- remove sympathetic tone

• reduce blood pressure, decrease in arteriolar and venomother tone (peripheral resistance)
• produce orthostatic hypotension
• moderate tachycardia (removal of PNS at SA node- vagal)

Question 18

ganglion blocking drug effects on GI

Answer 18

looks like muscarinic antagonist

tone is PNS- reduced secretion and motility- constipation

Question 19

ganglion blocking drugs on GU

Answer 19

-urinary retention (esp with prostatic hyperplasia), sexual function impairment bc requires both SNS and PNS

Question 20

other ganglion blocking drug effects

Answer 20

• block thermoregulatory sweating, all reflex sweating

- responses to autonomic drugs (catecholamines, etc) will be altered because you won’t have any ANS reflexes

Question 21

tertiary amines- muscarinic antagonists

Answer 21

atropine
scopolamine

pirenzepine

tolterodine

and more that are not listed here -_-

will cross CNS- used for motion sickness, etc.

Question 22

quaternary amines- muscarinic antagonists

Answer 22

atropine methyl nitrate
methscopolamine
ipratropium
propantheline
glycopyrrolate

used mainly for asthma or copd

Question 23

ganglion blocking drugs

Answer 23

hexamethonium
tripethaphan (lacks CNS effects)
mecamylamine

very effective at lowering bp, but lots of ANS side effects

Question 24

cholinesterase regenerator

Answer 24

pralidoxime (2-PAM)

effectively an anti-cholinergic by enabling AChE to break down ACh