Anti-cholinergics

Question 1

All direct anticholinergics contraindicated in pts with which comorbid?

Answer 1

Narrow-angle glaucoma. Except Ipratropium due to low systemic absorption

Question 2

MOA of Atropine?

Answer 2

M1 block - low gastric acid secretion, CNS confusion/delirium
M2 block - higher HR
M3 block - less saliva + bronchial secretions + sweat. Mydriasis, cycloplegia, inhibit micturition, less GI tone and motility + GI secretions

Question 3

Use of Atropine?

Answer 3

Treat Bradycardia
Treat Anticholinesterase overdose
For opthalmic exam - cycloplegia and mydriasis
GI antimotility agent to treat diarrhea (together with diphenoxylate)

Question 4

MOA of Benzatropine?

Answer 4

Tertiary amine alkaloid, more lipophilic than quaternary amine and cross BBB better for stronger CNS effects
Keep dopaminergic-cholinergic balance in striatum

Question 5

Uses of Benzatropine?

Answer 5

Treat Parkinson’s - 2nd/3rd line
Treat Parkinsonism as ADR of treatment with typical antipsychotics

Question 6

MOA of Scopolamine?

Answer 6

M2 - tachycardia
M2 - inhibit secretions and relax smooth muscles
CNS - antiemetic and amnesic

Question 7

Uses of Scopolamine?

Answer 7

Treat motion sickness
Adjunct for anaesthesia
Treat Urinary continence

Question 8

MOA of Ipratropium?

Answer 8

1. Quaternary amines poorly absorbed systemically and minimal CNS effects
2. M3 block - less bronchoconstriction and less bronchial secretions

Question 9

Uses of Ipratropium?

Answer 9

COPD 1st line
Taken by inhalation of asthma - 2nd line

Question 10

MOA of Oxybutynin

Answer 10

M1 - lower gastric acid prod via action on ECL cells

M3 - relax smooth muscle walls, raise sphincter tone and lower secretions

Question 11

Uses of Oxybutynin

Answer 11

Tachycardia
Lower GI motility
Lower secretions

Question 12

Shared Anticholinergic ADRs?

Answer 12

Blurred vision
Confusion / hallucinations
Mydriasis
Constipation
Urinary retention

Question 13

In what comorbid is Oxybutynin contraindicated in other than glaucoma?

Answer 13

Pyloric obstruction and retentive bladder

Question 14

Names of Non-depolarizing Nm blocking agents?

Answer 14

Pancuronium
Rocuronium
Atracurium

Question 15

MOA of NMBAs?

Answer 15

Block Nm nicotinic ACh receptors (nAChRs)
Block neurotransmission at Nm junctions
Cause paralysis of skeletal muscles
Onset: Fingers/eyes > limbs/trunk > diaphragm
Recovery: Diaphragm > limbs/trunk > finger/eyes

Question 16

Uses of Pancuronium?

Answer 16

Induction of paralysis for surgery or to facilitate mechanical ventilation
Intermediate-acting drug within 2-5 mins

Question 17

ADR of Pancuronium?

Answer 17

Histamine release at higher doses - Flushing, edema, erythema, hypotension and tachycardia
Weak antimuscarinic activity - High HR and high CO due to vagolytic effects

Question 18

Pharmacokinetics of NMBAs?

Answer 18

Poor oral absorption
Low lipid solubility - cannot cross BBB
Small Vd - cannot paralyze diaphragm

Question 19

Shorter-acting NMBAs?

Answer 19

Rocuronium and Atracurium

Question 20

MOA of Succinylcholine?

Answer 20

Nm nicotinic ACh receptor agonist
Causes depolarizing blockade - cannot be reversed by tetanic stimulation or cholinesterase inhibitor

Question 21

ADR of Succinylcholine?

Answer 21

Malignant hyperthermia - genetically susceptible patients with deficient or atypical plasma cholinesterase
Apnea - genetically susceptible patients can exhibit prolonged apnea due to paralysis of diaphragm.
Hypotension, arrhythmias, respiratory collapse
Raised Intraocular pressure

Question 22

Use of Succinylcholine?

Answer 22

Paralysis for brief surgical procedures

Question 23

MOA of Nicotine high dose as an indirect cholinergic?

Answer 23

Readily induces depolarizing blockade and secondary non-depolarizing blockade of ganglia and Nm junctions

Question 24

MOA of Botulinum toxin?

Answer 24

Toxin from Clostridium Botulinum
Cleaves SNARE proteins preventing exocytosis of Ach containing synaptic vesicles”

Question 25

Uses of Botulinum toxin?

Answer 25

Cervical dystonia
Blepharospasm - excessive blinking
Strabismus - squints
Migraine and other headache disorders
Upper limb spasticity
Cosmetic - Botox

Question 26

ADR of Botulinum toxin?

Answer 26

Paralysis of wrong muscle groups
Allergic reactions