Cholinergic Antagonists (8-21-15)

Question 1

Succinylcholine

Answer 1

*Indication: Neuromuscular block for electroconvulsive shock therapy or emergency intubation
*MOA: DEPOLARIZING block of muscle nicotinic receptors
*Elimination: Butyrl cholinesterase
1/2 life: 5-8 mins
*Contraindications: familial hyperthermia, skeletal muscle myopathies
*Toxicity/side-effects: ???

Nm inhibitor (Nm = skeletal muscle membrane nicotinic receptor)

Question 2

Pralidoxime

Answer 2

(2-PAM)

*Indication: Respiratory muscle weakness in organophosphate poisoning
*MOA: Peripheral AchE reactivator
Elimination: Urine
*1/2 life: ~75 mins
*Contraindications: ???
*Toxicity/side-effects: ???

Note: pts can die from paralysis of muscles of respiration in OG poisoning

Question 3

Atropine

Answer 3

*Indication: Cholinesterase inhibitor poisoning, reverse bradycardia (vagal origin), remove hypermotility of colon and hypertonic of SI, reverse mydriasis & cycloplegia (paralysis of ciliary muscle), stop urgency and frequency of micturition
*MOA: COMPETITIVE muscarinic antagonist (competes w/Ach at effector organ)
Elimination: Liver
1/2 life: 2hrs
*Contraindications: ???
*Toxicity/side-effects: atropine poisoning

Atropine toxicity: “Dry as a bone, red as a beet, mad as a hatter” (no sweating, cutaneous vasodilation, CNS toxicity which includes psychosis & inappropriate laughter)

ATROPINE POISONING:
PNS: dry mouth, difficulty swallowing, thirst, flushed skin, dilated pupils, blurred vision, tachycardia, inc bp, micturition difficulty
CNS : nervousness, confusion, hallucinations, muscular incordination, inappropriate laughter, psychosis

Question 4

Scopolamine

Answer 4

*Indication: Nausea and vomiting from motion sickness and chemotherapy, preparation for surgical anesthesia to reduce secretions
*MOA: COMPETITIVE muscarinic antagonist
Elimination: unknown
1/2 life: ~9.5 hrs for transdermal; 25 hrs for IV
*Contraindications: ???
*Toxicity/side-effects: ???

Question 5

Glycopyrrolate

Answer 5

*Indication: Prevent overstimulation of gut during reversal of neuromuscular blockade
*MOA: Muscarinic antagonist
Elimination: Urine
1/2 life: 0.5-2 hrs
*Contraindications: ???
*Toxicity/side-effects: ???

(*DOESN’T CROSS BBB)