Anti-cholinergics Flashcards
All direct anticholinergics contraindicated in pts with which comorbid?
Narrow-angle glaucoma. Except Ipratropium due to low systemic absorption
MOA of Atropine?
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
Use of Atropine?
Treat Bradycardia
Treat Anticholinesterase overdose
For opthalmic exam - cycloplegia and mydriasis
GI antimotility agent to treat diarrhea (together with diphenoxylate)
MOA of Benzatropine?
Tertiary amine alkaloid, more lipophilic than quaternary amine and cross BBB better for stronger CNS effects
Keep dopaminergic-cholinergic balance in striatum
Uses of Benzatropine?
Treat Parkinson’s - 2nd/3rd line
Treat Parkinsonism as ADR of treatment with typical antipsychotics
MOA of Scopolamine?
M2 - tachycardia
M2 - inhibit secretions and relax smooth muscles
CNS - antiemetic and amnesic
Uses of Scopolamine?
Treat motion sickness
Adjunct for anaesthesia
Treat Urinary continence
MOA of Ipratropium?
- Quaternary amines poorly absorbed systemically and minimal CNS effects
- M3 block - less bronchoconstriction and less bronchial secretions
Uses of Ipratropium?
COPD 1st line
Taken by inhalation of asthma - 2nd line
MOA of Oxybutynin
M1 - lower gastric acid prod via action on ECL cells
M3 - relax smooth muscle walls, raise sphincter tone and lower secretions
Uses of Oxybutynin
Tachycardia
Lower GI motility
Lower secretions
Shared Anticholinergic ADRs?
Blurred vision
Confusion / hallucinations
Mydriasis
Constipation
Urinary retention
In what comorbid is Oxybutynin contraindicated in other than glaucoma?
Pyloric obstruction and retentive bladder
Names of Non-depolarizing Nm blocking agents?
Pancuronium
Rocuronium
Atracurium
MOA of NMBAs?
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
Uses of Pancuronium?
Induction of paralysis for surgery or to facilitate mechanical ventilation
Intermediate-acting drug within 2-5 mins
ADR of Pancuronium?
Histamine release at higher doses - Flushing, edema, erythema, hypotension and tachycardia
Weak antimuscarinic activity - High HR and high CO due to vagolytic effects
Pharmacokinetics of NMBAs?
Poor oral absorption
Low lipid solubility - cannot cross BBB
Small Vd - cannot paralyze diaphragm
Shorter-acting NMBAs?
Rocuronium and Atracurium
MOA of Succinylcholine?
Nm nicotinic ACh receptor agonist
Causes depolarizing blockade - cannot be reversed by tetanic stimulation or cholinesterase inhibitor
ADR of Succinylcholine?
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
Use of Succinylcholine?
Paralysis for brief surgical procedures
MOA of Nicotine high dose as an indirect cholinergic?
Readily induces depolarizing blockade and secondary non-depolarizing blockade of ganglia and Nm junctions
MOA of Botulinum toxin?
Toxin from Clostridium Botulinum
Cleaves SNARE proteins preventing exocytosis of Ach containing synaptic vesicles”
Uses of Botulinum toxin?
Cervical dystonia
Blepharospasm - excessive blinking
Strabismus - squints
Migraine and other headache disorders
Upper limb spasticity
Cosmetic - Botox
ADR of Botulinum toxin?
Paralysis of wrong muscle groups
Allergic reactions
