ANS: Anticholinergic Flashcards
Cholinergic receptor subtypes
Nicotinic
Pentameric, 5 subunits. Ligand gated ion channels
Cholinergic receptor subtypes
Muscarinic
G protein coupled. M1, M3, M5 inositol phosphate pathway. M2, M4 inhibit adenylyl cyclase and reduce cAMP
M1
CNS, stomach
M2
Cardiac muscle, CNS, a/w smooth muscle
M3
A/w smooth muscle, glandular tissues
M4, M5
CNS
NM
Skeletal muscle at NMJ
Nn
Autonomic ganglia, adrenal medulla, CNS
Antimuscarinic drugs: MOA
Competitively antagonize Ach at muscarinic receptors. Cation pt fits into Ach’s place, inhibits binding. Allows SNS to dominate. Only reversed if Ach conc increases.
Antimuscarinics
Two diff structure types
Natural (atropine and scop) are tertiary amines. Alkaloids of belladonna plant. Crosses BBB and resp epithelium
Semi-synthetic (glyco and robinal) quaternary ammonion deriv
Atropine Effect on: sedation/mydriasis/nausea, inc HR, relaxing smooth muscle, anti-sialogogue
Sed +
Hr +++(Give if hr in 20s, kicks in fast)
Smooth musc ++
Anti sial +
Scopolamine Sedation/nausea/mydriasis Inc hr Relax smooth musc Anti sialogogue
Sed +++
Hr +
Relax +
Anti +++
Glycopyrrolate Sedation, nausea, mydriasis Inc hr Relax smooth muscle Anti sialogogue
Sed 0
Inc hr ++
Smooth muscl ++
Anti ++ (less SE than other drugs)
IV atropine
Onset
Duration
E 1/2t
1 min
30-60 min
2.3 hrs
IV atropine
Metab/excretion
18% unchanged in urine, rest undergoes hydrolysis
IV glycopyrrolate
Onset
Duration
E 1/2 t
2-3 min
30-60 hrs
1.25 hrs
IV glyco
Excretion
Unchanged via urine. Caution w renal pts.
Scopolamine
Metabolism, excretion
Extensively metab with only 1% excreted unchanged in urine
Tx bradycardia young vs old pts
Young pts have high baseline vagal tone, more tachycardia. Elderly have less tone, less pronounced tachycardia
Antimuscarinics always given when
W anticholinesterase drugs when antagonizing NMB
Ipratropium
Use
Dose
Bronchodilation
MDI 40-80 mcg/2 puffs
0.25-0.5 mg via neb
Ipratropium
Onset
Consider in whom before what
30-90 min
Asthmatics, COPD, smokers prior to a/w instrumentation
Ortho cases use anticholinergics for what
Caution using in who
Mydriasis and cycloplegia
Narrow angle glaucoma dangerous- increases IOP
Anticholinergics reduce what d/t opioids
Biliary and ureteral spasm. Biliary spasm can mimic angina
Scopolamine dose
IV
IM
Transdermal
pre op.
0.3-0.5 mg
or 5 mcg/kg IM
1.5 mg transdermal (5mcg/hr over 72 hrs) nausea
Atropine doses
Pre op iv
Bradycardia iv
Neb- bronchodilation
0.2-.4 mg
0.4-1 mg
2mg in 5 ml NS
Glycopyrrolate
IV dose pre op and bradycardia
0.1-0.2 mg IV
Central anticholinergic syndrome
What causes it
What happens
Tx
Scopolamine and atropine
Restless, hallucinate, unconscious, tired. Delayed emergence in PACU
Physostigmine 15-60 mcg/kg IV repeated Q1-2hrs
Atrovent and spiriva for what
COPD bronchodilation
Ditropan, Detrol, for what
Overactive bladder, nonspecific m receptor
Enablex, vesicare for
Overactive bladder. M3 specific, good if CAD
AChE inhibitors
Action
Increases what 3 things
Elevates conc of Ach by decreasing its metabolism. Increases transmission at Nm junction (reverses competitive NMB), increases PNS tone, increases central cholinergic activity
AChE inhib
Helpful in what disease which 2 specifically
MG- Nm junction disease. Pyridostigmine and neostigmine
AChE inhib
Role in glaucoma, which drug
Increases outflow of aqueous humor, physostigmine
AChE inhib
Role in abdomen
Helps dispenses, increases smooth muscle motility, neostigmine
AChE inhib
Specific for AD
Cognex, aricept, ex Elon, razadyne
AChE inhib
Total roles
MG, glaucoma, abd distension, AD/cognitive dysfunction
AChE inhib
Adverse effects
Peripheral ach effects GI tract. NVD, anorexia, flatulence, cramping. Dose dependent
AChE inhib
Contraindications
Unstable or severe CV disease
Uncontrolled epilepsy
Active PUD
Muscarinic agonists
Indications/drugs
Asthma (methacholine), miosis/decreased IOP (carbachol), GI and urinary tract motility (Bethanechol)
Depolarizing muscle relaxant
Name and action
Succ. Continuous activation of nicotinic receptor channels results in depolarization blockade
Nicotinic antagonists
Non depolarizing muscle relaxants
Action and names
Prevents endogenous ach binding to nicotinic receptors and subsequent muscle cell depolarization. Paralysis
Pancuronium, rocuronium, vecuronium