Cholinergic Agonists and Anticholinergic Flashcards
AUTONOMIC NERVOUS SYSTEM
SympatheticAdrenergic Neurotransmitter Norepinephrine Epinephrine Dopamine
Fight & Flight
ParasympatheticCholinergic
Neurotransmitter
Acetylcholine
Rest & Digest
Sleepy chicken
Sleepy chicken
Cholinergic
Cholinergic agonist
Parasympathomimetic
Bear
Bear
anticholinergic
Parasympatholytic
Negative feedback loop
natural process
fight of flight stimuli=> release of catecholamines
activates adrenergic receptors
a1
b1
b2
high level of catecholamines activating a2=>
stops adrenergic system
rest and digest stimuli=> release of acetycholine
activates muscarinic receptors
Drugs
adrenergic agonists BEAR
adrenergic antagonists CHICKEN
cholinergic CHICKEN
anticholinergic BEAR
Source of side effects:
ACh works in the parasympathetic system as well as in the somatic (efferent) receptors
Cholinergic Agonists(Parasympathomimetics)
Drugs that stimulate Parasympathetic NS
Mimic parasympathetic neurotransmitter acetylcholine (ACh)
Cholinergic receptors
are not just in autonomic NS;
they are also in somatic NS (see previous slide)
Muscarinic
Nicotinic
Muscarinic receptors
Located on smooth muscles and myocardium
(autonomic or involuntary muscles/glands)
Stimulated by ACh
Muscarinic receptors affect smooth muscle and cardiac muscle
Muscarinic
(smooth muscle and heart are suppressed by ACh)
CNS (is stimulated by ACh)
Nicotinic Receptors
Located on skeletal muscles
(somatic or voluntary muscles)
Stimulated by ACh
We need to know this to understand side-effects and drugs used for MG
Nicotinic receptors affect skeletal muscles contraction
Nicotinic (MS voluntary muscles is stimulated by ACh)
CNS (is stimulated by ACh)
Ach=
Acetylcholine (Ach) is a neurotransmitter activating parasympathetic nervous system (receptor sites on organs, tissues, and glands)
Muscarinic receptors affect smooth muscle and cardiac muscle
Nicotinic receptors affect skeletal muscles contraction
bethanechol
urinary retention
Direct acting
donepezil
memantine
Alzheimer’s disease
Indirect acting (AchE inhibitor)
neostigmine
MG,
retention,
ileus,
to reverse nondepolarizing neuromuscular block
pyridostigmine
MG,
to reverse nondepolarizing neuromuscular block
edrophonium
MG
Neuromuscular blockers:
depolarizing agents
non-depolarizing agents
non-depolarizing agents
(doxacurium or pancuronium)
cholinesterase inhibitors reverse non-depolarizing neuromuscular blockers,
need for reversal for longer duration of action and very slowly metabolized
(slow redistribution or renal excretion)
depolarizing agents
(succinylcholine)
cholinesterase inhibitors increase the neuromuscular blockage of depolarizing agents
(must NOT take cholinesterase inhibitors with depolarizing neuromuscular blockers),
no need for reversal
(short duration of action and metabolized)
Page 91 of ATI mentions the use of donepezil for Parkinson’s;
it was meant that this drug may be used to treat dementia (Alzheimer)
in patients with Parkinson and it is known to be safe although there
is a risk of worsening PD because PD is treated with anticholinergics.
Cholinergic side-effectsCholinergic crisis (OD)
excessive muscarinic stimulation
General:
HA, dizziness (poor perfusion to the brain due to low BP)
Eye: blurred vision (FALL) due to miosis and loss of accommodation (poor vision) in dim light
Lung: SOB due to bronchoconstriction, ↑ bronchial secretions
CV: bradycardia, dysrhythmias => low BP => dizziness and fall
GI: increased gastric secretions, motility (D/cramps, hyperactive bowel sounds)
GU: urgency, frequency, stress incontinence
Exocrine glands: hypersalivation, lachrimation
Cholinergic side-effectsCholinergic crisis (OD)
Excessive nicotinic stimulation by
indirect-acting drugs
muscle cramps, fasciculation (muscle twitching)
Excessive ACh in CNS => excitation, seizure
Reversal agent: atropine (anticholinergic)
Cholinergic side-effectsCholinergic crisis (OD)
NOTES
Muscarinic (smooth muscle and heart are suppressed by ACh)
Nicotinic (MS voluntary muscles is stimulated by ACh)
CNS (is stimulated by ACh)
SOB: shortness of breath
Lachrimation: too much tear production
Epiphora: inflammatory prevents tear drainage (superior/inferior puncta, canaliculi, lacrimal sac, nasolacrimal duct) noraml tear production
Cholinergic Agonist
Contraindication
Pregnancy/lactation
GI obstruction (abdominal pain)
GU obstruction (Ureter/urethra stone)
Cholinergic Agonist
Caution
Seizure
PUD
Asthma
Bradycardia & Low BP
PUD: peptic ulcer disease
Anticholinergic (Parasympatholytics)
Action
Inhibit action of ACh by occupying ACh receptors
Blocking parasympathetic nerves => sympathetic domination
Anticholinergic = anti-rest/digest = adrenergic
competitive antagonist (bind to ACh receptors with no effects) hence a blocker
Anticholinergics
Effects of anticholinergics (very similar to adrenergic)
GI:
↓ peristalsis/hypoactive bowel sounds,
↓ gastric secretions & salivation,
constipation
Eye:
mydriasis,
decrease accommodation in bright light
(photophobia)
Heart:
increase
HR,
BP
Lungs:
bronchodilation,
decrease bronchial secretions
GU:
relax detrusor muscle,
increase sphincter constriction (urinary retention)
CNS:
drowsiness,
decrease tremors and rigidity (used for PD)
Used to reverse cholinergic drugs
Anticholinergics
DRUGS
Atropine
Atropine
ROUTES
IV:
for symptomatic bradycardia
PO drop:
to reduce saliva (pre-op, palliative)
Ophthalmic drop: to produce mydriasis
& cycloplegia (pre-op)
IM:
for reversal for cholinergic OD
(OD with MG drugs)
Atropine
SIDE EFFECTS ADVERSE REACTIONS
Tachycardia, palpitations, nasal congestion, photophobia, blurred vision, dry mouth and skin, constipation, urinary retention, impotence, memory impairment, coma
cycloplegia (paralysis of the ciliary muscle hence prevent lens adjustment)
Atropine
CONTRAINDICATIONS
Contraindicated in glaucoma, BPH, MG
ATROPINE CHART
EYE
Ophthalmic drop
to produce mydriasis & cycloplegia
ATROPINE CHART
GI
ETC.
IV:
for symptomatic bradycardia
PO drop:
to dry up oral secretions
IM:
For reversal of cholinergic crisis
benztropin
anticholinergic that in combination with
dopaminergic,
inhibits the release of ACh in
CNS for Parkinsonism
(uninhibited ACh)
and for EPS (extrapyramidal syndrome)
CHART words
CP: cerebral palsy
IBS: irritable bowel syndrome
PUD: peptic ulcer disease
EPS: extrapyramidal syndrome
