Cholinergic Drugs Flashcards
Cholinergic Drugs action
also known as
Drugs that stimulate the parasympathetic nervous system (the opposing system to the sympathetic nervous system)
Also known as cholinergic agonists or parasympathomimetics
Mimic effects of the parasympathetic nervous system neurotransmitter acetylcholine (ACh)
Cholinergic Receptors
Two types, determined by:
-Location
-Action once stimulated
Nicotinic receptors
Muscarinic receptors
Nicotinic Receptors
location
Located in the ganglia of both systems
Named nicotinic because they can be stimulated by the alkaloid nicotine.
Muscarinic Receptors
location
Located postsynaptically in the effector organs of the parasympathetic system
-Smooth muscle
-Cardiac muscle
-Glands
Named muscarinic because they can be stimulated by the alkaloid muscarine.
Direct-acting cholinergic agonists
Bind to cholinergic receptors, activating them
Indirect-acting cholinergic agonists
also known as
action
Also known as cholinesterase inhibitors
Inhibit the enzyme acetylcholinesterase, which breaks down ACh
Results in more ACh available at the receptors
Indirect-Acting (Cholinesterase Inhibitors)
2 types
Differences between the two
Reversible
-Bind to cholinesterase for a short period of time
Irreversible
-Bind to cholinesterase for a long period of time
-Bind to cholinesterase and form a permanent covalent bond
-The body must make new cholinesterase to break these bonds.
Cholinergic Drug Effects
Effects seen when parasympathetic system is stimulated
This system is the “rest and digest” system.
Cholinergic drug 5 effects on body?
Stimulate intestine and bladder
-Increased gastric secretions
-Increased gastrointestinal motility
-Increased urinary frequency
Stimulate pupils
-Constriction (miosis)
-Reduced intraocular pressure
Increased salivation and sweating
Cardiovascular effects
-Decreased heart rate
-Vasodilation
Respiratory effects
-Bronchial constriction, narrowed airways
At recommended doses, cholinergics primarily affect _____ receptors.
At high doses, cholinergics stimulate ______ receptors.
Desired effects are from _____ receptor stimulation.
Many undesirable effects are caused by stimulation of ________ receptors.
At recommended doses, cholinergics primarily affect muscarinic receptors.
At high doses, cholinergics stimulate nicotinic receptors.
Desired effects are from muscarinic receptor stimulation.
Many undesirable effects are caused by stimulation of nicotinic receptors.
Direct-acting drugs indication
Reduce intraocular pressure
Useful for glaucoma and intraocular surgery
-carbachol
-pilocarpine
-Topical application because of poor oral absorption
pilocarpine
Useful for glaucoma and intraocular surgery
bethanechol
Direct-acting drug
Increases tone and motility of bladder and gastrointestinal (GI) tract
Relaxes sphincters in bladder and GI tract, allowing them to empty
Helpful for postsurgical atony of the bladder and GI tract
Oral dose or subcutaneous injection
succinylcholine
Direct-acting drug: succinylcholine
Used as a neuromuscular blocker in general anaesthesia
Intravenous
Indirect-acting drugs indications
Increase ACh concentrations at the receptor sites, which leads to stimulation of the effector cells
Cause skeletal muscle contractions
Used for diagnosis and treatment of myasthenia gravis
Used to reverse neuromuscular blocking drugs
Used to reverse anticholinergic poisoning (antidote)
-Example: physostigmine
physostigmine
Indirect acting
Used to reverse anticholinergic poisoning (antidote)
donepezil (Aricept®)
Indirect-acting anticholinesterase drugs
Used for treatment of mild to moderate Alzheimer’s disease
Cholinergic drugs Contraindications
Known drug allergy
GI or genitourinary (GU) tract obstruction
Bradycardia
Defects in cardiac impulse conduction
Hyperthyroidism
Epilepsy
Hypotension
Chronic obstructive pulmonary disease
Parkinson’s disease
Cholinergic drugs AEs
Adverse effects are a result of overstimulation of the parasympathetic system.
Cardiovascular
Bradycardia, hypotension, syncope, conduction abnormalities (atrioventricular block and cardiac arrest)
Central nervous system
Headache, dizziness, convulsions, ataxia
Gastrointestinal
Abdominal cramps, increased secretions, nausea, vomiting, diarrhea, weight loss
Respiratory
Increased bronchial secretions, bronchospasms
Other
Lacrimation, sweating, salivation, miosis
Cholinergic Crisis
Circulatory collapse, hypotension, bloody diarrhea, shock, and cardiac arrest.
SLUDGE (salivation, lacrimation, urinary incontinence, diarrhea, gastrointestinal cramps, and emesis)
Early signs
Abdominal cramps, salivation, flushing of the skin, nausea and vomiting, transient syncope, transient complete heart block, dyspnea, and orthostatic hypotension
Cholinergic Crisis treatment
Treatment in early phase: atropine sulphate, a cholinergic antagonist
Treatment of severe cardiovascular reactions or bronchoconstriction: epinephrine, an adrenergic agonist
Cholinergic drugs interactions
Anticholinergics, antihistamines, sympathomimetics; Antagonize cholinergic drugs, resulting in decreased responses
Other cholinergic drugs; Additive effects
bethanechol (Duvoid®)
direct or indirect?
indicated for?
AEs
Interaction
Direct-acting cholinergic agonist
Uses
-Treatment of acute postoperative and postpartum nonobstructive urinary retention
-Management of urinary retention associated with neurogenic atony of the bladder
Contraindications
Known drug allergy, hyperthyroidism, peptic ulcer, active bronchial asthma, cardiac disease or coronary artery disease, epilepsy, and parkinsonism
Adverse effects: syncope, hypotension with reflex tachycardia, headache, seizure, GI upset, and asthmatic attacks
Interactions: acetylcholinesterase inhibitors (i.e., indirect-acting cholinergics)
donepezil (Aricept)
action
indicated for?
AEs
Intercations
Cholinesterase inhibitor that works centrally in the brain to increase levels of ACh by inhibiting acetylcholinesterase
Used in the treatment of mild to moderate Alzheimer’s disease
Similar cholinesterase inhibitors include galantamine and rivastigmine.
Contraindications: known drug allergy
Adverse effects: GI upset (including ulcer risk caused by increased gastric secretions), drowsiness, dizziness, insomnia, and muscle cramps.
The effects on the cardiovascular system are complex and may include bradycardia, syncope, hypotension with reflex tachycardia, or hypertension.
Interacting drugs: anticholinergics (counteract donepezil effects) and nonsteroidal anti-inflammatory drugs (NSAIDs)
