Cholinergic drugs Flashcards
Cholinergic Drugs what is it?
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)
what are the two types of cholinergic receptors?
Nicotine receptors and muscarinic receptors.
what are the two types of cholinergic receptors determined by?
- location
- Action once stimulated.
Nicotinic Receptors are?
Located in the ganglia of both systems
Named nicotinic because they can be stimulated by the alkaloid nicotine.
Cholinergic Drugs: Mechanism of Action, Direct-acting cholinergic agonists
Bind to cholinergic receptors, activating them
Cholinergic Drugs: Mechanism of Action, Indirect-acting cholinergic agonists
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) - reversible
Bind to cholinesterase for a short period of time
Indirect-Acting (Cholinesterase Inhibitors) - 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.
Drug Effects
Effects seen when parasympathetic system is stimulated
This system is the “rest and digest” system.
Sympathetic nervous system: “flight or fight”
Drug Effects - stimulates intestine and bladder
Increased gastric secretions
Increased gastrointestinal motility
Increased urinary frequency
Drug effects - stimulates pupils
Constriction (miosis)
Reduced intraocular pressure
whats another drug effects
Increased salivation and sweating
Cholinergic Drug Effects - Cardiovascular effects
Decreased heart rate
Vasodilation
Cholinergic Drug Effects - Respiratory effects
Bronchial constriction, narrowed airways
Cholinergic Drug Effects
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.
Indications - Direct-acting drugs
Reduce intraocular pressure
Useful for glaucoma and intraocular surgery
Indications - Direct-acting drugs
pilocarpine
Indications
Topical application because of poor oral absorption
what does direct acting bethanechol do?
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
Indications - Direct-acting drug succinylcholine do?
Used as a neuromuscular blocker in general anaesthesia
Intravenous
Indications - Indirect-acting drugs
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
Indications - Indirect-acting anticholinesterase drugs, and what drug is it.
Used for treatment of mild to moderate Alzheimer’s disease. donepezil (Aricept®)
Indications - memantine (Ebixa®)
Not a cholinergic drug
Also used in the treatment of Alzheimer’s disease
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
Adverse Effects
Adverse effects are a result of overstimulation of the parasympathetic system.
Adverse Effects - Cardiovascular
Bradycardia, hypotension, syncope, conduction abnormalities (atrioventricular block and cardiac arrest)
adverse fx - CNS system
Headache, dizziness, convulsions, ataxia
adverse fx - GI
Abdominal cramps, increased secretions, nausea, vomiting, diarrhea, weight loss
adverse fx - respiratory
Increased bronchial secretions, bronchospasms
other adverse fx
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)
Cholinergic Crisis - Early signs
Abdominal cramps, salivation, flushing of the skin, nausea and vomiting, transient syncope, transient complete heart block, dyspnea, and orthostatic hypotension
Cholinergic Crisis - treatments in early phase
atropine sulphate, a cholinergic antagonist
Cholinergic crisis - Treatment of severe cardiovascular reactions or bronchoconstriction:
epinephirine
Interactions
Anticholinergics, antihistamines, sympathomimetics
Antagonize cholinergic drugs, resulting in decreased responses
Other cholinergic drugs
Additive effects
bethanechol (Duvoid®) is a what?
Direct-acting cholinergic agonist
bethanechol (Duvoid®) uses?
Treatment of acute postoperative and postpartum nonobstructive urinary retention
Management of urinary retention associated with neurogenic atony of the bladder
bethanechol (Duvoid®) contraindications?
Known drug allergy, hyperthyroidism, peptic ulcer, active bronchial asthma, cardiac disease or coronary artery disease, epilepsy, and parkinsonism
bethanechol (Duvoid®) adverse fx
syncope, hypotension with reflex tachycardia, headache, seizure, GI upset, and asthmatic attacks
bethanechol (Duvoid®) - interactions
acetylcholinesterase inhibitors (i.e., indirect-acting cholinergics)
donepezil (Aricept) does what?
Cholinesterase inhibitor that works centrally in the brain to increase levels of ACh by inhibiting acetylcholinesterase. Similar cholinesterase inhibitors include galantamine and rivastigmine.
donepezil (Aricept) uses?
Used in the treatment of mild to moderate Alzheimer’s disease
donepezil (Aricept) contraindications
known drug allergy
donepezil (Aricept) adverse fx
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.
donepezil (Aricept) - Interacting drugs
anticholinergics (counteract donepezil effects) and nonsteroidal anti-inflammatory drugs (NSAIDs)
pyridostigmine (Mestinon®) is what?
Indirect-acting cholinergic drugs that work to increase ACh by inhibiting acetylcholinesterase
pyridostigmine (Mestinon®) use
myasthenia gravis
Edrophonium (Tensilon)
indirect-acting cholinergic drug that is used to diagnose myasthenia gravis. It can also be used to differentiate between myasthenia gravis and cholinergic crisis.
pyridostigmine, and physostigmine uses.
reversing the effects of nondepolarizing neuromuscular blocking drugs; treating severe overdoses of tricyclic antidepressants; and antidote after toxic exposure to nondrug anticholinergic agents, including those used in chemical warfare
Ginkgo uses
Common uses
Prevent memory loss
Vertigo
Tinnitus
Gingko adverse fx
May cause GI upset, headache, bleeding
Gingko potential interactions
Potential interactions
Aspirin
NSAIDs
Anticoagulants
Anticonvulsants
Nursing Implications (Assessment)
Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, and coronary artery disease.
Perform baseline assessment of vital signs and systems overview.
Medications should be>
Medications should be taken as ordered and not abruptly stopped.
Doses should be spread evenly apart to optimize the effects of the medication.
Therapeutic effects of anti-Alzheimer’s drugs may not occur for up to?
6 weeks
______is the antidote for cholinergics, and it should be available in the patient’s room for immediate use if needed.
Atropine
Monitor for therapeutic effects
Alleviated signs and symptoms of myasthenia gravis
Monitor for therapeutic effects - In postoperative patients with decreased GI
In postoperative patients with decreased GI peristalsis, monitor for:
Increased bowel sounds
Passage of flatus
Occurrence of bowel movements
Monitor for therapeutic effects.
In patients with urinary retention or hypotonic bladder how?
In patients with urinary retention or hypotonic bladder, urination should occur within 60 minutes of bethanechol administration.
Monitor for therapeutic effects - In patients with Alzheimer’s disease how?
Improvement in symptoms
Improvement in mood and decrease in confusion
