Cholinergics Flashcards
What is acetylcholinesterase?
An enzyme that breaks down acetylcholine
What is miosis?
Very constricted pupils
What is a cholinergic agonist?
Drugs that mimic the effects of the neurotransmitter acetylcholine (and therefore the parasympathetic nervous system)
agonist = to stimulate/increase the effects
Not limited to a specific site –> many undesired systemic effects
Work either directly or indirectly on ACh receptors
(AKA parasympathomimetic)
What is Myasthenia gravis?
- A chronic autoimmune disorder affecting the muscles
- Patients make antibodies to ACh receptors, causes destruction of them
- Progressive weakness and lack of muscle control with periodic acute episodes
What is Alzheimer’s Disease?
- A progressive disease that causes neural degeneration in the cortex
- Leads to marked loss of memory, decreased ability to perform ADLs
- Believe there is a progressive loss of ACh producing neurons
What are the effects of the parasympathetic nervous system?
REST AND DIGEST
* Pupil constriction
* ⬆️ salivation
* ⬆️ respiratory secretions
* ⬆️ peristalsis
* Vasodilation (in most blood vessels)
* Bronchoconstriction
* ⬇️ heart rate
* ⬇️ blood pressure
* Bile release
* Urination
Lifespan Considerations of Cholinergic Drugs
In Children
- Increased risk of adverse effects
- Dosages should be based off weight
Lifespan Considerations of Cholinergic Drugs
In Adults
- Caution against driving while on medication
- No studies on safety during pregnancy/lactation
- Use alternative method to breastfeeding
Lifespan Considerations of Cholinergic Drugs
In Older Adults
- More likely to have adverse effects
- More likely to have toxic levels
- Start low and go slow
- Institute safety precautions
Direct Acting Cholinergic Agonists
Mechanism of Action
- Mimics acetylcholine at the receptor sites (muscarinic or nicotinic) on the surfaces of the target cells of the postganglionic cholinergic nerves
- Causes an increased stimulation of the cholinergic receptor
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Indications
- Urinary Retention (Bethanechol)
- To induce miosis (carbachol)
- Treat dry mouth (cevimeline & pilocarpine)
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Drug Names
- Bethanechol (urinary retention)
- Carbachol (to induce miosis)
- Cevimeline (treats dry mouth)
- Pilocarpine (treats dry mouth)
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Contraindications
Absolute:
* Allergy
* Any condition that would be exacerbated by parasympathetic effects: Bradycardia, hypotension
* Peptic Ulcer Disease, GI obstruction or recent GI surgery
* Asthma (can cause bronchoconstriction)
* Bladder obstruction
* Epilepsy and parkinsonism (can worsen)
Caution:
* Pregancy and lactation
Direct-Acting Cholinergic Agonists: 🍄 Muscarinic
Adverse Effects
💩 Diarrhea, involuntary defecation, cramps
🤮 Nausea, vomiting, increased salivation
💓 Bradycardia, heart block, hypotension
🫣 Urinary urgency
💦😳 Flushing or increased sweating
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Drug Interactions
Acetylcholinesterase Inhibitors
(Indirect-Acting Cholinergic Agonists)
Can lead to a cholinergic crisis!
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Assessment
History:
* Contraindications & Cautions
Physical:
* Vitals
* Lung sounds
* Bowel sounds
* Bladder distention
* Input & Output
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Nursing Diagnoses
- Impaired Comfort (r/t GI effects)
- Altered cardiac output (r/t CV effects)
- Impaired urinary elimination (r/t GU effects)
- Injury risk (r/t blurry vision, changes in visual acuity)
- Diarrhea (r/t GI effects)
- Knowledge Deficit
Direct-Acting Cholinergic Agonists: 🍄Muscarinic
Implementation/Patient Teaching
- Ensure proper administration of opthalmic preparations
- Administer oral drugs on an empty stomach
- Monitor response closely
- Provide safety precautions (fall risk) if pt experiences poor visual acuity
- Monitor urinary output
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Indications
Smoking cessation
(Work mostly in CNS - quicker acting than muscarinc receptor agonists)
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Drug Names
- Bupropion (weakly inhibits neuronal reuptake of NE and Dopamine)
- Varenicline (acts as nicotine receptor partial agonist)
- Nicotine (replacement therapy)
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Contraindications
Absolute:
* Allergy
* Seizure disorder (Bupropion) reduces seizure threshold
Caution:
* Pregnancy and lactation
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Adverse Effects
💓 Tachycardia, hypertension (due to too much increased fluid)
🧠 Seizures, neuropyschiatric adv. effects, dizziness, strange dreams
🤢Nausea and dry mouth
😡Skin rash (r/t cholinergic urticaria)
MORE potential for CNS effects than muscarinic agonists
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Drug Interactions
TOO MANY to name
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Assessment
History:
* Contraindications & Cautions
* Amount of tobacco use
* Sleep patterns
* suicidal thoughts and behaviors
Physical:
* Lung sounds
* Heart Sounds
* Vital Signs
* ECG
* mood, affect
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Nursing Diagnoses
- Impaired comfort (r/t GI effects)
- Altered cardiac output (r/t CV effects)
- Injury risk (r/t seizures or neurpsychiatric side effects)
- Knowledge deficit
Direct-Acting Cholinergic Agonists: 🚬 Nicotinic
Implementation/Patient Teaching
- ensure proper administration of nicotine replacement preparations
- Check for med interactions
- May be taken with or without food
- Dose may be adjusted
- Safety precautions for neuropsychiatric effects or seizure activity
- Correct # of patches changed at the right times
- Take OFF old patches before applying new one
- Report changes in CNS effects
Indirect-Acting Cholinergic Agonists
Indications
- Myasthenia gravis
- Alzheimer’s Disease
Indirect-Acting Cholinergic Agonists
Drugs to treat Myasthenia gravis
- Neostigmine (strong influence at neuromuscular junction)
- Pyridostigmine (longer duration of action than neostigmine)
- Edrophonium (diagnostic agent…. no longer used - too many false positives)
Indirect-Acting Cholinergic Agonists
Adverse Effects
💓 Bradycardia, hypotension
💩 Increased GI activity and secretions
💛 Increased bladder tone = overactive bladder
🟢 Relaxation of GI and Genitourinary sphincters
🫁 Bronchoconstriction
👁️ Pupil constriction
Indirect-Acting Cholinergic Agonists
Drug Interactions
- NSAIDs (cause GI erosions)
- Cholinergic Drugs (can cause Increased secretions)
Combining the drugs can lead to a Gastric Bleed
Indirect-Acting Cholinergic Agonists
Drugs used to treat Alzheimer’s Disease
- Galantamine (avail. in solution for easy swallowing)
- Rivastigmine (avail. in solution for easy swallowing)
- Donepezil (once a day dosing, rapidly dissolving tablet)
How does nerve gas affect Cholinergic receptors?
- Permanently and irreversibly binds to Acetylcholinesterase –> leads to significant increase in Acetylcholine
- Treatment: Atropine and Pralidoxime (anticholinergics)
Indirect-Acting Cholinergic Agonists
Assessment
History:
* Contraindications & cautions
Physical:
* Neuro: Orientation, affect, reflexes, ability to perform ADLs
* Vital Signs
* ECG
* Urinary output
Labs:
* Renal and Liver function tests
Indirect-Acting Cholinergic Agonists
Nursing Diagnoses
- Altered thought processes (r/t CNS effects)
- Impaired comfort (r/t GI effects)
- Decreased cardiac output (r/t blood pressure changes, arrhythmias, and vasodilation)
- Injury risk (r/t CNS effects)
- Diarrhea (r/t GI stimulatory effects)
- Knowledge deficit
Indirect-Acting Cholinergic Agonists
Implementation
- If given via IV, go slowly
- Maintain atropine sulfate on standby for cholinergic crisis
- Discontinue drug if: excessive salivation, diarrhea, emesis, or frequent urination
- Oral drug with meals
- If going into surgery, notify surgeon that they are on cholinergic drugs
- Monitor Alzheimer’s pts for progress
- Arrange for supportive care and comfort measures
