Ch32: Cholinergic Agonist Notes
High-Yield Drug Summary Table
Drug Name | Indications | Key NCLEX / High-Yield Points |
|---|---|---|
Bethanechol (Duvoid) | Post-op/postpartum urinary retention; neurogenic bladder | Antidote: Atropine; Administer on empty stomach ( hour before or hours after meals); Caution in Asthma/COPD due to bronchospasm. |
Varenicline (Chantix) | Smoking cessation | Psychiatric Safety: Monitor for mood changes, suicidal ideation, and seizures; Start week before quit date. |
Pyridostigmine (Reginal) | Myasthenia Gravis (MG) | Strict Dosing Schedule; Monitor muscle strength; Antidote: Atropine (reverses cholinergic crisis). |
Donepezil (Aricept) | Alzheimer's Disease | Take at bedtime; Avoid NSAIDs (risk of GI bleed/ulcers); Monitor for bradycardia and heart block. |
Comprehensive Pharmacological Summary
Drug Class | Drug Name | Mechanism / Action | Pharmacokinetics | Side Effects (Adverse in Bold) | Nursing Considerations & Interactions |
|---|---|---|---|---|---|
Direct-acting Muscarinic | Bethanechol (Duvoid) | Mimics acetylcholine; increases parasympathetic activity and bladder contraction. | Oral administration. | Bradycardia, hypotension, bronchospasms, abdominal cramps, salivation. | Administer on empty stomach; Monitor heart rate/BP; Encourage voiding every - hours. |
Direct-acting Nicotinic | Varenicline (Chantix) | Partial nicotinic agonist; reduces nicotine cravings and withdrawal. | High bioavailability; absorbed in - hours; liver/lung/kidney metabolism. | Suicidal ideation, seizures, mood changes, abnormal dreams, insomnia. | Assess tobacco use/psychiatric history; Interaction: Alcohol; Quit smoking between days - of treatment. |
Indirect-acting (AChE Inhibitor) | Pyridostigmine (Reginal) | Inhibits acetylcholinesterase, increasing ACh at the neuromuscular junction. | Not specified. | Cholinergic crisis, bradycardia, hypotension, nausea, diarrhea. | Monitor muscle strength; Take strictly on schedule; Have Atropine available; Report myasthenia vs. cholinergic crisis. |
Indirect-acting (AChE Inhibitor) | Donepezil (Aricept) | Reversible AChE inhibitor; increases ACh in the CNS to maintain cognition. | Not specified. | Gastric ulcers/GI bleeding, heart block, bradycardia, insomnia. | Administer at bedtime; Avoid NSAIDs; Monitor cognition and cardiac status; Use caution with cardiac disease. |
Concise High-Yield NCLEX Summary
Emergency Management
Antidote: Atropine must remain at the bedside when treating patients with cholinergic agonists to reverse life-threatening cholinergic crises.
Bronchoconstriction Risk: Due to parasympathetic stimulation, these drugs are often contraindicated or used with extreme caution in patients with Asthma or COPD.
Critical Administration & Safety
Gastrointestinal/Aspiration Safety: Bethanechol is taken on an empty stomach to minimize GI upset/vomiting.
Orthostatic Hypotension: Teach all patients to rise slowly from sitting or lying positions to prevent fainting and falls.
Dosing Consistency: Especially in Myasthenia Gravis, abrupt cessation of Pyridostigmine must be avoided to prevent rapid return of muscle weakness.
Drug-Specific Risks
NSAID Interaction: Clients on Donepezil should avoid NSAIDs to prevent gastric bleeding, as the drug independently increases the risk of ulcers.
Neuropsychiatric Risks: Varenicline requires close monitoring for behavior changes, depression, or suicidal thoughts particularly during the first few weeks of therapy.