Cholinergic Drugs

Cholinergic Drugs

Describe the cholinergic drug effects on major body systems.

Discuss the nursing process related to the care of patients receiving cholinergic drugs for select problems.

Cholinergic Drugs Drugs that stimulate the

parasympathetic nervous system (PSNS) opposing system to the SNS Known as: cholinergic agonists or

parasympathomimetics Mimic the effects of the PSNS neurotransmitter:

acetylcholine (Ach) Two types of Receptors:

determined by: Location & Action once stimulated Muscarinic receptors – recommended doses with

desired effect Nicotinic receptors – higher doses with undesirable

effects

Cholinergic DrugsMechanism of Action

Direct-acting cholinergic agonists Bind to cholinergic receptors, activating them

Indirect-acting cholinergic agonists Inhibit the enzyme acetylcholinesterase -

preventing, which breaks down ACh - more ACh is available at the receptors

Reversible - Bind to cholinesterase for a period of minutes to hours

Irreversible - Bind to cholinesterase and form a permanent covalent bond The body must make new cholinesterase to

break these bonds

Cholinergic Drugs“rest and digest” system

“SLUDGE”

Salivation Lacrimation Urinary incontinence Diarrhea Gastrointestinal cramps Emesis

Cholinergic DrugsDrug Effects

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

Cholinergic DrugsDrugs

Bethanechol (Urecholine) – urinary retention

Cevimeline (Evoxac) – Xerostomia Memantine (Namenda) – Alzheimer’s

dementia Physostigmine (Antilirium) – reversal

of anticholinergic drugs effects Pyridostigmine (Mestinon) –

Myasthenia gravis

Cholinergic DrugsIndications

Direct-acting drugs Reduce intraocular pressure

Topical useful for glaucoma and intraocular surgery pilocarpine

Cholinergic DrugsIndications

Direct-acting drug—bethanechol (Urecholine)

Increases tone and motility of bladder and GI tract

Relaxes sphincters in bladder and GI tract, allowing them to empty

Used to reverse postsurgical atony of the bladder and GI tract

Oral dose or SC injection

Cholinergic DrugsIndications

Indirect-acting drugs

Cause skeletal muscle contractions

Used for diagnosis and treatment of myasthenia gravis Pyridostigmine (Mestinon) – Myasthenia gravis

Used to reverse neuromuscular blocking drugs/anesthesia

Used to reverse anticholinergic poisoning (antidote) Examples: physostigmine (Antilirium)

Cholinergic DrugsIndications

Indirect-acting drugs—cevimeline (Evoxac)

Used to treat xerostomia (dry mouth) resulting from Sjögren’s syndrome

Cholinergic DrugsAdverse Effects

Adverse effects are a result of overstimulation of the PSNS

Cardiovascular Bradycardia, hypotension, conduction abnormalities (AV

block and cardiac arrest) CNS

Headache, dizziness, convulsions Gastrointestinal

Abdominal cramps, increased secretions, nausea, vomiting Respiratory

Increased bronchial secretions, bronchospasm Other

Lacrimation, sweating, salivation, loss of binocular accommodation, miosis

Cholinergic DrugsInteractions

Anticholinergics, antihistamines, sympathomimetics Antagonize cholinergic drugs, resulting

in decreased responses Other cholinergic drugs

Additive effects

Cholinergic DrugsNursing Implications

Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, or coronary artery disease

Perform baseline assessment of vital signs and systems overview

Medications should be taken as ordered and not abruptly stopped

The doses should be spread evenly apart to optimize the effects of the medication

Overdosing can cause life-threatening problems. Only physicians should adjust the dosages

Cholinergic DrugsNursing Implications

Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing

When cholinergic drugs are prescribed for Alzheimer’s disease, be honest with caregivers and patients that the drugs are for management of symptoms, not a cure

Therapeutic effects of anti-Alzheimer’s drugs may not occur for up to 6 weeks

Cholinergic DrugsNursing Implications

Monitor for therapeutic effects Alleviated signs and symptoms of myasthenia

gravis In postoperative patients with decreased GI

peristalsis, look for: Increased bowel sounds Passage of flatus Occurrence of bowel movements

In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of bethanechol administration

ALSO monitor for adverse effects