Last updated on May 16th, 2022 at 08:58 pm
Cholinergic Agonists Nursing Implications
Cholinergic agonists Nursing Pharmacology
Cholinergic agonists are agents that act on the parasympathetic nervous system. These are drugs that mimic or modify the effects of acetylcholine (ACh) increasing the activity at the ACh receptor sites.
ACh is the primary neurotransmitter of the parasympathetic nervous system (PNS). Cholinergic agonists activate the PNS and are thus known as parasympathomimetics.
Types of Cholinergic Agonists
Cholinergic agonists are divided into two categories, namely direct and indirect agonists. These drugs are usually administered topically, orally, or parenterally.
- Direct-acting cholinergic agonists. These medications usually have an onset of effects within 30 to 90 minutes, with a peak effect at 60 to 90 minutes. Drug effects can last between one to six hours.
- Indirect-acting cholinergic agonists. These drugs can have an onset of effects in 35-45 minutes for oral administration, 15 minutes for intramuscular administration and five minutes for intravenous administration. All routes will have effects that may last between three to six hours.
Actions and Indications for Cholinergic Agonists
Cholinergic agonists are used for a variety of neurological diseases. The drugs are classified depending on their mode of action.
Direct-acting cholinergic agonists act by directly working on the muscarinic ACh receptors. This does the same action as ACh on the parasympathetic nervous system affecting the smooth muscles of the body. They can be used to address the following:
- Asthma: assess airway hyperresponsiveness
- Urinary retention in postoperative and neurogenic ileus
- Xerostomia (especially in Sjögren syndrome)
Indirect-acting cholinergic agonists act by blocking the hydrolysis of ACh by acetylcholinesterase. Thus, it promotes the prolonged action of naturally occurring ACh in the body. These can be used to address the following:
- Alzheimer disease
- Myasthenia gravis
- Postoperative and neurogenic ileus and urinary retention
- Postoperative reversal of neuromuscular blockade
- Antidote for anticholinergic toxicity
In all these cases, the cholinergic agonists affect the tone of smooth muscles, and their action may have the following clinical manifestations:
- decreased myocardial contractility
- increased bladder tone
- increased bronchial mucus secretion
- increased gastric motility
- relaxation of gastrointestinal and bladder sphincters
- pupillary constriction
- slowed heart rate
- stimulation of the salivary, gastric, and sweat glands
Side Effects and Adverse Effects of Cholinergic Agonists
The side effects of most cholinergic agonists include:
- abdominal cramps
- hot flushes
- involuntary defecation
- nausea and vomiting
- urinary urgency
Given the action of cholinergic agonists, the treatment must include monitoring for the following adverse effects:
- blurred vision
- cardiac dysrhythmias
- heart block
- increased salivation
Contraindications and Cautions Against Cholinergic Agonists
Cholinergic agonists are contraindicated in the treatment of patients with the following conditions:
Chronic obstructive pulmonary disease (COPD)
|Cholinergic agonists can exacerbate the symptoms by increasing secretions|
|Coronary artery disease||Cholinergic agonists can exacerbate the symptoms by increasing vasodilation and decreasing cardiac motility|
|Epilepsy and Parkinsonism||Cholinergic agonists can exacerbate the symptoms by overstimulating neural pathways|
|Bladder obstruction||Cholinergic agonists can overstimulate the detrusor muscle|
|Hyperthyroidism||Cholinergic agonists can precipitate atrial fibrillation|
|Hepatic and Renal dysfunction||The liver metabolizes Cholinergic agonists|
|Pregnancy and lactation||Cholinergic agonists may have adverse effects on the fetus or the neonate. Cholinergic agonists can also induce labor.|
|Allergy to the components of the drug being used||To avoid hypersensitivity reaction|
Caution must be practiced in using cholinergic agonists in patients with cardiovascular diseases since these drugs can cause bradycardia and hypotension.
There are also precautions that must be taken for patients across the ages undergoing treatment with cholinergic agonists.
Children are at a higher risk of complications such as diarrhea, gastrointestinal upset, increased salivation (may lead to choking), and loss of control in the bowels and the bladder.
Adults are advised not to operate heavy machinery due to side effects such as dizziness, gastrointestinal upset, and urinary urgency. Older adults are highly susceptible to the effects of cholinergic agonists.
Thus, they may need periodic dose adjustment, and monitoring for signs of renal and hepatic impairment.
Toxicity to cholinergic agonists can manifest as:
- Miosis – excessive shrinking of the pupil of the eye
- Sweating, and
In case of overdose, atropine may be administered parenterally to reverse the symptoms. Acute cholinergic intoxication will present as altered mental status, convulsions, and coma.
When the paralysis of respiratory muscles occur, mortality is usually not far behind.
Drug Interactions with Cholinergic Agonists
Direct-acting cholinergic agonists are known to have interactions with acetylcholinerase inhibitors by increasing their cholinergic effects.
When used with non-steroidal anti-inflammatory drugs (NSAIDs), patients may also have an increased risk of bleeding in the gastrointestinal tract.
Atropine, a muscarinic antagonist, is known to reverse the effects cholinergic agonists.
Nursing Assessment Prior to Administration of Cholinergic Agonists
Before treatment with cholinergic agonists is started, the patient must be assessed for the following:
- Allergies to avoid hypersensitivity reactions
- Pregnancy and lactation to avoid untoward effects on the fetus or neonate
- Gastrointestinal obstruction, Asthma, COPD, Coronary Artery Disease, Epilepsy, Hyperthryroidism as these are contraindications
- Baseline central nervous system function to establish stimulation of the nervous system
- Baseline vital signs to establish stimulation of the cardiovascular system
- Abdominal tone, sounds, and measurement to establish gastrointestinal tone and fluid retention
- Daily intake and output to establish fluid retention
Nursing Care Plans for Patients on Cholinergic Agonists
Possible Nursing Diagnoses
- Decreased Cardiac Output related to cardiovascular effects of cholinergic agonists
- Impaired Urinary Elimination related to the effects of cholinergic agonists on the bladder
- Acute Pain related to gastrointestinal effects of cholinergic agonists
- Diarrhea or Constipation
- Risk for Ineffective Airway Clearance
- Risk for Ineffective Breathing Pattern
- Risk for Injury/ Falls related to side effects of cholinergic agonists (e.g., drowsiness)
- Deficient Knowledge related to new drug prescription
|Cholinergic Agonists Nursing Interventions||Rationales|
|Verify the patient’s diagnosis and the need for administering cholinergic agonists.||To confirm the indication for administering cholinergic agonists.|
|Check the patient’s allergy status.||Previous allergic reaction to cholinergic agonists may render the patient unable to take them. Alternatives to cholinergic agonists should therefore be considered in case of allergy.|
|Assess if the patient is pregnant or lactating.||Cholinergic agonists should not be prescribed to a pregnant woman or lactating mother as these drugs can potentially harm the fetus or newborn. They can also induce labor of pregnant women.|
|Assess the patient’s mucous membranes and his/her ability to swallow. If giving intravenously, assess the suitability of the vein or the status of the central venous access device or CVAD.||To check for any potential problems with administration, hydration, and absorption.|
To ensure that the right form of cholinergic agonists is given through the right route.
|Check for current medications that include acetylcholinerase inhibitors and non-steroidal anti-inflammatory drugs.||Acetylcholinerase inhibitors should be used cautiously with cholinergic agonists as these can abruptly increase the potency of cholinergic agonists. Taking NSAIDs and cholinergic agonists may increase the risk for internal gastrointestinal upset as manifested by diarrhea or constipation.|
|Check the patient’s serum electrolyte levels.||Patients on cholinergic agonists are at risk for electrolyte imbalance due to several side effects, such as vomiting and diarrhea.|
|Ask the patient for any medical or family history of cardiovascular diseases.||Cholinergic agonists can cause cardiovascular effects such as bradycardia and hypotension.|
Nursing Planning and Intervention
|Cholinergic Agonists Nursing Interventions||Rationales|
|Administer cholinergic agonists on time as prescribed.||Cholinergic agonists should always be taken on time to prevent any delays and errors during treatment.|
|Administer cholinergic agonists with meals as much as possible.||To ensure optimal absorption and therapeutic action by cholinergic agonists. To prevent gastrointestinal side effects|
|Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking cholinergic agonists. Instruct the patient on how to self-administer oral cholinergic agonists.||To inform the patient on the basics of cholinergic agonists, as well as to empower him/her to safely self-administer the medication.|
|Monitor the patient’s input and output.||Cholinergic agonists may cause impaired urinary elimination.|
|Advise the lactating mother or pregnant woman to avoid any cholinergic agonist. Actively recommended a suitable medication that can mimic cholinergic agonists).||Pregnant women who are lactating/ breastfeeding are not allowed to take cholinergic agonists as they may induce labor and/or harm the baby.|
|Commence a stool chart and advise the patient on how to do it.||To check for any diarrhea, constipation, of voluntary defecation.|
|Towards the end of the course of cholinergic agonists, inform the patient if the cholinergic agonists need to be stopped.||Abruptly stopping some types of cholinergic agonists such as prednisone may cause withdrawal symptoms such as fatigue, joint pain, lightheadedness, and dizziness.|
|Advise the patient to not operate heavy machinery or drive a vehicle while on cholinergic agents.||Cholinergic agonists may cause hypotension, dizziness, and blurry vision, which may put the patient at high risk for injury or falls.|
|Routinely check for the blood glucose level of the patient, especially if they are diabetic.||Cholinergic agonists can increase plasma glucose levels.|
|Administer supportive medications as needed. These may include:Pain relievers for abdominal cramps and gastrointestinal upsetAnti-nausea medications Report these side effects to the doctor and stop the cholinergic agonist if adverse events occur.||Administer supportive medications to help the patient cope with taking cholinergic agonists. Stopping the cholinergic agonist therapy in cases of adverse events help to prevent complications and stabilize the patient.|
|Cholinergic Agonists Nursing Interventions||Rationales|
|Ask the patient to repeat the information about cholinergic agonists.||To evaluate the effectiveness of health teaching on cholinergic agonists.|
|Monitor the patient’s serum electrolyte levels and renal function.||To ensure that the cholinergic agonists did not cause any electrolyte imbalance or renal dysfunction.|
|Monitor the patient’s response to cholinergic agonists.||To check if the cholinergic agonists are effective or if the dose needs to be adjusted.|
|Ensure that an appropriate anti-cholinergic drug is available during treatment.||Cholinergic agonists may cause toxicity if administered in high doses. Having an anti-cholinergic drug can help reverse the symptoms of drug toxicity.|
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