A Guide to Opioid Agonists for Nurses

• Opioid agonists are potent pain-relieving drugs used for acute, chronic, and terminal illnesses, including morphine, codeine, fentanyl, and oxycodone. 
• They work by binding to opiate receptors in the central and peripheral nervous systems, mimicking the effects of endorphins and causing analgesia and cough suppression. 
• However, opioid agonists have adverse effects like respiratory depression and constipation that require cautious administration and proper nursing processes.

Opioid agonists are powerful pain-relieving drugs used to treat acute, chronic, and terminal illnesses. The gold standard opioid agonist is morphine, but other options include codeine, fentanyl citrate, and oxycodone.

Opioid agonists work by binding to the opiate receptor site in the central and peripheral nervous systems, stimulating the opiate receptors and mimicking the effects of endorphins to relieve pain. However, adverse effects such as respiratory depression and constipation can occur. Therefore, administering opioid analgesics requires cautiousness and proper nursing processes.  

In this article, we will review the pharmacology of opioid agonists, their uses, adverse effects, drug interactions, and nursing considerations.  

An Introduction to Opioid Agonists

To control large amounts of pain, you need to administer opioid agonists. They include: 

• codeine 
• fentanyl citrate 
• hydrocodone 
• hydromorphone hydrochloride 
• levorphanol tartrate 
• meperidine hydrochloride 
• methadone hydrochloride 
• morphine sulfate  
• oxycodone 
• oxymorphone 
• propoxyphene 
• remifentanil 
• tramadol 

The gold standard opioid agonist is morphine.  

Opioid agonists can be given through any route. However, inhalation administration is uncommon. When given orally, they are readily absorbed from the gastrointestinal tract. 

Transmucosal and intrathecal opiates are fast acting. When given intravenously, they provide immediate relief. Through subcutaneous and IM routes, absorption may be delayed, especially in patients with poor circulation.  

Opioid agonists reduce pain by binding to the opiate receptor site in the central and peripheral nervous systems. They stimulate the opiate receptors and mimic the effects of endorphins—the naturally occurring pain-relieving substances in the body. Hence it leads to analgesia and cough suppression. Adverse effects, such as constipation and respiratory depression can also occur due to the receptor site binding. 

Opioid agonists cause blood vessel dilation, especially of the face, head, and neck. Additionally, they suppress the cough center in the brain, resulting in antitussive effects along with constriction of the bronchial muscles. If in excess, any of these effects can become adverse effects. For example, if too much vasodilation occurs, it can result in hypotension.  

Opioid agonists are prescribed to: 

• Relieve severe pain due to acute, chronic, and terminal illnesses 
• Control diarrhea 
• Suppress cough  
• For temporary maintenance of opioid addiction (methadone) 
• For the induction and maintenance of general anesthesia (fentanyl and remifentanil) 
• In patients with pulmonary edema or left-sided heart failure, morphine relieves shortness of breath by dilating peripheral blood vessels, keeping more blood in the periphery, and decreasing cardiac preload.
  

Opioid Agonist Drug Interactions and Adverse Reactions

Drug Interactions

Drug interactions that may occur with opioid agonists are: 

• Amitriptyline, protease inhibitors, phenytoin, diazepam, and rifampin can affect the activity of opiates.  
• Tricyclic antidepressants, phenothiazines, or anticholinergics, when given with opiates, can result in severe constipation and urinary retention.  
• Opioid analgesics affect the activity of carbamazepine, warfarin, beta-adrenergic blockers, and calcium channel blockers. 
• Alcohol, sedatives, hypnotics, and anesthetics, that affect respiration, when given with opioid analgesics, can cause respiratory depression.  

Adverse Reactions

The most common adverse reaction of opioid analgesics is dose-related respiratory depression. It decreases the rate and the depth of breathing and worsens as the dose is increased. That can lead to periodic, irregular breathing or trigger asthmatic attacks in a susceptible patient. Therefore be cautious before administering an opioid analgesic to a patient having asthma or any other respiratory condition.  

Other adverse effects of opioids are: 

• Orthostatic hypotension  
• Flushing  
• Pupil constriction 
  

Meperidine can cause: 

• Palpitations and tachycardia  
• Tremors  
• Delirium  
• Seizures and neurotoxicity- if administered for over 48 hours.
  

Opioid Agonists and the Nursing Process

With opioids, you need to practice the following nursing processes:

Nursing Assessment

• Before starting the therapy, obtain the baseline assessments of the patient’s pain and assess them after the drug administration to know the drug’s effectiveness.  
• Before giving each dose, check the respiratory status of the patient. The respiratory depression with opioids may remain longer than the analgesia. 
• Monitor the patient for any adverse drug reactions.  
• Check the patient for drug tolerance and dependence. Often the first sign of opioid tolerance is shortened duration of action.

Key Nursing Diagnoses

• Acute pain due to an underlying health condition 
• Ineffective breathing pattern due to opioids 
• Deficient knowledge of the drug therapy 

Planning Outcome Goals

• The patient’s pain will be reduced. 
• The breathing pattern will remain normal with opioid therapy.  
• The patient and their family members will have an understanding of the drug therapy. They will also verbalize the understanding and intended effect of the opiates. 

Implementation

• With opioid therapy, keep an opioid antagonist such as naloxone and resuscitative equipment on hand.  
• Give intravenous preparations slowly, preferably in a diluted solution. Otherwise, a concentrated solution given at faster rates can increase the risk of adverse reactions.  
• With intramuscular and subcutaneous drug administration, be cautious in patients with decreased platelet count, chilled, hypovolemic, or shock. Rotate injection sites to avoid induration.  
• Oral solutions are of various dose strengths. Therefore check every time you administer the oral solution.  
• To gain maximum effectiveness, give the drug as scheduled rather than as per the patient’s need. 
• To avoid atelectasis, ask the postoperative patient to turn, cough, and take a deep breath every two hours.  
• If the patient complains of gastrointestinal irritation, give them the drug with food.  
• To prevent constipation, give the patient a fiber-rich diet or a stool softener.  
• Know that the withdrawal symptoms of opioids are tremors, agitation, nausea, and vomiting. They may occur if you stop the therapy abruptly. Monitor the patient for these signs and symptoms when you stop the therapy and provide supportive treatment.  

Evaluation

• The patient acknowledges a pain reduction.  
• The patient maintains an adequate breathing pattern with a normal breathing rate and rhythm and pink skin color.  
• The patient and their family have an understanding of drug therapy. 

The Bottom Line

In conclusion, an opioid agonist is a crucial class of drugs used for controlling severe pain, cough, and diarrhea. However, they can have serious adverse effects, such as respiratory depression and constipation, that require careful monitoring by healthcare professionals.

The nursing processes involved in administering opioid agonists involve assessing the patient’s pain level and respiratory status, implementing measures to prevent adverse reactions, and evaluating the patient’s response to treatment. By following these processes, healthcare professionals can ensure the safe and effective use of opioid agonists in patients who need them.

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