Opioids are powerful pain-relieving drugs that work by binding to specific receptors in the nervous system. They come in two main types: agonists, which activate these receptors, and antagonists, which block them. Understanding how these drugs work is crucial for safe and effective pain management.

Nurses play a vital role in administering opioids and monitoring patients for side effects. Proper assessment, careful dosing, and patient education are key to maximizing pain relief while minimizing risks. Opioid safety is a critical concern, given the potential for addiction and overdose.

Opioid Agonists and Antagonists

Opioid agonists vs antagonists

• Opioid agonists bind to and activate opioid receptors (mu, kappa, delta) producing analgesic effects by mimicking the actions of endogenous opioids (endorphins, enkephalins, dynorphins)
  • Commonly used opioid agonists include morphine, oxycodone, fentanyl, hydromorphone, and codeine
• Opioid antagonists bind to opioid receptors without activating them, blocking the effects of opioid agonists and preventing or reversing their actions
  • Opioid antagonists like naloxone and naltrexone are used to treat opioid overdose or opioid-induced side effects

Mechanisms of common opioid drugs

• Opioids bind to specific receptors in the central and peripheral nervous systems, and activation of these receptors leads to inhibition of pain transmission and modulation of pain perception
  • Opioids also affect other systems such as respiratory, gastrointestinal, and immune systems
• Indications for opioid use include moderate to severe acute pain (post-operative, trauma), chronic pain (cancer-related pain, palliative care), cough suppression (codeine, hydrocodone), and diarrhea (loperamide, diphenoxylate)
• Major side effects of opioids include respiratory depression, sedation and drowsiness, nausea and vomiting, constipation, pruritus (itching), urinary retention, and tolerance and physical dependence with prolonged use

Nursing considerations for opioids

• Assessment involves evaluating pain intensity, character, and location using appropriate pain scales, monitoring vital signs especially respiratory rate and sedation level, and assessing for contraindications and risk factors (respiratory disorders, renal or hepatic impairment)
• Administration requires following the "5 rights" of medication administration (right patient, drug, dose, route, and time), starting with the lowest effective dose and titrating based on patient response and side effects, and using equianalgesic dosing when converting between different opioids or routes of administration
• Monitoring includes regularly reassessing pain control and side effects, watching for signs of respiratory depression, oversedation, or allergic reactions, and monitoring bowel function and implementing prophylactic measures to prevent constipation
• Safety measures involve securing and properly storing opioid medications to prevent diversion or misuse, disposing of unused or expired opioids according to institutional policies and local regulations, and educating patients and caregivers about safe storage, disposal, and potential risks

Patient education for opioid safety

• Proper use instructions include taking opioids exactly as prescribed by the healthcare provider, not changing the dose or frequency without consulting the prescriber, and not crushing, chewing, or breaking extended-release or long-acting formulations
• Patients should be informed about common side effects and how to manage them (stool softeners for constipation, antiemetics for nausea) and advised to report severe or persistent side effects to their healthcare provider
• Patients should be cautioned about potential drug interactions with other CNS depressants (alcohol, benzodiazepines, sedatives) and advised to inform all healthcare providers about their opioid use
• Risks of prolonged opioid use include tolerance, physical dependence, and addiction, and patients should be warned about the dangers of sharing opioids or taking them in ways not prescribed
  • Patients should be educated on the signs and symptoms of opioid overdose and the use of naloxone if available
• Safe storage and disposal practices emphasize the importance of storing opioids securely and out of reach of children or pets and instructing patients on proper disposal methods for unused or expired opioids

Opioid Use Disorder and Treatment

• Opioid use disorder is a chronic condition characterized by problematic patterns of opioid use leading to significant impairment or distress
• The endogenous opioid system plays a crucial role in pain modulation, reward, and addiction, and is the target of both opiates (naturally derived from opium poppy) and synthetic opioids
• Treatment options for opioid use disorder include:
  • Methadone: A long-acting opioid agonist used in medication-assisted treatment to reduce cravings and withdrawal symptoms
  • Buprenorphine: A partial opioid agonist that helps manage withdrawal symptoms and cravings while having a lower risk of respiratory depression