Opioids

• Opioid agonists (morphine) work by mimicking opioid peptides and activating mu receptors to cause analgesia, respiratory depression, euphoria, and sedation
• Opioid agonists are CNS depressants
• Morphine should be used with caution for patients with head injuries, profound CNS depression, respiratory depression, coma, asthma, emphysema, cardiovascular disease, hypotension, BPH, urethral stricture, and liver impairment
• Adverse effects of Morphine include respiratory depression, constipation, orthostatic hypotension, urinary retention, cough suppression (increases mucus in airways and lungs), nausea, vomiting, dysphoria, drowsiness/mental clouding, miosis (pinpoint pupils), neurotoxicity (causes delirium and agitation), and an itching sensation
• Morphine also causes the release of histamine
• Morphine is used for moderate to severe pain (pain above 4/10); usually post-operative pain, labor/delivery pain, and chronic pain
• Morphine is contraindicated after biliary tract surgery
• Tolerance for Morphine develops to analgesia, sedation, and euphoria effects; very little tolerance develops to constipation and miosis
• Morphine can cause physical dependence; do not abruptly stop administration as it will cause abstinence syndrome
• Symptoms of abstinence syndrome include sweating, irritability, nausea, vomiting, tremors, headaches, and muscle spasms
• Before administering Morphine, assess pain, respiratory rate, alertness, LOC, and vitals; withhold morphine if respirations are below 12 or if patient's LOC is diminished
• Morphine should be administered on a fixed schedule (especially after surgery) to keep levels safe and therapeutic
• Naloxone is an opioid antagonist that is indicated for the reversal of an opioid overdose
• Naloxone works by blocking the effects of opioids at mu receptors
• Naloxone should be given in a series of small doses; its half-life is shorter than most opioids so repeated dosing is required until the opioid overdose has passed
• Dosage of Naloxone should be carefully measured in opioid addicts, an excessive dose can put the patient from toxicity into withdrawal