💊 Strong Opioids (Morphine, Oxycodone)

Strong opioids are potent analgesic drugs primarily used for the management of severe acute and chronic pain. They are full agonists at opioid receptors, providing significant pain relief.

These drugs act as agonists at mu-opioid receptors in the central nervous system, spinal cord, and peripheral tissues. Activation of these receptors leads to inhibition of neurotransmitter release involved in pain transmission, resulting in analgesia. They also produce euphoria and respiratory depression.

Strong opioids are indicated for the relief of severe pain, such as that associated with cancer, myocardial infarction, or severe trauma. They are also used in palliative care for symptom control. They can be used for acute post-operative pain management.

Absolute contraindications include acute respiratory depression, severe obstructive airways disease, and paralytic ileus. They are also contraindicated in acute alcoholism, head injury (due to masking of symptoms), and in patients with known hypersensitivity. Caution is needed in severe renal or hepatic impairment.

Common adverse effects include nausea, vomiting, constipation, sedation, and dizziness. The most serious adverse effect is respiratory depression, which can be life-threatening. Other effects include pruritus, urinary retention, miosis, and potential for dependence and addiction with prolonged use.

Patients receiving strong opioids require close monitoring of respiratory rate, depth, and oxygen saturation, especially during initiation and dose titration. Pain scores and sedation levels should be regularly assessed. Bowel function must be monitored, and prophylactic laxatives are often required. Renal and hepatic function should be considered for dose adjustments.

When prescribing, always assess the patient's pain, previous opioid exposure, and risk factors for adverse effects (e.g., respiratory compromise, renal/hepatic impairment). Counsel on common side effects like constipation (and prescribe laxatives), drowsiness, and the risk of dependence. Emphasise not to drive or operate machinery. Check for drug interactions with other CNS depressants.

Understanding the principles of opioid prescribing, including titration, rotation, and management of side effects, is critical. The role of naloxone in opioid overdose is a high-yield topic. Differentiating between tolerance, physical dependence, and addiction is important. Morphine is often the benchmark strong opioid.

SBAs often focus on the management of opioid-induced side effects, particularly constipation and respiratory depression. Questions may also cover opioid conversion calculations (though specific numbers are avoided in this context, the principle is important) and the appropriate use in palliative care. The concept of opioid tolerance and dependence is also frequently tested.