Opioids

A 58-year-old man with metastatic pancreatic cancer presents to the palliative care clinic with severe, uncontrolled pain (8/10 on visual analogue scale) despite being on paracetamol 1 g QID and ibuprofen 400 mg TDS for the past 3 weeks. On examination, he appears cachectic but alert and oriented. His respiratory rate is 16/min, oxygen saturation 98% on room air, and blood pressure 128/82 mmHg. The palliative care physician decides to initiate opioid therapy. Which of the following opioids is the most appropriate first-line choice for this patient?

A 58-year-old man with advanced pancreatic cancer presents to the palliative care clinic with severe, uncontrolled pain (VAS 9/10). He has been on paracetamol 1 g QID and ibuprofen 400 mg TDS for 2 weeks without relief. On examination, he appears cachectic and in distress. His vital signs are: BP 128/82 mmHg, HR 92/min, RR 16/min, SpO₂ 96% on room air. Liver function tests show mild elevation of transaminases. Which opioid would be the most appropriate choice for initiating analgesia in this patient?

Which opioid receptor subtype is primarily responsible for analgesia and respiratory depression?

A 58-year-old man with advanced pancreatic cancer on morphine 60 mg/day for cancer pain presents to the emergency department with severe respiratory depression (RR 8/min, SpO₂ 82% on room air) and pinpoint pupils. His wife reports he accidentally took a double dose 2 hours ago. What is the most appropriate immediate next step in management?

Which of the following opioids undergoes glucuronidation to form active metabolites that accumulate in renal failure?