Breast cancer-analgesic mechanism of action for oxycodone

Q7. Sally was diagnosed with breast cancer 2 years ago. The cancer has metastasised (spread) to Sally’s bones, therefore Sally is receiving palliative care. Over the past 12 months Sally has been treated with the strong opioid oxycodone in order to relieve pain and increase her quality of life.
A. Explain the analgesic mechanism of action for oxycodone.
B. The dose of oxycodone required to achieve an adequate analgesic effect for Sally has increased significantly over the past 12 months. What term is used to describe this phenomenon and explain a mechanism by which this could occur.
C. After the latest increase in oxycodone dose, Sally develops symptoms of severe respiratory depression and low blood pressure. Explain the reason for this development and what could be done to reverse these symptoms.