SC PRN — anticipatory
Prescribe ahead in case of need. Always look for reversible causes before re-dosing.
Symptom
Pain
Pain present?
YES
Opioid naïve?
YES → Morphine SC PRN
First line
Morphine
2.5–5 mgSC PRN
Opioid naïve — titrate to effect
If on background opioid
PRN breakthrough = 1/6th of the 24-hour SC opioid dose. Discuss with palliative care if unsure.