Opioid Selection and Management for Pain Relief

Introduction to Opioid Therapy

The American Society of Clinical Oncology and the National Comprehensive Cancer Network recommend morphine, oxycodone, hydromorphone, and fentanyl as the most commonly used opioids for pain management, with morphine being the standard first-choice opioid for moderate to severe pain 1, 2, 3

For mild to moderate pain, codeine, tramadol, and dihydrocodeine are recommended, with specific dosing and duration guidelines 1, 2
For moderate to severe pain, morphine, oxycodone, hydromorphone, fentanyl, and methadone are recommended, with consideration of their relative potencies and potential side effects 1, 2, 3, 4

The National Comprehensive Cancer Network recommends oral morphine as the opioid of first choice for moderate to severe cancer pain due to its effectiveness, tolerability, and low cost 1, 2
For patients with severe pain requiring urgent relief, parenteral opioids are recommended, with a relative potency ratio of oral to parenteral morphine between 1:2 and 1:3 2, 4

Morphine is the standard starting drug for opioid-naïve patients, with an initial oral dose of 5-15 mg or 2-5 mg IV, but should be avoided in patients with renal disease and hepatic insufficiency 3, 5
Methadone is more complicated to use due to marked inter-individual differences in plasma half-life and duration of action, and should be initiated only by physicians with experience and expertise in its use 3, 4, 5
Fentanyl is not indicated for rapid opioid titration and should only be used after pain is controlled by other opioids, with a conversion ratio from IV to transdermal fentanyl of 1:1 3

Opioid selection should consider the patient's pain intensity, current analgesic therapy, and concomitant medical conditions, with individualized approaches necessary due to great variability in patient response to different opioids 3, 6
When switching between opioids, use caution with dose conversion as relative effectiveness varies considerably among patients, and opioid rotation may improve the therapeutic window and establish a more advantageous analgesia/toxicity relationship 2, 6