What are the recommended analgesics for cancer pain management?

Recommended Analgesics for Cancer Pain Management

Cancer pain management should follow the WHO analgesic ladder, starting with non-opioid analgesics for mild pain, progressing to weak opioids for moderate pain, and strong opioids for severe pain, with adjuvant medications added at any step as needed. 1, 2

Assessment of Pain

• Pain should be evaluated at every clinical encounter using standardized self-reporting tools such as visual analog scales (VAS), numerical rating scales (NRS), or verbal rating scales (VRS) 1, 2
• Pain assessment should characterize type, location, intensity, duration, and temporal patterns to guide appropriate analgesic selection 2

Treatment Algorithm Based on Pain Intensity

Mild Pain (WHO Level I)

• First-line: Acetaminophen/paracetamol (1g every 4-6 hours, maximum 4g/day) 1
• Alternative: NSAIDs, particularly effective for inflammatory or bone pain 1
• When using NSAIDs long-term, gastroprotection is recommended to prevent GI toxicity 1, 2
• NSAIDs should be used with caution in patients with renal impairment, heart failure, or hypertension 2

Moderate Pain (WHO Level II)

• First-line: Combination products containing acetaminophen plus a weak opioid (codeine, dihydrocodeine, tramadol) 1
• Tramadol is particularly useful due to its dual mechanism of action (μ-opioid agonist and serotonin/norepinephrine reuptake inhibitor) 3
• Controlled-release formulations of codeine, dihydrocodeine, and tramadol improve convenience 1
• Low doses of strong opioids (morphine, oxycodone) may also be used for moderate pain 1

Severe Pain (WHO Level III)

• First-line: Morphine (oral route preferred) 1
• Alternatives: Hydromorphone or oxycodone in both immediate-release and controlled-release formulations 1
• Transdermal fentanyl for patients with stable opioid requirements, inability to swallow, poor tolerance to morphine, or poor compliance 1
• Methadone is effective but should be initiated only by physicians experienced in its use due to complex pharmacokinetics 1
• For urgent pain relief, parenteral opioids (intravenous or subcutaneous) should be used 1

Administration Principles

• Provide around-the-clock dosing for persistent pain 2
• Include "breakthrough" doses (typically 10-15% of total daily dose) for transient pain exacerbations 2
• Oral administration is preferred when possible 1
• Two products of the same pharmacological class with the same kinetics should not be prescribed together 1

Adjuvant Analgesics

• Adjuvant analgesics can be added at any step of the WHO ladder 1, 4
• Consider anticonvulsants, antidepressants, or corticosteroids for neuropathic pain 2, 4
• Bone-modifying agents (bisphosphonates, denosumab) should be considered for bone pain 2
• Adjuvant analgesics should be initiated at lower dosages and escalated as tolerated 4

Important Considerations

• Recent evidence suggests acetaminophen may not improve pain control or decrease total opioid use in patients already on strong opioid regimens 5
• For very severe pain, consider skipping WHO level II and proceeding directly to strong opioids 1
• Non-pharmacological approaches including radiation therapy for bone pain, nerve blocks, and interventional procedures should be considered as complementary strategies 2

Monitoring

• Regular reassessment of pain control and medication side effects is essential 1, 2
• Adjust treatment based on changes in pain intensity, side effects, and disease progression 2
• Anticipate and proactively manage opioid-related side effects (constipation, nausea, sedation) 6

Remember that most cancer pain can be effectively controlled with appropriate analgesic therapy, and no cancer patient should suffer with unrelieved pain 6.