What are the recommended treatments for intractable pain?

Treatment for Intractable Pain

For intractable pain, a stepwise pharmacological approach beginning with strong opioids such as morphine or oxycodone, combined with appropriate co-analgesics based on pain type, is recommended as first-line therapy. 1

Pharmacological Management

First-Line Therapy

• Strong Opioids (WHO Level III):

  • Morphine: Starting dose 20-40 mg oral daily, no upper limit 1
  • Oxycodone: Starting dose 20 mg oral daily, no upper limit 1
  • Fentanyl transdermal: Starting dose 12 μg/h (only for opioid-tolerant patients) 2
  • Hydromorphone: Starting dose 8 mg oral daily 1

• Breakthrough Pain Management:

  • Provide rapid-onset, short-acting opioids at 10-15% of total daily dose 1
  • Adjust baseline regimen if >4 breakthrough doses needed per day 1

For Neuropathic Pain Components

• Add one of the following co-analgesics:
  • Tricyclic antidepressants (nortriptyline, desipramine) 1
  • Anticonvulsants (gabapentin, pregabalin) 1
  • SNRIs (duloxetine, venlafaxine) 1, 3

Management of Resistant Pain

For Pain Inadequately Controlled by First-Line Therapy

1. Interventional Approaches:

   • Nerve blocks for localized pain 1
   • Radiotherapy for bone metastases or neural compression 1
   • Surgery for impending/evident fractures or hollow organ obstruction 1

2. Advanced Pharmacological Options:

   • Ketamine (subanesthetic doses) for truly intractable pain 1
   • Methadone for complex cases (requires expertise due to variable conversion ratios) 1
   • Intrathecal opioid delivery systems for selected cases 4

3. For Refractory Pain at End of Life:

   • Consider sedation when pain is truly refractory and causing suffering 1
   • Agents may include opioids, neuroleptics, benzodiazepines, barbiturates, or propofol 1

Managing Opioid Side Effects

• Constipation: Prophylactic laxative therapy required
• Nausea/Vomiting: Antiemetics, particularly during initiation
• CNS Toxicity: Consider opioid rotation if drowsiness, confusion, hallucinations, myoclonus occur
• For severe toxicity: Naloxone for emergency reversal of overdose 1

Special Considerations

Neuropathic Pain

• Neuropathic pain often responds poorly to opioids alone 1
• First-line options:
  • Tricyclic antidepressants (amitriptyline, nortriptyline) 1, 5
  • Gabapentin or pregabalin 1
• For central post-stroke pain:
  • Amitriptyline 75mg at bedtime or lamotrigine as first-line 3

Cancer Pain

• Follow WHO analgesic ladder but accelerate steps for severe pain
• Consider bisphosphonates for bone metastasis pain 1
• Radiotherapy provides excellent relief for bone metastases 1

Common Pitfalls to Avoid

1. Inadequate dosing: Titrate to effect, not to a predetermined ceiling dose for strong opioids
2. Fear of addiction: Should not prevent appropriate pain management in truly intractable pain
3. Monotherapy approach: Intractable pain often requires multimodal analgesia targeting different pain mechanisms 6
4. Ignoring breakthrough pain: Failure to provide rescue medication leads to poor pain control
5. Overlooking side effects: Proactive management of side effects improves adherence and quality of life
6. Using fentanyl patches in opioid-naïve patients: Only appropriate for opioid-tolerant patients 2

Remember that intractable pain often involves multiple pain mechanisms and requires careful assessment and individualized treatment approaches targeting the specific pain generators and mechanisms involved.