Pain relief in palliative care

1. Pain relief in palliative care A brief review Dr Catherine O’Doherty Consultant in Palliative Medicine, BTUH

2. Pain “Pain is what the patient says hurts” An unpleasant sensory and emotional experience associated with actual or potential tissue damage

4. Pain in advanced cancer 80% of patients experience pain Of those with pain, one third have one pain, one third have two pains, one third have three or more pains

5. Causes of symptoms in cancer patients Related to the cancer Related to its treatment Co-existent pathology

6. Classification of pain Nociceptive Somatic Visceral Neuropathic Nerve compression Nerve injury

7. Principles of analgesic use By mouth By the clock By the ladder All patients on regular opioid analgesia need an immediate release preparation to be available for breakthrough pain

9. Non-opioid analgesics Paracetamol NSAIDs Useful for bone, soft tissue and liver capsule pain

10. Conventional NSAIDs Non-selective COX inhibitors eg ibuprofen, diclofenac Variable potency Side effects include gastric irritation/ ulceration, renal impairment, fluid retention, inhibition of platelet aggregation

11. Step 2 opioids Codeine Dihydrocodeine Dextropropoxyphene Tramadol

12. Tramadol Step 2 and ?Step 3 opioid Monoamine re-uptake inhibitor Available in IR and SR formulations ?Ceiling effect

13. Step 3 analgesics Morphine Diamorphine Fentanyl Oxycodone Hydromorphone Methadone

14. Step 3 analgesics: but not in palliative care Pethidine (?Buprenorphine)

15. Morphine Opioid of first choice for moderate to severe cancer pain Mu opioid receptor agonist Drowsiness, dizziness, mental clouding, nausea and vomiting can occur on initiation Constipation is main ongoing side effect

16. Morphine - formulations Immediate release – tablets, liquid and concentrated liquid Modified release – 12hrly, 24hr Suppository Injection – diamorphine (given sc is 3x as potent mg for mg as oral morphine), morphine sulphate (given sc is 2x as potent mg for mg as oral morphine)

17. How to start a patient on morphine Talk to the patient Start a low dose of regular morphine Remember to prescribe breakthrough analgesia Always co-prescribe a laxative Ensure an anti-emetic is available

18. How to start a patient on morphine Assess for pain relief and side effects If pain still present and opioid sensitive, increase dose by 30-50%

19. Fentanyl Semi-synthetic opioid About 80x as potent as parenteral morphine Rapidly undergoes first pass metabolism Available in transdermal, oral transmucosal and injectable forms

20. Transdermal fentanyl “Patch” changed every 72 hours Best reserved for patients whose opioid requirements are stable May be useful when oral drug delivery is difficult Can be used if opioid switch is needed (use conversion chart) May be issues over breakthrough analgesia

21. Oral transmucosal fentanyl citrate (OTFC) Rapid onset of action Short duration of action Only licensed for use in patients already on regular strong opioids Role probably lies in treatment of rapidly escalating, unpredictable breakthrough pain

22. Oxycodone Semi-synthetic mu and kappa opioid agonist Available in MR (12hrly) and IR (4hrly) formulations Analgesia similar to that obtained with morphine Oral oxycodone 2x as potent mg for mg as oral morphine May cause fewer psychogenic side effects Injectable form available (given sc is 2x as potent mg for mg as oral oxycodone)

23. Methadone Widely available in liquid and tablet form Half life 17-100 hours Relative potency variable Mu and delta opioid agonist NMDA receptor antagonist May be more useful than morphine in neuropathic pain Injectable form can be used in syringe drivers

24. Which pains are opioid sensitive? Most pains have some degree of opioid sensitivity Nociceptive: somatic and visceral Neuropathic: nerve compression and nerve injury

25. Why might pains persist despite opioids? (1) The pain itself Inflammatory pain: soft tissue, muscle infiltration, bone metastasis Neuropathic pain: particularly sympathetically maintained Raised intracranial pressure Muscle spasm

26. Why might pain persist despite opioids? (2) Other reasons Underdosing Poor absorption Insufficient attention to psychological aspects

27. Management of neuropathic pain Often partially opioid sensitive Consider early use of adjuvant analgesics Tricyclic antidepressants Anticonvulsants Antiarrhythmics Corticosteroids can be useful TENS, nerve blocks can help

28. Gabapentin and Pregabalin Anticonvulsants Licensed for use in neuropathic pain No evidence that they are more effective than older anticonvulsants in neuropathic pain

29. Interventional pain relief in palliative care Nerve blocks Continuous epidural infusions Continuous spinal infusions

30. Syringe drivers A method of drug delivery by continuous subcutaneous infusion Useful in situations where the drug cannot be absorbed by the oral route Remember there is nothing magical or sinister about a syringe driver!

31. Non-drug analgesia TENS Acupuncture Reflexology Relaxation techniques Psychological intervention

32. Conclusions Pain is a common symptom in patients with life limiting disease and this can adversely affect their quality of life The underlying pathophysiology needs to be considered carefully to allow a structured approach to analgesia A holistic approach should be adopted in order to optimise symptom control