• Prescrire Int. 2011 Nov 1;20(121):268-73.

AbstractAdequate pain management is crucial in maintaining the best possible quality of life for terminally ill patients. This article examines pain management in the palliative care setting, based on a review of the literature using the standard Prescrire methodology. Accurate pain evaluation, preferably by the patient, is essential for guiding treatment decisions. Some causes of pain are amenable to specific treatments. The expected benefits and harms of the various treatment options and procedures must be weighed on a case by case basis. Quality of life should always be the first priority. The World Health Organization has developed a "three-step analgesic ladder", based on the use of increasingly potent analgesics: step I analgesics include paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs); codeine is the standard step II analgesic; and morphine is the standard step III analgesic. Fentanyl is an alternative to morphine. The daily morphine dose must be determined for each patient. Morphine titration starts with oral doses given every 4 hours, but additional doses can be taken every hour if necessary. Total consumption is then used to calculate the dose required the following day. A sustained-release product can be used to reduce the number of doses required when a consistently effective daily dose has been established. When patients are unable to take morphine orally, it can be given by subcutaneous injection, and by subcutaneous or intravenous infusion. Pumps allow the patient to self-administer morphine on demand. Fentanyl transdermal patches are another option for stable pain. Immediate-release oral forms and injections are useful for preventing or treating breakthrough pain. If morphine requirements increase during treatment, the most likely explanations are exacerbations of pain or an excessively long interval between doses. Pharmacological tolerance and psychological dependence are rare during palliative care. In case of renal failure, the morphine dose should be reduced, sustained-release morphine should be replaced by immediate-release morphine, or morphine should be replaced by fentanyl, as fentanyl metabolism is only slightly affected by renal function. The main adverse effects of morphine are constipation, nausea and vomiting. Drowsiness is frequent at initiation of treatment. Respiratory depression is rare when morphine is introduced gradually. Tricyclic antidepressants and carbamazepine have acceptable harm-benefit balances in patients with neuropathic pain. Cannabinoids are another option but have not been adequately assessed. Localised refractory pain may respond to local anaesthesia, chemical neurolysis or surgical ablation. In practice, it is best to allow patients to control their own analgesic consumption, within limits set by their physician to prevent dosing errors.

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