The changing of opioids to improve pain relief and drug tolerance in patients

Opioid switching is the term given to the clinical practice of substituting one strong opioid with another, in an attempt to achieve a better balance between pain relief and side effects. This is an established clinical practice for patients with cancer pain, but the evidence is based on case reports and uncontrolled studies, and no randomised trials met the inclusion criteria for this review. In addition, the case reports and uncontrolled studies are inconsistent in their reporting of the reasons for opioid switching (whether the change was made because of intolerable side effects, inadequate pain relief, or both). It is also unclear whether the initial opioid was being given at a high enough, but tolerable, dose to achieve maximum pain relief. Opioids are increasingly used for non-cancer pain, but the practice of opioid switching does not yet appear to be established in this group of patients.