Opioid-induced hyperalgesia, opioid rotation and opioid combinations

摘要

Strong opioid analgesics are recommended for the management of moderate to severe pain including that which occurs following surgery and trauma and in many patients with cancer. Apart from pain relief, opioid analgesics also produce a range of common side-effects including respiratory depression, nausea, vomiting, sedation, constipation and pruritus and less frequently, myoclonus and delirium. In terms of the incidence and severity of opioid-induced side-effects, it has long been appreciated by front-line clinicians that individual patients may respond better to one strong opioid analgesic than another, whether in terms of superior pain relief and/or improved tolerability.These clinical observations of 'between-opioid' differences within individuals led to the practice of 'opioid rotation' whereby patients experiencing poor pain relief and intolerable opioid-related side-effects to one strong opioid analgesic are rotated to another as a means of improving opioid tolerability and restoring satisfactory pain relief. Consistent with earlier anecdotal reports of the success of opioid rotation, several recent prospective clinical trials have shown that rotation from one strong opioid to another is an effective means for restoring satisfactory analgesia with tolerable side-effects in most patients who would otherwise experience intolerable side-effects and poor pain relief. In termsof the mechanism(s) underpinning the clinical success of 'opioid rotation', this likely involves both pharmacokinetic and pharmacodynamic factors.