Non-opioid analgesic drugs

Pain is a major cause of distress, both physical and psychological and is also associated with increased inpatient hospital stays, poor wound healing and prolonged rehabilitation. Opioids are a mainstay of treatment for acute pain, although they are associated with significant morbidity through adverse effects such as respiratory depression, psychosis, and nausea and vomiting. The non-opiate analgesics avoid some of these effects, although are not panaceas, non-steroidal anti-inflammatory drugs (NSAIDS), for example, are associated with renal and gastric damage, which precludes their use in elderly patients and those with renal impairment. This article reviews the underlying pain pathways and the ways in which these pathways may be modulated in the pursuit of side-effect-free analgesia. Existing medications target these pathways, although there are evolving targets for analgesics. The advantages and disadvantages of the current non-opioid mainstays of treatment are reviewed. Other centrally acting medications, both research (nociceptin, neuropeptides, cannabinoids) and clinical (gabapentin, carbamazepine) are also considered. Combinations of existing analgesics underlie the principles of multimodal analgesia; non-opioid adjuncts are known to reduce postsurgical opioid requirements and improve rehabilitation and discharge. The answer may lie in synergistic dual-acting medications, which are discussed with reference to the COX-inhibiting nitric oxide donors and dual lipoxygenase/cyclooxygenase inhibitors.