Prospects and challenges in opioid analgesia for pain management.

Pain is still one of the most prevalent and distressing symptom in patients with chronic pain. Opioids are the most potent existing analgesics available in clinical practice. However, they are not always effective, particularly in the non-cancer population. Alternately adverse effects may limit their analgesic activity. Several different drug-development strategies have attempted to reduce side effects by exploiting anatomic barriers to drug distribution and to provide different analgesic mechanisms, as in the case of the oxycodone-naloxone combination or tapentadol. New delivery systems have been developed for a more effective management of breakthrough pain. Pharmacogenetics could play a critical role in personalizing pain management in the future.