The attractiveness of opposites: agonists and antagonists.

Opioid-induced bowel dysfunction, of which constipation is the most common aspect, is a major limiting factor in the use of opioids for pain management. The availability of an oral, long-acting formulation of oxycodone and naloxone represents a highly significant development in pain management. The combination of an opioid analgesic with an opioid antagonist offers reliable pain control with a significant reduction in the burden of opioid-induced constipation.