Opioid effectiveness, addiction, and depression in chronic pain.

Opioids are a viable treatment for chronic pain, but their use requires individualization, specified treatment goals, and patient education. Opioid responsiveness is influenced by patient-centered characteristics, including a predisposition to opioid side effects, psychological distress, and opioid use history; pain-centered characteristics, which involve the temporal pattern, rapidity of onset, severity, and type of pain; and drug-centered characteristics relating to the impact of specific types of opioids on specific patients. Thus, opioid doses should be titrated to achieve a favorable balance between analgesia and adverse effects. Opioid therapy can be enhanced through the adjunct administration of agents such as NMDA antagonists, calcium channel blockers, clonidine, and even low-dose opioid antagonists. Controversy exists over 1) the long-term use of opioids for non-cancer pain, and patients receiving opioids for long periods must be monitored carefully for signs of addictive and aberrant behavior, 2) the impact of opioid therapy on emotional depression in patients with chronic pain, and 3) whether opioid therapy causes cognitive impairment in the elderly. Our ability to determine the validity of such assertions and the exact role of opioids in the treatment of chronic pain will benefit from further study.