Opioid therapy for chronic pain.

N Engl J Med 2003;349:1943-53. Copyright © 2003 Massachusetts Medical Society. pium is a bitter, brown, granular powder derived from the seedpod of the poppy ( Papaver somniferum ). People have used opium for the relief of pain and suffering for thousands of years. Before the 19th century, opium was cultivated and used chiefly in the Middle East, whereas in Europe and the United States it was a luxury available mainly to the elite. During the 19th century, several historical events conspired to make opium and other opioids more readily available. The production of opium increased rapidly, and after the morphine alkaloid was identified in 1806 pharmacologic production of opioid drugs began. Use of morphine-containing tinctures such as laudanum became commonplace, especially in the treatment of the “travails” and “boredom” of Victorian women. Morphine-containing cures for colic, diarrhea, dysmenorrhea, and other painful conditions were widely available and could be bought from doctors and pharmacists. With the rise of the “street use” of opium and heroin, legal controls were introduced. In the United States, the first attempts to control the abuse of narcotics came at the end of the 19th century, when a few states instituted limited controls. By the 1940s, opioids were so tightly restricted that they could be used legally only when they were prescribed by physicians according to strict regulatory controls. The legal use of opioids was thus placed entirely in the hands of physicians, who were, and still are, liable to lose their medical licenses and risk criminal prosecution if they prescribe these drugs inappropriately. The immediate effect of such strict regulatory control was that physicians became reluctant to prescribe opioids, and as a result pain was woefully undertreated. 1 Through the efforts of advocates of pain control, toward the end of the 20th century opioid therapy was reestablished as an invaluable and accepted treatment for acute pain, pain due to cancer, and pain caused by a terminal disease. The most difficult issue now facing physicians who treat patients with chronic pain probably is whether and how to prescribe opioid therapy for chronic pain that is not associated with terminal disease, including pain experienced by the increasing number of patients with cancer in remission who need long-term opioid therapy. Many of the issues involved in the treatment of patients with pain due to cancer in remission are the same as those in the treatment of patients with chronic pain that is unrelated to malignant conditions. Our review addresses specific questions about dose and toxicity in the light of recent studies that suggest a need to modify current practices in the use of opioid therapy for chronic pain.