Morphine is the principal constituent of opium and can range in concentration from 4 to 21 percent. Commercial opium is standardized to contain 10-percent morphine. In the United States, a small percentage of the morphine obtained from opium is used directly (about 15 tons): the remaining is converted to codeine and other derivatives (about 120 tons). Morphine is one of the most effective drugs known for the relief of severe pain and remains the standard against which new analgesics are measured. Like most narcotics, the use of morphine has increased significantly in recent years. Since 1990, there has been about a 3-fold increase in morphine products in the United States.

Morphine is marketed under generic and brand name products including "MS-Contin®," Oramorph SR®," MSIR®," Roxanol®," Kadian®," and RMS®." Morphine is used parenterally (by injection) for preoperative sedation, as a supplement to anesthesia, and for analgesia. It is the drug of choice for relieving pain of myocardial infarction and for its cardiovascular effects in the treatment of acute pulmonary edema. Traditionally; morphine was almost exclusively used by injection. Today, morphine is marketed in a variety of forms, including oral solutions, immediate and sustained-release tablets and capsules, suppositories, and injectable preparations. In addition, the availability of high-concentration morphine preparations (i.e., 20-mg/ml oral solutions, 25-mg/ml injectable solutions, and 200-mg sustained-release tablets) partially reflects the use of this substance for chronic pain management in opiate-tolerant patients.