NARCOTIC DRUGS IN NEW DELIVERY SYSTEMS DESERVE FURTHER STUDY, NIH PAIN PANEL RECOMMENDS; NEW RESEARCH SHOULD FOCUS ON MORE EFFICACIOUS ANALGESICS

Patient-controlled analgesia, epidural administration and transdermal absorption were identified as drug delivery techniques for further study with currently available narcotics by an NIH Consensus Panel at its May 19-21 meeting, "The Integrated Approach to the Management of Pain." In a presentation to the conference, Ness Coyle, RN, Memorial Sloan-Kettering Cancer Center, noted the advantages of epidural and intrathecal routes of administration, which include longer duration on less drug compared to intramuscular or intravenous administration and potential achievement of analgesia with fewer side effects. Coyle also discussed the disadvantages of these methods, such as later onset of analgesia, respiratory despression and the invasiveness of the required catheterization. Pointing out the effect of different analgesic agents using the same delivery method, Coyle added that epidural or intrathecal delivery of a hydrolipid such as methadone is associated with a shorter onset of action and duration of analgesic effect than similar administration of a hydrophillis such as morphine. The conference panel recommended expanded research aimed at discovering and developing more effective analgesic drugs with larger margins of safety. "Precise knowledge about the pharmacology of known drugs is important," the panel said, "but to develop drugs with new intrinsic actions new drug molecules are needed. While suggesting a focus for future research, the panel gave its support to continued research on endorphins, enkephalins and narcotic receptors that show promise of producing better analgesic drugs. Three general categories of pain were identified by the panel: acute pain, or pain following surgery, severe injury or disease; chronic, malignant pain associated with cancer or other progressive disorders; and chronic, nonmalignant pain in persons whose tissue injury is nonprogressive or healed. The panel said that many hospitalized patients with acute pain continue to suffer because their treatment has been with narcotic analgesics in too low a dosage or at too long an interval between dosages. The consensus statement explained that reasons for undermedication of patients with acute pain "include incorrect assessment, insufficient knowledge of the pharmacology of the prescribed drug, personal attitudes of the care-givers and patients themselves about narcotics analgesics, and concern about the problems of addiction and respiratory depression that is greater than the actual risk." In the chronic malignant pain area, the panel noted parallels in the inadequate treatment of cancer pain with the inadequate treatment of acute pain. But unlike acute pain, which is usually treated for a short period of time, chronic malignant pain requires extended treatment, bringing up the issues of tolerance and physical dependence. "There is an indication that when dosage requirement increases, the reason can be disease progression and not increased tolerance," the panel said. "Physical dependence does occur but is not of clinical significance in advanced disease." The consensus panel described people with chronic nonmalignant pain as a heterogeneous group. "They have a variety of illnesses and have been treated with a wide variety of medication and other therapies, often with limited success," the panel said. "In an effort to alleviate the pain, drug dosage is often progressively raised to the point at which significant side effects appear." Panel member Ronald Dougherty, MD, medical director of Pelion Inc., offered his observations as head of a pain clinic. "There is no safe Rx narcotic for the treatment of chronic pain," he emphasized. Dougherty further noted that people will often take more and more of a given drug for their pain "because they don't know any better and their physician, who is not taught any different in medical school, also doesn't know any better, because he doesn't know what other techniques to use."