POTENTIATION OF OPIOID ANALGESIA BY PSYCHOSTIMULANT DRUGS - A REVIEW

Recent research has investigated drug combinations that enhance the an algesic effectiveness of their component substances. Many studies have examined the combination of opioids and psychostimulant drugs, such a s amphetamine and methylphenidate. Despite the positive results report ed in the literature, this combination is rarely used in clinical prac tice. The purpose of this paper is to review the literature on the opi oid-amphetamine combination. Experiments with animal and human subject s provide convincing evidence that d-amphetamine or methylphenidate po tentiate the analgesic effects of morphine Psychostimulant drugs have been shown in animal studies to possess intrinsic analgesic properties and to have the ability to enhance the analgesic properties of opioid s when both types of drugs are given in combination. Studies with huma n subjects have confirmed the enhancement of opioid analgesia by amphe tamines and, in addition, have demonstrated that psychostimulant drugs produce a decrease in somnolence and an increase in general cognitive abilities. The greater cognitive alertness, moreover, allows the use of larger opioid doses, which can produce a substantial increase in an algesia. These results indicate another possible method to enhance the quality of life in patients with difficult pain problems. Although th e enhanced cognitive effects are well established the effects on pain need further study to determine the mechanisms of action and the drug combinations and administration patterns that would maximize their eff ects. (C) U.S. Cancer Pain Relief Committee, 1998.