부산대학교 도서관

Patients with chronic (malignant and non-malignant) pain are increasingly being treated with powerful opioids. The trend in palliative care is to use morphine or similar opioids earlier in the natural course of illness. This increased use of morphine and its analogues has alerted physicians to possible adverse cognitive effects of these drugs, which had previously been neglected Such cognitive impairment is most likely to occur when morphine-therapy is commenced, or when there is a significant increase in the patient's morphine intake (dose escalation). However, there is no data on the 'acute-on-chronic' effects of morphine on subjective ratings, psychomotor performance or cognitive functioning in pain-patients receiving long-term, maintenance opioids. The current study aimed to address this gap in the current knowledge by investigating the effects of acute - 'breakthrough' - morphine on psychomotor and cognitive functioning in patients who were also taking long-acting, 'morphine-like' opioids. Using a double-blind cross-over design, 14 patients receiving palliative care were assessed on 2 occasions: once before and after their breakthrough morphine, and once before and after placebo. It was found that anterograde impairments of episodic memory were induced by a breakthrough dose of morphine and were most pronounced when remembering occurred after a time delay. There were also retrograde impairments observed when patients given morphine recalled a story they heard before morphine. Evidence for executive function deficit was obtained on the Reitan's Trials task. Although breakthrough-morphine produced significantly more self-rated pain-relief than placebo, patients could not distinguish between the two treatments. Finally, patients did not seem to respond to the reinforcing effects of morphine and neither were they susceptible to changes in mood ratings following their breakthrough dose. These findings suggest that patients will experience some significant impairment in cognitive functioning following their intake of breakthrough morphine which could impinge on their everyday functioning.