CONTINUOUS REACTION-TIME AFTER SINGLE-DOSE, LONG-TERM ORAL AND EPIDURAL OPIOID ADMINISTRATION

Auditory continuous reaction time was studied in three treatment group s. Twenty opioid naive patients received intramuscular morphine 0.1 5 mg kg-1 bodyweight for premedication. Thirty-one cancer patients were treated with oral opioids, 180 mg morphine per 24 h (median). Twenty-t wo cancer patients were treated with epidural morphine, 79 mg morphine per 24 h (median). The treatment groups were compared to a control gr oup of 44 healthy persons taking no analgesics. The reaction time was measured using 152 auditory signals and summarized as 10%, 50% and 90% percentiles. Analysing reaction time distributions, the opioid naive patients showed the greatest difference to the control group in the sh ortest reaction times while chronic opioid users showed the greatest d ifference for the longest reaction times. There seems to be a qualitat ive difference in reaction time distribution, between opioid naive ind ividuals treated with single dose morphine and cancer patients in long -term treatment.