[Prevention by naloxone of adverse effects of epidural morphine analgesia for cancer pain].

Forty cancer patients were randomly assigned to two groups (n = 20). All had incapacitating pain unresponsive to the usual non opioid analgesic drugs. An epidural catheter was set up at the level of the most painful metamere, and made to pass subcutaneously so as to exit either in the supraclacicular fossa, or on the patient's flank. At T0, the patients were given 4 mg morphine hydrochloride diluted in 10 ml normal saline. Thirty min later, patients in the naloxone group (group N) were given a 0.4 mg bolus, followed by a constant rate infusion of 5 micrograms.kg-1.h-1, of naloxone hydrochloride during 18 h. Patients in group P (placebo) were given normal saline instead. The degree of pain was studied with a visual analogue scale and analgesia was assessed by a clinician on a five point scale. These two parameters were obtained half an hour after the injection of morphine and 2, 4, 6 and 24 hours later. At the same time, the patients were questioned about adverse side-effects: nausea, vomiting, pruritus, dysuria, urinary retention. Respiratory depression was assessed clinically and biologically (blood gas measurements at the afore mentioned times). Heart rate, systolic and diastolic blood pressure were also measured. There was no statistically significant difference between the groups in quality and duration of analgesia. Pain reached its lowest level 4 h after the injection of morphine, returning to half its original value at the 24th h. This was also true for the incidence of nausea (11 in group N, 5 in group P), vomiting (3 in both groups), and urinary retention (6 in group P, 5 in group N).(ABSTRACT TRUNCATED AT 250 WORDS)