Pretreatment with controlled-release morphine for pain after hysterectomy.

In a double-blind randomised study, two dosing regimens for controlled-release morphine tablets were compared against placebo to ascertain the extent of prophylactic postoperative pain control in 51 women undergoing abdominal hysterectomy. One group of patients received controlled-release morphine every 12 h for 2 days before surgery, a second group received a single dose of controlled-release morphine 2 h before surgery and a third group received placebo. Patient-controlled analgesia system demands were compared for the first 38 h after surgery and 10-point pain scores and McGill pain questionnaires were compared for the first 6 postoperative days and at 6 weeks after surgery. During the first 2 days after surgery, patients reported high levels of pain which were similar in all groups. Pain scores on the third and fourth postoperative days were significantly lower in those who had a single pre-operative dose of controlled-release morphine compared with placebo and those who had been treated with-morphine every 12 h for 2 days (p = 0.043 and 0.024 for third and fourth day respectively). Patient-controlled analgesia demands were also fewer and less variable in those patients receiving the single dose of morphine 2 h before surgery. The study shows a beneficial analgesic effect of a single pre-operative dose of morphine, but shows no benefit for a more prolonged pre-operative dosing regimen.