Effect of combining naloxone and morphine for intravenous patient-controlled analgesia.
BACKGROUND
An early study showed that a naloxone infusion decreased the incidence of morphine-related side effects from intravenous patient-controlled analgesia. The authors tested the hypothesis that a more convenient combination of morphine and naloxone via patient-controlled analgesia would decrease the incidence of side effects compared to morphine alone.


METHODS
Patients scheduled for hysterectomy under general anaesthesia were enrolled in a double-blind, randomized, placebo-controlled trial. Patients received a standardized general anesthetic and postoperative patient-controlled analgesia. They were randomized to receive 60 mg patient-controlled analgesia morphine in 30 ml saline or 60 mg morphine in 30 ml saline with naloxone 0.8 mg. Parameters for patient-controlled analgesia were a 1-mg bolus of morphine with a 5-min lockout and no background infusion. Patient recall of nausea, vomiting, itching, and pain (at rest and with movement) were assessed at 6 and 24 h postoperatively by verbal rating score. Pain was also assessed by a 0- to 100-mm visual analog score, and sedation was assessed by an observer. The amount of morphine used and the requirements for symptomatic treatment were also recorded.


RESULTS
Ninety-two patients completed the study, with no significant differences in outcomes between groups. At 24 h, the incidence of nausea was 84.8% in each group; the incidence of pruritus was 56.5% in the naloxone group and 58.7% in the placebo group. There were also no differences in symptomatic treatment requirements, pain scores, morphine use, or sedation between groups. The median dose of naloxone received equated to 0.38 microg x kg-1 x h-1 over 24 h.


CONCLUSIONS
There was no benefit from administering naloxone combined with morphine via patient-controlled analgesia.
Sartain
James B
JB
University of Queensland, Australia.
Barry
John J
JJ
Richardson
Christopher A
CA
Branagan
Helen C
HC
D000328:Adult; D016058:Analgesia, Patient-Controlled / Q000379:methods*; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000768:Anesthesia, General; D000932:Antiemetics / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007044:Hysterectomy; D011939:Mental Recall; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009270:Naloxone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D010147:Pain Measurement / Q000187:drug effects; D020250:Postoperative Nausea and Vomiting / Q000503:physiopathology; D011398:Promethazine / Q000627:therapeutic use; D011537:Pruritus / Q000139:chemically induced / Q000453:epidemiology
D000701:Analgesics, Opioid; D000932:Antiemetics; D009292:Narcotic Antagonists; D009270:Naloxone; D009020:Morphine; D011398:Promethazine