Antiemetic and analgesic-sparing effects of diphenhydramine added to morphine intravenous patient-controlled analgesia.
BACKGROUND
This study was designed to examine the analgesic and dose-related antiemetic efficacy of diphenhydramine-morphine mixture for intravenous patient-controlled analgesia (PCA).


METHODS
Healthy women, undergoing abdominal total hysterectomy were recruited to this double-blinded randomized placebo-controlled study. Patients were randomly allocated to one of three groups (n=40 each). In group 1, patients received saline at induction and morphine 1 mg ml(-1) alone for postoperative PCA. Patients in groups 2 and 3 received diphenhydramine 30 mg i.v. at induction and were given a 1.2:1 or a 4.8:1 ratio, respectively, of diphenhydramine-morphine mixture for postoperative PCA.


RESULTS
A total of 112 patients completed the study. The incidence of postoperative nausea (31.6% vs 67.6%, P<0.01) and vomiting (15.8% vs 40.5%, <0.05) was significantly lower in group 3 than in group 1. Furthermore, the incidence of severe nausea was significantly lower in group 3 than in group 1 (2.6% vs 24.3%, P<0.05). The rescue antiemetic requirements were also significantly less in group 3 than in group 1 (5.3% vs 24.3%, P<0.05). However, there was no significant difference between group 2 and group 1 in any of the comparisons. Pain intensity, 24-h morphine consumption and diphenhydramine-related side-effects, such as sedation or dry mouth, did not differ among the three groups.


CONCLUSIONS
An initial bolus of diphenhydramine 30 mg at anaesthetic induction followed by postoperative PCA with a 4.8:1, but not 1.2:1, diphenhydramine-morphine mixture provides an effective antiemetic efficacy without morphine-sparing effects.
Lin
T-F
TF
Department of Anesthesiology, National Taiwan University Hospital, 7 Chung San South Road, Taipei, Taiwan.
Yeh
Y-C
YC
Yen
Y-H
YH
Wang
Y-P
YP
Lin
C-J
CJ
Sun
W-Z
WZ
D000328:Adult; D000368:Aged; D016058:Analgesia, Patient-Controlled / Q000379:methods*; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D000932:Antiemetics / Q000627:therapeutic use*; D004155:Diphenhydramine / Q000627:therapeutic use*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006801:Humans; D007044:Hysterectomy; D007262:Infusions, Intravenous; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy; D020250:Postoperative Nausea and Vomiting / Q000139:chemically induced / Q000517:prevention & control
D000701:Analgesics, Opioid; D000932:Antiemetics; D006634:Histamine H1 Antagonists; D009020:Morphine; D004155:Diphenhydramine