Postoperative analgesia using a low-dose, oral-transdermal clonidine combination: lack of clinical efficacy.
OBJECTIVE
To determine if a lower than previously reported oral-transdermal clonidine regimen could reduce postoperative morphine requirements without producing systemic side effects.


METHODS
Double-blind, randomized, placebo-controlled study.


METHODS
University-affiliated hospital.


METHODS
29 healthy, ASA physical status I and II females undergoing elective abdominal hysterectomy.


METHODS
Patients received preoperative oral clonidine 4 to 5 mu/kg and a 7 cm2 transdermal clonidine patch (0.2 mg/24 hours) or a placebo tablet and patch.


RESULTS
Postoperative patient-controlled analgesia pumps provided morphine during the 48-hour study period. Morphine use, hemodynamic changes, and nonhemodynamic side effects were recorded. Additionally, visual analog pain scales (VAPS) and plasma concentrations of morphine and clonidine were measured. We found that low-dose clonidine had no potentiating effect on morphine analgesia. Postoperative morphine use, VAPS, and morphine plasma levels were similar between the control and clonidine-treated groups. Nevertheless, patients in the clonidine group experienced a significantly greater incidence of intraoperative and postoperative hypotension and bradycardia than did the control group. No differences were noted in the incidence of nonhemodynamic side effects.


CONCLUSIONS
The low-dose oral-transdermal clonidine regimen evaluated failed to reduce postoperative morphine requirements, although patients who received clonidine were still at risk for developing hypotension.
Owen
M D
MD
Department of Anesthesiology, Saint Luke's Hospital of Kansas City, MO, USA.
Fibuch
E E
EE
McQuillan
R
R
Millington
W R
WR
D000279:Administration, Cutaneous; D000284:Administration, Oral; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007044:Hysterectomy; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy*
D000316:Adrenergic alpha-Agonists; D000701:Analgesics, Opioid; D004338:Drug Combinations; D009020:Morphine; D003000:Clonidine