Enhancement of the epidural morphine-induced analgesia by systemic nifedipine.

We evaluated postoperative pain relief and incidence of side effects of the combination of epidural morphine (0.5 mg) and sublingual nifedipine (10 mg). Thirty-six patients were submitted to elective operations and divided into 4 groups receiving placebo (groups A and B) or morphine (groups C and D) by the epidural route, followed by sublingual placebo (groups A and C) or nifedipine (groups B and D) administered in a double-blind fashion. The mean (+/- S.E.M.) periods of analgesia were 16.6 +/- 1.6 (A), 15 (B) 105 +/- 77.0 (C), and 428.8 +/- 72.0 (D) min. No patient had pruritus, excessive sedation or respiratory depression. Episodes of nausea and/or vomiting requiring no specific therapy were observed in groups A, B and D. Nifedipine-treated groups also had a significant fall in blood pressure which was controlled by rehydration. These results indicate that epidural morphine-induced postoperative pain relief may be enhanced by systemic administration of nifedipine, with easily controlled side effects.