Objectives: To assess the analgesic efficacy and tolerability of co-administration of pre-emptive single oral dose of sustained release morphine and sub- anesthetic ketamine infusion for modified radical mastectomy (MRM) with axillary evacuation.

Methods: Sixty four adult female patients scheduled for MRM were divided to two groups, morphine group (n=32) received preoperative oral sustained release morphine tablet, 30 mg and placebo group (n=32) received placebo tablet. Both groups received preoperative ketamine bolus, 0.5 mg/kg followed by continuous infusion 0.1 mg/kg/h for 24 h postoperatively. VAS pain score, time to first analgesic request, 24 h analgesic consumption were reported.

Results: The mean VAS pain score during movement was significantly decreased in morphine group in comparison to placebo group from 2 h till 72 h postoperatively, 2 h (2.87 ± 1.0 vs. 4.53 ± 1.67) mean difference (-1.67) (95% CI)-(2.38-0.95), 72 h (1.20 ± 0.76 vs. 1.83 ± 0.91) mean difference (-0.63) (95% CI)-(1.07-0.20) while the mean VAS pain score during rest was significantly decreased in morphine group in comparison to placebo group from 2 h till 24 h postoperatively, 2 h (2.03 ± 0.85 vs. 3.47 ± 0.93) mean difference (-1.33) (95% CI)-(1.78-0.90), 24 h (1.40 ± 0.72 vs. 1.77 ± 0.68) mean difference (-0.37) (95% CI)-(0.73-0.01).

The median (IQ) time to first analgesic request was significantly delayed in morphine group in comparison to placebo group, 11.8 (9.7:14.2) h vs. 2.3 (2.1:2.5) h, (P<0.001).

The number (percentage) of patients required paracetamol in the first postoperative 24 h was significantly lower in morphine group in comparison to placebo group, 10 (33%) vs. 30 (100 %) (P<0.001).

Conclusion: Analgesic technique based on pre-emptive sustained release oral morphine and perioperative infusion of sub-anesthetic dose of ketamine provides satisfactory analgesia for patients undergoing MRM.