Résumé
BACKGROUND: Tramadol is a weak opioid agonist with antinociceptive effects through its action on the mu-receptor and by inhibiting the neuronal re-uptake of both noradrenaline and serotonin. Tramadol is commonly used for treatment of mild to moderate post-operative pain. An oral form of sustained-release tramadol (SR) was recently formulated for reducing the administration frequency from qid to bid. OBJECTIVE: To evaluate the analgesic efficacy and safety of two doses of oral tramadol SR for the treatment of pain after modified radical mastectomy. STUDY DESIGN: Randomized, double blind, placebo-controlled trial. METHOD: Fifty women were randomly allocated to receive either tramadol SR 100 mg (group T), or placebo tablet (group P) orally approximately 1 hour before surgery with a repeat dose administered 12 hours later by nurses not apprised of the patient groupings. All patients received the standard general anesthesia. Post-operatively, nurses in the research team assessed pain using a visual analog scale 0-100 mm at rest (rVAS) and during arm movements (mVAS) at admission to postanesthesia care unit (PACU) (T0) and 2 (T2), 6 (T6), 12 (T12) and 24 (T24) hours after surgery. Rescue analgesia was provided for 24 hours via a morphine-loaded patient-controlled analgesia (PCA) device at 1 mg bolus with a 5-minute lockout interval. Cumulative morphine consumption and adverse events were recorded. RESULTS: Twenty-five patients with comparable baseline characteristics from each group were studied. The proportions of patients with VAS > 30 (both rVAS and mVAS) at each measurement period were not significantly different between the groups except for the mVAS at T24, where the proportion in group T was higher than group P (48% vs 20%, 95% CI of difference: -53%, -3%, p = 0.04). The median morphine consumption in both groups at T2, T6, T12 and T24 were comparable. No serious adverse effects were observed; however, patients in group T reported nausea and vomiting more than group P (56% vs 24%, p = 0.02). CONCLUSION: Two doses of oral tramadol SR 100 mg had no effect on post-operative pain scores and morphine consumption in patients who underwent modified radical mastectomy. In fact, more patients in the tramadol group reported nausea and vomiting than the placebo group.