Compatibility of tramadol hydrochloride injection with selected drugs and solutions

T ramadol hydrochloride is a cen-trally acting synthetic analgesicwith a dual mechanism of action.1,2 Tramadol and its O-desmethyl metabolite (M1) bind to opioid receptors, with M1 having a 200-fold higher affinity for binding to these receptors. Tramadol has also been shown to inhibit the uptake of norepinephrine and serotonin, sug-gesting that its antinociceptive activi-ty is mediated by both opioid and nonopioid mechanisms.1,3 In pa-tients with diabetic neuropathy, therapy with oral tramadol resulted in low pain scores and high pain-relief scores.4 Tramadol produced ef-fective analgesia with minimal ad-verse effects in cancer patients with chronic pain.5 Tramadol is also a use-ful alternative in patient-controlled epidural analgesia when patients cannot receive combined spinal– epidural analgesia for labor pains.6 There are some clinical situations in which tramadol must be combined with other drugs, such as for patients with postoperative pain who requir