ARE TRAMADOL-ENANTIOMERS MORE SUITABLE FO R POSTOPERATIVE PAIN THERAPY THAN THE RACEMATE - A RANDOMIZED, PLACEBO-CONTROLLED AND MORPHINE-CONTROLLED DOUBLE-BLIND-STUDY

The goal of this prospective, randomised and double-blind pilot-study was to investigate the analgesic potency and the side-effects of trama dol enantiomers in clinical practice. One hundred patients recovering from orthopaedic surgery with a postoperative pain intensity of more t han 50 on a visual analogue scale 0-100 mm (Table 1)were recruited for the study. They were treated in a randomised, double-blind way with a maximal dose of 150 mg i.v. (+)-, (-)-tramadol, racemate, or 15 mg i. v. morphine or saline in the placebo group (5 groups, 20 patients each ). The primary criterium of efficacy was the number of responders defi ned as patients with a pain reduction of at least 20 on VAS after 40 m in. ln case of pain, responders were allowed to continue with the doub le-blind drug up to six hours. The non-responders were treated with mo rphine as the res cue analgesic. The secondary criterium was the incid ence and severity of side-effects. Six patients terminated the study p rematurely. One patient was excluded because of an allergic reaction t o morphine, one patient could not be treated sufficiently with morphin e four were excluded because of protocol violations. There were 8 resp onders in the (+)-tramadol-,6 in the (-)-tramadol-and 6 in the racemat e group, 16(P<0,05) in the morphine group, and 5 in the placebo group . Pain intensity after 40 min was reduced by 20 (p<0,05), 17(p<0,05), 17(p<0,05),36 (p<0,01 vs placebo, p<0,05 vs (+)-,(-)tramadol,and racem ate group) and 5 mm on the VAS in the (+)-,(-)-, (+/-)-tramadol-, morp hine-and placebo-group, respectively. Thirty eight adverse events like nausea, vomiting, PCO2-in crease, and urinary retention occurred in 2 0 patients, most frequently in the (+)-tramadol-and morphine group. Se dation was significantly less profound in the (-)-tramadol group 1-4 h postoperatively. There were no side-effect in the tramadol racemate g roup. The enantiomers were equal to the racemate in analgesic potency, but inferior by far to morphine. They showed more adverse events and, hence, can not be preferred to the racemate in postoperative pain the rapy.