The interaction of tilidine and pethidine in postoperative pain.

The mode of interaction between the new, non-narcotic analgesic tilidine and pethidine was studied in the treatment of postoperative pain. The potency ratio 3:1 (pethidine:tilidine) found previously was used in the comparison. Thus 0.25 mg/kg of pethidine with 0.75 mg/kg of tilidine and 0.5 mg/kg of pethidine with 1.5 mg/kg of tilidine were compared with 0.5 mg/kg and with 1.0 mg/kg of pethidine. These drug combinations proved to be equipotent with the pethidine dosages used. Consequently the mode of interaction seemed to be additive synergism. The onset of action was slightly faster with pethidine, but the duration of action was longer with pethidine-tilidine combinations. Respiratory depression and sedation were less evident after pethidine-tilidine combinations than after equianalgesic doses of pethidine. Circulatory effects were similar in all groups. No statistical difference in other side effects could be demonstrated between the groups.