[Potentiation of the effect of non-depolarizing muscle relaxants by acylaminopenicillins. Studies on the example of vecuronium].

In a prospective controlled clinical study interactions between nondepolarizing muscle relaxants and acylaminopenicillins were investigated electromyographically. Six patients in each group received either apalcillin, azlocillin, mezlocillin or piperacillin during the operation. Muscle relaxation was maintained using the short acting nondepolarizing relaxant vecuronium, which shows no cumulative effect within clinical dosages. The intra-individual comparison with the control period (100%) showed a significant prolongation of the duration of action after a fixed dose of vecuronium. The mean increase was +26% following apalcillin, +46% after piperacillin, +38% following mezlocillin and +55% following azlocillin. The shortest time of the control periods was 8.6 min and the maximum time was 32.6 min. We also found a significant depression of the EMG-response. No significant differences could be detected between the four antibiotics. The method described here has proven to be sensitive enough to detect clinically relevant interactions with muscle relaxants. As a result of our study, caution seems to be necessary if acylaminopenicillins are administered in the early postoperative period.