ABSTRACT
To study the mechanism of CAIMA (Computer assisted instant monitoring drug administration), atracurium, a new non - depolarizing muscle relaxant was used in isolated rat diaphragm. The doses and administration rate were precisely controlled by using an improved flowing-bath system. The results showed that with increasing drug concentration, onset time shortened,over-shoot time prolonged, initial recovery rate reduced and onset rate, over-shoot extent and recovery index increased. The over-shoot existed at any pharmacologically effective concentrations and it was positively correlated to drug concentration. As a result of need-dependent and intermittent (pulsatil) drug administration, one maximally profited effect from over-shoot, that is, the effect could be maintained with over-shoot at the administration interval. Hence, the total dose could be dramatically reduced. Furthermore, for a given effect, it needs lower drug concentration with CAIMA than with classical methods and so the effect was nuch more stable.