No Tachyphylaxis with Prolonged, Continuous Bupivacaine

Tachyphylaxis has been clinically documented by Cohen et al. [1], Bromage et al. [2], and Spoerel et al. [3]. Bromage and his associates reported that a form of acute tolerance, or tachyphylaxis, develops with repeated doses of local anesthetics [2]. In their report on 329 epidural injections in 140 patients, lidocaine, mepivacaine, or prilocaine was used. When intervals between injection were long, the dose response curves decayed exponentially. However, augmentation of response occurred if the interval between disappearance of analgesia and reinjection was shorter. They hypothesized that augmentation was due to the additive effect of subanesthetic residues remaining from the previous injection. Tucker and Mather simulated a regimen for postoperative pain relief using continuous epidural infusion of lidocaine [4]. They predict that there should be considerable local accumulation without corresponding diminution of the required anesthetic dosage.