Etidocaine differs from lidocaine by the addition of an alkylchain and the extension of one ethyl group on the tertiaryamine to a butyl group. The additional lipophilicity givesetidocaine a quicker onset, longer half-life, and an increasedpotency compared with lidocaine. This may make etidocainedesirable for use when A and C nerve fibers are beinganesthetized for long surgical procedures (＞2 hours).Thetertiary nitrogen pKa is 7.74, which is similar to lidocaine’spKa (7.8).
Clinical Use
Etidocaine is the most potent amino amide local anestheticand is used for epidural anesthesia, topical anesthesia,and for peripheral nerve or plexus block. Etidocaine blockslarge fast-conducting neurons quicker than the sensory neuronsand may leave epidural patients unable to move yetsensitive to painful procedures. Etidocaine has the samepotential for cardiac toxicity as bupivacaine and the decreasedreports probably are results of the decreased use ofetidocaine.
