Duration of anesthetic effect for Carbocaine (mepivacaine) and Xylocaine (lidocaine)

Fråga: What is the duration of anesthetic effect for Carbocaine (mepivacaine) and Xylocaine (lidocaine) in foot block anesthesia?

Svar: The half-life for mepivacaine is 1.9 hours during elimination (1). The half-life of lidocaine and its active metabolite monoethylglycinexylidide after an intravenous bolus dose is about 1.5-2 and 2,5 hours (2). A search of the literature was directed at studies comparing the duration of effect of the drugs administered locally. Only older comparative reports were found.

In a case series of 40 patients 5-6 ml 1 % lidocaine or 2 % mepivacaine was given for regional anesthesia during surgery on the anterior part of the foot. N. peroneus superficialis was blocked at the ankle and n. tibialis posterior behind the medial malleolus. Alimemazine or droperidol and pethidine, and atropine were given as pre-medication. The effect of 1 % lidocaine lasted for between 90 and 120 minutes whereas the effect of 2 % mepivacaine lasted for between 240 and 360 minutes (3).

Twelve healthy volunteers were given local anesthetics for anesthesia of the mouth in another study. An effect was seen that lasted in average 31,4 minutes (SD 16,1) for 3 % lidocaine, 20,7 minutes (SD 19,0) for 2 % lidocaine, and 4,6 minutes (SD 4,4) for 3 % mepivacaine. These differences were significant with a 98 % confidence interval. The anesthesia was effective at maximum stimulation in 100 % of the cases with 3 % lidocaine, 75 % of the cases with 2 % lidocaine and 58,3 % with 3 % mepivacaine, all administered in 0,5 ml doses (4).

In a third study different local anesthetics for ulnar block was compared in 35 healthy volunteers. In average first sensation of pain occurred after 99 minutes for mepivacaine and 40 minutes for lidocaine. Complete return of pain sensation occurred after 133 and 65 minutes respectively. Subjects received 1 ml 0,5 and 1 % solutions of lidocaine and mepivacaine. No differences in effect duration were observed between the different administered concentrations for each substance (5).

CONCLUSION

Few studies were identified on the subject. Comparisons of effect duration depend on the strength and dose of the drugs compared as well as the locale for administration. Comparisons between different studies on the matter with different circumstances are therefore difficult. In a case series of regional anesthesia during foot surgery the effect of 1 % lidocaine lasted for between 90 and 120 minutes whereas the effect of 2 % mepivacaine lasted for between 240 and 360 minutes. Fass. Carbocain (mepivacain) AstraZenea (cited 2010-11-15) Fass. Xylocain (lidokain) AstraZeneca (cited 2014-03-14) Boussaton E, Rigaud J, Pech C, Baudet B, Gay R. (Locoregional anesthesia of the foot for forefoot surgery). (Article in French) Ann Fr Anesth Reanim 1985;4(5):395-7 von Ballmoos E, Graf H. (Effect of different local anesthetics in a double-blind trial). (Article in German) SSO Schweiz Monatsschr Zahnheilkd 1982 Jan;92(1):21-8 Albert J, Lofstrom B. Bilateral ulnar nerve blocks for the evaluation of local anaesthetic agents. Acta Anaesthesiol Scand 1961;5:99-105