Send to

Choose Destination
Pharmacology. 2009;83(6):356-9. doi: 10.1159/000217584. Epub 2009 May 7.

Comparison of the potency of lidocaine and chloroprocaine in sciatic nerve block in Sprague-Dawley rats.

Author information

Department of Anesthesiology, New York Methodist Hospital, Brooklyn, NY 11215, USA.



This study investigates the relative potencies and ED(50) of the local anesthetics lidocaine and chloroprocaine in a sciatic block in Sprague-Dawley rats.


The study involved 80 rats (chloroprocaine n = 40, lidocaine n = 40). Each rat was injected close to the sciatic nerve with 0.1 ml of the concentration of local anesthetic being tested. Using the up-and-down allocation technique, the next concentration was determined by the response of the previous subject to a higher or lower concentration. A successful block was assessed by pinching the fifth metatarsal. Absent vocalization and a very weak withdrawal response were defined as the onset of block.


Using the up-and-down methodology, the estimates of ED(50) for chloroprocaine was 0.1 ml of 1.2% (with 95% CI of 1.1-1.6), and that for lidocaine was 0.1 ml of 0.65% (with 95% CI of 0.65-0.88), giving a lidocaine/chloroprocaine potency ratio of 1.85 (with 95% CI of 1.66-2.61).


Using the results of this study, the effects of the two drugs can be compared using the commercially available concentrations of chloroprocaine and lidocaine in a peripheral nerve block.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for S. Karger AG, Basel, Switzerland
Loading ...
Support Center