Open AccessEnhancement of Bupivacaine Sensory Blockade of Rat Sciatic Nerve by Combination With Phenol
Author(s) -
Grigory Kizelshteyn,
Mosses Bairamian,
Mario A. Inchiosa,
Joseph E. Chase
Publication year - 1992
Publication title -
anesthesia and analgesia/anesthesia and analgesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.404
H-Index - 201
eISSN - 1526-7598
pISSN - 0003-2999
DOI - 10.1213/00000539-199204000-00005
Subject(s) - bupivacaine , medicine , sciatic nerve , blockade , anesthesia , saline , local anesthetic , nerve block , sensory system , sensory nerve , psychology , receptor , cognitive psychology
We sought to determine whether the addition of phenol would enhance a bupivacaine nerve block. The effects on nerve conduction of bupivacaine (0.125%) and phenol (0.5%), singly and combined, were evaluated in vivo on the rat sciatic nerve. Three groups of 10 animals each were used. The left sciatic nerve was infiltrated with 0.125% bupivacaine, 0.5% phenol, or a solution that contained 0.125% bupivacaine and 0.5% phenol. The right limb served as control (saline injected). Motor deficits (visual assessment) and sensory blockade (hot-plate assay) were evaluated at 30-min intervals after injection. Phenol injected alone produced no motor blockade. The incidence of motor blockade at 30 min for 0.125% bupivacaine was 70% (P = 0.003), and for the combination treatment, 80% (P = 0.001). The analgesia score derived from the hot-plate test was more and persisted longer for the combination treatment than for either 0.125% bupivacaine or 0.5% phenol given singly; e.g., the average sensory block score after 150 min for the combination treatment was 1.0 compared with 0.1 for either bupivacaine or phenol given alone (P = 0.003). Analysis of the areas under the sensory score-time curves also demonstrated enhanced blockade from the combination treatment, which would be consistent with a synergism of the separate Na(+)-channel blocking effects of charged and uncharged local anesthetics. These findings may suggest other candidates for clinically useful combinations of amine and neutral local anesthetics.