[A comparative study of membrane destructive action of dibucaine HCl and bupivacaine HCl].
Membrane destructive action of dibucaine HCl and bupivacaine HCl was examined in vitro using red blood cells. The EC50 value (local anesthetic concentration needed to destroy half of red blood cells in vitro) of each local anesthetic was determined at pH 5.0, 6.0 and 7.0 to obtain a pH-EC50 curve. The pH change of each commercially available local anesthetic solution (0.3% dibucaine HCl and 0.5% bupivacaine HCl) was also determined with the dilution by cerebrospinal fluid to yield a pH-concentration curve. The EC50 values of dibucaine HCl were 0.17%, 0.18% and 0.13% at pH 5.0, 6.0 and 7.0, respectively. The EC50 values of bupivacaine HCl were 1.36% and 1.36% at pH 5.0 and 6.0, respectively. The EC50 value of bupivacaine HCl at pH 7.0 could not be measured for the low solubility in water at pH 7.0. The pH-EC50 curve of dibucaine HCl intersected the pH-concentration curve, although the pH-EC50 curve of bupivacaine located in the right side (higher concentration) for the pH-concentration curve of bupivacaine HCl, which implies clinical level of dibucaine HCl may produce membrane destruction action and low possibility of membrane destruction with clinical level of bupivacaine HCl.
Katsuki
Hiroshi
H
Department of Anesthesia, Miyazaki Shigun-Ishikai Hospital, Miyazaki 880-0834.
Komatsu
Miki
M
Egawa
Hisako
H
Nagata
Naoto
N
Takasaki
Mayumi
M
D000779:Anesthetics, Local / Q000009:adverse effects*; D002045:Bupivacaine / Q000009:adverse effects*; D003992:Dibucaine / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000187:drug effects*; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques
D000779:Anesthetics, Local; D003992:Dibucaine; D002045:Bupivacaine