[The influence of heparin administration on the plasma protein binding of lidocaine during epidural anesthesia].
The influence of heparin administration on the protein binding of lidocaine was investigated in this study. Epidural anesthesia was conducted in 20 patients undergoing vasoconstructive surgery, and the changes of lidocaine concentration and its protein binding ratio after heparin administration were estimated. Protein binding ratio of lidocaine decreased rapidly after the commencement of heparin injection until attaining the minimal rate of 50.3 +/- 8.8%, and it then recovered gradually. There was a distinct negative correlation between the reduction in protein binding ratio of lidocaine and the increase of non-esterified fatty acid (NEFA) based on the activated lipoprotein lipase after heparin administration. This reduction of protein binding ratio after heparin was in safety range so that practically no dangerous adverse reaction was seen in these patients. The detailed mechanism was elucidated in an in vitro study. Normal concentration of NEFA (300 microEq.l-1) increased the protein binding ratio of lidocaine, and high concentration of NEFA (1800 microEq.l-1) decreased the ratio on human serum albumin (HSA). Heparin (1.0 unit.ml-1) itself, however, showed no influence for protein binding ratio onto HSA. Concerning alpha 1-acid glycoprotein (AAG), NEFA did not show any influence on the binding ratio, and heparin decreased it little. Consequently, it can be said that the protein binding ratio of lidocaine was mainly affected by NEFA concentration.
Nozaka
T
T
Department of Anesthesiology, Asahikawa Medical College.
D000368:Aged; D000767:Anesthesia, Epidural; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D008012:Lidocaine / Q000378:metabolism*; D008875:Middle Aged; D011485:Protein Binding / Q000187:drug effects; D012709:Serum Albumin / Q000378:metabolism*; D014656:Vascular Surgical Procedures
D012709:Serum Albumin; D006493:Heparin; D008012:Lidocaine