These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Metabolism of lidocaine by purified rat liver microsomal cytochrome P-450 isozymes.
    Author: Oda Y, Imaoka S, Nakahira Y, Asada A, Fujimori M, Fujita S, Funae Y.
    Journal: Biochem Pharmacol; 1989 Dec 15; 38(24):4439-44. PubMed ID: 2604746.
    Abstract:
    The metabolism of lidocaine was studied using rat liver microsomes or a reconstituted lidocaine monooxygenase system with one of eight forms of cytochrome P-450 purified from liver microsomes from untreated- (P450 UT-2 and UT-5), phenobarbital- (P450 PB-1, PB-2, PB-4, and PB-5) or 3-methylcholanthrene- (P450 MC-1 and MC-5) treated rats. A reverse phase high-performance liquid chromatography system capable of simultaneously assaying four major lidocaine metabolites, namely, monoethylglycinexylidide (MEGX), 3-hydroxylidocaine (3-OH LID), methylhydroxylidocaine (Me-OH LID) and glycinexylidide (GX), was employed to determine the rate of formation of each metabolite. Untreated microsomes generated MEGX, Me-OH LID, and 3-OH LID, but the formation of GX was not detected. In male rat liver microsomes, MEGX was the major metabolite of lidocaine when a concentration of 1 mM was employed. The formation of MEGX and Me-OH LID was increased significantly (P less than 0.01) by microsomes from phenobarbital-treated rats, and the formation of 3-OH LID was increased with 3-methylcholanthrene. The study with the reconstituted system with purified cytochrome P-450 isozymes revealed that all eight forms of cytochrome P-450 used have an ability to N-deethylate lidocaine to form MEGX. Among these isozymes, cytochrome P450 PB-4 and P450 UT-2 showed a higher turnover number for the formation of MEGX. Me-OH LID was formed exclusively by P450 PB-5, and 3-OH LID exclusively by P450 MC-1. Selectivity of cytochrome P450 PB-5 for aromatic methyl hydroxylation of lidocaine was confirmed by an inhibition study; formation of Me-OH LID by microsomes of rats treated with phenobarbital was inhibited completely by antibody against P450 PB-5. It was concluded that different cytochrome P-450 isozymes metabolize lidocaine with a different rate and different position selectivities. Since a specific substrate of cytochrome P450 PB-5 (P-450e) is not known, lidocaine may be a useful substrate for the identification of P450 PB-5.
    [Abstract] [Full Text] [Related] [New Search]