Involvement of cytochrome P450 3A4 in N-dealkylation of buprenorphine in human liver microsomes

Life Sci. 1997;60(22):1953-64. doi: 10.1016/s0024-3205(97)00160-4.


Buprenorphine is a long acting analgesic of the opiate family. Recently, it has been proposed for the opioid dependency treatment at a large scale. The drug is extensively metabolized by the hepatic cytochrome P450 in man, yielding a N-dealkylated metabolite, norbuprenorphine. The specific forms of P450 involved in this oxidative N-demethylation were examined in a panel of 18 human liver microsomal preparations previously characterized with respect to their P450 contents. Buprenorphine was N-dealkylated with an apparent Km of 89 +/- 45 microM (n = 3). The metabolic rates were 3.46 +/- 0.43 nmol/(min x mg of protein). This metabolic pathway was strongly correlated with 6 catalytic activities specific to P450 3A4 and with the immunodetectable P450 3A content of liver microsomal samples (r = 0.87). Buprenorphine metabolism was 62-71% inhibited by three mechanism-based inhibitors (TAO, erythralosamine, gestodene), by nifedipine as competitive inhibitor (Ki = 129 microM) and by ketoconazole 0.6 microM (25% residual activity), all these inhibitors specific to P450 3A. Among 10 heterologously expressed P450s tested, only P450 3A4 was able to dealkylate buprenorphine with a turnover number of 9.6 min(-1). Morever, this catalytic activity was inhibited up to 80% (vs control) by anti-rat P450 3A antibody. Taken together, all these data demonstrate that P450 3A4 is the major enzyme involved in hepatic buprenorphine N-dealkylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkylation
  • Buprenorphine / antagonists & inhibitors
  • Buprenorphine / pharmacokinetics*
  • Chromatography, High Pressure Liquid
  • Cytochrome P-450 CYP3A
  • Cytochrome P-450 Enzyme System / metabolism*
  • Humans
  • Microsomes, Liver / metabolism*
  • Mixed Function Oxygenases / metabolism*
  • Narcotic Antagonists / pharmacokinetics*
  • Substrate Specificity


  • Narcotic Antagonists
  • Buprenorphine
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • CYP3A protein, human
  • Cytochrome P-450 CYP3A