Characterization of the enzyme responsible for the metabolism of sumatriptan in human liver

Biochem Pharmacol. 1994 Mar 29;47(7):1253-7. doi: 10.1016/0006-2952(94)90397-2.


Studies have been undertaken to investigate the enzymes responsible for the metabolism of [14C]sumatriptan in man. Oxidative deamination of sumatriptan to form the indole acetic acid derivative is the only phase 1 pathway evident in man and both cytochrome P450 (P450) and monoamine oxidase (MAO) are capable of catalysing this type of reaction. The metabolism of [14C]sumatriptan was therefore investigated in vitro in a preparation derived from human liver, which was shown, by the use of the probe substrates [14C]testosterone (P450), [3H]5HT (MAO-A) and [14C]benzylamine (MAO-B) to be a rich source of both enzyme systems. Incubation with clorgyline and deprenyl, probe inhibitors of MAO-A and MAO-B, respectively, showed that [14C]sumatriptan was metabolized by MAO-A; there was no evidence of P450 involvement in its metabolism. The data in this study therefore indicate that the enzyme MAO-A is the major enzyme responsible for the metabolism of sumatriptan in human liver.

MeSH terms

  • Clorgyline / pharmacology
  • Female
  • Humans
  • Liver / enzymology*
  • Male
  • Monoamine Oxidase / metabolism*
  • NADP / pharmacology
  • Selegiline / pharmacology
  • Sumatriptan / metabolism*


  • Selegiline
  • NADP
  • Sumatriptan
  • Monoamine Oxidase
  • Clorgyline