High affinity of quinidine for a stereoselective microsomal binding site as determined by a radioreceptor assay

Experientia. 1984 Sep 15;40(9):973-4. doi: 10.1007/BF01946465.


The techniques of the radioreceptor binding assay were applied to detect stereoselective binding of quinidine and quinine to a site on human liver microsomes. Binding of 3H-dihydroquinidine was 50% inhibited by 20-100 nM quinidine, while its enantiomer quinine did not displace the 3H-ligand at concentrations up to 500 nM. This stereoselectivity agreed with the affinity values measured by functional enzyme assays of cytochrome P450 activity using sparteine or debrisoquine as substrates.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding, Competitive
  • Humans
  • Microsomes, Liver / metabolism*
  • Molecular Conformation
  • Quinidine / analogs & derivatives
  • Quinidine / metabolism*
  • Quinine / metabolism
  • Radioligand Assay


  • hydroquinidine
  • Quinine
  • Quinidine