first-pass effect

https://doi.org/10.1351/goldbook.FT06824
@B00667@ and, in some cases, @E02038@ of a substance in the liver after absorption from the intestine and before it reaches the @ST06802@ circulation.
Source:
PAC, 2004, 76, 1033. (Glossary of terms used in toxicokinetics (IUPAC Recommendations 2003)) on page 1052 [Terms] [Paper]