First-pass Effect 2 : This is the chemical alteration resulting from biotransformation of a xenobiotic before it reaches the systemic circulation. Such biotransformation by the liver is referred to as a hepatic first-pass effect
Heriot-Watt University, School of Life Sciences, Some Terms Used In Toxicology and Chemical Safety, Edinburgh, UK 1992. http://www.who.int/ipcs/publications/methods/harmo nization/en/compilation_nov2001.pdf, (Tox and Chem Sfty - Amer) {85}