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en.wikipedia.org/wiki/First_pass_effect

The first pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism whereby the concentration of a drug, specifically when administered orally, is greatly reduced before it reaches the systemic circulation. It is the fraction of drug lost during the process of absorption which is generally related to the liver and gut wall.

medical-dictionary.thefreedictionary.com/first-pass+metabolism

first-pass metabolism the intestinal and hepatic degradation or alteration of a drug or substance taken by mouth, after absorption, removing some of the active substance from the blood before it enters the general circulation. Synonym(s): first-pass effect first-pass me·tab·o·lism , first-pass effect (fĭrst-pas mĕ-tab'ŏ-lizm, e-fekt') The ...

www.ncbi.nlm.nih.gov/pubmed/6362950

First-pass elimination takes place when a drug is metabolised between its site of administration and the site of sampling for measurement of drug concentration. Clinically, first-pass metabolism is important when the fraction of the dose administered that escapes metabolism is small and variable.

www.hempurecbd.com/what-is-firstpass-metabolism

In medical terms, first-pass metabolism or presystemic metabolism is defined as the rapid uptake and metabolism of an active compound into inactive compounds by the liver, immediately after enteric absorption and before it reaches the systemic circulation.

www.sciencedirect.com/.../first-pass-effect

A first-pass effect is defined as a low systemic availability of the drug as a result of significant metabolism. Although a first-pass effect can occur in a variety of tissues, including the intestines Doherty and Pang (1997) and uterus De Ziegler et al (1997), it is most often observed with the liver. Drug absorbed from the gastrointestinal tract travels immediately to the liver through the ...

www.magonlinelibrary.com/doi/abs/10.12968/npre.2017.15.6.303

All drugs given by the oral route undergo a degree of first pass metabolism either in the gut or the liver, with some drugs being destroyed before they reach the systemic circulation. This pharmacokinetic process affects the bioavailability of drugs administered by this route and is an important consideration for the prescriber.

study.com/academy/lesson/the-first-pass-effect-in-pharmacology.html

The First Pass Effect. When you take a medication by mouth, it doesn't just magically get into your body and start doing its thing. It actually has to go through a whole host of organs and a big ...

www.researchgate.net/post/Can_someone_provide_a_simple_explanation_for_the_1st...

With most psychoactive substances, first pass liver metabolism can make a very significant difference in the amount of the drug that ends up reaching the brain and other organs. When a patient is ...

pharmawiki.in/.../uploads/2014/01/Bioavailability-And-First-Pass-Metabolism.pdf

4. first pass metabolism 5. primary systems effect presystemic metabolism 6. hepatic enzymes 7. drug interactions involving drug metabolism 8. evidences of first pass effect 9. liver extraction ratio 10. relationship between absolute bioavailability and liver extraction 11. estimation of reduceds bioavailability due to liver metabolism ...

www.encyclopedia.com/.../first-pass-metabolism

first-pass metabolism n. a process in which a drug administered by mouth is absorbed from the gastrointestinal tract and transported via the portal vein to the liver, where it is metabolized. As a result, in some cases only a small proportion of the active drug reaches the systemic circulation and its intended target tissue. First-pass metabolism can be bypassed by giving the drug via ...