First pass effect | EPFL Graph Search

Are you an EPFL student looking for a semester project?

Work with us on data science and visualisation projects, and deploy your project as an app on top of GraphSearch.

The first pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism at a specific location in the body which leads to a reduction in the concentration of the active drug, specifically when administered orally, before it reaches the site of action or systemic circulation. It is the fraction of drug lost during the process of absorption which is generally related to the liver and gut wall. The liver is the major site of first pass effect; it can also occur in the lungs, vasculature or other metabolically active tissues in the body. Notable drugs that experience a significant first-pass effect are buprenorphine, chlorpromazine, cimetidine, diazepam, ethanol (drinking alcohol), imipramine, insulin, lidocaine, midazolam, morphine, pethidine, propranolol, and tetrahydrocannabinol (THC). First pass metabolism may occur in the liver (for propranolol, lidocaine, clomethiazole, and NTG) or in the gut (for benzylpenicillin and insulin). After a drug is swallowed, it is absorbed by the digestive system and enters the hepatic portal system. It is carried through the portal vein into the liver before it reaches the rest of the body. The liver metabolizes many drugs, sometimes to such an extent that only a small amount of active drug emerges from the liver to the rest of the circulatory system. This first pass through the liver thus may greatly reduce the bioavailability of the drug. An example of a drug where first pass metabolism is a complication and disadvantage is the antiviral drug, Remdesivir. Remdesivir cannot be orally administered because the entire dose would be trapped in the liver with little reaching the systemic circulation and reaching organs and cells affected by, for example, SARS-CoV-2. For this reason, Remdesivir is administered by IV infusion, bypassing the portal vein. However, significant hepatic extraction still occurs because of second pass metabolism, whereby a fraction of venous blood travels through the hepatic portal vein and hepatocytes.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts (28)

Related courses (2)

CH-332: Medicinal chemistry

Sitting at the crossroad of organic chemistry and medicine, this course outlines how an initial hit compound transitions into a lead candidate, and ultimately a drug, in the modern drug discovery worl

BIO-478: Pharmacology and pharmacokinetics

This course introduces the student to the fudamentals of pharmacology, pharmacokinetics and drug-receptor interactions. It discusses also pharmacogenetics and chronopharmacology, to exemplify the chal

Related lectures (2)

Explores drug absorption, distribution, and clinical implications, focusing on salicylate poisoning and drug trapping in lysosomes.

Explores the historical perspective, properties, and applications of X-rays, including diffraction, atomic resolution, and spectral colors of elements.

Explores drug absorption, distribution, and clinical implications, focusing on salicylate poisoning and drug trapping in lysosomes.

Explores the historical perspective, properties, and applications of X-rays, including diffraction, atomic resolution, and spectral colors of elements.

Drug

A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhalation, injection, smoking, ingestion, absorption via a patch on the skin, suppository, or dissolution under the tongue. In pharmacology, a drug is a chemical substance, typically of known structure, which, when administered to a living organism, produces a biological effect.

First pass effect

Intramuscular injection

Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have larger and more numerous blood vessels than subcutaneous tissue, leading to faster absorption than subcutaneous or intradermal injections. Medication administered via intramuscular injection is not subject to the first-pass metabolism effect which affects oral medications.