Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2024 Oct 22;22:961. doi: 10.1186/s12967-024-05737-z

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2024

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

PMC Copyright notice

Fig. 2 — Caffeine metabolism pathway and metabolites. Caffeine is primarily metabolized in the liver, undergoing demethylation and oxidation. The main route of caffeine metabolism in humans is via CYP1A2 catalyzed N-3 demethylation to paraxanthine (around 84%), N-1 demethylation to theophylline (around 8%) and N-7 demethylation to theobromine (around 8%). Other than theobromine, paraxanthine, and theophylline, the major metabolites in urine are 3-methylxanthine, 1-methylxanthine, 1-methyl uric acid, 5-acetylamine-6-formylamine-3-methyluracil (AFMU), 5-acetylamino-6-amino-3-methyluracil, 1,7-dimethyl uric acid and 3,7-dimethyl uric acid, which are secondary metabolites of theobromine, paraxanthine, and theophylline catalyzed by CYP1A2, CYP2A6, N-acetyltransferase 2 and xanthine oxidase