Liver gets the first opportunity to filter oral drugs before the rest of body. Agents like vitamin C are given to cancer patients intravenously because the liver is so effective.
Your understanding of the process of food getting into the body is a bit off.
Our intestines directly pass nutrients into our circulatory system (blood). There is nothing that routes to the liver over all the other organs, first.
https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works