What is the "first-pass effect" of drugs?

Question

How PO (oral) drugs are affected?

Answer 1

The first pass effect is the change (more commonly, decrease) in activity of the drugs in the body after being ingested orally. This is because after absorption in the intestines, the drugs are carried directly to the liver where they are metabolized to other substrates, either more active or inactivated forms of the drug. To avoid this phenomenon, drugs are administered via different routes, like IV and sublingual. Sublingual administration does not decrease the drug effect because the drugs are not carried directly to the liver.

Answer 2

First Pass Effect

Answer 3

When they pass thru liver were drugs are metabolized and transformed into other substances with or without pharmacologic effect. Some drugs when pass thru liver get inactivated so it’s not good, and others transforms into its active forms, so to avoid this “first pass metabolism” it’s preferred be given IV

Answer 4

the 1st pass effect occur by the dose of the drug reach the circulation again after passing through the liver and being detoxified