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 is greatly reduced before it reaches the systemic circulation.
Good & thanks. The first-pass effect is the biotransformation and/or excretion of a drug by intestinal and hepatic, including biliary, mechanisms following absorption of the drug from the gastrointestinal tract (GIT), before the drug gains access to the systemic circulation.
Yes Sir,
The systemic circulation every time bring blood to liver usually a part of drug get metabolized and pharmacokinetics studies have revealed the first pass effect depend on many parameters such as-
1. Physiochemical property of drug
2.Affinity to bind with plasma protein
3. Patholgical conditions where degradative enzyme have more activity
4. and many more
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