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Phase I Biotransformation

Meaning

Phase I Biotransformation is the initial metabolic stage of detoxification, primarily occurring in the liver, where lipophilic compounds, including steroid hormones and environmental toxins, are chemically modified to prepare them for subsequent excretion. This process involves introducing or exposing a polar functional group, such as a hydroxyl group, through oxidation, reduction, or hydrolysis reactions. The resulting metabolites are often more chemically reactive and sometimes temporarily more toxic than the parent compound, necessitating a robust Phase II process.