3. Metabolism: what happens to absorbed chemicals?

The products we ingest (food, drugs) or which enter the body are transformed by the action of our "internal biochemical factory" according to detoxification mechanisms in order to be :

• or used as energy or constituents;

• or neutralized and excreted.

The liver is the main organ, containing an abundance of enzymes that transform the chemical substance into polar, water-soluble metabolites that are more easily excreted via the urinary tract. Untransformed lipophilic elements are stored in the bile and excreted in the small intestine for reabsorption or excretion in the faeces.

Metabolism generally takes place in two phases.

• Phase I: transformation of the substance by redox and hydrolysis. Oxidations catalyzed...