When a drug is metabolized by the action of a specific enzyme of the hepatic metabolism phases, it is said that “is substrate” of the enzyme. When this enzyme is the most important pathway through which metabolizes, we talk aboutprimary pathway.
However, in many cases the same drug can also be metabolized in a minority by other enzymes, which in general is usually a mechanism of defense of the body against blockages ( by the action of genetics or xenobiotics), of the primary pathway, to avoid toxic effects. In this case we talk aboutsecondary pathway.
The genetic polymorphisms that affect the enzymes that carry these secondary pathways have clinical effects, except for exceptions, a much smaller effect. That is why when establishing the relationship: “drug – genetic polymorphism – clinical effect and its consequences”, usually the primary pathways are onlyused, in order to simplify, for practical-clinical purposes, the therapeutic decisions to be taken.
Dr. Juan Sabater-Tobella
European Specialist in Clinical Chemistry and Laboratory Medicine (EC4)Member of the Pharmacogenomics Research NetworkMember of the International Society of Pharmacogenomics and Outcomes ResearchPresidente de EUGENOMIC®
Last modified: Nov 20, 2018 @ 5:26 pm