*2.3. Substrates*

Substrates are drugs that bind to the active site of an enzyme and are transformed into metabolites while being present in this active site. The biotransformation process of a drug may involve multiple enzymes leading to various metabolites; each metabolic route relies on specific characteristics. The strength of attraction between an enzyme and a substrate is measured as the "binding affinity". A substrate can exhibit varying binding affinity for an active site depending on their chemical structure and physical properties. Based on their binding affinity for a specific enzyme, substrates can be classified into weak, intermediate, and strong affinity substrates. Advanced clinical decision support systems (such as MedWise™) depict the various degrees of affinity by different colors: light yellow (weak), dark yellow (intermediate), and orange (strong affinity).
