Take aromatase inhibitors for example. In order for a molecule to stop the enzyme aromatase from converting androgens into estrogens, it must meet 6 criteria:
Not get broken down by the acidity or enzymes in the stomach (or get broken down in a helpful way)
Not get recognized as waste by the body and be absorbed through the small intestine
Not get broken down by the liver (or get broken down in a helpful way)
Get inside the cells that produce aromatase, via diffusion through the cell membrane or through a protein
Stop the production or inhibit the performance of aromatase
Not stop the production or inhibit performance of another enzyme
Despite all these criteria, multiple aromatase inhibitors exist. How did scientist find a molecule that meet all the criteria? What in biology and chemistry are they taking into account?