bioavailability

Bioavailability is the degree to which a substance is able to enter the body and be used by it. It is important because it determines how much of a drug or other substance will be actually absorbed in the body, and how much will be left over. For example, if you take a pill with 100 milligrams of a drug, but the drug has low bioavailability, then it might mean that only 10 milligrams actually get into your body.