### Question
What does bioavailability mean?


### Answer
**Bioavailability** has the following meaning in *21 U.S.C. § 355*:

> the rate and extent to which the active ingredient or therapeutic ingredient is absorbed from a drug and becomes available at the site of drug action

#### Citation:
  - *21 U.S.C. § 355*
  - Heading: **CHAPTER 9-FEDERAL FOOD, DRUG, AND COSMETIC ACT > SUBCHAPTER V-DRUGS AND DEVICES > Part A-Drugs and Devices**

