The FDA publishes a book called Approved Drug Products with Therapeutic Equivalence Evaluations, which is more commonly known as the:

The Orange Book identifies drug products approved on the basis of safety and effectiveness by the FDA. It also contains therapeutic equivalence evaluations for generic drugs, using Therapeutic Equivalence codes such as AA, AB, BC, and BD. If the first letter of the code is an ‘A’, the FDA has concluded that the generic formulation is therapeutically equivalent to the reference drug. If the first letter is a ‘B’, the FDA has concluded that the compared drugs are not equivalent. The second letter of the code gives more detailed information about formulations. The Orange Book also lists the patents which are purported to protect each drug.