|(a) The determination of the drug product to be substituted as authorized by the Subchapter A, Chapter 562 of the Act, is the professional responsibility of the pharmacist, and the pharmacist may not dispense any product that does not meet the requirements of the Subchapter A, Chapter 562 of the Act. As specified in Chapter 562 of the Act and § 309.2 of this title (relating to definitions), a generically equivalent product is one that is pharmaceutically equivalent and therapeutically equivalent to the drug prescribed. (b) Pharmacists shall use as a basis for the determination of generic equivalency as defined in the Subchapter A, Chapter 562 of the Act, the following: (1) For drugs listed in the publication, pharmacists shall use Approved Drug Products With Therapeutic Equivalence Evaluations (Orange Book) and current supplements published by the Federal Food and Drug Administration, within the limitations stipulated in that publication, to determine generic equivalency. Pharmacists may only substitute products that are rated therapeutically equivalent in the Orange Book and have an "A" rating. "A" rated drug products include but are not limited to, those designated AA, AB, AN, AO, AP, or AT in the Orange Book. (2) For drugs not listed in the Orange Book, pharmacists shall use their professional judgment to determine generic equivalency.