Tennessee Code Title 53. Food, Drugs and Cosmetics § 53-10-208

(a) In making substitutions as allowed by this part, the pharmacist may use drugs and drug products manufactured within the territorial limits of any one (1) of the states of the United States, or of any other country, if the products have been approved by the federal food and drug administration (FDA), and have been given an “A” therapeutic equivalent rating by the FDA in the agency's publication, “Approved Drug Products with Therapeutic Equivalence Evaluations”, also known as the “Orange Book”. “A” rated drug products are those that the FDA considers to be therapeutically equivalent to other pharmaceutically equivalent products, including, but not limited to, drug products for which:

(b) This section shall not apply to generic drugs and drug products that have not been rated.

(c) For those drugs that have not been evaluated and rated for bioequivalency by the FDA, pharmacists are permitted to use their professional judgment in selecting a generic product for substitution.