Drug products classified as therapeutically equivalent can be substituted with the full expectation that the substituted product will produce the same clinical effect and safety profile as the prescribed product. Drug products are considered to be therapeutically equivalent only if they meet these criteria:

• they are pharmaceutical equivalents (contain the same active ingredient(s); dosage form and route of administration; and strength.)
• they are assigned by FDA the same therapeutic equivalence codes starting with the letter "A ." To receive a letter "A", FDA
• designates a brand name drug or a generic drug to be the Reference Listed Drug (RLD).
• assigns therapeutic equivalence codes based on data that a drug sponsor submits in an ANDA to scientifically demonstrate that its product is bioequivalent (i.e., performs in the same manner as the Reference Listed Drug).