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Generic versus Therapeutic Substitution

In the debate over the cost of prescription medicines, two terms – generic substitution and therapeutic substitution – are often confused. While both methods of substitution are seen as ways to lower prescription costs, only generic substitution assures that the patient receives exactly the same prescription ordered by their doctor.

Generic Substitution

A generic product is the same as its brand name counterpart. To receive the FDA’s "AB" rating, or therapeutic equivalence rating, the generic pharmaceutical manufacturer must prove that its drug has the same active ingredients, same dosage form, same standards for purity and quality, same standards for manufacturing, and same amount of drug absorbed over the same time as the equivalent brand product. Generics must meet the same stringent government standards for strength, purity and potency as the brand name version.

The generic drugs are generally dispensed under the chemical name of the active ingredient. Occasionally generics may be a slightly different size, shape or color than their brand counterpart. But these cosmetic differences have no impact on the safety or effectiveness of a generic prescription drug.

When a generic pharmaceutical product is substituted for the brand product, the patient is receiving a product that is the same as the brand product but costs as much as 80% less. There is no difference in the safety or efficacy profile, and the patient can expect to have the same efficacy and safety profile regardless of whether the prescription is filled with a brand or generic product.

Therapeutic Substitution

Therapeutic substitution can be a bit confusing. The key, however, is to understand that when one drug is therapeutically substituted for another, the patient is receiving an entirely different drug, although it has the same indication.

There are a number of products—both over-the-counter and prescription—that are used to treat the same ailment. They have different active ingredients, different dosages, and may work inside the body differently. Yet, they can be used to treat the same disease or symptom.

An example makes this clear. To treat a headache, a patient can use a number of medicines, such as an aspirin-based product or a product with ibruprofen (Motrin™, for example). Both chase the headache away, but they are different chemicals that treat the headache differently.

In therapeutic substitution, one chemical is substituted for another chemical, although the FDA has approved both for the treatment of a specific condition. Given that some individuals react to chemicals differently, a patient who has received a therapeutic substitution may experience different results and side-effects than they had on their original prescription.