Definitions given below apply specifically to the terms used in this guide. They may have different meanings in other contexts.

bioavailability

The rate and extent of availability of an active drug ingredient from a dosage form as determined by its concentration/time curve in the systemic circulation or by its excretion in urine.

bioequivalence

Two pharmaceutical products are bioequivalent if they are pharmaceutically equivalent and their bioavailabilities (rate and extent of availability) after administration in the same molar dose are similar to such a degree that their effects, can be expected to be essentially the same.

dosage form

The form of the completed pharmaceutical product, e.g., tablet, capsule, elixir, injection, suppository.

therapeutic equivalence

Two pharmaceutical products are therapeutically equivalent if they are pharmaceutically equivalent and after administration in the same molar dose their effects, with respect to both efficacy and safety, will be essentially the same as can be derived from appropriate studies (bioequivalence, pharmacodynamic, clinical or in vitro studies).

generic product

The term “generic product” has somewhat different meanings in different jurisdictions and in this document use of the term is avoided as much as possible, and the term “multisource pharmaceutical product” (see definition below) has been applied. Generic products may be marketed either under the nonproprietary approved name or under a new brand (proprietary) name. They may sometimes be marketed in dosage forms and/or strengths different from those of the innovator products. However, where the term “generic product” had to be used in this document it means a pharmaceutical product, usually intended to be interchangeable with the innovator product, which is usually manufactured without a licence from the innovator company and marketed after expiry of patent or other exclusivity rights.

innovator pharmaceutical product

Generally, the innovator pharmaceutical product is that which was first authorized for marketing, (normally as a patented drug) on the basis of documentation of efficacy, safety and quality (according to contemporary requirements). When drugs have been available for many years, it may not be possible to identify an innovator pharmaceutical product.

interchangeable pharmaceutical product

An interchangeable pharmaceutical product is one which is therapeutically equivalent to a reference product.

multisource pharmaceutical products

Multisource pharmaceutical products are pharmaceutically equivalent products that may or may not be therapeutically equivalent. Multisource pharmaceutical products that are therapeutically equivalent are interchangeable.

pharmaceutical equivalence

Products are pharmaceutical equivalents if they contain the same amount of the same active substance(s) in the same dosage form that meet the same or comparable standards and are intended to be administered by the same route. However, pharmaceutical equivalence does not necessarily imply therapeutic equivalence as differences in the excipients and/or the manufacturing process can lead to differences in product performance.

reference product

A reference product is a pharmaceutical product with which the new product is intended to be interchangeable in clinical practice. The reference product will normally be the innovator product for which efficacy, safety and quality have been established. Where the innovator product is not available the product which is the market leader may be used as a reference product, provided it has been authorized for marketing and its efficacy, safety and quality has been established and documented.