generic drug

Once a brand-name drug's patents and exclusivity expire, anyone may make a copy. A generic drug is exactly that copy: a product containing the same active pharmaceutical ingredient, at the same strength, in the same dosage form, intended to work the same way in the body as the original. It is the reason a medicine that cost a fortune when new can later cost pennies.

Crucially, a generic manufacturer does not have to repeat the original drug's huge clinical trials. The molecule is already known to be safe and effective; what the generic must prove is that its version delivers the same active ingredient to the bloodstream in essentially the same way. This is shown through bioequivalence studies, which compare the rate and extent of absorption against the reference product within an accepted statistical range. The approval pathway is therefore much shorter and cheaper, which is what drives prices down once competition arrives.

Generics are chemically identical small molecules, which is why this works cleanly. The inactive ingredients — the excipients, coatings, and colors — may differ, so a generic can look different and occasionally a patient notices a difference, but the active substance is the same compound. The model does not extend straightforwardly to large biologic drugs, whose complex molecules cannot be copied identically; those have a separate, more demanding pathway.