Basic Concepts and Requirements of Galenic Formulations

Biologics or biopharmaceuticals can be active substances that are based on proteins, and they are demanding on formulation scientists. If such substances were administered orally, they would be broken down by the digestive fluids in the gastrointestinal tract before they could enter the bloodstream and reach their target site. Biologics are therefore administered by injection into a vein or subcutaneously (under the skin). In order to be injected, the active substance must be available in solution. At the same time, it must be possible to store a medicine over a relatively long period of time if it is to be usable in practice. However, if a biologics is formulated in a ready-to-use solution, there is a risk that the protein molecules will agglomerate (clump together) during prolonged storage and that they will lose their effectiveness. In this case, the formulation scientists must reconcile the need to both preserve efficacy and achieve a long shelf life. In many cases, this challenge can be solved using the technique of freeze-drying (lyophilisation). After this gentle method of drying, the protein molecules often remain stable for at least six months. Shortly before injection the active substance is dissolved in a solution, e.g. in a prefilled syringe.