Additional Excipients

An excipient is pharmacologically inert by itself, but when used in combination with an active ingredient provides appreciable benefits. Biological molecules are inherently less stable than small molecules and formulation development is often challenging. Furthermore, complex molecular structure, lack of well-defined stability-indicating assays and a multitude of degradation pathways create major hurdles for the formulation development of biologics. The selection of excipients is crucial to successful development of injectable biologics formulation.

With a growing number of injectable protein therapeutics in development, stabilization during processing and storage presents a major challenge for the biologics formulator Two examples are presented here, one to illustrate the pH effect on solubility of three r-GH formulations, and also on stability of an anti-trypsin antibody. It should be noted that an osmotic agent is often employed to stabilize the tertiary protein structure In addition, a preservative is used for bacteriostatic effect and an antioxidant for prevention of oxidative degradation