Each alternative mode brings with it a unique set of formulations problems. Parenteral delivery introduces a complex set of formulation issues because of the complex chemical and physical properties of biomolecules, and the importance of tertiary and quaternary protein structure, as well as primary and secondary structure. Analysis of biomolecule stability is another complicated issue since a molecule can appear stable by several physical and chemical criteria and yet lose its bioactivity. Patient and health care practitioner issues must also be considered in formulation of biomolecules, especially when products are to be used in an outpatient setting. Difficult reconstitution procedures, delicate stability profiles, or single access vials for expensive products can all create problems with patient acceptance and compliance.
Gene therapy brings another set of opportunities and challenges.
On one hand, genes can be used as a mode of in vivo delivery of biologically active proteins, but on the other hand, delivery of nucleic acids in viral vectors or as nucleic acids requires new modes of formulation and delivery. To download the entire paper through the members-only option, Acrobat Reader is needed.