ABSTRACT
INTRODUCTION The advent of recombinant biotechnology and efficient synthetic processes has facilitated the development of a wide variety of protein and peptide therapeutics. Although a plethora of delivery routes and methods have been examined for the administration of these materials, to date the administration of these molecules is dominated by injection. Of these injected molecules, only a few, mostly high-dose antibodies, are administered by intravenous (IV) infusion; the vast majority being delivered by subcutaneous (SC) injection. Further, efforts are ongoing to identify formulation strategies to allow delivery of highdose biopharmaceuticals such as antibodies that can also be administered by SC injection. Although SC injection is a prominent delivery route for many biopharmaceuticals, relatively little is known about specific events that might occur to these therapeutic agents following their injection into a SC site that could affect their pharmacokinetic (PK) properties, pharmacodynamic (PD) outcome(s), and metabolic fate.
