Strategies to overcome hepatic clearance of endogenous proteins – molecular and formulation approaches

The medical use of biologics is often limited by rapid elimination from circulation. This review explores formulation strategies for enhancing the pharmacokinetic profiles of therapeutic proteins with hepatic clearance as a major route of elimination. Pharmacokinetic and hepatic clearance mechanisms of selected endogenous proteins - tissue-type plasminogen activator, glucagon-like peptide 1, insulin and interferon-β - are detailed and discussed. Molecular optimization and formulation strategies for these four biologics highlight the overcoming of pharmacokinetic limitations resulting in successful clinical approvals. The assessment of genetic engineering, bioconjugation, fusion proteins, and protein drug delivery systems for their potential to prolong serum half-life should facilitate prospective development of pharmacological active macromolecules failing due to their rapid elimination in the liver. Overall, this review elucidates the relationships among formulation design, protein structure, and hepatic clearance, and their combined impact on therapeutic efficacy.