Protein stability and viscosity in molecularly crowded high-concentration biologics

Area of Science:

• Biophysics
• Formulation Science
• Protein Engineering

Background:

• Protein biologics administration is shifting towards high-concentration subcutaneous delivery for patient convenience.
• This shift is limited by protein instability and high viscosity at concentrations above 100 mg/mL.
• Understanding molecular crowding effects on protein structure and function is crucial.

Purpose of the Study:

• To elucidate mechanisms of protein instability and viscosity in high-concentration formulations.
• To explore strategies for developing stable and deliverable high-concentration protein therapeutics.
• To discuss the interplay between drug product formulation and delivery devices.

Main Methods:

• Review of underlying mechanisms of protein instability in crowded environments.
• Analysis of intermolecular interactions (steric, electrostatic, hydrogen-bonding, hydrophobic).
• Exploration of formulation design, protein engineering, and advanced delivery strategies.

Main Results:

• High concentrations lead to protein self-association, increased viscosity, and phase separation.
• Rational formulation design and protein engineering can enhance stability and reduce viscosity.
• Arginine and its derivatives can disrupt protein-protein interactions and lower viscosity.
• Advanced delivery systems and device innovations can circumvent viscosity limitations.

Conclusions:

• Developing stable, high-concentration biologics requires an integrated approach combining mechanistic understanding, biophysics, formulation, and device engineering.
• Overcoming biophysical challenges is key to enabling patient-centric subcutaneous protein therapies.
• Further innovation in formulation and delivery devices is essential for future biologic drug products.