Formulation Composition and Process Affect Counterion for CSP7 Peptide.

Area of Science:

• Pharmaceutical Sciences
• Biopharmaceutical Formulation
• Peptide Chemistry

Background:

• Counterions, such as acetate, are essential in peptide salt forms and are preferred over others like trifluoroacetate due to safety.
• Volatile counterions can be lost during lyophilization, posing challenges for peptide formulation stability.
• Caveolin-1 scaffolding domain (CSP7) salt forms influence counterion volatilization.

Purpose of the Study:

• To investigate the impact of excipients and lyophilization conditions on preserving volatile counterions.
• To understand how volatile compound loss affects peptide stability and aggregation.
• To optimize lyophilized peptide formulations for counterion retention.

Main Methods:

• Utilized 1H and 19F NMR spectroscopy to determine counterion-to-peptide molar ratios.
• Evaluated the effects of various excipients, focusing on pH modifiers and bulking agents.
• Analyzed lyophilization parameters, including chamber pressure and formulation ratios.

Main Results:

• pH modifier excipients significantly influenced counterion loss during lyophilization.
• Optimizing the bulking agent to CSP7 molar ratio effectively preserved volatile compounds.
• Increased chamber pressure during lyophilization reduced the sublimation rate of volatile compounds.
• Loss of volatile compounds led to pH shifts in reconstituted solutions, causing CSP7 aggregation.

Conclusions:

• Formulation and processing optimization are key to preserving volatile counterions during lyophilization.
• Maintaining volatile compound integrity minimizes pH changes and enhances peptide stability.
• This study provides strategies for developing stable lyophilized peptide products with desirable counterions.