Exploring the chemical space for freeze-drying excipients

Area of Science:

• Pharmaceutical Science
• Physical Chemistry

Background:

• Freeze-drying commonly uses limited excipients like mannitol, glycine, sucrose, and trehalose.
• Excipient selection impacts drug stability and formulation performance.

Purpose of the Study:

• To combine theoretical molecular descriptor analysis with large-scale experimental screening for evaluating a wide range of freeze-drying excipients.
• To identify novel bulking agents and lyoprotectants beyond conventional choices.

Main Methods:

• Characterization of sugars, polyols, and amino acids using modulated differential scanning calorimetry (mDSC) and X-ray powder diffraction (XRPD) after freeze-drying.
• Analysis of molecular descriptors using hierarchical cluster analysis and principal component analysis.
• Correlation of molecular descriptors with experimental freeze-drying outcomes.

Main Results:

• Excipients clustered based on size- and weight-related molecular descriptors.
• Increasing molecular size correlated with higher amorphization likelihood and glass transition temperature.
• Molecular descriptors showed better predictive power for lyoprotectant performance than for bulking agents.

Conclusions:

• A broad range of excipients can be evaluated for freeze-drying suitability using a combined theoretical and experimental approach.
• New potential bulking agents and lyoprotectants were identified, expanding formulation options.
• Understanding molecular descriptor-performance relationships aids rational excipient selection in freeze-drying.