Long-Term Amorphous Drug Stability Predictions Using Easily Calculated, Predicted, and Measured Parameters

Area of Science:

• Pharmaceutical Sciences
• Physical Chemistry
• Materials Science

Background:

• Amorphous solid forms of drugs offer advantages in solubility and bioavailability, especially for poorly water-soluble compounds.
• However, amorphous drugs can be physically unstable, prone to crystallization over time, impacting drug product performance.
• Predicting and ensuring amorphous stability is critical for successful drug formulation and development.

Purpose of the Study:

• To develop a predictive model for the amorphous stability of drugs, focusing on poorly water-soluble compounds.
• To identify key molecular, thermodynamic, and kinetic parameters influencing the long-term physical stability of amorphous drug forms.
• To create statistical models that can support rapid decision-making in pharmaceutical formulation.

Main Methods:

• Selection of 25 neutral, poorly soluble compounds with diverse properties from marketed drugs.
• Assessment of physical stability via polarized light microscopy over 6 months, monitoring crystallization of amorphous films.
• Development of multiple linear regression models using calculated/predicted and measured physicochemical parameters.

Main Results:

• Inclusion of measured parameters significantly improved the predictive ability of the statistical models.
• The best model achieved 82% prediction accuracy, incorporating parameters like melting temperature, glass transition temperature, enthalpy of fusion, and lipophilicity.
• A simpler model using molecular weight and enthalpy of fusion also provided good predictions.

Conclusions:

• Statistical models incorporating readily accessible parameters can effectively predict long-term amorphous drug stability.
• These models can accelerate the decision-making process in drug formulation development.
• Understanding key factors influencing amorphous stability is vital for developing stable and effective drug products.