Tailored ASD destabilization - Balancing shelf life stability and dissolution performance with hydroxypropyl...

Amorphous solid dispersions (ASDs) are widely used to improve solubility and dissolution of poorly water-soluble drugs. These systems rely on the amorphous state of the active pharmaceutical ingredient (API) to enhance its bioavailability. However, maintaining the amorphous state during storage is a challenge due to risks of crystallization and phase separation. Prior research has shown that polymer selection and formulation design are critical for ASD stability. This paper addresses a specific gap: how to balance long-term physical stability with optimal dissolution performance in ternary ASD systems. The study explores the use of hydroxypropyl cellulose in combination with other polymers to achieve this balance. No prior work had resolved the conflict between stability and dissolution in these systems. This paper introduces a new approach using thermodynamic modeling to predict optimal polymer ratios.

The study aimed to evaluate the potential of ternary ASDs containing hydroxypropyl cellulose and another polymer to stabilize fenofibrate and simvastatin while improving their dissolution behavior. The researchers sought to determine if these systems could maintain physical stability during storage while achieving high supersaturation and prolonged dissolution. The motivation was to address the known trade-off between stability and performance in ASD formulations. The authors tested specific polymer combinations to find the optimal balance. They also aimed to validate thermodynamic predictions using experimental stability and dissolution data. The study focused on fenofibrate and simvastatin as model APIs with poor solubility. The goal was to identify formulation strategies that could be applied broadly in ASD development.

The researchers used the PC-SAFT thermodynamic model to predict optimal polymer ratios and maximum API loads for stability. They combined hydroxypropyl cellulose with either PVP VA64 or hydroxypropyl cellulose acetate succinate. The model estimated miscibility and thermodynamic stability of the polymer blends. Experimental validation included three-month stability tests to assess physical changes. Dissolution performance was measured using in vitro methods to evaluate supersaturation and duration. The study compared predicted stability with observed physical stability. The dissolution behavior of the most stable ASDs was analyzed to determine if stability came at the cost of performance. The results were compared across polymer combinations to identify trends.

The thermodynamic predictions identified the most stable ASDs for each polymer combination. These ASDs showed the lowest risk of crystallization and phase separation during storage. However, the most stable formulations had the worst dissolution performance. The study found that stability and dissolution were inversely related in the tested systems. The maximum API load predicted by the model matched the observed stability in most cases. The ASDs containing hydroxypropyl cellulose and PVP VA64 showed moderate stability and dissolution. The hydroxypropyl cellulose acetate succinate combination provided better dissolution but less stability. The three-month stability tests confirmed the model predictions. The dissolution data revealed a clear trade-off between long-term stability and high supersaturation.

The study demonstrated that in ternary ASDs containing hydroxypropyl cellulose, physical stability and dissolution performance are in conflict. The most stable formulations had the poorest dissolution behavior. The authors propose that this trade-off is inherent to the polymer combinations tested. The PC-SAFT model accurately predicted stability but did not account for dissolution performance. The results suggest that optimizing ASDs requires balancing polymer ratios to meet both stability and dissolution criteria. The findings highlight the need for formulation strategies that address both aspects simultaneously. The authors suggest that future work should explore alternative polymer combinations or processing methods to overcome this limitation. The study provides a framework for evaluating ASDs using thermodynamic modeling and experimental validation.