The role of light anhydrous silicic acid on physical stability of troglitazone solid dispersion under humidified conditions

• Aerosil exhibited a stabilizing effect on solid dispersion under humid conditions.
• The stabilizing effect could not be predicted based on the evaluation of Tg.
• Hydrophobic Aerosil stabilized solid dispersion stronger than hydrophilic Aerosil.
• The stabilizing mechanism was speculated based on the comparative results.

The aim of this study was to confirm whether light anhydrous silicic acid (Aerosil) could exhibit a stabilizing effect on the physical stability of solid dispersion under humidified conditions. Ternary solid dispersions consist of 50% troglitazone, and various ratios of polyvinyl pyrrolidone and Aerosil were prepared using the co-milling method and then evaluated for their crystallizing behavior under storage conditions. The results showed that Aerosil has a stabilizing effect against crystallizing in the dihydrate of troglitazone under humidified conditions and has an appropriate ratio range (Troglitazone/PVP/Aerosil = 50/30–20/20–30) in the ternary solid dispersion, when considering total quality satisfaction such as physical stability and dissolution. Furthermore, it was found that hydrophobized Aerosil R805 has a stronger stabilizing effect than hydrophilic Aerosil 200. The stabilizing mechanism was discussed based on the comparative results and possible molecular interaction.

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