Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review

The emulsion-based topical semisolid dosage forms present a high degree of complexity due to their microstructures which is apparent from their compositions comprising at least two immiscible liquid phases, often times of high viscosity. These complex microstructures are thermodynamically unstable, and the physical stability of such preparations is governed by formulation parameters such as phase volume ratio, type of emulsifiers and their concentration, HLB value of the emulsifier, as well as by process parameters such as homogenizer speed, time, temperature etc. Therefore, a detailed understanding of the microstructure in the DP and critical factors that influence the stability of emulsions is essential to ensure the quality and shelf-life of emulsion-based topical semisolid products.

Highlights

• The factors affecting the stability of emulsion semisolid products were analyzed
• Assessing and predicting the long- term physical stability of emulsion semisolid products was explored
• Various strategies to stabilize emulsions contained in semisolid products were established
• Accelerated assessment of physical stability to predict the shelf life was demonstrated both experimentally and theoretically

This review aims to provide an overview of the main strategies used to stabilize pharmaceutical emulsions contained in semisolid products and various characterization techniques and tools that have been utilized so far to evaluate their long-term stability. Accelerated physical stability assessment using dispersion analyzer tools such as an analytical centrifuge to predict the product shelf-life has been discussed. In addition, mathematical modeling for phase separation rate for non-Newtonian systems like semisolid emulsion products has also been discussed to guide formulation scientists to predict a priori stability of these products.

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Excipients mentioned in the study: Pemulen

Abu Zayed Md Badruddoza, Thean Yeoh, Jaymin C Shah, Taylor Walsh, Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review, Journal of Pharmaceutical Sciences, 2023, ISSN 0022-3549, https://doi.org/10.1016/j.xphs.2023.03.014.