Dynamic rheology as a quantitative method for real-time tracking of excipient solvation in non-aqueous hydroxypropylcellulose topical gels.

This article describes a method to quantitatively track the solvation of HPC in a non-aqueous solvent system during topical gel manufacture. Where visual observation and microscopy could not establish a trend, straight-forward rheological profiling demonstrated a correlation between increased solvation of hydroxypropyl cellulose polymer (viscosity modifier) and decreased tan δ, indicating the formation of a viscoelastic gel network over time during processing. This correlation serves as a valuable tool for process optimization and HPC solvation tracking in non-aqueous topical gel formulations.