The potential of Raman spectroscopy as a process analytical technique during formulations of topical gels and emulsions

Purpose. The primary objective of this study is to investigate the possibility of using Raman spectroscopy as a process analytical technique ( PAT) for quality control during manufacturing of topical dosage forms. Methods. A fiber-optic Raman probe was used to monitor the formulation of pharmaceutical gel and emulsion in laboratory scale. Raman shifts of typical commercial raw materials used in topical dosage forms were measured to ascertain the potential of this technique for monitoring and analyzing topical products. Spectra of some well-characterized topical gels manufactured in our laboratory were also measured. Results. Commercial raw materials were found to be Raman sensitive. Due to the difference in chemical composition, raw materials exhibit characteristic peaks that can be exploited to monitor formulation processes. Spectra taken during formulation of an emulsion using Carbopol Ultrez as thickener and Tefose as emulsifying agent show changes in Raman shifts immediately after major formulation steps. Conclusions. The findings from this work suggest that Raman spectroscopy can be a valuable process analytical technique for quality control of topical gel and cream formulations.