Quantification of Soluplus® and copovidone polymers in dissolution media: Critical systematic review

Polymer-based solid dispersions including amorphous solid dispersions (ASD) are viable strategies to enhance the release of poorly soluble drugs. The concurrency of the drug and polymer release and the concentration of polymer in dissolution media directly influence the drug release and the precipitation rate. Thus, it is important to investigate the release of the polymer along with the drug. The aim of this critical systematic review was to summarize the available quantification methods for frequently used water-soluble polymers such as Soluplus® and copovidone with additional focus on the simultaneous determination of both polymer and drug in the dissolution media. Non-systematic review on widely and long-time used povidone was additionally conducted in order to fill the "gaps" of available quantification methods. The review aims to provide a comprehensive picture of the quantification opportunities for these polymers. APCI-MS and Py-GC/MS methods could be applied for quantification, however; these techniques require specific expensive equipment and expertise in data interpretation. Based on this review, size exclusion chromatography (SEC) appears to be the most preferable quantification method for Soluplus® and copovidone in dissolution media, due to its simplicity and versatility. The semi-quantitative approaches (FTIR, UV and Raman spectroscopy) were outlined as indicative assessment that can be verified by other quantitative methods. The strengths and weaknesses of modern methods (liquid; size exclusion coupled with pyrolysis-gas chromatography and tandem mass spectrophotometry) embracing advanced equipment for polymer quantification were also discussed.