# Color Assessments and Glycolysis of Cetylpyridinium Chloride-Containing Aqueous Solutions and Commercial Mouthwashes

## TL;DR

This study shows that QAC test strips can effectively assess bioavailable CPC in mouthwashes and correlate with glycolysis outcomes.

## Contribution

The study introduces QAC test strips as a novel, efficient method for assessing bioavailable CPC in oral care products.

## Key findings

- QAC test strips showed significant differences in CPC solutions and correlated well with glycolysis outcomes.
- Commercial mouthwashes also demonstrated a strong correlation between color assessments and glycolysis.
- Zinc salts in some mouthwashes may affect QAC-based color assessments.

## Abstract

Background: Effective cetylpyridinium chloride (CPC)-based mouthwashes critically depend on maintaining maximum levels of bioavailable CPC to deliver optimum antimicrobial benefits. While this is traditionally assessed using cellulose-based methods, from economic and efficiency perspectives, there remains a need to identify other potential methods of assessing bioavailable CPC. Here, we explored whether quaternary ammonium compound (QAC) test strips are sensitive to CPC-based formulations, and if so, whether there might exist a possible correlation with glycolysis outcomes. Methods: Quantitative color parameters were obtained using spectrophotometric assessments of QAC test strips immersed in simple CPC solutions and eight commercial CPC-based mouthwashes available in the USA. Then, using our established glycolysis model, we assessed the glycolytic response of both the simple CPC solutions and commercial CPC-based mouthwashes, and compared these data sets. Results: Significant differences (p < 0.05) among the CPC simple solutions were found. Importantly, spectrophotometric assessments and glycolysis trials produced good correlations. Evaluations of the commercial mouthwashes further underlined this correlation, even though those that comprise zinc salts may impact QAC-based color. Conclusions: Based on these results, we believe the use of QAC test strips provides an attractive option to formulators and brands specializing in the development and/or testing of CPC-based oral care formulations.