Spray coverage analysis of topical sprays formed by cold thermoreversible hydrogels

Abstract

Objective

Sprayable hydrogel formulations are promising topical treatments for skin wounds due to their ability to reduce application pain, prolong drug release, and provide moisture to promote skin healing. These viscoelastic materials, however, present challenges in spray ability which can be overcome using a thermoreversible hydrogels sprayed as lower viscosity liquids at cooler temperatures. The purpose of this research was to evaluate the impact of thermoreversible hydrogel formulation and device characteristics on topical spray patterns and to develop metrics to accurately describe surface coverage.

Methods

Cold solutions of Pluronic F127 were prepared at 15, 17, and 20% (w/w) and tested to determine their rheological properties. Formulations were sprayed from hand-held atomizing pump dispersers under cold conditions and two distinct areas of their spray patterns analyzed: the concentrated core and the full spray pattern. Traditional analysis of spray patterns was conducted to determine major and minor axes, ovality, and total area. In addition, new scripts were developed to evaluate the concentrated core.

Results

The full spray pattern analysis quantified the total area over which the spray would extend a flat surface, while the concentrated core analysis quantified the continuous region where a drug dose would be concentrated. The combination of formulation viscosity, sprayer nozzle, and spray distance produced spray patterns from highly concentrated to highly dispersed. These parameters can be controlled to generate desired hydrogel spray patterns for application on skin surfaces.

Conclusion

The developed metrics provide a basis for topical spray analysis that can inform future product performance.

Keywords:

• Spray analysis
• topical delivery
• pluronic
• hydrogel
• spray pattern

Acknowledgements

We thank PhD candidates Kevin Tobin and Jackson Russo (Dr. Nicole Brogden’s laboratory) for their assistance in running the ARES-G2 rheometer.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Financial support for a student fellowship to RS is acknowledged from the Center for Biocatalysis and Bioprocessing at the University of Iowa and the NIH Predoctoral Training Program in Biotechnology (grant number T32-GM008365). CR was financially supported by the PhRMA foundation’s predoctoral drug delivery fellowship [award number 886306] and the National Science Foundation [grant number 2003037]. Research reported in this publication was supported by the National Institutes of Health [grant number R35GM124551]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by Pharmaceutical Research and Manufacturers of America Foundation.