The team, made up of colleagues from Universidad de la República in Uruguay and Universidad Nacional de Córdoba in Argentina, published their findings in the October issue of the International Journal of Cosmetic Science, stating that physico-chemical and sensory techniques enabled the identification.
The study was devised to develop bioadhesive hydrogels for skin application, using caffeine as a model active ingredient, with the team explaining that the use of bioadhesive hydrogels for skin care presents important advantages such as a long-lasting effect.
Through the research, they found that formulations which combined carbomer homopolymer type C with xanthan gum or with carbomer copolymer type B were the most promising for bioadhesive skin products.
Caffeine release profiles of selected formulations were also not statistically different, notes the study stating that both hydrogels gradually released the active ingredient, reaching approximately 80% within the first five hours.
“In this context, it could be concluded that the selected hydrogels are suitable bioadhesive hydrogel formulations for cosmetic application on the skin,” says the study.
In the study, eight hydrogels were formulated using binary combinations of a primary polymer (carbomer homopolymer type C (Carbopol 980) or kappa carrageenan potassium salt (Gelcarin GP-812 NF) and a secondary polymer (carbomer copolymer type B (Pemulen TR-1), xanthan gum or guar gum).
They were characterized by means of physico-chemical and sensory methods, and caffeine hydrogels were formulated using two of the most promising formulations regarding adhesion properties and sensory characteristics, before in vitro active ingredient release studies were carried out.
The research found that in general, the hydrogel formulations showed an elastic rheological behaviour.
Complex viscosity of carbomer homopolymer type C hydrogels was shown to be higher than that of the kappa carrageenan hydrogels.
Of the two hydrogels selected to study the release of caffeine, both presented similar release profiles which were well described by the Higuchi model, which relates drug concentration to the square root of time.
Caffeine release was exclusively controlled by a diffusive process.