Design of propolis-loaded film forming systems for topical administration: The effect of acrylic acid derivative polymers

Abstract In situ film forming systems are an alternative to the conventional dosage forms for topical application, performing superior contact and adhesiveness, with a consequent sustained and efficacious therapy. Propolis (PRP) is an extremely versatile natural compound due to its constitutive complexity and in terms of biological properties and uses as healing, anti-inflammatory, anti-cancer, antimicrobial, antiviral, and antifungal activities. In this work, the thermoresponsive polymer (poloxamer 407) and bioadhesive polymers derived from the acrylic acid were utilized to prepare dispersed systems containing different concentrations of propolis extract, and they were evaluated in terms of film forming capability. The gelation temperature and mechanical characteristics were also investigated so that some systems could be selected from a factorial design. The selected formulations presented good mechanical and rheological structuring properties, and they could incorporate the PRP extract. These systems denoted plastic flow behavior and viscoelasticity, and the PRP extract presence evinced greater capacity of the systems to support higher shear stress. When PRP extract was present, the systems with Carpobol 974P or polycarbophil (F7 and F10) presented greater structuring, with superior flexibility and rupture resistance. Moreover, they showed easiness for topical administration, with good spreadability and softness. Its excellent film forming capacity proved ex vivo, encourages further investigations for topical application.