Thermogelling emulsions for topical drug delivery

The proposed research involves the synthesis of temperature-responsive branched copolymer surfactants (BCSs) to produce emulsions which dramatically increase in viscosity upon warming from room to body temperature. These so-called “thermogelling” systems have a number of topical applications, for instance in vaginal drug delivery, where the material can flow through an applicator, then increase in viscosity upon entry to the vagina, improving retention of the dosage form whilst reducing messiness. The FACTS 001 trial studying HIV prophylaxis found that messiness and leakage of a vaginal gel containing tenofovir reduced patient compliance, and ultimately led to a great reduction in efficacy (Mehendale et al., Int. Health, 2012, 4, 63-9.). This research will build upon the ‘engineered’ emulsions introduce by Weaver and co-workers (e.g. Angew. Chem. 2009, 48, 2131–2134), which undergo a pH-dependent sol-gel transition, but will use temperature as a trigger to induce gelation. The applicant has conducted research on temperature-responsive copolymers (Fillipov et al., Langmuir, 2016, 32, 5314–5323), and aims to use this experience to produce thermogelling emulsion systems.