PROJECT SUMMARY The effective long-term management of HIV infection in pediatric patients faces a multitude of challenges such as lack of age-appropriate pediatric formulations, high pill burden, unavailability of oral liquid formulations, poor palatability of existing pediatric formulations, forgetfulness, and emerging independence in adolescents. These challenges and psychosocial, behavioral, and socioeconomic barriers and health disparities have led to poor adherence and only ~50% of children living with HIV are able to receive antiretroviral therapy. While the intramuscular long-acting cabotegravir-rilpivirine (RPV) nanosuspension is highly effective in the long-term management of HIV infections in adults and adolescents, there is a strong need to develop a non-invasive, room temperature stable formulation that can allow for self-administration, high adherence and long-term HIV therapy in children and adolescents affected with HIV. The non-invasive transdermal route is yet to be explored for the delivery of potent second-generation antiretroviral drugs. Our preliminary study showed that dolutegravir (DTG) has a great potential to be delivered as a transdermal formulation compared to cabotegravir whereas rilpivirine, due to its high crystallinity and low aqueous and lipid solubility was not amenable for transdermal delivery. Ionic liquids (ILs) are low-melting organic salts with a melting point < 100°C and pharmaceutically acceptable fatty anionic permeation enhancers can be used to develop amphiphilic ILs with excellent drug solubilization capacity, lipid solubility, and transdermal permeability. We hypothesize that rilpivirine (RPV) and generally regarded as safe (GRAS) fatty anionic permeation enhancers can be assembled to develop amphiphilic RPV ILs with excellent lipid solubility and solubilization capacity for DTG and that subsequent incorporation of RPV IL(s) and DTG into transdermal lipid-based formulations such as nanoemulsion-based gel will improve transdermal delivery of DTG-RPV combination. Our preliminary data show that a prototype nanoemulsion containing IL of RPV (RPV docusate) and DTG combination showed significantly higher in vitro permeability of RPV and DTG through skin mimicking Strat-M membrane compared to DTG-RPV suspension. Aim 1 will focus on the development, characterization, and in vitro evaluation of nanoemulsion-based gel formulations containing various RPV ILs and DTG combination suitable for transdermal delivery. Aim 2 will focus on the pharmacokinetic evaluation of transdermal nanoemulsion-based gel containing RPV IL and DTG combination in NSG mice to establish the proof of concept. Aim 3 will evaluate the in vivo antiretroviral efficacy of nanoemulsion-based gel containing RPV IL and DTG combination in a humanized mouse model of HIV infection. The successful completion of this proposal will lead to the development of pharmaceutically viable formulations containing combination antiretroviral drugs for effective l...