PROJECT SUMMARY Two-drug regimen (2-DR) containing potent second-generation integrase inhibitor (INI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) are currently available as oral formulation (dolutegravir-rilpivirine) and long-acting injectable nanosuspension (cabotegravir-rilpivirine) for HIV prophylaxis and therapy. Oral 2-DR tablet (Juluca; dolutegravir-rilpivirine) is equally effective but with significantly lower adverse effects compared to the three-drug regimen based on 2 NRTIs. However, dolutegravir (DTG) and rilpivirine (RPV) both have pH dependent solubility, low oral bioavailability and long-term use of INI can lead to metabolic diseases including diabetes. Given the need for lifelong administration of these drugs, strategies that can improve the oral bioavailability of DTG and RPV are highly desirable for optimal drug utilization and to achieve a reduction in therapeutic dose and dose-related side effects. While the intramuscular long-acting cabotegravir-RPV nanosuspension is highly effective in the long-term management of HIV infections, there is a strong need to develop a non-invasive, strategy that can allow for self-administration and long-term HIV therapy. The non- invasive transdermal route is yet to be explored for the delivery of 2-DR containing INI and NNRTI. Ionic liquids (ILs) are low-melting organic salts with a melting point < 100°C and pharmaceutically acceptable fatty cations and/or anions can be used to develop amphiphilic ILs with excellent drug solubilization capacity. Pharmaceutically acceptable cations and fatty anions can be assembled into amphiphilic ILs with excellent biocompatibility and drug solubilization capabilities. We hypothesize that carnitine, a generally regarded as safe (GRAS) cation and fatty anionic permeation enhancers with GRAS status can be assembled to develop amphiphilic ILs with excellent solubilization capacity for hydrophobic drugs such as DTG and RPV and that subsequent incorporation of these ILs into oral lipid-based formulations (LBFs) such as self-nanoemulsifying systems (SNES) and transdermal LBFs such as nanoemulsion-based gel will improve oral and transdermal delivery of DTG-RPV combination. Our preliminary data show that a co-processed mixture of DTG and RPV has very high solubility (RPV: ~ 166 mg/g and DTG: 334 mg/ml) in amphiphilic carnitine IL (carnitine salcaprozate) and carnitine salcaprozate containing DTG-RPV mixture showed significantly higher in vitro permeability 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 of carnitine ILs containing DTG-RPV combination suitable for oral and transdermal delivery. Aim 2 will focus on the pharmacokinetic evaluation of oral and transdermal lipid nanoformulations of carnitine IL containing DTG-RPV combination in healthy mice to establish the proof of concept. The successful completion of this proposal will lea...