Pharmacokinetic and Tissue Distribution Profile of Long Acting Tenofovir Alafenamide and Elvitegravir Loaded Nanoparticles in Humanized Mice Model

Purpose: Non-adherence to the antiretroviral (ARV) regimen is a critical factor in determining efficacy of ARV drugs for pre-exposure prophylaxis (PrEP). A long-acting parenteral formulation may be an effective alternative to daily oral dosing. A pharmacokinetic and tissue distribution study of drug-loaded nanoparticle (NP) was performed in female humanized CD34⁺-NSG mice. Methods: Mice received 200 mg/kg each of tenofovir alafenamide (TAF) and elvitegravir (EVG) as free drugs (TAF + EVG solution) or as drug loaded NP (TAF + EVG NP) formulation by subcutaneous (SubQ) administration. Plasma and tissue were collected to determine tenofovir (TFV) and EVG concentrations using LC-MS/MS. Non-compartmental analysis was performed using WinNonlin. Results: SubQ administration of TAF + EVG NP formulation resulted in long residence time and exposure for both drugs. The AUC_(0-72h) of TFV and EVG was 14.1 ± 2.0, 7.2 ± 1.8 μg × hr./mL from drugs in solution (free) and the AUC_(0-14day) for the same drugs was 23.1 ± 4.4, 39.7 ± 6.7 μg × hr./mL from NPs. The observed elimination half-life (t_1/2) for TFV of free and NPs were 14.2 h, 5.1 days and for EVG 10.8 h, 3.3 days, respectively. Conclusion: This study documents that a TAF + EVG NP provides sustained release, which can overcome patient non-adherence to dosing and may facilitate prediction of appropriate protective drug concentration for HIV prophylaxis.