Daily oral conventional ART, even in fixed dose combination forms, has inherent limitations such as patient adherence and disparate drug kinetics; both potentially impacting therapeutic outcomes. Oral dosing has also been shown to produce lower and limited tissue exposure where residual virus persists. To address these limitations, we have developed a tissue- and cell-targeted long-acting anti-HIV nanosuspension containing 4 drugs. The aim of this study is to characterize the blood and tissue pharmacokinetics of all four drugs 5 weeks following drug administration.
Four pigtail macaques received a single subcutaneous injection of a 4-in-1 anti-HIV drug combination nanoparticle (DcNP) formulation composed of lopinavir (LPV), ritonavir (RTV), tenofovir (TFV) lamivudine (3TC) and lipidic excipients. Blood samples and lymph node biopsies were obtained at defined time points up to 5 weeks following drug administration. Drug levels in plasma, lymph node and peripheral blood mononuclear cells (LNMC and PBMC) were analyzed with a validated LC-MS/MS assay.
The injections were well tolerated and no injection site reactions were noted. PBMC and plasma levels of the three active drugs (hydrophobic LPV, hydrophilic TFV and 3TC) were sustained for 5 weeks; these data are depicted in Figure 1. When compared to plasma levels, PBMC drug exposures were 12-, 16-, and 42-fold higher for LPV, RTV, and 3TC, respectively. Notable extended apparent terminal half-lives of LPV, TFV, and 3TC were observed in plasma [219.1 hours (LPV), 63.1 hours (TFV), and 136.3 hours (3TC)]. These were even further extended in PBMCs [1045.7 hours (LPV), 105.9 hours (TFV), and 127.7 hours (3TC)]. Eight days after drug administration, LPV, TFV and 3TC levels in LNMCs were 102-, 2.9-, and 352-fold higher than those in plasma.
A single injection of one DcNP nanosuspension containing four drugs exhibited persistent drug levels in LMNC, PBMC, and plasma for 5 weeks. Though these drugs have disparate physiochemical properties, we were able to successfully co-formulate all into a single nanosuspension. This formulation demonstrated both cell- and tissue-targeted properties in addition to sustained pharmacokinetic profiles. With interspecies scaling and appropriate dose adjustments, this 4-in-1 HIV drug-combination could be considered for long-acting treatment with the potential to overcome lymphatic drug insufficiency and limitations with patient adherence.