Abstract
Lipid-derived prodrugs can enhance the oral bioavailability of therapeutic agents by promoting uptake into the lymphatic system. Chylomicrons (CMs) are lipoproteins that transport dietary lipids into the lymphatics. However, their role in the systemic distribution of orally administered lipid prodrugs remains understudied. We developed an in vitro assay demonstrating that human intestinal enterocyte-like cell-derived CMs incorporate lipid prodrugs, and that the efficiency of this incorporation varies as a function of the lipid promoiety. We synthesized a series of lipid prodrugs of tenofovir (TFV), an important but poorly bioavailable anti-HIV agent. These lipid prodrugs, featuring a benzyloxyglycerol (BOG) motif and/or an ω-CF3 group, demonstrated improved metabolic stability and favorable antiviral activity in vitro, relative to unfunctionalized lipid conjugate TFV exalidex (TXL). Additionally, the ω-CF3 and BOG modifications significantly increased prodrug uptake into CMs in vitro. Subsequent mouse pharmacokinetic (PK) studies revealed higher systemic drug levels of orally dosed ω-CF3 BOG prodrugs relative to TXL, as well as substantially enhanced lung distribution. This study is the first to quantify drug incorporation into human intestinal enterocyte-like cell-derived CMs using LC-MS/MS. In conclusion, highly lipophilic TFV prodrugs efficiently incorporate into CMs in vitro, and mouse PK data is consistent with lymphatic absorption in vivo, providing a framework for the rational design and screening of lipid-based prodrugs for optimization of drug distribution.
Keywords:
HIV; absorption; chylomicrons; distribution; lipids; lipoproteins; lymphatic system; prodrugs; tenofovir.