Peptide prodrugs: Improved oral absorption of lopinavir, a HIV protease inhibitor

Abstract

Lopinavir (LVR) is extensively metabolized by CYP3A4 and is prevented from entering the cells by membrane efflux pumps such as P-gp and MRP2. In an approach to evade the first-pass metabolism and efflux of LVR, peptide prodrugs of LVR [valine-valine-lopinavir (VVL) and glycine-valinelopinavir (GVL)] were synthesized. Prodrugs were identified with 1 H and 13 C NMR spectra and LC/ MS/MS was employed to evaluate their mass and purity. Solubility studies indicated that the prodrugs have much greater solubility as compared with LVR in water. In vitro evaluations were performed to determine affinities for efflux proteins (P-gp and MRP2) and CYP3A4 and permeabilities across intestinal barrier. Accumulation and transport data of VVL and GVL across MDCKII-MDR1 and MDCKII-MRP2 cells indicated evasion of prodrugs' efflux by P-gp and MRP2 significantly. Permeability studies across Caco-2 cells indicated that the prodrugs are transported by peptide transporters and have increased permeability as compared with LVR. VVL and GVL exhibited significantly better degradation rate constants as compared with LVR in rat liver microsomes. Enzymatic stability studies in Caco-2 cell homogenate indicated that the peptide prodrugs are first converted to the ester intermediate and then finally to the parent drug. Overall, the advantages of utilizing peptide prodrugs include chemical modification of the compound to achieve targeted delivery via peptide transporters present across the intestinal epithelium, significant evasion of efflux and CYP3A4 mediated metabolism and significantly better solubility profiles. Therefore, in vitro studies demonstrated that peptide prodrug derivatization of LVR may be an effective strategy for bypassing its efflux and enhancing its systemic bioavailability.

Stereoisomeric Prodrugs to Improve Corneal Absorption of Prednisolone: Synthesis and In Vitro Evaluation

“…Significant improvement in aqueous solubility by amino acid and dipeptide prodrugs may generate compounds amenable for topical administration. Results obtained from prodrug aqueous solubility are consistent with previously published reports from our laboratory (36)(37)(38).…”

Ocular Sustained Release Nanoparticles Containing Stereoisomeric Dipeptide Prodrugs of Acyclovir

“…The culture medium was replaced every alternate day during the growth period. 16 Prodrugs stability in rPCEC and rabbit ocular tissue homogenates Hydrolysis of prodrugs was performed in cell and ocular tissue homogenates. The method is described in the following sections.…”

“…The quantity of formazan product was measured at 485 nm, and the absorbance is directly proportional to the number of living cells in the culture. 16,17 Uptake studies Uptake studies were conducted with confluent rPCECs. Cells were washed thrice with DPBS after aspirating the medium from each well.…”

Interaction of Ocular Hypotensive Agents (PGF2α Analogs—Bimatoprost, Latanoprost, and Travoprost) With MDR Efflux Pumps on the Rabbit Cornea

“…Our laboratory has reported that dipeptide prodrug derivatization of effl ux pump substrates such as quinidine, saquinavir, and lopinavir causes significant reduction in their affi nity toward effl ux pumps. [35][36][37] This hypothesis holds true even in this study, where affi nity toward effl ux pumps is slightly diminished due to prodrug modifi cation. But, it is important to note that complete evasion of effl ux could be realized by simultaneously targeting an infl ux nutrient transporter.…”

“…But, it is important to note that complete evasion of effl ux could be realized by simultaneously targeting an infl ux nutrient transporter. [35][36][37] Finally, the extent of effl ux inhibition in the presence of specifi c inhibitors in rPCEC might be comparatively less, since it is a primary culture in comparison to MDCK-transfected cell lines employed in this study, which overexpresses effl ux proteins.…”