Targeting SVCT for enhanced drug absorption: Synthesis and in vitro evaluation of a novel vitamin C conjugated prodrug of saquinavir

Abstract

In order to improve oral absorption, a novel prodrug of saquinavir (Saq), ascorbyl-succinic-saquinavir (AA-Su-Saq) targeting sodium dependent vitamin C transporter (SVCT) was synthesized and evaluated. Aqueous solubility, stability and cytotoxicity were determined. Affinity of AA-Su-Saq towards effluxpump P-glycoprotein (P-gp) and recognition of AA-Su-Saq by SVCT were studied. Transepithelial permeability across polarized MDCK-MDR1 and Caco-2 cells were determined. Metabolic stability of AA-Su-Saq in rat liver microsomes was investigated. AA-Su-Saq appears to be fairly stable in both DPBS and Caco-2 cells with half lives of 9.65 and 5.73 h, respectively. Uptake of [3H]Saquinavir accelerated by 2.7 and 1.9 fold in the presence of 50 μM Saq and AA-Su-Saq in MDCK-MDR1 cells. Cellular accumulation of [14C]AA diminished by about 50–70% relative to control in the presence of 200 μM AA-Su-Saq in MDCK-MDR1 and Caco-2 cells. Uptake of AA-Su-Saq was lowered by 27% and 34% in the presence of 5 mM AA in MDCK-MDR1 and Caco-2 cells, respectively. Absorptive permeability of AA-Su-Saq was elevated about 4-5 fold and efflux index reduced by about 13-15 fold across the polarized MDCK-MDR1 and Caco-2 cells. Absorptive permeability of AA-Su-Saq decreased 44% in the presence of 5 mM AA across MDCK-MDR1 cells. AA-Su-Saq was devoid of cytotoxicity over the concentration range studied. AA-Su-Saq significantly enhanced the metabolic stability but lowered the affinity towards CYP3A4. In conclusion, prodrug modification of Saq through conjugation to AA via a linker significantly raised the absorptive permeability and metabolic stability. Such modification also caused significant evading of P-gp mediated efflux and CYP3A4 mediated metabolism. SVCT targeted prodrug approach can be an attractive strategy to enhance the oral absorption and systemic bioavailability of anti-HIV protease inhibitors.

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).…”

“…Cellular uptake studies were performed in MDCK-MDR1 cells as this cell line is widely employed to study P-gp interactions with substrate drugs (30,(35)(36)(37)43). As shown in Fig.…”

Binding of novel fullerene inhibitors to HIV-1 protease: insight through molecular dynamics and molecular mechanics Poisson–Boltzmann surface area calculations

“…The increased saquinavir-like character of compounds 22 and 23 may have additionally contributed to the low Caco-2 and MDCK permeability. This is not surprising since it is known that saquinavir has low intestinal permeability; indeed, clinical studies have measured saquinavir permeability to Caco-2 and MDCK to be 9.3 ± 1 nm/s and 4.63 ± 0.25 nm/s, respectively [67]. In conclusion, it was observed that increased polar character along with great resemblance to saquinavir structure lowered the permeability values for the drug-modified fullerene compounds.…”

A Minireview: Usefulness of Transporter-Targeted Prodrugs in Enhancing Membrane Permeability

“…107 AA-Su-SQV targeting SVCT also exhibited about 4-5 fold higher influx permeability and 13-15 fold reduced efflux in MDCK-MDR1 and Caco-2 cells. 116 These reports suggest that prodrug-targeted SLC transporters can circumvent or reduce P-g-mediated efflux transport and can improve intestinal absorption of P-gp substrate drugs. However, it is important to consider that all water soluble nutrients such as amino acids, dipeptides and tripeptides, glucose, vitamins, bile acids, nucleoside, and so forth are basically absorbed from the small intestine by SLC transporter-mediated transports.…”

“…116 The oral bioavailability of SQV is known to be quite low. Absorptive permeability of AA-Su-SQV was elevated about 4-to 5-fold and efflux index reduced by about 13-to 15-fold across the polarized MDCK-MDR1 and Caco-2 cells.…”