Discovery of 2-aminoisobutyric acid ethyl ester (AIBEE) phosphoramidate prodrugs for delivering nucleoside HCV NS5B polymerase inhibitors.

Our HCV research program investigated novel 2'-dihalogenated nucleoside HCV polymerase inhibitors and identified compound 1, a 5'-phosphoramidate prodrug of 2'-deoxy-2'-α-bromo-ß-chloro uridine. Although 1 had a favorable in vitro activity profile in HCV replicons, oral dosing in dog resulted in low levels of the active 5'-triphosphate (TP) in liver. Metabolism studies using human hepatocytes provided a simple assay for screening alternative phosphoramidate prodrug analogs. Compounds that produced high TP concentrations in hepatocytes were tested in dog liver biopsy studies. This method identified 2-aminoisobutyric acid ethyl ester (AIBEE) phosphoramidate prodrug 14, which provided 100-fold higher TP concentrations in dog liver in comparison to 1 (4 and 24 h after 5 mg/kg oral dose).

Synthesis and evaluation of 2'-dihalo ribonucleotide prodrugs with activity against hepatitis C virus.

Hepatitis C virus (HCV) nucleoside inhibitors have been a key focus of nearly 2 decades of HCV drug research due to a high barrier to drug resistance and pan-genotypic activity profile provided by molecules in this drug class. Our investigations focused on several potent 2'-halogenated uridine-based HCV polymerase inhibitors, resulting in the discovery of novel 2'-deoxy-2'-dihalo-uridine analogs that are potent inhibitors in replicon assays for all genotypes. Further studies to improve in vivo performance of these nucleoside inhibitors identified aminoisobutyric acid ethyl ester (AIBEE) phosphoramidate prodrugs 18a and 18c, which provide high levels of the active triphosphate in dog liver. AIBEE prodrug 18c was compared with sofosbuvir (1) by co-dosing both compounds by oral administration in dog (5 mg/kg each) and measuring liver concentrations of the active triphosphate metabolite at both 4 and 24 h post dosing. In this study, 18c provided liver triphosphate concentrations that were 6-fold higher than sofosbuvir (1) at both biopsy time points, suggesting that 18c could be a highly effective agent for treating HCV infected patients in the clinic.

Integrity and efficiency: AbbVie's journey of building an integrated nonregulated bioanalytical laboratory.

While bioanalytical outsourcing is widely adopted in the pharmaceutical industry, AbbVie is one of the few large biopharmaceutical companies having an internal bioanalytical unit to support nearly all its drug metabolism and pharmacokinetic studies. This article highlights our experience and perspective in building an integrated and centralized laboratory to provide early discovery and preclinical-stage bioanalytical support with high operational efficiency, cost-effectiveness and data integrity. The advantages of in-house nonregulated bioanalytical support include better control of data quality, faster turnaround times, real-time knowledge sharing and troubleshooting, and lower near- and long-term costs. The success of an in-house model depends upon a comprehensively optimized and streamlined workflow, fueled by continuous improvements and implementation of innovative technologies.

Prodrug Strategies to Improve the Solubility of the HCV NS5A Inhibitor Pibrentasvir (ABT-530).

A research program to discover solubilizing prodrugs of the HCV NS5A inhibitor pibrentasvir (PIB) identified phosphomethyl analog 2 and trimethyl-lock (TML) prodrug 9. The prodrug moiety is attached to a benzimidazole nitrogen atom via an oxymethyl linkage to allow for rapid and complete release of the drug for absorption following phosphate removal by intestinal alkaline phosphatase. These prodrugs have good hydrolytic stability properties and improved solubility compared to PIB, both in aqueous buffer (pH 7) and FESSIF (pH 5). TML prodrug 9 provided superior in vivo performance, delivering high plasma concentrations of PIB in PK studies conducted in mice, dogs, and monkeys. The improved dissolution properties of these phosphate prodrugs provide them the potential to simplify drug dosage forms for PIB-containing HCV therapy.