HCV Protease Inhibitors Telaprevir Research Articles

Chemoselective intermolecular hydrogen bonding in peptides: An electronic and topological study on the H-bonding selectivities in peptidomimetic HCV protease inhibitor telaprevir

Chemoselectivity in intermolecular hydrogen bonding in polypeptides is demonstrated via a comprehensive study on the H-bonding characteristics of the peptidomimetic hepatitis C protease inhibitor telaprevir (1) using well-established computational tools. Starting with a QTAIM and NBO analysis of the H-bonding selectivities observed in the crystal structure of 1 and its 4-HBA cocrystal, the analysis was extended to model systems of the amino acid residues of 1 (P1res, P3res, and P4res) complexed with formic acid. The carboxylic acid/amide H-bonding of these models showed consistently stronger H-bonding at the P3 residue. The degree of chemoselectivity was quantified by comparing the QTAIM and NBO parameters between the P1res-FA, P3res-FA, and P4res-FA models. The chemoselectivity in 1 is consistent with the calculations of the FA residue models. These results demonstrate the impact of chemoselectivity in non-covalent interactions and can be extended to understanding H-bonding selectivities in polypeptides, proteins, and other macromolecular systems.

Determination of the HCV Protease Inhibitor Telaprevir in Plasma and Dried Blood Spot by Liquid Chromatography-Tandem Mass Spectrometry.

Telaprevir is a protease inhibitor used in the treatment of hepatitis C virus infection. Analytical methods for telaprevir should separate the compound from its R-diastereomer VRT-127394, which is 30-fold less active. The objective of this work was to develop liquid chromatography-tandem mass spectrometer (LC-MS/MS) assays for telaprevir both in plasma and in dried blood spot (DBS), capable of stabilizing the equilibrium and chromatographically separating the 2 epimers. Human plasma was acidified with formic acid and frozen within 1 hour after collection to stabilize the equilibrium between the 2 telaprevir diastereomers ex vivo in plasma. After protein precipitation, the sample was analyzed with LC-MS/MS. For the DBS assay, sampling paper was impregnated with citric acid solution to achieve stabilization of the epimers on the sampling paper. DBS samples were extracted before LC-MS/MS analysis. LC-MS/MS analysis comprised online solid-phase extraction and separation on a C18 column, with the mass spectrometer operating in TurboIonSpray-negative ionization mode and performing multiple reaction monitoring. The assays were linear over the concentration range of 0.1-10 mg/L in plasma and DBS. Accuracies ranged from 97% to 106% in plasma and from 93% to 99% in DBS. Within- and between-day coefficients of variation were <7.9% in plasma and <9.3% in DBS. Human whole blood samples with hematocrit values of 27%-47% gave reproducible quantitation results in the DBS assay, and spot volume did not affect results of the DBS assay either. Acidified plasma with telaprevir was stable for 5 hours at 20°C, and telaprevir on impregnated DBS paper was stable for at least 3 months at 4°C or at 20°C. An assay was developed and validated for the determination of telaprevir in human plasma, separating telaprevir from its R-diastereomer VRT-127394. In addition, a DBS assay was developed, which avoids immediate centrifuging, acidification, and freezing of patient samples to stabilize the equilibrium between the 2 telaprevir diastereomers.

Synthesis of a Key Building Block for HCV Protease Inhibitor Telaprevir

Key words telaprevir - stereoselective lithiation - carboxylation - classical resolution

Asymmetric Synthesis of 3,4‐Disubstituted Proline Derivatives: Application in Synthesis of Hepatitis C Virus Protease Inhibitor Telaprevir

AbstractA practical asymmetric synthesis of 3,4‐disubstituted proline derivatives has been realized with high stereoselectivity and moderate yield. The key steps involved are desymmetric ring‐opening reaction of commercially available anhydrides, intramolecular Strecker reaction and thermodynamically controlled cyanide hydrolysis. Based on this methodology, the synthesis of HCV protease inhibitor Telaprevir was achieved.

Stereoselective Lithiation and Carboxylation of Boc-Protected Bicyclopyrrolidine: Synthesis of a Key Building Block for HCV Protease Inhibitor Telaprevir

A stereoselective process for the manufacture of bicyclopyrrolidine 7 to 2 has been developed. The process utilizes a stereoselective lithiation/carboxylation sequence. The achiral diamine ligand DPBP induces excellent diastereocontrol, and resolution with (S)-THNA provides the corresponding salt of 8 in high er and dr. Subsequent processing of 8 gives 2 as the oxalate salt in an overall yield of 27% from 7 (based on total molar charge of 7). Compound 2 was obtained with high chemical and chiral purities. The process was successfully demonstrated on >100 kg scale.

Pharmacokinetic Interaction between Telaprevir and Methadone

Hepatitis C virus (HCV) antibody is present in most patients enrolled in methadone maintenance programs. Therefore, interactions between the HCV protease inhibitor telaprevir and methadone were investigated. The pharmacokinetics of R- and S-methadone were measured after administration of methadone alone and after 7 days of telaprevir (750 mg every 8 h [q8h]) coadministration in HCV-negative subjects on stable, individualized methadone therapy. Unbound R-methadone was measured in predose plasma samples before and during telaprevir coadministration. Safety and symptoms of opioid withdrawal were evaluated throughout the study. In total, 18 subjects were enrolled; 2 discontinued prior to receiving telaprevir. The minimum plasma concentration in the dosing interval (C(min)), the maximum plasma concentration (Cmax), and the area under the plasma concentration-time curve from h 0 (time of administration) to 24 h postdose (AUC(0-24)) for R-methadone were reduced by 31%, 29%, and 29%, respectively, in the presence of telaprevir. The AUC0-24 ratio of S-methadone/R-methadone was not altered. The median unbound percentage of R-methadone increased by 26% in the presence of telaprevir. The R-methadone median (absolute) unbound C(min) values in the absence (10.63 ng/ml) and presence (10.45 ng/ml) of telaprevir were similar. There were no symptoms of opioid withdrawal and no discontinuations due to adverse events. In summary, exposure to total R-methadone was reduced by approximately 30% in the presence of telaprevir, while the exposure to unbound R-methadone was unchanged. No symptoms of opioid withdrawal were observed. These results suggest that dose adjustment of methadone is not required when initiating telaprevir treatment. (This study has been registered at ClinicalTrials.gov under registration no. NCT00933283.).

Compensatory substitutions in the HCV NS3/4A protease cleavage sites are not observed in patients treated unsuccessfully with telaprevir combination treatment

BackgroundDevelopment of compensatory mutations within the HIV p7/p1 and p1/p6 protease cleavage site region has been observed in HIV-infected patients treated with protease inhibitors. Mechanisms of fitness compensation may occur in HCV populations upon treatment of HCV protease inhibitors as well.FindingsIn this study, we investigated whether substitutions in protease cleavage site regions of HCV occur in response to a treatment regimen containing the NS3/4A protease inhibitor telaprevir (TVR). Evaluation of viral populations from 569 patients prior to treatment showed that the four NS3/4A cleavage sites were well conserved. Few changes in the cleavage site regions were observed in the 159 patients who failed TVR combination treatment, and no residues displayed evidence of directional selection after the acquisition of TVR-resistance.ConclusionsCleavage site mutations did not occur after treatment with the HCV protease inhibitor telaprevir.

PMO-166 Early experience with telaprevir for patients with advanced fibrosis or cirrhosis

IntroductionThe direct-acting HCV protease inhibitor telaprevir has recently been licensed for treatment of chronic genotype 1 HCV infection, and promises significant improvements in sustained virological response for these patients. However...