Mechanisms and Predictions of Drug-Drug Interactions of the Hepatitis C Virus Three Direct-Acting Antiviral Regimen: Paritaprevir/Ritonavir, Ombitasvir, and Dasabuvir.

To assess drug-drug interaction (DDI) potential for the three direct-acting antiviral (3D) regimen of ombitasvir, dasabuvir, and paritaprevir, in vitro studies profiled drug-metabolizing enzyme and transporter interactions. Using mechanistic static and dynamic models, DDI potential was predicted for CYP3A, CYP2C8, UDP-glucuronosyltransferase (UGT) 1A1, organic anion-transporting polypeptide (OATP) 1B1/1B3, breast cancer resistance protein (BCRP), and P-glycoprotein (P-gp). Perpetrator static model DDI predictions for metabolizing enzymes were within 2-fold of the clinical observations, but additional physiologically based pharmacokinetic modeling was necessary to achieve the same for drug transporters.

Metabolism and Disposition of Pan-Genotypic Inhibitor of Hepatitis C Virus NS5A Ombitasvir in Humans.

Ombitasvir (also known as ABT-267) is a potent inhibitor of hepatitis C virus (HCV) nonstructural protein 5A (NS5A), which has been developed in combination with paritaprevir/ritonavir and dasabuvir in a three direct-acting antiviral oral regimens for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of ombitasvir in humans without coadministration of paritaprevir/ritonavir and dasabuvir. Following the administration of a single 25-mg oral dose of [(14)C]ombitasvir to four healthy male volunteers, the mean total percentage of the administered radioactive dose recovered was 92.

Metabolism and Disposition of the Hepatitis C Protease Inhibitor Paritaprevir in Humans.

Paritaprevir (also known as ABT-450), a potent NS3-4A serine protease inhibitor [identified by AbbVie (North Chicago, IL) and Enanta Pharmaceuticals (Watertown, MA)] of the hepatitis C virus (HCV), has been developed in combination with ombitasvir and dasabuvir in a three-direct-acting antiviral agent (DAA) oral regimen for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of paritaprevir in humans. After the administration of a single 200-mg oral dose of [(14)C]paritaprevir coadministered with 100 mg of ritonavir to four male healthy volunteers, the mean total percentage of the administered radioactive dose recovered was 96.

Metabolism and Disposition of Hepatitis C Polymerase Inhibitor Dasabuvir in Humans.

Dasabuvir [also known as ABT-333 or N-(6-(3-(tert-butyl)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-2-methoxyphenyl)naphthalen-2-yl)methanesulfonamide] is a potent non-nucleoside NS protein 5B polymerase inhibitor of the hepatitis C virus (HCV) and is being developed in combination with paritaprevir/ritonavir and ombitasvir in an oral regimen with three direct-acting antivirals for the treatment of patients infected with HCV genotype 1. This article describes the mass balance, metabolism, and disposition of dasabuvir in humans. After administration of a single oral dose of 400-mg [(14)C]dasabuvir (without coadministration of paritaprevir/ritonavir and ombitasvir) to four healthy male volunteers, the mean total percentage of the administered radioactive dose recovered was 96.

Toxicokinetic evaluation of atrasentan in mice utilizing serial microsampling: validation and sample analysis in GLP study.

Background: A semi-automated 96-well protein precipitation followed by HPLC-MS/MS method for the determination of atrasentan (2R-[4-methoxyphenyl]-4S-[1,3-benzodioxol-5-yl]-1-[N,N-di-(N-butyl)-aminocarbonyl-methyl]-pyrrolidine-3R-carboxylic acid) in mouse whole blood was developed, validated and utilized in GLP toxicokinetic evaluations. Six 40-µl whole blood samples were collected from a single mouse over the course of a 12 h blood collection window. To avoid sample volume losses, whole blood was selected as the matrix in place of the more typically used plasma.

Challenges in the indirect quantitation of acyl-glucuronide metabolites of a cardiovascular drug from complex biological mixtures in the absence of reference standards.

This paper describes the quantitation of acyl-glucuronide metabolites (M26 and M5) of a cardiovascular-drug (torcetrapib) from monkey urine, in the absence of their reference standards. LC/MS/MS assays for M1 and M4 (aglycones of M26 and M5, respectively) were characterized from normal and base-treated urine, as their respective reference standards were available. The in vivo study samples containing M26 and M5 were treated with 1 n sodium hydroxide to hydrolyze them to their respective aglycones.

Rapid determination of the applicability of hydrophilic interaction chromatography utilizing ACD labs log D suite: a bioanalytical application.

Hydrophilic interaction chromatography (HILIC) is an effective technique for retaining and separating polar compounds. This approach offers several advantages for bioanalytical liquid chromatography/mass spectrometry, considering that a majority of active pharmaceutical ingredients are polar amines. HILIC employs high concentrations of relatively polar organic mobile phase components (i.

Signal suppression/enhancement in HPLC-ESI-MS/MS from concomitant medications.

This paper presents a study of the signal suppression and enhancement effects in assays based on HPLC-ESI-MS/MS detection. The major focus was to investigate the effect of signal suppression/enhancement of typical co-administered (concomitant) medications, i.e.

Strategies for bioanalysis of an oligonucleotide class macromolecule from rat plasma using liquid chromatography-tandem mass spectrometry.

Electrospray ionization (ESI) liquid chromatography-tandem mass spectrometry (LC/MS/MS) assays provide high-throughput and selective methods for quantitation of small molecules. Use of LC/MS/MS assays for macromolecules, like oligonucleotides, is challenging due to lack of sensitivity and low analyte recovery from biomatrixes. Due to this fact, the method of choice for oligonucleotides quantitation remains hybridization-based ligand-binding assays.

Method for internal standard introduction for quantitative analysis using on-line solid-phase extraction LC-MS/MS.

A novel approach for on-line introduction of internal standard (IS) for quantitative analysis using LC-MS/MS has been developed. In this approach, analyte and IS are introduced into the sample injection loop in different steps. Analyte is introduced into the injection loop using a conventional autosampler (injector) needle pickup from a sample vial.

Development and application of a new on-line SPE system combined with LC-MS/MS detection for high throughput direct analysis of pharmaceutical compounds in plasma.

A technique using a fully automated on-line solid phase extraction (SPE) system (Symbiosis, Spark Holland) combined with liquid chromatography (LC)-mass spectrometry (MS/MS) has been investigated for fast bioanalytical method development, method validation and sample analysis using both conventional C18 and monolithic columns. Online SPE LC-MS/MS methods were developed in the automated mode for the quantification of model compounds (propranolol and diclofenac) directly in rat plasma. Accuracy and precision using online SPE LC-MS/MS with conventional C18 and monolithic columns were in the range of 88-111% and 0.