D-α-tocopheryl polyethylene glycol 1000 succinate-containing vehicles provide no detectable chemoprotection from oxidative damage.

The objective of this study was to evaluate potential protective effects of vehicles containing d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), which may impact nonclinical safety assessments of oxidative processes. This was achieved by evaluating plasma, liver and adrenal gland concentrations of d-α-tocopheryl succinate (TS) and d-α-tocopherol as well as oxidative status of plasma following oral dosing of TPGS-containing vehicles, intraperitoneal (IP) dosing of TS or ex vivo treatment of blood with H2O2. Male and female rats were dosed orally with formulations containing 5% or 40% TPGS (70 or 550 mg kg(-1) day(-1) TS, respectively) for 1 week. A control group was dosed orally with polyethylene glycol-400 (PEG-400; no vitamin E) and positive control animals received a single 100 mg kg(-1) day(-1) IP injection of TS. Whole blood from untreated animals was treated ex vivo with 5 or 50 mm H(2)O(2), with or without TS (0.5, 5, 50 or 500 µm) or ascorbate (1 mm), for 1 h. Oral TPGS treatments did not affect d-α-tocopherol concentrations in plasma or adrenal glands and caused only transient increases in liver. Concentrations of TS in plasma, liver and adrenal glands were undetectable in control animals, but increased in all other groups. Oral administration of TPGS did not reduce plasma lipid peroxidation in vivo. Substantially greater TS concentrations used ex vivo (100× greater than in vivo) were also unable to reduce lipid peroxidation in H2O2 -treated whole blood. These results provide evidence that administration of oral TPGS vehicles is unlikely to impact nonclinical safety assessments of pharmaceuticals.

A rugged and accurate liquid chromatography-tandem mass spectrometry method for the determination of asunaprevir, an NS3 protease inhibitor, in plasma.

Asunaprevir (BMS-650032) is a potent hepatitis C virus (HCV) non-structural protein protease inhibitor currently in Phase III clinical trials for the treatment of HCV infection. A rugged and accurate LC-MS/MS method was developed and validated for the quantitation of asunaprevir in rat, dog, monkey, rabbit and mouse plasma. A systematic method screening and optimization strategy was applied to achieve optimized mass spectrometry, chromatography, and sample extraction conditions. The validated method utilized stable-isotope labeled D9-asunaprevir as the internal standard. The samples were extracted by liquid-liquid extraction using 10% ethyl acetate in hexane. Chromatographic separation was achieved with gradient elution on a Waters Atlantis dC18 analytical column. Analyte and its internal standard were detected by positive ion electrospray tandem mass spectrometry. The standard curve, which ranged from 5.00 to 2000ng/mL for asunaprevir, was fitted to a 1/x(2) weighted linear regression model. The intra-assay precision was within ±3.6% CV, inter-assay precision was within ±4.0% CV, and the assay accuracy was within ±8.1% of the nominal values in all the species. The method was successfully applied to support multiple pre-clinical toxicokinetic studies in different species.

A convenient strategy for quantitative determination of drug concentrations in tissue homogenates using a liquid chromatography/tandem mass spectrometry assay for plasma samples.

Quantitative determination of drug concentrations in tissue homogenates via liquid chromatography-tandem mass spectrometry (LC-MS/MS) is commonly conducted using the standards and analytical quality controls (QCs) prepared in the same matrix (tissue homogenates), to keep the matrix and its effects consistent on the analytes during sample extraction and analysis. In this manuscript, we proposed to analyze tissue homogenate samples using an LC-MS/MS assay with the standards and analytical QCs prepared in plasma after tissue homogenate samples were appropriately diluted with plasma. BMS-650032 was used as a model compound, and its validated dog plasma assay was used for dog liver sample analyses. The tissue matrix effect was evaluated by diluting liver homogenate QCs with drug-free plasma at different dilution factors to determine the minimum required dilution factor (MRDF) at which tissue matrix has insignificant impact to the plasma assay. The percentage deviation of the measured concentration from the nominal concentration was used as an indicator of the tissue matrix effect. The results suggested that the tissue matrix effect was decreased as the plasma dilution factor increased. Based on the results of the tissue matrix effect evaluation, liver homogenate samples were analyzed after appropriate dilutions with plasma at the MRDF or greater dilution factors. The results confirmed that this approach generates accurate data, and the process is very convenient and economic. This approach has been used on the analyses of different tissues (liver and brain) and biofluid (bile) to support several drug development programs.

Role of tumor necrosis factor in toluene diisocyanate asthma.

Nearly 9 million workers are exposed to chemical agents associated with occupational asthma, with isocyanates representing the chemical class most responsible. Isocyanate-induced asthma has been difficult to diagnose and control, in part because the biologic mechanisms responsible for the disease and the determinants of exposure have not been well defined. Isocyanate-induced asthma is characterized by airway inflammation, and we hypothesized that inflammation is a prerequisite of isocyanate-induced asthma, with tumor necrosis factor (TNF)-alpha being critical to this process. To explore this hypothesis, wild-type mice, athymic mice, TNF-alpha receptor knockout (TNFR), and anti-TNF-alpha antibody-treated mice were sensitized by subcutaneous injection (20 micro l on Day 1; 5 micro l, Days 4 and 11), and challenged 7 d later by inhalation (100 ppb; Days 20, 22, and 24) with toluene diisocyanate (TDI). Airway inflammation, goblet cell metaplasia, epithelial cell damage, and nonspecific airway reactivity to methacholine challenge, measured 24 h following the last challenge, were reduced to baseline levels in TNF-alpha null mice and athymic mice. TNF-alpha deficiency also markedly abrogated TDI-induced Th2 cytokines in airway tissues, indicating a role in the development of Th2 responses. Despite abrogation of all indicators of asthma pathology, TNF-alpha neutralization had no effect on serum IgE levels or IgG-specific TDI antibodies, suggesting the lack of importance of a humoral response in the manifestation of TDI-induced asthma. Instillation studies with fluorescein-conjugated isothiocyanate and TDI suggested that TNF-alpha deficiency also resulted in a significant reduction in the migration of airway dendritic cells to the draining lymph nodes. Taken together, these results suggest that, unlike protein antigens, TNF-alpha has multiple and central roles in TDI-induced asthma, influencing both nonspecific inflammatory processes and specific immune events.