A practical HPLC-MS method for the analysis of nitrosamine drug substance related impurities using an inexpensive single quadrupole mass spectrometer.

Nitrosamine drug substance related impurities (NDSRIs) are often analyzed using high performance liquid chromatography (HPLC) with mass spectrometry (MS) detection. Due to high sensitivity requirements, high resolution MS or MS/MS is commonly used. However, it is difficult to implement this type of method for routine analysis at a supply site.

Senescence of endplate osteoclasts induces sensory innervation and spinal pain.

Spinal pain affects individuals of all ages and is the most common musculoskeletal problem globally. Its clinical management remains a challenge as the underlying mechanisms leading to it are still unclear. Here, we report that significantly increased numbers of senescent osteoclasts (SnOCs) are observed in mouse models of spinal hypersensitivity, like lumbar spine instability (LSI) or aging, compared to controls.

Pain behavior and phenotype in a modified anterior lumbar disc puncture mouse model.

Background: An experimental study was performed to improve the anterior approach model of intervertebral disc degeneration (IVDD).

Objective: The aims of this study were to investigate the anterior approach model of IVDD for the cause of death, phenotypes, and underlying mechanisms of low back pain in mice.

Method: In this study, we conducted an anterior puncture procedure on a cohort of 300 C57BL/6J mice that were 8 weeks old.

Senescence of endplate osteoclasts induces sensory innervation and spinal pain.

Spinal pain affects individuals of all ages and is the most common musculoskeletal problem globally. Its clinical management remains a challenge as the underlying mechanisms leading to it are still unclear. Here, we report that significantly increased numbers of senescent osteoclasts (SnOCs) are observed in mouse models of spinal hypersensitivity, like lumbar spine instability (LSI) or aging, compared to controls.

On the Risk of Nitrosamine Contamination During Drug Product Blister Packaging.

Most N-Nitrosamine compounds are found to be genotoxic in several animal species. Some are classified as probable or possible human carcinogens and very low acceptable daily intake has been established such as 96 ng/day for N-nitrosodimethylamine (NDMA) and 26.5 ng/N-nitrosodiethylamine (NDEA).

Acetylshikonin promoting PI3K/Akt pathway and inhibiting SOX4 expression to delay intervertebral disc degeneration and low back pain.

This study investigated the molecular mechanism by which acetylshikonin inhibits SOX4 expression via the PI3K/Akt pathway to delay intervertebral disc degeneration (IVDD) and low back pain (LBP). Bulk RNA-seq, RT-qPCR, Western blot analysis, immunohistochemical staining, small interfering RNA (siSOX4), lentivirus (lentiv-SOX4 ), and imaging techniques were used to assess SOX4 expression and validate its upstream regulatory pathway. Acetylshikonin and siSOX4 were injected into the IVD to measure IVDD.

A Full Evaporation Static Headspace Gas Chromatography Method with Nitrogen Phosphorous Detection for Ultrasensitive Analysis of Semi-volatile Nitrosamines in Pharmaceutical Products.

The recent detection of potent carcinogenic nitrosamine impurities in several human medicines has triggered product recalls and interrupted the supply of critical medications for hundreds of millions of patients, illuminating the need for increased testing of nitrosamines in pharmaceutical products. However, the development of analytical methods for nitrosamine detection is challenging due to high sensitivity requirements, complex matrices, and the large number and variety of samples requiring testing. Herein, we report an analytical method for the analysis of a common nitrosamine, N-nitrosodimethylamine (NDMA), in pharmaceutical products using full evaporation static headspace gas chromatography with nitrogen phosphorous detection (FE-SHSGC-NPD).

Development of a simple liquid chromatography method for dissolution testing of low dose desogestrel and ethinylestradiol tablets.

Accurate quantitation of low dose, multi-active dissolution samples poses unique challenges in the pharmaceutical industry, often resulting in separate HPLC methods for each active or the use of multiple detectors for increased sensitivity. In this study, we report a fast, isocratic HPLC method utilizing only UV detection for dissolution testing of low dose desogestrel and ethinylestradiol tablets. Rapid separation is completed in 5 min using isocratic elution at a flow rate of 0.

Dehydrocostus lactone (DHC) suppresses estrogen deficiency-induced osteoporosis.

Osteoporosis is a chronic bone lytic disease, because of inadequate bone ossification and/or excessive bone resorption. Even though drugs are currently available for the treatment of osteoporosis, there remains an unmet need for the development of more specific novel agents with less adverse effects. Dehydrocostus lactone (DHC), a natural sesquiterpene lactone, was previously found to affect the differentiation of inflammatory cells by inhibiting NF-κB pathways, and garnered much interest for its anti-cancer properties via SOCS-mediated cell cycle arrest and apoptosis.

Analysis of thermolabile residual solvents in a spray dried dispersion using static headspace gas chromatography.

In this study, we discuss the development of a static headspace gas chromatography method for the analysis of residual acetone as well as its enriched impurities including mesityl oxide and diacetone alcohol, in a spray dried dispersion. The major challenges include the instability of mesityl oxide and diacetone alcohol at high temperature and peak tailing of diacetone alcohol. It was found that the headspace oven temperature has to be controlled to 150°C or below to prevent degradation beyond an acceptable level (< 1%).

Challenging pharmaceutical analyses by gas chromatography with vacuum ultraviolet detection.

Vacuum ultraviolet (VUV) detector for gas chromatography (GC) provides qualitative spectral information from 125 nm to 240 nm. In this article, this information was applied to facilitate the development of a GC method for challenging pharmaceutical applications. Seven organic solvents were screened for trace level water content using VUV detection at 168 nm, and the results were used to identify n-hexane as a suitable diluent for 4-ethoxy-1,1,1-trifluoro-3-buten-2-one (ETFBO), a water reactive compound.

Characterization of impurities of HIV NNRTI Doravirine by UHPLC-high resolution MS and tandem MS analysis.

World Health Organization estimates that 34 million individuals globally are living with Human Immunodeficiency Virus (HIV). Doravirine is a non-nucleoside reverse transcriptase inhibitors (NNRTI) being evaluated by Merck for the treatment of HIV-1 infection. Drug regulation authorities require the purity of a pharmaceutical to be fully defined.

Direct Observation of the Biaxial Stress Effect on Efficiency Droop in GaN-based Light-emitting Diode under Electrical Injection.

Light-emitting diode (LED) efficiency has attracted considerable interest because of the extended use of solid-state lighting. Owing to lack of direct measurement, identification of the reasons for efficiency droop has been restricted. A direct measurement technique is developed in this work for characterization of biaxial stress in GaN-based blue LEDs under electrical injection.

Simple spectrophotometry method for the determination of sulfur dioxide in an alcohol-thionyl chloride reaction.

Thionyl chloride is often used to convert alcohols into more reactive alkyl chloride, which can be easily converted to many compounds that are not possible from alcohols directly. One important reaction of alkyl chloride is nucleophilic substitution, which is typically conducted under basic conditions. Sulfur dioxide, the by-product from alcohol-thionyl chloride reactions, often reacts with alkyl chloride to form a sulfonyl acid impurity, resulting in yield loss.

Efficient HPLC method development using structure-based database search, physico-chemical prediction and chromatographic simulation.

Development of a robust HPLC method for pharmaceutical analysis can be very challenging and time-consuming. In our laboratory, we have developed a new workflow leveraging ACD/Labs software tools to improve the performance of HPLC method development. First, we established ACD-based analytical method databases that can be searched by chemical structure similarity.

Rapid separation of desloratadine and related compounds in solid pharmaceutical formulation using gradient ion-pair chromatography.

We reported the development of an ion-pair chromatographic method to separate desloratadine and all known related compounds in Clarinex Tablets, which use desloratadine as active pharmaceutical ingredient (API). For the first time, baseline separation for desloratadine and all known related compounds was achieved by utilizing a YMC-Pack Pro C(18) column (150 mm x 4.6 mm I.

Comparison study of porous, fused-core, and monolithic silica-based C18 HPLC columns for Celestoderm-V Ointment analysis.

In this paper, three C18 columns with different substrates (i.e., porous ACE-3 C18, 3 microm, fused-core Halo C18, 2.

Mechanism for the separation of large molecules based on radial migration in capillary electrophoresis.

We demonstrate a novel separation mechanism for large molecules based on their radial migration in capillary electrophoresis with applied hydrodynamic flow (HDF). The direction of radial migration depends on the direction of the applied HDF relative to the electric field. The radial migration velocities are size-dependent, which could be attributed to the different degree of deformation under shear flow.

Mechanism of microbial aggregation during capillary electrophoresis.

We studied the aggregation of a rod-shaped bacteria, Bifidobacterium infantis, during capillary electrophoresis (CE). A microscope with an intensified CCD camera was employed to monitor the migration and aggregation of bacteria, which are labeled with fluorescent dye Syto 9 and excited with a 488-nm argon ion laser. A collision-based aggregation mechanism is proposed, in which collisions between microbes result from different mobilities and migration directions in the electric field.

Mechanistic aspects in the generation of apparent ultrahigh efficiencies for colloidal (microbial) electrokinetic separations.

Under specific experimental conditions, the electrokinetic separation of certain microorganisms can produce peaks of very high apparent efficiencies (approximately 10(6)-10(10) theoretical plates/m). This is unusual in that no deliberate focusing mechanism was employed. To investigate this process further, the separation was monitored in real time using a charge-coupled device (CCD) imaging system.

Anomalous radial migration of single DNA molecules in capillary electrophoresis.

We report the unexpected radial migration of DNA molecules in capillary electrophoresis (CE) with applied Poiseuille flow. Such movement can contribute to anomalous migration times, peak dispersion, and size and shape selectivity in CE. When Poiseuille flow is applied from the cathode to the anode, DNA molecules move toward the center of the capillary, forming a narrow, highly concentrated zone.