An Overview of Advances in the Chromatography of Drugs Impurity Profiling.

A systematic literature survey published in several journals of pharmaceutical chemistry and of chromatography used to analyze impurities for most of the drugs that have been reviewed. This article covers the period from 2016 to 2020, in which almost of chromatographic techniques have been used for drug impurity analysis. These chromatography techniques are important in the analysis and description of drug impurities. Moreover, some recent developments in forced impurity profiling have been discussed, such as buffer solutions, mobile phase, columns, elution modes, and detectors are highlighted in drugs used for the study. This primarily focuses on thorough updating of different analytical methods which include hyphenated techniques for detecting and quantifying impurity and degradation levels in various pharmaceutical matrices.

Vasoactive intestinal peptide (VIP) conducts the neuronal activity during absence seizures: GABA seems to be the main mediator of VIP.

Absence epilepsy is classified as a childhood generalized epilepsy syndrome with distinctive electroencephalographic patterns. The Wistar Albino Glaxo originating from Rijswijk (WAG/Rij) strain is a very well validated animal model of absence epilepsy that also shows behavioral deficits. In addition to the gastrointestinal system, VIP is highly expressed throughout numerous brain regions, and it plays crucial roles as a neurotransmitter and as a neuromodulatory, neurotrophic and neuroprotective factor in both the central and peripheral nervous systems. In this study, adult WAG/Rij rats were divided into two groups (n = 10): a group that was administered VIP (25 ng/kg i.p.) every 2 days for 15 days and an age-matched control group that was administered physiological saline. Electrical brain activity and behavior (depressive- like behavior, learning and memory and anxiety) were investigated in both groups. In addition, the extracellular concentrations of GABA and glutamate and the GABA/glutamate ratio were measured by high-performance liquid chromatography in microdialysate samples collected from the somatosensorial cortex of WAG/Rij rats. Our results demonstrated that VIP treatment significantly suppressed the total duration and number of spike wave discharges in WAG/Rij rats. However, VIP had no significant effect on behavior. VIP increased the extracellular concentration of GABA and the GABA/glutamate ratio in the somatosensory cortex. In conclusion, VIP has suppressive effects on absence seizures, possibly by increasing the GABA concentration and inducing the transformation of glutamate to GABA in the somatosensory cortex of WAG/Rij rats.

Determination of Ochratoxin-A in the brain microdialysates and plasma of awake, freely moving rats using ultra high performance liquid chromatography fluorescence detection method.

In this study, a simple, efficient and rapid Ultra High Performance Liquid Chromatography method with fluorescence detection (UHPLC-FLD) has been developed and validated for the determination of Ochratoxin-A (OTA) in rat brain microdialysates and plasma samples. Six adult male wistar rats were used in the study and a single dose (5 mg/kg b.w.) of OTA was given by intraperitoneal (i.p.) injection. Rat blood and microdialysate samples were collected simultaneously after i.p. injection in awake freely moving rats, over a twelve-hour period. An UHPLC analysis was performed on a Zorbax Eclipse Plus C8 (150 mm × 3.0 mm ID × 1.8 µm particles) column with a mobile phase of acetonitrile:water:phosphoric acid (50:50:0.1, v/v) using a flow rate of 0.6 mL/min. The fluorescence detector was set at 330 nm excitation and 460 nm emission wavelengths. Diflunisal (DIF) was used as an internal standard (IS). OTA and IS were separated within 5 min under these conditions. The method was validated in terms of linearity, precision, accuracy, limit of detection, limit of quantification, and stability. Calibration curves obtained with spiked biological matrices show good linearity with high correlation coefficients. The intra- and inter-day assay variability was <5% for the OTA. The limit of detection and the limit of quantification values were found to be 0.490 ng/mL and 1.48 ng/mL for plasma; 0.0900 ng/mL and 0.270 ng/mL for microdialysate samples, respectively. This method was successfully applied for the monitoring of OTA levels in the rat brain and plasma samples.