Quantification of Grapiprant and Its Stability Testing under Changing Environmental Conditions.

Grapiprant is a new analgesic and anti-inflammatory drug belonging to the piprant class, approved in 2016 by the FDA Veterinary Medicine Center for the treatment of pain and inflammation associated with osteoarthritis in dogs. It acts as a highly selective antagonist of the EP4 receptor, one of the four prostaglandin E2 (PGE2) receptor subtypes. It has been shown to have anti-inflammatory effects in rat models of acute and chronic inflammation and clinical studies in people with osteoarthritis.

Analysis of Nefopam by TLC-densitometry. A Study of Degradation Mechanism in Solutions Under Stress Conditions.

A new, simple, selective, precise and accurate thin-layer chromatographic method for quantification of nefopam hydrochloride in formulations has been established and validated. TLC F254 silica gel plates in combination with a mixture of chloroform : methanol : glacial acetic acid (9 : 2: 0.1, v/v/v) as mobile phase were used.

Hydrolysis of 2,4-dithiophenobarbital.

Hydrolysis of 2,4-dithiophenobarbital in aqueous solutions of pH 2-12 was investigated at 40 and 60 degrees C using UV spectrophotometry. The values of reaction order, rate constants, pKa1 and pKa2 and activation energy were determined. The preliminary estimation of degradation products was accomplished using thin layer chromatography.

Stability of 2-thiophenobarbital and its N-methyl derivatives in the presence of beta-cyclodextrin.

The rates of hydrolysis of thiophenobarbital and its N-mono- and N,N'-dimethyl-derivatives were determined under different conditions of pH and temperature using UV spectroscopy. They were compared with those obtained in the presence of different concentrations of beta-cyclodextrin. It was found that the compounds degrade with different rates and beta-cyclodextrin retards the hydrolysis.

Hydrolysis of N,N- and N,S-dimethyl derivatives of 2-thiophenobarbital.

Kinetics of hydrolysis of N,N- and N,S-dimethyl-2-thiophenobarbital and products of this reaction were investigated. The UV spectroscopy served as a tool for kinetic investigations and chromatography was used to separate and isolate the main products of hydrolysis. These products were identified by spectroscopic methods and the course of hydrolysis of both isomers was compared.

Hydrolysis of N- and S-monomethyl derivatives of 2-thiophenobarbital.

Kinetics of hydrolysis of S-methyl-2-thiophenobarbital in aqueous solutions was investigated using the UV spectroscopic method within the pH range 1.5-12.9 at 60 degrees C.