Analysis of barbituric acid derivatives in biological objects

Abstract

Barbituric acid derivatives produce an inhibiting action on the central nervous system and are widely used in medicine as calming, hypnotic, and anticonvulsant drugs. In clinics, these compounds are employed for the treatment of epilepsy, chorea, and spastic paralysis [1,2]. Barbital sodium and barbamyl -drugs belonging to the group of barbituric acid derivatives -are of interest as compound producing rapid pharmacological effect. These substances are readily dissolved and rapidly absorbed in the gastrointestinal tract. However, both barbital sodium and barbamyl are characterized by pronounced toxicity (leading to inhibition of the cerebral cortex, suppression of the respiratory center and cardiac activity, toxic damage of cerebral capillaries, and a strong hypotensive effect) and may lead to narcotic dependence.It was reported that poisoning with barbital sodium and barbamyl may lead to lethal outcome. Therefore, the development of an effective, rapid, and economical scheme for the investigation of biological objects with respect to the presence and content of barbituric acid derivatives is an important task, in particular, from the standpoint of chemicotoxicological analysis and forensic examination [3,4].The aim of this study was to select the optimum conditions for the extraction of poisons belonging to barbituric acid derivatives from the tissues of cadaveric liver, since liver is the organ involved in the localization and detoxication of poisons. We have also developed methods for the purification of extracts from biogenic impurities, for qualitative identification, and for quantitative determination. The proposed analytical scheme is compared to the existing methods used for the analysis of barbiturates. EXPERIMENTAL PARTThe extraction of drugs from cadaveric tissues is usually performed with hydrophilic solvents (aqueous solutions of acids and alkalis) and amphiphilic liquids (ethanol, acetone, acetonitrile). However, the most promising direction of development in this direction is related to the use of lipophilic extractants (in particular, chloroform) and their mixtures with hydrophilic and amphiphilic solvents [5 -8]. This is confirmed by the results of our systematic investigations of the extraction of drugs possessing acidic, basic, and weakly basic character [9 -11].Selection of the optimum conditions for the extraction of barbituric acid derivatives with chloroform from biological materials depends on the physicochemical properties of these substances (acidity, tautomerism, solubility in aqueous and organic phases) and a particular biological material [5,12,13].In our experiments, barbital sodium and barbamyl were extracted from model mixtures comprising 5 g of a cadaveric liver tissue (without signs of putrefaction) with addition of 0.5 ml of an aqueous solution containing 1000.0 mg of barbiturates (control samples were mixed with pure water). The level of barbiturate in the model mixtures was selected so as to correspond to lethal doses of the drugs: 5.0 -25.0 g for barbital sodium (lethal concen...