DEVELOPMENT OF CONDITIONS FOR ISOLATION OF PREGABALIN FROM BIOLOGICAL FLUIDS

Abstract

Introduction. The drug Pregabalin (trade names: “Lyrica®”, “Pregabalin”, “Algerica”, “Replica”) has found wide application in Medicine as an anticonvulsant and analgesic. Since 2008, cases of non-medical use of the drug have been registered, most often by drug addicts, in high dosages to obtain a drug-like effect, to “enhance” the effect of narcotic and other psychoactive drugs, as well as to eliminate withdrawal syndrome after stopping taking drugs. The aim of the study was to develop a method for isolating and determining pregabalin from biological fluids by liquid-liquid extraction, including for the purposes of chemical-toxicological analysis (CTA). Research methods. The study was performed with model blood and urine samples containing pregabalin. During the blood study, the formed elements were pre-precipitated by adding 10 % trichloroacetic acid solution. Extractive purification was performed with hexane at pH 1 and the drug was extracted from biological fluids with chloroform at pH 8. The obtained extracts were additionally subjected to TLC purification. Pregabalin in eluates from chromatograms was determined by UV spectrophotometric method. Results and their discussion. The Rf value of pregabalin in the mobile phase – toluene – acetone – ethanol – 25 % ammonia (45 : 45 : 7 : 3) was 0.64 ± 0.02. Ninhydrin was the most sensitive for the detection of pregabalin. The limit of quantification (LOD) when using this reagent is 0.1 μg of the drug in the sample. The UV spectra of the eluates from the chromatograms had maximum light absorption at a wavelength of 203 ± 2, and the nature of the light absorption coincided with the UV spectrum of the standard solution of pregabalin in methanol solution. Quantitative determination was performed at λmax 203 nm according to the equation of the calibration graph y = 0.0991x - 0.0696. The developed methods allowed to isolate 51.32 + 0.85 % of pregabalin from urine, from blood plasma – 31.27 + 0.81 %. Conclusions. Effective conditions for sample preparation of biological fluids by the method of liquid-liquid extraction for pregabalin have been determined. The results obtained are of practical importance for creating an algorithm for toxicological examination of biological objects for the presence of the specified drug in case of lethal intoxications.