The main focus of the master's thesis is chloroquine, used as an antimalarial and evaluated as a potential candidate drug against Sars-CoV-2 virus. The work was performed in support of an in vivo study of the pharmacokinetic properties of a new pharmaceutical dosage form with chloroquine, performed at the Institute of Pathology, Faculty of Medicine, University of Ljubljana. The pharmacokinetics of chloroquine and its metabolite desethylchloroquine has not been fully explained, and their tissue distribution is particularly poorly understood.
The aim of this master's thesis was to develop and validate bioanalytical methods for measuring chloroquine and its active metabolite desethylchloroquine concentration in blood, urine, and selected rat tissues, and to measure analyte concentrations in study samples.
During the development of the sample preparation process, solid phase extraction with a reverse-phase and ion exchange retention mechanism and liquid-liquid extraction with various organic solvents were tested. The latter procedure provided the best results, and tert-butyl methyl ether was used as the extraction solvent. Chromatographic and mass spectrometric parameters were also optimized. The developed method was evaluated on the basis of partially adjusted criteria from European Medicines Agency guidelines for the validation of bioanalytical methods and applied to samples from the in vivo study. In rat blood, chloroquine and desethylchloroquine concentrations were (1339 ± 280) μg/L and (419 ± 62) μg/L, and in urine (30820 ± 8955) μg/L and (7495 ± 2510) μg/L, respecitvely. The mean concentration of chloroquine in the liver was (230 ± 217), in the kidneys (121 ± 91), in the heart (15 ± 9), in skeletal muscle (3.6 ± 1.1), in the brain (1.9 ± 1.4), and in fat (1.9 ± 0.8) μg/g tissue. The mean concentration of desethylchloroquine was several fold lower: in the liver (54 ± 34), in the kidneys (21 ± 0.5), in the heart (3.7 ± 1.0), in skeletal muscle (0.4 ± 0.1), in the brain (0.6 ± 0.4), and in fat tissue (0.6 ± 0.2) μg/g tissue.
The results obtained show a successful application of the developed method to the samples from preclinical study. They also reveal highly uneven distribution of chloroquine and its active metabolite in the blood, urine and in different organs; the results are also in good agreement with literature data.
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