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Biomedical subjects

V Marko

Publications and source records attributed to V Marko.

15 recordsLinked to original sources
PubMed1991

Study of the solid phase extraction of pentoxifylline and its major metabolite as a basis of their rapid low concentration gas chromatographic determination in serum.

A gas-liquid chromatographic method for the determination of pentoxifylline and its secondary alcohol metabolite in serum has been developed. The method is based on the combination of solid phase extraction, capillary column separation and nitrogen-phosphorus detection of the analytes. Optimization of the solid phase extraction conditions permitted a low concentration determination, with limits of determination of 2 ng/mL and 10 ng/mL for pentoxifylline and its metabolite, respectively. The simplicity and rapidity of the extraction step was preserved.

Chromatography, Gas↗
PubMed1991

Evaluation of 3H-CGP 12177 and 3H-DHA binding to beta 2-adrenoceptors of rat reticulocytes by means of affinity spectra.

3H-CGP 12177 and 3H-DHA binding to rat reticulocyte beta 2-adrenoceptors by using an excess of 1 x 10(-5) mol l-1 propranolol was evaluated by means of affinity spectra. To describe the 3H-CGP 12177 interaction with rat reticulocytes a binding isotherm valid for one single class of specific binding sites was found to be satisfactory. On the other hand, a more complex binding isotherm had to be used for the description of the 3H-DHA interaction with rat reticulocytes. This observation further supports the preferred application of 3H-CGP 12177 over 3H-DHA for radio-receptor assay of beta-adrenoceptor blockers.

Animals↗
PubMed1990

Polar interactions in solid-phase extraction of basic drugs by octadecylsilanized silica.

Polar interactions between basic drugs (pentacaine, propranolol, and stobadin) and C18 silanized silica are studied along with hydrophobic interactions by using elution profiles of the drugs obtained with six organic solvents. The elution ability of the liquids towards basic drugs depends positively on their proton acceptor properties and negatively on their dipole interaction properties. Addition of triethylamine, a strong proton acceptor, to the liquids improves their elution ability, resulting in practically total recovery in all instances. The shapes of elution profiles indicate the presence of multiple types of interactions between C18 silica sorbent and basic drugs, ranging from those that originate from hydrophobic interactions to those originating from solute-sorbent ionic forces.

Acetates↗
PubMed1989

Influence of beta-adrenoceptor blocking drugs on lipid-protein interaction in synaptosomal membranes. An ESR study.

The influence of the beta-adrenoceptor blocking drugs atenolol, doberol, propranolol and exaprolol on synaptosomal membranes was studied using ESR spectroscopy of stearic acid spin labeled at the 16th position. The drugs changed the ESR spectra of the label in the membranes, where in addition to changes of a fluid lipid component they increased the proportion of a motionally-restricted component. No motionally-restricted component was found in the samples prepared from brain total lipid liposomes treated with the drugs. The drug propensities at 20 mmol/l concentration to increase the proportion of the motionally-restricted component in the following order, control less than doberol approximately atenolol less than or equal to propranolol less than exaprolol did not correlate with their potency to influence the dynamics of the bulk lipid membrane phase. The motionally-restricted component induced by exaprolol increased with raising temperature and prolongation of time of the sample incubation. The results indicate that the beta-adrenoceptor blocking drugs influence lipid-protein interaction in the synaptosomal membranes, which could be important for elucidation of their mechanism of biological membrane activities.

Adrenergic beta-Antagonists↗
PubMed1987

Selective solid-phase extraction of mexiletine from human serum prior to its GLC analysis.

A rapid and sensitive method for the GLC determination of mexiletine in human serum is described. The liquid-liquid extraction was replaced by the solid-phase extraction procedure for sample preparation using Separcol SI C 18 cartridges. The two-step elution of the cartridges after serum application was used-first with 50% acetonitrile in water for eluting endogenous compounds from serum, then with methanol to displace purified mexiletine. The recovery by this procedure was 83.6%. This selective solid-phase extraction offers an acceptable alternative to liquid extraction, and in combination with GLC-FID analysis is suitable for clinical pharmacokinetic studies of mexiletine.

Chromatography, Gas↗
PubMed1986

Determination of carbisocaine, heptacaine and pentacaine in plasma by capillary gas chromatography with nitrogen-selective detection.

A gas-liquid chromatographic method is described for the determination of the local anaesthetics carbisocaine, heptacaine and pentacaine in plasma. A C(18) solid-phase extraction was used in a modification to increase selectivity. Following on-column derivatization with trimethylanilinium hydroxide, the analytes were determined by means of capillary gas chromatography and nitrogen-phosphorus selective detection. In comparison with flame ionization detection, the sensitivity of NPD was 20 times higher with a limit of determination in plasma of 10 ng ml(-1).

Journal Article↗
PubMedDate not supplied

Disposition of ethimizol, a nootropic drug, in rats and mice.

The pharmacokinetics of ethimizol, a nootropic drug, were studied in rats and mice using [2-14C]-4,5-di(methylcarbamoyl)-1-ethyl-imidazole. Autoradiography in mice injected iv showed a rapid and homogeneous distribution of the label into the tissues, brain included, and its excretion by the urinary pathway. The determination of ethimizol in plasma, organs, and excreta was based on combined extraction and the TLC procedure. In rats, the elimination half-life of ethimizol after iv administration of 10 mg/kg was 25 min, and its distribution volume was 1.4 liters/kg. The tissue/plasma concentration ratio for organs investigated was 1 immediately after iv administration, with a subsequent gradual increase. Based on this, saturable tissue binding of ethimizol in the liver, kidney, and brain was suggested. The drug was almost completely absorbed after administration, yet its systemic availability was only 32%. The brain uptake index of ethimizol was 101% as compared to 3H2O. Ethimizol was eliminated by metabolism. The labeled metabolites were predominantly excreted in the urine.

Animals↗