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L Soltés

Publications and source records attributed to L Soltés.

At least 37 records · Page 2Linked to original sources
PubMed1991

High-performance liquid chromatographic determination of bilirubin distribution on serum proteins.

We describe a high-performance liquid chromatographic method for the determination of bilirubin distribution on serum proteins. The procedure is based on both size-exclusion and adsorptive properties of the column packing material LiChrosorb Diol. The elution of all sample constituents is accomplished by means of an aqueous mobile phase containing phosphate buffered solution of adult serum, supplemented by a small amount of bilirubin. The different distribution of bilirubin on albumin, beta-lipoprotein, and as free (loosely bound) pigment fraction is exemplified by assaying normal adult and infant sera.

Adult↗
PubMed1991

Pharmacokinetics of stobadin and of the sum of its metabolites in rats during repeated administration.

Stobadin dihydrochloride was administered p.o. to rats at a dose of 1 mg kg-1 once daily for 25 consecutive days. The peak and trough concentrations of the sum of stobadin metabolites, determined from Days 6-16 of treatment, demonstrated a steady-state. The mean daily excretion of 3H-radioactivity during this period was 43 per cent and 52 per cent of the administered dose into urine and faeces, respectively. The terminal half-life of stobadin in plasma following a 25-day chronic treatment was 78.3 min, which was shorter than the value of 95.3 min, determined in a single dose experiment. The data indicate that no accumulation of stobadin and of its labelled metabolites occurs in the course of repeated administration of 3H-stobadin.

Administration, Oral↗
PubMed1991

Interaction of pirprofen enantiomers with human serum albumin.

The interaction of pirprofen enantiomers with human serum albumin (HSA) was investigated by means of high-performance liquid chromatography (HPLC), circular dichroism (CD), and 1H NMR spectroscopy. HPLC experiments indicated that both pirprofen enantiomers were bound to one class of high-affinity binding sites (n(+) = 1.91 +/- 0.13, K(+) = (4.09 +/- 0.64) x 10(5) M-1, n(-) = 2.07 +/- 0.13, K(-) = (6.56 +/- 1.35) x 10(5) M-1) together with nonspecific binding (n'K'(+) = (1.51 +/- 0.21) x 10(4) M-1, n'K'(-) = (0.88 +/- 0.13) x 10(-4) M-1). Slight stereoselectivity in specific binding was demonstrated by the difference in product n(+)K(+) = (0.77 +/- 0.08) x 10(6) M-1 vs. n(-)K(-) = (1.30 +/- 0.21) x 10(6) M-1, i.e., the ratio n(-)K(-)/n(+)K(+) = 1.7. CD measurements showed changes in the binding sites located on the aromatic amino acid side chains (a small positive band at 315 nm and a pronounced negative extrinsic Cotton effect in the region 250-280 nm). The protein remains, however, in its predominantly alpha-helical conformation. The 1H NMR difference spectra confirmed that both pirprofen enantiomers interacted with HSA specifically, most probably with site II on the albumin molecule.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1991

Determination of pentoxifylline in serum by high-performance thin-layer chromatography.

An analytical method to study the bioavailability of newly developed pentoxifylline sustained-release tablets has been developed and assessed in experiments on dogs. For the isolation of pentoxifylline and its metabolites from serum solid-liquid extraction was applied by involving the internal standard probe. HPTLC plates with a preconcentration zone were used for separation of the analysed substances, using chloroform-methanol (95:5, v/v). Quantification was by densitometric detection. The detector response was linear in the concentration range investigated for pentoxifylline: 0.02-1.5 micrograms ml-1 of serum.

Administration, Oral↗
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

High-performance liquid chromatographic determination of beta-adrenoceptor blocking agents in body fluids.

Several reports have been published reviewing high-performance liquid chromatographic (HPLC) methods for the determination of beta-adrenoceptor blocking agents (beta-blockers) in biological materials (Flouvat et al., 1981; Mehta, 1983; Marko and Soltés, 1984; Ahnoff et al., 1985; Tkaczyková and Safarík, 1987). Of these, the paper by Mehta (1983) briefly summarizes the interrelationship between physiocochemical properties of beta-blockers with prechromatographic treatment of biological samples, as well as with the HPLC methods used for the determination of 12 beta-adrenoceptor blocking drugs. The work by Ahnoff et al. (1985) concerning the monitoring of cardiovascular drugs also deals with HPLC assays of 18 beta-blockers in plasma. The Appendix to this report presents the great majority of HPLC methods for determining 30 beta-blockers in various body fluids. HPLC methods providing resolution and determination of individual beta-blocker enantiomers have not been included since this topic is being covered by Walle and Walle (1989). The Appendix is just a guide to the methods reviewed for the HPLC determination of parent beta-blockers as well as some of their metabolites co-assayed in various body fluids. It does not include details such as the internal standard, recovery, setting of the detector, limit of determination, etc., given in the individual methods listed. The isolation technique of the drug(s) from the given body fluid represents the main step in the sample work-up procedure. Along with this information, only the type of the HPLC column packing and the detection principle used by each method's developers are given.

Adrenergic beta-Antagonists↗
PubMed1989

Study of bilirubin binding in human serum by high-performance liquid chromatography.

We describe a high-performance single-run liquid chromatographic method for the separation of protein-bound and "free" (loosely bound) bilirubin in human serum samples. The procedure is based on both the size-exclusion and the adsorptive properties of the column packing material, LiChrosorb Diol. The elution of all sample constituents is accomplished by means of an aqueous mobile phase containing a phosphate-buffered solution of human serum albumin or adult serum, supplemented by a small amount of bilirubin. The efficacy of the developed method is exemplified by assaying the bilirubin binding to human adult and infant sera.

Adult↗
PubMed1989

[Methods of measuring respiratory volume and minute ventilation in children in the youngest age groups].

Three modes of measuring tidal volume, minute ventilation and respiration rate in children of the youngest age groups are presented. Differences of the methods as applied in the given age groups are pointed out as well as factors which adversely affect the objectivity of the results. The method using open system spirometer during physiological sleep was found to have the lowest accuracy as the contact of the mask with the naso-oral region of the child's face affects the respiratory center (the child hyperventilates). The plethysmographic method requires the most demanding equipment, yet its great advantage is that the child is not in direct contact with the scanner during recording of data. For routine examinations the most advantageous method is by means of open system spirometer at sleep induced by chloral hydrate, which substantially eliminates the effect of the contact with the mask on the respiration of the child.

Humans↗
PubMed1987

Dose-dependent pharmacokinetics of a xanthine-related nootropic drug, ethimizol, in rats.

Pharmacokinetics of the respiratory analeptic ethimizol, 4,5-bis(methylcarbamoyl)-1-ethylimidazole, with recently recognized nootropic properties, its metabolite 4-carbamoyl-5-methylcarbamoyl-1-ethylimidazole and of two metabolites of unknown structure was studied in plasma of rats after intravenous administration of the [2-14C]-labelled compound in 5 doses: 1.1, 3.3, 10, 20, and 30 mg/kg. The apparently monoexponential time course of dose normalized ethimizol plasma concentrations were not superimposable and the derived pharmacokinetic parameters were dose-dependent. The elimination rate constant and the initial volume of distribution decreased with increasing dose. The AUC versus dose relationship displayed disproportionate increases with increasing dose. Plasma ethimizol failed to obey the Michaelis-Menten kinetics and in an attempt to rationalize the observed nonlinearity a complete competitive product inhibition was suggested. Similar to the parent drug, the three metabolites exhibited a distinctly dose-dependent behavior as could be deduced from their dose-normalized concentration-time curves.

Animals↗
PubMed1985

Pharmacokinetics of ethimizol in man.

The pharmacokinetics of ethimizol were studied in healthy volunteers given 1 mg/kg i.v. or 2 mg/kg orally. The serum concentrations of ethimizol were determined by HPLC. After i.v. infusion the kinetics of ethimizol could be described by a one-compartment model in 4 and by a two-compartment model in 1 subject. The elimination half-lives ranged from 34.1 to 79.2 min and the apparent volumes of distribution from 0.4 to 1.3 l/kg. After oral administration, the absorption half-lives ranged from 7.3 to 57.1 min. The absolute bioavailability varied between 3.6 and 22.2%. The binding of ethimizol to plasma proteins was less than 10%.

Anti-Inflammatory Agents↗