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Biomedical subjects

T Trnovec

Publications and source records attributed to T Trnovec.

At least 73 records · Page 4Linked to original sources
PubMed1989

Fate of 14C-terpolymer (methylmethacrylate-14C, 2-hydroxyethylmethacrylate, butylacrylate) nanoparticles after peroral administration to rats.

The fate of 14C-terpolymer (methylmethacrylate-14C, 2-hydroxyethylmethacrylate, butylacrylate) nanoparticles was studied in male Wistar rats after peroral administration. These nanoparticles may reach systemic circulation as evidenced by the plasma 14C level, excretion of the label in the urine, as well as organ label deposition. It was found that at least 2% of the dose of 14C was absorbed from the gastrointestinal tract. As expected, the radioactive nanoparticles were excreted predominantly via the feces. The amount of the label in the gastrointestinal tract, liver, and carcasses fell below the limit of detection on day seven after administration. However in the spleen and lung some slight radioactivity persisted after 7 d of experiment.

Acrylates↗
PubMed1988

BEQUIV interactive microcomputer program for testing equivalence in two-group comparative bioavailability trials.

The BEQUIV program, written in the BASIC language, employs an algorithm based on the Anderson and Hauck approach for testing equivalence in two-group comparative bioavailability trials (7). Options for calculation of basic statistical parameters and analysis of variance were included in view of the maximal flexibility of the program. Performance of the program was demonstrated by means of a numerical example taken from the pharmacokinetic literature. The program is designed for the non-statistically trained user.

Biological Availability↗
PubMed1988

Stability studies of 14C-Cytostasan solutions and its extraction using dicarbolide of cobalt.

In this study the stability of 14C-Cytostasan (1, bendamustine), in water solutions was investigated. In distilled water a rapid degradation of carrier-free 14C-1 occurred. The degradation products of 14C-1 are 14C-monohydroxy-1 and 14C-dihydroxy-1 (evidence with the TLC). The degradation rate of 14C-1 was reduced by addition of nonlabelled 1 to the 14C-1 stock solution. The possibility of using distribution coefficient as a stability indicator of 14C-1 solutions was investigated. A number of organic solvents ranging from polar to nonpolar were used for extraction of 14C-1 from water solution. Only ethyl acetate was slightly effective. The distribution coefficient of 14C-1 was dramatically enhanced in presence of dicarbolide of cobalt (DC-H+) in benzene at extraction from HClO4 (0.5 mol.l-1).

Bendamustine Hydrochloride↗
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↗
PubMed1987

Pharmacokinetics of the new local anaesthetic N-[2-(2-Heptyloxyphenylcarbamoyloxy)ethyl]piperidinium chloride in rats and mice.

Pharmacokinetics of a local anaesthetic of the carbanilate type (Heptacaine; in the following briefly called HCP), was studied using a labelled product, N-[2-(2-[1-14C]-heptyloxyphenylcarbamoyloxy)ethyl]piperidinum++ + chloride. Determination of HCP in biological material was based on double extraction of HCP from alkaline media into n-heptane. The plasma concentration of HCP following i.v. administration to rats was approximated by a biexponential function. An open two-compartment pharmacokinetic model was conferred to the data. The model parameter estimates are as follows: terminal elimination half-life 3.80 +/- 0.15 h, distribution volume at steady state 9.31 l/kg, total body clearance 73.4 ml/min/kg, mean residence time 2.1 h. The systemic availability of the orally given HCP in solution was 35.8%. The HCP plasma AUC vs. dose relationship was linear within doses ranging from 2.78 to 4.33 mg/kg. The brain uptake index of HCP in comparison with 3H2O was 62.2%. Autoradiography in mice injected i.v. showed a heterogeneous distribution of the label in the tissues and its excretion by the urinary and biliary pathways. HCP showed strong affinity to the lung tissue. During 96 h after i.v. administration, 21% and 62% of the 14C dose was excreted into urine and faeces, respectively, and after oral administration, the excretion was 17% and 43%, respectively.

Administration, Oral↗
PubMed1986

[Etimizol absorption from the small intestine in dogs: the dependence on dosage].

As etimizol has been previously reported to be of low bioavailability, the kinetics of its absorption from the dog intestinal loop was investigated in chronic experiments. After administration of etimizol at doses of 10 or 1 mg/loop mean residence time of etimizol in the loop was 20.1 and 7.6 min, respectively, with mean standard deviation being 3.1 and 0.8, respectively. It was concluded that overall etimizol absorption from small intestine was high and its low bioavailability resulted from presystemic drug metabolism, as well as that the absorption kinetics was dose-dependent, with saturation reached at higher drug doses.

Animals↗
PubMed1985

Absorption of exaprolol from the in-situ gastrointestinal tract of rats and dogs.

The absorption rate of the beta-adrenoceptor blocking drug, exaprolol, from the gastrointestinal tract was studied using in-situ methods in the rat and dog. Exaprolol was rapidly absorbed from the small and large intestine of rats and from the ileum of dogs. The cardiac output and regional blood flow decreased in rats to approximately one half of the original values within 30 min of the in-situ experiment. The logarithm of the amount vs time plots from dogs were linear, whereas with rats a curvilinearity appeared apparently because of the blood flow-limited absorption kinetics of this highly lipophilic drug. The data obtained suggest that exaprolol is suitable for administration in sustained release form.

Adrenergic beta-Antagonists↗
PubMed1985

Absorption of pentacaine from ulcerous rat stomach.

Pentacaine is a local anaesthetic which exhibited positive effects on healing of model ulcers in the rat stomach. The in situ disappearance of pentacaine from the ulcerous and intact rat stomach was studied. Gastric ulcers were produced by oral administration of phenylbutazone (200 mg . kg-1) 3.5 h before absorption experiment. Pentacaine exhibited a biexponential decrease from the lumen of the stomach, the rate of which was essentially the same in both groups. The total amount of pentacaine absorbed was small because of extremely low absorption rate.

Absorption↗
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↗
PubMed1985

The rate and extent of calcium bioavailability from two oral dosage forms in rats.

The purpose of the present work was to compare oral bioavailability of calcium from two calcium preparations, Calcium Sandoz forte 500 mg and Calcium Spofa effervescens. The pharmacokinetic study was carried out on rats, and plasma levels of 45Ca after administration of labelled calcium solutions were determined. Appropriate equations describing the two-compartment open model and the one-compartment model with first order absorption were fitted to the observed i.v. and oral data, respectively, using weighted nonlinear least-squares regression analysis. The extent and the time profile of the rate of 45Ca systemic bioavailability were assessed. Both parameters suggested identical bioavailability of calcium from the two dosage forms compared.

Administration, Oral↗