Search results for "Half-Life"
showing 10 items of 108 documents
Dose-Related Concentrations of Neuroactive/Psychoactive Drugs Expected in Blood of Children and Adolescents
2020
PURPOSE Therapeutic drug monitoring is highly recommended for children and adolescents treated with neurotropic/psychotropic drugs. For interpretation of therapeutic drug monitoring results, drug concentrations (C/D) expected in a "normal" population are helpful to identify pharmacokinetic abnormalities or nonadherence. Using dose-related concentration (DRC) factors obtained from pharmacokinetic data, C/D ranges expected under steady state can be easily calculated by multiplication of DRC by the daily dose. DRC factors, however, are defined only for adults so far. Therefore, it was the aim of this study to estimate DRC factors for children and adolescents and compare them with those of adul…
Disposition of ciprofloxacin following intravenous administration in dogs
1994
The pharmacokinetics of ciprofloxacin (CIP) following intravenous administration in dogs have been investigated. The drug was administered at three doses (2.5, 5 and 10 mg/kg body weight) and was assayed in biological fluid samples (plasma and urine) by an HPLC method. The plasma concentration-time curves were best described by a two-compartment open pharmacokinetic model. The drug was widely distributed (Vd(area) almost 3 l/kg), being distributed in the dog more rapidly than in other species (t1/2(lambda 1) 3 min approximately). The elimination half-life (t1/2 lambda 2) was 129-180 min which is similar to values obtained in other species. The unchanged drug eliminated in urine was less tha…
Inhibition of cancer growth by resveratrol is related to its low bioavailability.
2002
The relationship between resveratrol (RES) bioavalability and its effect on tumor growth was investigated. Tissue levels of RES were studied after i.v. and oral administration of trans-resveratrol (t-RES) to rabbits, rats, and mice. Half-life of RES in plasma, after i.v. administration of 20 mg t-RES/kg b.wt., was very short (e.g., 14.4 min in rabbits). The highest concentration of RES in plasma, either after i.v. or oral administration (e.g., 2.6 +/- 1.0 microM in mice 2.5 min after receiving 20 mg t-RES/kg orally), was reached within the first 5 min in all animals studied. Extravascular levels (brain, lung, liver, and kidney) of RES, which paralleled those in plasma, were always1 nmol/g f…
Analysis of ceftriaxone and ceftazidime distribution in cerebrospinal fluid of and cerebral extracellular space in awake rats by in vivo microdialysis
1995
In vivo microdialysis was used to estimate the extracellular concentrations of ceftazidime and ceftriaxone, two expanded-spectrum cephalosporins commonly used in the treatment of bacterial meningitis, in two brain regions (the right corpus striatum and the left lateral ventricle) of awake, freely moving rats. Antibiotics were administered by constant intravenous infusion at 18 mg/h until steady-state levels were reached. Ceftriaxone levels measured at the steady state in the extracellular space of the corpus striatum (0.80 ± 0.17 J.tg/ml) were statistically equivalent to those obtained in the cerebrospinal fluid of the lateral ventricle (0.71 ± 0.15 J.tg/ml). The ratios of these levels in t…
INULIN BASED HYDROGEL FOR ORAL DELIVERY OF FLUTAMIDE: PREPARATION, CHARACTERIZATION AND IN VIVO RELEASE STUDIES
2012
The ability of a hydrogel obtained by crosslinking INUDV and PEGBa to facilitate sustained release of flutamide is examined. The hydrogel is prepared in pH = 7.4 PBS and no toxic solvents or catalysts are used. It is recovered in microparticulate form and its size distribution is determined. Mucoadhesive properties are evaluated in vitro by reproducing gastrointestinal conditions. Flutamide is loaded into the hydrogel using a post-fabrication encapsulation procedure that allows a drug loading comparable to that of market tablets. Drug-loaded microparticles are orally administered to cross-bred dogs and the in vivo study demonstrates their ability to prolong the half-life of the principal ac…
Fate and effects of the trehalase inhibitor trehazolin in the migratory locust (Locusta migratoria).
2009
Abstract Trehalose is the main haemolymph sugar in many insect species. To be utilized trehalose must be hydrolysed into its glucose units by trehalase (EC 3.2.1.28). Inhibitors of trehalase have attracted interest as possible pesticides and tools for studying the regulation of trehalose metabolism in insects. To make full use of these inhibitors requires knowledge of their fate and effects in vivo. To this end we have measured trehazolin in locusts using a method based on the specific inhibition of a trehalase preparation. After injection of 20 μg, trehazolin decreased in haemolymph with a half-life of 2.6 days and after 10 days almost 95% had disappeared. Trehazolin did not reach the intr…
Efficacy and safety of Wilate in paediatric VWD patients under 6 years of age - results of a prospective multicentre clinical study including recover…
2013
Treatment with exogenous von Willebrand factor (VWF) is indicated in patients with von Willebrand disease (VWD) in whom treatment with 1-deamino-8-d-arginine vasopressin/desmopressin is contraindicated. Wilate is a new generation plasma-derived concentrate of native VWF and coagulation factor VIII (FVIII) (in a physiological 1:1 ratio) developed for the treatment of VWD. This is the first study to report safety, efficacy and in vivo recovery (IVR) data from 15 paediatric patients less than 6 years of age who received Wilate for either prophylaxis, on-demand treatment or for treatment in surgical procedures during a prospective open-label trial (VWD type 1: 5, type 2A: 1, type 2B: 2, type 3:…
Using transdermal iontophoresis to increase granisetron delivery across skin in vitro and in vivo: effect of experimental conditions and a comparison…
2010
The objectives of the study were (i) to investigate the effect of experimental parameters on the iontophoretic transport of granisetron, (ii) to identify the relative contributions of electromigration (EM) and electroosmosis (EO), (iii) to determine the feasibility of delivering therapeutic amounts of drug for the treatment of chemotherapy-induced nausea and vomiting and (iv) to test the in vitro results in a simple animal model in vivo. Preliminary in vitro studies using aqueous granisetron formulations investigating the effect of drug concentration (5, 10, 20 and 40 mM) and current density (0.1, 0.2, 0.3 mA cm(-2)) were performed using porcine ear skin. As expected, cumulative delivery in…
Low bioavailability of amoxicillin in rats as a consequence of presystemic degradation in the intestine.
1994
Several studies have been carried out to elucidate the causes of the low oral bioavailability of amoxicillin in rats. The hepatic first-pass effect of the antibiotic was estimated by comparing the area under the plasma drug concentration-versus-time curve from time zero to infinity (AUC0-infinity) obtained after injecting the drug into a mesenteric vein with the AUC0-infinity value obtained after injecting the drug into the jugular vein of conscious rats. No hepatic first-pass effect was detected. The bioavailability of amoxicillin after intraduodenal administration was only 51%, and the fraction of the dose remaining in the intestine at the end of the experiment was 4.5%. This was far less…
Steady state concentrations of clomipramine and its major metabolite desmethylclomipramine in rat brain and serum after oral administration of clomip…
2000
Twenty male Sprague-Dawley rats received five oral doses of clomipramine 20 mg/kg at 4-h intervals. The animals were decapitated 1, 2, 3, 5 and 12 h after the last dose for determination of clomipramine and desmethylclomipramine in serum and frontal cerebral cortex. Time dependent concentrations of clomipramine and desmethylclomipramine paralleled in serum and brain. Half-lives were similar in serum and brain with 7.8 versus 6.2 h and 5.5 versus 5.0 h for clomipramine and desmethylclomipramine, respectively. Absolute concentrations, however, were markedly higher in brain than in serum - 12.5 fold for clomipramine and 7.4 fold for desmethylclomipramine. The data indicate that serum and brain…