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Biomedical subjects

D Castoldi

Publications and source records attributed to D Castoldi.

12 recordsLinked to original sources
PubMed1992

Influence of glutathione administration on the disposition of free and total platinum in patients after administration of cisplatin.

The kinetics of platinum (Pt) was studied in 12 patients suffering from non-small-cell lung cancer or pleural mesothelioma. Each subject received an infusion of cisplatin (CDDP, 80 mg/m2), and six patients were pretreated with glutathione (GSH, 2.5 g given i.v.) at 15 min prior to the cisplatin infusion. After a 3- to 4-week interval, all patients were given a second course of treatment on the same schedule. A biexponential model was fitted to plasma concentrations of total and ultrafilterable Pt. The excretion of Pt in urine was evaluated during the first 48 h after the CDDP infusion. Following the administration of CDDP alone or with GSH pretreatment, the pharmacokinetic parameters of Pt did not significantly differ between the treatments. Also, the unbound fraction determined at each sampling time did not vary significantly between the treatments. However, it is noteworthy that the mean values obtained for the terminal half-life, the volume of distribution, the renal clearance, the percentage of the dose excreted in the urine, and the mean residence time of total Pt were higher in patients who had been pretreated with GSH, suggesting that GSH might increase both the rate of Pt elimination and the extent of Pt distribution and, as a consequence of the latter, might prolong the residence time of Pt in the body. In addition, the unbound fraction of Pt from the 4th to the 48th was higher following the first dose of CDDP+GSH than after treatment with CDDP alone. Because of the rather high variability in the values of the parameters obtained, further work is planned using a larger number of patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

First dose and steady state pharmacokinetics of nimesulide and its 4-hydroxy metabolite in healthy volunteers.

The pharmacokinetics of nimesulide (4-nitro-2-phenoxymethane-sulfonanilide, NMS), a non-steroidal antiinflammatory drug, and of its 4-hydroxy metabolite (4-nitro-2-(4'-hydroxy-phenoxy)-methane sulfonanilide, OH-NMS) was studied after a single oral dose (200 mg) and after repeated treatments (100 mg every 12 hours for 7 days) of NMS to two groups of 12 healthy volunteers. Plasma concentrations of NMS and OH-NMS were followed for 48 hours after the single dose and up to the 12th hour on the 1st day and on the 7th day during repeated treatment. After the single dose of 200 mg peak plasma concentrations of the drug (9.85 micrograms/ml) were reached at 3.17 hours and the half-life during the elimination phase was 4.95 hours. The metabolite reached highest plasma levels (3.03 micrograms/ml) at 5.33 hours and its apparent half-life was similar to that of the parent drug (4.78 hours). NMS plasma levels on the 7th day, predicted from the results of the 1st day, were similar to the measured values. The pharmacokinetics of NMS or OH-NMS after single or repeated dose was not time or dose dependent.

Adult↗
PubMed1989

Dose-response decrease in plasma tryptophan and in brain tryptophan and serotonin after tryptophan-free amino acid mixtures in rats.

Rats fasted 15 hours were treated p.o. with increasing amounts (660 and 1320 mg/kg body weight) of a mixture containing a fixed proportion of seven essential amino acids (L-phenylalanine 13.6%, L-leucine 6.0%, L-isoleucine 12.1%, L-methionine 12.1%, L-lysine 30.3%, L-threonine 10.6%, L-valine 15.2%) and lacking tryptophan. The mixtures produced a dose-response decrease of free (by 34% after the lower dose and by 58% after the higher dose of the mixture) and total (by 10 and 31%) plasma tryptophan and of brain tryptophan (by 38 and 65%), serotonin (by 17 and 41%) and 5-hydroxyindole acetic acid (by 21 and 49%). The mechanisms of these changes are discussed.

Amino Acids↗
PubMed1988

Decrease in plasma tryptophan after tryptophan-free amino acid mixtures in man.

Male healthy subjects, fasting 12 hours, ingested increasing amounts of a mixture containing a fixed proportion of seven essential amino acids (L-isoleucine 11.5%, L-leucine 18.0%, L-lysine 13.1%, L-methionine 18.0%, L-phenylalanine 18.0%, L-threonine 8.2%, L-valine 13.1%) and lacking tryptophan. The diets produced a rapid fall in plasma tryptophan which was proportional to the total amount of the amino acids ingested. Following the highest dose administered (36.6 g) plasma tryptophan fell to a minimum of about 35% the initial level and remained markedly reduced at 6 hours after treatment. The mechanism of this decrease and its potential clinical relevance are discussed.

Adult↗
PubMed1987

Normal and slow-release formulations of bezafibrate: a comparative pharmacokinetic study in man.

In this study the pharmacokinetics of a new slow-release formulation of bezafibrate (a hypolipaemic drug) were evaluated in a group of six healthy volunteers. In the first part of the study the bioavailability of this formulation was compared to the normal preparation of bezafibrate. In the second part of the experiment the possible accumulation was studied. The subjects were administered the slow-release preparation at 08h00 for seven consecutive days. The resulting data indicate that the slow-release formulation shows a lower dispersion of Tmax values. There was an increase of the plasma half-life from 1.9 to 5.5 h, but a possibility of accumulation could be excluded.

Adult↗
PubMed1987

Pharmacokinetics of isosorbide mononitrate in a new sustained release oral form in comparison with a conventional formulation.

40 mg of isosorbide mononitrate (isosorbide-5-mononitrate, IS5MN) in conventional (Ismo 20) and sustained release formulations (Ismo Diffutab) were administered to 5 male healthy volunteers. The administration of the sustained release formulation was repeated for seven days in order to evaluate the possible occurrence of accumulation. Pharmacokinetic data showed that the sustained release formulation reached significantly lower and delayed mean peak plasma levels compared with the conventional formulation, respectively 452.8 +/- 67.8 ng/ml and 706.7 +/- 57.3 (mean +/- SE) (p less than 0.05). Peak times were 4.6 +/- 0.2 and 2.4 +/- 0.2 (p less than 0.005) h, respectively. A longer plasma half-life together with larger AUC for the sustained release formulation was also observed. The pharmacokinetic parameters of the sustained release formulation are consistent with a therapeutic usefulness and suggest further clinical evaluation.

Administration, Oral↗
PubMed1985

Determination of bezafibrate in human plasma and urine by high-performance liquid chromatography.

A selective and time-saving high-performance liquid chromatographic method to assess bezafibrate plasma and urine levels is described. Bezafibrate is extracted from plasma matrix using diethyl ether, after acidification with hydrochloric acid. The urine samples are directly analysed, after dilution with the mobile phase. The method is used to assess bezafibrate plasma and urine levels in man, after administration of therapeutic doses of bezafibrate. The results obtained are in agreement with previously published data.

Bezafibrate↗
PubMed1979

Gas chromatographic determination of glibenclamide in plasma.

A gas-chromatographic method for glibenclamide determination in plasma is described. It involves derivatization of the drug with dinitrofluorobenzene and the use of an electron-capture detector. The quantitative evaluation is performed using tolbutamide as internal standard. Characteristics and specificity of the method for the principal metabolite of glibenclamide are examined.

Administration, Oral↗