PubMed Health⌕ Search

Biomedical subjects

L F Chasseaud

Publications and source records attributed to L F Chasseaud.

At least 127 records · Page 7Linked to original sources
PubMed1977

Plasma concentrations, bioavailability and dissolution of chlorpropamide.

The bioavailability of chlorpropamide from two new formulations (Melitase tablets) has been compared to that from a reference formulation which is currently in clinical use as a hypoglycaemic agent. In both rate and extent of bioavailability, all three formulations may be considered equivalent, providing allowances are made for differences in drug content. With 95% confidence, the mean bioavailability of chlorpropamide from the new formulations was within about 16% of the mean from the reference formulaion, and formulation-related differences were not statistically significant. Although all three formulations were shown to have similar dissolution profiles, dissolution of chlorpropamide was pH-dependent in vitro. Dissolution was almost complete during 30 min at pH 7.2, but only 40%-60% had dissolved during 90 min at pH 2.0. A peak mean concentration of 22.7 mug/ml was reached 3 h after administration of 2 x 100 mg tablets of the new formulation and peak mean concentrations of 26.8 mug/ml and 27.4 mug/ml were reached 3 h and 4 hours after administration of one 250 mg tablet of the new formulation and one 250 mg tablet of the reference formulation respectively. Formulation-related differences of mean plasma concentrations (after scaling for equal doses of 250mg) were not significant and each formulation provided similar plasma concentrations at corresponding times after administration. Statistically significant subject-related differences in all the parameters of bioavailability were shown by analyses of variance.

Adolescent↗
PubMed1977

The metabolism of benzyl isothiocyanate and its cysteine conjugate.

1. The corresponding cysteine conjugate was formed when the GSH (reduced glutathione) or cysteinylglycine conjugates of benzyl isothiocyanate were incubated with rat liver or kidney homogenates. When the cysteine conjugate of benzyl isothiocyanate was similarly incubated in the presence of acetyl-CoA, the corresponding N-acetylcysteine conjugate (mercapturic acid) was formed. 2. The non-enzymic reaction of GSH with benzyl isothiocyanate was rapid and was catalysed by rat liver cytosol. 3. The mercapturic acid was excreted in the urine of rats dosed with benzyl isothiocyanate or its GSH, cysteinyl-glycine or cysteine conjugate, and was isolated as the dicyclohexylamine salt. 4. An oral dose of the cysteine conjugate of [14C]benzyl isothiocyanate was rapidly absorbed and excreted by rats and dogs. After 3 days, rats had excreted a mean of 92.4 and 5.6% of the dose in the urine and faeces respectively, and dogs had excreted a mean of 86.3 and 13.2% respectively. 5. After an oral dose of the cystein conjugate of [C]benzyl isothiocyanate, the major 14C-labelled metabolite in rat urine was the corresponding mercapturic acid (62% of the dose), whereas in dog urine it was hippuric acid (40% of the dose). 5. Mercapturic acid biosynthesis may be an important route of metabolism of certain isothiocyanates in some mammalian species.

Acetylcysteine↗
PubMed1977

Plasma isosorbide dinitrate concentrations in human subjects after administration of standard and sustained-release formulations.

After sublingual administration of 5 mg of isosorbide dinitrate, mean plasma concentrations (+/-SD) peaked (8.9+/-3.1 ng/ml) at 15 min after dosing and declined with a half-life of 30 min. After oral administration of 5 mg, mean concentrations peaked (3.1+/-0.7 ng/ml) at 30 min and declined with a half-life of 40 min. After oral administration of 20 mg in a sustained-release tablet, mean concentrations initially peaked (1.4+/-1.2 ng/ml) at 40 min, declining to 0.9+/-0.5 ng/ml after 8 hr. Mean concentrations were maintained above half the mean peak level during 10 hr. Because of probable rapid first-pass metabolism, the bioavailability of isosorbide dinitrate after administration of the oral dose of the standard tablet was 58% of that from the sublingual dose, and the bioavailability from the sustained-release tablet was 47% of that from the sublingual dose of the standard tablet. The time course of mean plasma concentration data could be described by a one-compartment model; but a more complex model, taking the pass effect into account, probably is needed for a better description of the pharmacokinetics of isosorbide dinitrate.

Administration, Oral↗
PubMed1977

Plasma concentrations and bioavailability of clofibric acid from its calcium salt in humans.

The bioavailability of clofibric acid from formulations containing calcium clofibrate along and mixed with calcium carbonate (1:1 w/w) was compared to that from a standard clofibrate formulation in a crossover study in 12 human subjects. The 95% confidence intervals of bioavailability differences were such that they were unlikely to be detected in clinical practice; all three formulations may be considered bioequivalent, although the bioavailability rate was probably greater from the formulation containing calcium clofibrate alone. Peaks of mean concentrations of 80 +/- 13,67 +/- 16, and 64 +/- 18 microgram/ml +/- SD occurred after administration of 853 mg of clofibric acid calcium salt alone, 809 mg of clofibric acid calcium salt mixed with calcium carbonate, and 885 mg of clofibrate, respectively; mean concentrations declined from peak levels with half-lives of 15-17 hr.

Adult↗
PubMed1977

Renal and bone uptake of tartaric acid in rats: comparison of L(+) and DL-Forms.

Plasma concentrations of radioactivity declined biphasically with half-lives of about 15 and 58 h respectively in rats dosed with monosodium DL-[14C]tartrate for 7 days at a dose level of 2.73 g/kg/day. Uptake and retention of radioactivity occurred in blood cells, kidneys and bones where it was detected for at least 12 days after dosing. Renal retention (11202 +/- 4469 ppm at 6 h, n = 7) was probably due to precipitation of the poorly soluble calcium DL-tartrate in the tubules leading to increased kidney weight, nephrotoxicity and even death. The more soluble, naturally-occurring L(+)-[14C] tartrate was not retained in the kidneys (1287 +/- 118 ppm at 6 h, n = 8) when administered to rats under the same conditions, and the initial decline of plasma concentrations of radioactivity was more rapid (t 0.5 approx. 3 h). For this reason, monosodium L(+)-tartrate was non-toxic at 2.73 g/kg/day whereas monosodium DL-tartrate was toxic at this dosage.

Animals↗
PubMed1977

Disposition of the hypoglycaemic sulphonylurea CS 476.

The disposition of radioactivity was studied after administration of a new oral hypoglycaemic agent, 14C-labelled CS 476, to rats, rabbits and dogs at a pharmacologically active dose level of 0.2 mg/kg and to human subjects at a therapeutic dose level of 5 mg. After oral doses, most of the drug was excreted in the faeces by rats and dogs and faecal radioactivity was obtained from biliary excretion. Rabbits and humans excreted most of the dose in urine. Unchanged CS 476 was the major radioactive component in the plasma of all the species during 6 hours after dosing, and was extensively bound to the plasma proteins. The half-life of CS 476 in plasma was 2 hours in dogs and humans, and 16 hours in rabbits. Drug accumulation did not occur in dog and rabbit plasma during a period of consecutive daily doses and the half-lives after the last of the repeated doses were similar to those found after single doses. In rats, plasma concentrations were relatively low, and did not reach the peak level found in female rats until 24 hours after dosing. CS 476 was extensively biotransformed. The apparent species-dependent disposition of CS 476 may explain differences in tolerance to chronic doses.

Administration, Oral↗
PubMed1977

High performance liquid chromatographic determination of dothiepin and northiaden in human plasma and serum.

A method has been developed for the separation and measurement of dothiepin and the N-demethyl metabolites, northiaden, in human plasma or serum by high performance liquid chromatography. The method uses a structurally-related drug, amitriptyline, as an internal standard and provides a limit of detection of about 10 ng/ml for each component. At a concentration of 20 ng/ml, northiaden and dothiepin could be measured with +/-11% and +/- 6% of the mean respectively and at 200 ng/ml within +/-3% and 1% of the mean. The method has been applied to the analysis of serum from patients undergoing dothiepin therapy.

Chromatography, High Pressure Liquid↗
PubMed1977

The metabolism of the neuroleptic agent 1 (4'-fluorophenyl)-4-(cyclohexyl-1'-piperzinyl-4'-carboxylated)-butan-1-one hydrochloride in rats and man.

1. An oral dose the neuroleptic agent 1-(4'-fluorophenyl)-4-(cyclohexyl-1'-(14C)piperazinyl-4'-carboxylate)butan-1-one was mainly eliminated in the urine within 12 h by rats and man. During 5 days, 63-6% and 83-3% was eliminated in the urine of rats and man respectively. 2. Plasma concentrations in man related a maximum during 30 min to 1 h, representing 1-43 microgram equiv./ml. The proportion of unchanged drug in plasma decreased from 48% at 15 min to less than 10% after 1 h. 3. Seven major radioactive components were detected in the chloroform extract of basified rat urine and five major components in similar extracts of human urine. The major rat metabolites were isolated and identified by mass spectrometry as components resulting from mono- and dihydroxylation in the cyclohexane ring, reduction of the keto group to a secondary alcohol and hydrolysis and decarboxylation of the cyclohexylcarbamoyl group. The major metabolite in the rat urine extract was the dihydroxylated secondary alcohol derivative while the major human metabolite was the monohydroxylated secondary alcohol derivative. The metabolites were also partly eliminated as conjugates.

Administration, Oral↗
PubMed1977

Identification of an N-oxide as the major metabolite of the analgesic O-(diethylaminoethyl)-4-chlorobenzaldoxime hydrochloride in dogs.

1. After oral administration to dogs of the analgesic O-(diethylaminoethyl)-4-chloro[7-14C]benzaldoxime hydrochloride together with piperazine hydrochloride (2:1, w/w), at a dose of 4.5 mg/kg, the radioactivity was well absorbed and rapidly excreted. During 5 days, 81 percent of the dose (ca. 50 percent in 12 h) was excreted in urine and 10 percent in faeces. 2. Rates and routes of excretion of radioactivity were not altered in animals pre-treated with the drug for fourteen days. 3. Peak mean plasma concentrations of radioactivity (5.5 microgram equiv./ml) occurred at 90 min after an oral dose and were higher than those at 2 min following an equivalent intravenous (3.4 microgram equiv./ml) or rectal (4.0 microgram equiv./ml) dose which gave a max. at 45 min. 4. The drug was rapidly and extensively metabolized and no unchanged drug was detected in the plasma or urine. The major urinary metabolite was the N-oxide of the parent compound accounting for 34 percent and 23 percent dose excreted in the urine of males and females respectively during 12 h after administration.

Analgesics↗
PubMed1977

Plasma concentrations of isosorbide dinitrate after oral administration of a sustained-release formulation to human subjects.

1. A peak of mean plasma concentrations of isosorbide dinitrate of 5.8 ng/ml was reached at 0.5 h after a single oral dose of 5 mg in a standard tablet formulation. Thereafter mean concentrations declined with a half-life of about 48 min. 2. A peak of mean concentrations of isosorbide dinitrate of 3.2 ng/ml was reached at 2--4 h after a single oral dose of 20mg in a sustained-realease capsule formulation (Iso Mack Retard). Thereafter mean concentrations declined by about twofold during 6 h and were still detectable at 12 h after dosing. 3. When corrected by dose/bodyweight variations, the mean area under the isosorbide dinitrate plasma concentration curve from the sustained-release capule was 76% of that from the standard tablet and this formulation-related difference in bioavailability was statistically significant (p less than 0.05). 4. The results showed that sustained-release formulation is a useful way to maintain plasma concentrations of isosorbide dinitrate for several hours.

Adult↗
PubMed1977

The disposition of radioactivity after administration of the anthelminthic methyl-14C-5-cyclopropylcarbonyl-2-benzimidazole carbamate (ciclobendazole) to rats and dogs.

1. The disposition of radioactivity has been studied in rats and dogs after administration of a new anthelminthic agent, 14C-labelled methyl-5-cyclopropylcarbonyl-2-benzimidazole carbamate (14C-ciclobendazole). 2. An oral dose of 14C-ciclobendazole (4 mg/kg) to rats was rapidly absorbed and about 70% and 20% of the dose was excreted in the faeces and urine, respectively, during 2 days. Bile duct cannulated rats excreted about 80% of the dose in 48-h bile, about 2% in the faeces and about 10% in the urine showing that an oral dose was well-absorbed and that some enterohepatic circulation probably occurred. The excretion of radioactivity in the bile was less after i.v. administration. 3. An oral dose of 14C-ciclobendazole (4 mg/kg) to dogs was mainly eliminated during 2 days with about 80% of the dose in the faeces and only about 10% in the urine. Anaesthetised bile duct-cannulated dogs, excreted between 26% and 35% of an oral dose in the bile during 24 h and up to 58% of an oral dose was absorbed at this time. 4. The tissue distribution of radioactivity in rats and dogs after single or multiple oral doses of 14C-ciclobendazole (4 mg/kg) showed that there was no unusual accumulation or localisation of radioactivity in the measured tissues. Highest concentrations were present in the intestinal tract, liver and kidneys, organs associated with biotransformation and excretion and also in the lungs and adrenals. 5. After oral administration of 14C-ciclobendazole to rate at three different dose levels (4, 40 and 400 mg/kg), peak plasma levels occurred at 15-30 min and declined with similar half-lives (about 20 h). A comparison of peak concentrations and areas under the plasma concentration-time relationships showed that the absorption of ciclobendazole was probably dose-dependent, a lower proportion probably being absorbed at higher doses. After repeated daily oral dosing with 14C-ciclobendazole (4 mg/kg), there were no significant changes in either the daily plasma concentrations or the biological half-life measured after the last dose, indicating that ciclobendazole probably did not induce or inhibit its own metabolism when dosed repeatedly at 4 mg/kg. 6. A comparison of the areas under the plasma concentration-time relationships after oral, i.p. and i.v. administration of 14C-ciclobendazole to rates indicated that there was no signigicant uptake by the liver during first pass and that an oral dose was well absorbed by rats. 7. The peak plasma concentration in the dog, after an oral dose of 14C-ciclobendazole (4 mg/kg) was reached at about 30 min and declined with a half-life of about 3 h. 8. Ciclobendazole was probably well-absorbed by rats and dogs and excreted more rapidly by the latter species than by the former Relatively higher plasma concentrations of drug and/or metabolites were thus achieved in rats than in dogs.

Administration, Oral↗
PubMed1977

The distribution of radioactivity in pregnant rats after repeated oral doses of the diuretic agent Etozolin.

1. The distribution of radioactivity has been studied by whole-body autoradiography after administration of daily oral doses of (2-14C)-ethyl (Z)-(3-methyl-4-oxo-5-piperidino-thiazolidin-2-ylidene)acetate (etozolin, Gö 687, Elkapin) at a dose level of 100mg/kg to pregnant rats during the 10th to the 17th day of gestation. 2. After the last dose, most of the radioactivity was excreted rapidly and was mainly assoicated with the gastrointestinal and urinary tracts and kidneys of the mothers. 3. Maximal distribution in the mothers occurred at 3--6 h after the last dose, and radioactivity at these times was detectable also in the lungs, muscle mass, fat, mammary and uterine tissue, the reticuloendothelial system, placentae, some ducted and endocrine glands, and in blood, but not in brain or spinal cord. At 4 days, traces of radioactivity had persisted in kidneys, liver, lungs, thyroid and placentae. 4. Radioactivity was present in low and uniform concentrations in most foetal tissues such as the heart, lungs and lens and in even lower concentrations in the brains of the foetuses during 3--6 h after dosing, but was not detected in foetal tissues at 2 days. Concentrations of radioactivity in maternal tissues were at all times much higher compared with those in foetal tissues at corresponding times after dosing.

Administration, Oral↗
PubMed1977

Blood levels and bioavailability of ascorbic acid after administration of a sustained-release formulation to humans.

Plasma and whole blood concentrations of ascorbate have been measured after administration of 1000 mg of the vitamin as standard or sustained-release capsule formulations to human subjects. A peak of mean whole blood and plasma concentrations of 8.5 mug/ml and 5.7 mug/ml respectively (corrected for predose concentrations of "endogenous" ascorbate) occurred at 12 h and 6 h respectively after administration of a sustained-release formulation. After administration of a standard formulation, the peak of mean whole blood and plasma concentrations of 9.4 mug/ml and 8.6 mug/ml respectively occurred at 4 h. In whole blood, mean concentrations of ascorbate declined with a half-life of about 34 h. The bioavailability of ascorbate from the sustained-release formulation was 149% and 180% of that from the standard formulation by calculation from whole blood and plasma concentration data respectively.

Adult↗
PubMed1976

Serum concentrations of methaqualone after repeated oral doses of a combination formulation to human subjects.

Concentrations of methaqualone have been measured in the serum of five male human subjects receiving five consecutive evening doses of a combination formulation containing methaqualone (250 mg), carbromal (300 mg) and benactyzine (0.33 mg) in each tablet. After administration of the first dose, mean peak serum concentrations of methaqualone (1.2 mug/ml) occurred at 3 h. After obtaining peak levels, mean concentrations of methaqualone declined rapidly during the next 6 h and thereafter more slowly during the next 18 h. After administration of the last (fifth) dose, mean peak serum concentrations of methaqualone (1.9 mug/ml; 1.5 mug/ml above the predose level) occurred at 2 h. After attaining peak levels, mean concentrations of methaqualone declined rapidly during the next 6 h, and thereafter more slowly, with a half-life of approximately 10 h. Mean concentrations of methaqualone in serum samples 24 h after the second, third, fourth or fifth doses were not significantly different (0.3 mug/ml - 0.6 mug/ml) during this period of dosing. This suggests that significant accumulation of methaqualone in the serum did not occur during a period of five consecutive evening doses of the combination formulation.

Administration, Oral↗