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Biomedical subjects

A Assandri

Publications and source records attributed to A Assandri.

11 recordsLinked to original sources
PubMed1978

Physiological disposition of a series of rifamycins in rat: a comparative study.

The disposition of four C3-substituted piperazinyl rifamycins was studied in the rat following the intravenous administration of 5 mg/kg of the 14C-labelled antibiotics. Considerable quantitative differences in the pharmacokinetics of these antibiotics were shown in blood levels, tissue distributions and body clearances. Feces were largely the major route of elimination for the parent drug and metabolites. The results suggest that the liver compartimentalization, regulating the biliary excretion, is to be the kinetic parameter affecting the pharmacokinetic behaviour of this class of antibiotics.

Animals↗
PubMed1977

Protein binding of rifampicin to bovine serum albumin as measured by gel filtration.

A "large zone-small zone elution method" with Sephadex G-25 has been developed for the study of the interactions of [14C]rifampicin with bovine serum proteins. The method was demonstrated to be capable of yielding both qualitative and quantitative information about the binding reactions. However, its application requires a large amount of experimental work, and therefore it should be reserved for instances when other procedures are not applicable, e.g., with highly lipophilic ligands.

Chromatography, Gel↗
PubMed1977

Protein binding of a series of rifamycins to bovine serum albumin as measured by the "two-phase partition" technique.

A "two-phase partition technique" was developed and improved so as to be useful for the study of the interaction of proteins with low-molecular-weight ligands. The technique permits the macromolecule to be present almost entirely in one of the two aqueous phases without the aid of any physical solid interface, which is particularly useful in studies of lipophilic ligands. Compared with the other two-phase systems set up for binding studies, that used in this work takes advantage of the use of a more suitable medium, which permits a better protein partition even at very low ionic strengths. As an example of its usefulness the measurement of the binding parameters of a series of rifamycins to bovine serum albumin is reported.

Buffers↗
PubMed1977

Studies of binding C3-substitute rifamycins to human and bovine serum albumin.

The interactions of a series of C3-substituted rifamycins with human and bovine serum albumins were studied in order to find possible correlations between the degree of binding and the structural features of the various molecules. The results obtained indicate some of the physicochemical properties and, therefore, of the structural requirements which appear to determine or influence the bonding mechanisms of this series of rifamycins. Two types of interaction were found to exist, ionic and hydrophobic types. The findings suggest that the inhibition by protein of the antibacterial activities of these antibiotics depends on the type of bonding mechanism rather than the degree of binding.

Chemical Phenomena↗
PubMed1977

Isolation and characterization of 7-hydroxydiftalone beta-glucuronide.

Metabolic studies on diftalone (I), a new non-steroidal antiinflammatory agent, demonstated that 7-hydroxydiftalone beta-glucuronide (V) is the main urinary metabolite. The isolation of (V) from the urine of a dog treated with 14C-diftalone was performed by liquid-liquid partition after precolation through Amberlite XAD-2 and IRC-50 (H+). All the steps were followed by radio-detection and by thin layer radio-chromatography. Compound (V) was characterized mainly by mass spectrometry after esterification with diazomethane and silylation with BSA.

Animals↗
PubMed1976

Competition between diftalone and other drugs for the binding site(s) on human serum albumin.

The influence of a series of drugs on the binding of diftalone to human serum albumin was investigated by equilibrium dialysis. The results indicated that among the different drugs tested phenylbutazone, indomethacin, warfarin and tolbutamide were, in the order listed, the most effective in displacing diftalone from its binding site(s). Additional investigation showed that there was no consistent inhibition by diftalone of warfarin and tolbutamide binding to albumin. The information obtained might prove useful in clinical therapy whenever a combination of drugs is to be administered.

Acetaminophen↗
PubMedDate not supplied

Metabolism of 5-isopropyl-1-methyl-2-nitro-1H-imidazole. Identification of some urinary metabolites in the dog.

The metabolism of 5-isopropyl-1-methyl-2-nitro-1H-[2-14C] imidazole in dogs has been investigated after oral administration of 50 mg/kg. Three main metabolites, still containing the nitro group and accounting for about 50% of the total radiocarbon, together with a small amount of the unchanged drug, were isolated from the urine within 48 hr. The structures were determined by mass, infrared, and nuclear magnetic resonance spectroscopy. The biotransformations giving rise to the metabolites isolated involve the isopropyl chain of the molecule, either at the tertiary carbon atom or at one of the two methyl groups, or both. Thus, the metabolic behavior of this 2-nitroimidazole derivative appears to be similar to that previously demonstrated for the class of the isomeric 5-nitroimidazoles.

Animals↗
PubMedDate not supplied

Metabolism of deflazacort in the rat, dog and man.

The metabolism of [2'-14C]deflazacort, (11 beta, 16 beta)-21-(acetoxyl)-11-hydroxy-2'-methyl-5'H-pregna-1, 4-dieno[17,16-d]oxazole-3,20-dione, orally given to rats, dogs, and humans, has been studied. From the urine of the three species and from rat bile and liver preparations, five main metabolites I-V have been isolated and their structures investigated by physicochemical analysis: 1,(5 beta,11 beta,16 beta)-11,21-dihydroxy-2'-methyl-5'H-pregn-1-eno[17,16-d]oxazole-3,20-dione; II, (11 beta,16 beta)-11,21-dihydroxy-2'-methyl-5'H-pregna-1,4-dieno[17,16-d]oxazole-3,20-dione; III, (6 beta,11 beta,16 beta)-6,11,21-trihydroxy-2'-methyl-5'H-pregna-1,4-dieno[17,16-d]oxazole-3,20-dione; IV, (3 epsilon,11 beta,16 beta)-3,11,21-trihydroxy-2'-methyl-5'H-pregn-5-eno[17,16-d]oxazol-20-one. Metabolites II and III are quantitatively the most important in the urine of the rat, dog, and man; metabolite V, whose structure is uncertain, has been found in human and rat urine. In the formation of metabolites I-V the fused 2-methyloxazoline ring is unmetabolized, whereas the steroid moiety follows the general metabolic pathways reported for other related corticosteroids.

Animals↗