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Biomedical subjects

R Zini

Publications and source records attributed to R Zini.

At least 91 records · Page 5Linked to original sources
PubMed1982

Multiple human serum binding of two thienopyridinic derivatives, ticlopidine and PCR 2362, and their distribution between HSA, alpha1-acid glycoprotein and lipoproteins.

The binding of two drugs, ticlopidine and PCR 2362, chemically related to thienopyridin, potent antiaggregant agents, was studied in vitro to serum and to the corresponding isolated proteins, HSA, alpha 1-AGP, VLDL, LDL and HDL, using equilibrium dialysis at pH 7.4 and 37 degrees. The binding of these drugs to HSA and lipoproteins was non-saturable. The binding capacity of the lipoproteins was much greater than that of HSA and appeared to be dependent on lipid content. The binding capacities of the apoproteins were less than 10% of that observed for the native lipoproteins suggesting that drug-lipoprotein binding involves drug solubilization in the lipid phase of lipoproteins rather than a classical binding to definite sites. However drug binding to alpha 1-AGP was saturable with n = 3 for both and K = 89,000 and 33,000 for ticlopidine and PCR 2362, respectively. At physiological concentration, alpha 1-AGP binding capacity represented 15% of total serum binding capacity which could double in pathological states, in which the level of this protein is increased.

Humans↗
PubMed1981

Evidence for a concentration-dependent polymerization of a commercial human serum albumin.

Polymerization of a commercial human serum albumin (Sigma A-1887) was investigated by two different techniques, high-performance liquid chromatography and gel electrophoresis. The chromatographic technique was based on the frontal analysis principle using a column which excludes polymers but retains monomers. The results allowed the determination of the monomer--polymer affinity constant, X = 526 +/- 100. The electrophoresis technique was performed with a polyacrylamide gel containing sodium dodecyl sulphate in order to separate the different polymer species according to their molecular weights. The two techniques gave results in good accordance and showed a concentration-dependent aggregation. The higher the human serum albumin concentration, the more the monomer proportion decreases.

Chromatography, High Pressure Liquid↗
PubMed1980

Binding of digitoxin, digoxin and gitoxin to human serum albumin.

The binding of three digitalis glycosides, digitoxin, digoxin and gitoxin, to human serum albumin was studied in vitro by equilibrium dialysis. The results obtained showed that binding is a non saturable process and that probably the same binding mechanism is involved for each of the three drugs. Their binding sites seem to be different from of those of acidic and basic drugs. However, the three drugs were found to be partially displaced by large amounts of fatty acids.

Digitalis Glycosides↗
PubMed1979

Phenytoin binding to human albumin.

Binding of phenytoin to human plasma proteins and to human serum albumin is studied using equilibrium dialysis method at pH 7.4 and 37 degrees C. Phenytoin is mainly bound to albumin, the percentage of bound drug being constant over a wide range of total drug concentrations. Calculation of the drug binding parameters show a low affinity, k = 745 M-1, and a high number of binding sites, n = 8. Palmitic acid and some acidic drugs, warfarin and phenylbutazone added to human serum albumin, decreased phenytoin binding in a non competitive way. Basic and non-ionizable drugs, on the other hand, did not modify phenytoin binding.

Anilino Naphthalenesulfonates↗
PubMed1979

The fate of ticlopidine in the organism. II.--Distribution and elimination of ticlopidine 14C after a single oral administration in the rat.

In the Rat, distribution and elimination of Ticlopidine C14 after a single oral dose of 25 mg/kg were studied and compared with that observed after a single intravenous injection of the same dose. The plasma decreases of total radioactivity were found to be identical regardless of adminstration route, indicating almost complete absorption of the labelled molecule. The elimination half-life, which was 1.56 +/- 0.08 days, was equivalent to the half-life measured after intravenous injection, and no difference in tissues distribution was observed. As in the case of intravenous injection, the radioactivity was eliminated principally in the feces and only to a slight degree in the urine.

Administration, Oral↗
PubMed1977

Modification of the binding of sulphamidochlorobenzoic acid to human albumin by palmitic acid contamination of albumin.

Palmitic acid a common contaminant of albumin preparations, competitively inhibits the binding of sulphamidochlorobenzoicacid (SCBA) to human albumin thus decreasing its observed affinity. The effect of palmitic acid depends on its concentration, i.e. the purity and concentration of the albumin preparation used. The correct value for SCBA affinity was obtained by correcting the experimental data according to the palmitic acid concentration by use of a multiligand analysis method.

Albumins↗
PubMed1976

Binding of four sulphonamides to human albumin.

The four sulphonamides studied--furosemide, tolbutamide, sulfafurazole and sulfonamidochlorobenzoic acid--bind to human albumin at the same sites but with decreasing affinity. These sites are also common to other drugs, namely acenocoumarin, chlorophenoxyisobutyric acid, phenylbutazone and warfarin. In plasma, the four sulphonamides considered bind mainly to albumin, but also, at higher concentrations, to globulins, to an extent that increases as their affinity for albumin lessens.

Acenocoumarol↗