Biomedical subjects

H M Ruijten

Publications and source records attributed to H M Ruijten.

3 recordsLinked to original sources

PubMed1989

Determination of drug protein-binding by high-performance liquid chromatography using a chemically bonded bovine albumin stationary phase.

A liquid chromatographic method for the determination of the degree of protein-binding of drugs has been established, using a stationary phase to which bovine serum albumin has been bonded chemically. In a structurally heterogeneous group of compounds, results of the method correlate well with protein-binding data obtained by equilibrium dialysis (r = 0.89, n = 23, p less than 0.001). Within a series of analogous piperazines a good correlation is found (r = 0.981, n = 11, p less than 0.001). The chromatographic method allows automation of the measurement of protein-binding of large series of compounds with protein-binding ranging between 10 and 99%. The method is not expensive and is less time consuming than equilibrium dialysis. Only 1 mg of technical-grade material is required to determine the protein-binding, and radioactive labelling of the material is not necessary.

Animals↗

PubMed1984

Conical precolumn as loading buffer for the main column.

A conical high-performance liquid chromatographic precolumn was developed to cope with the problems that arise during the processing of large volumes of biological samples. The shape of the column was designed so as to offer a large loading capacity at the front of the precolumn. The stainless-steel construction, which is pressure resistant up to 40 MPa, can be fully integrated into high-performance systems. In the present work, the precolumn arrangement was used in the assay of pamoic acid in human plasma and in the isolation of radioactive metabolites from pools of animal urine and of supernatants from liver homogenates. Apart from extremely polar compounds, which were not retained on the precolumn, recovery of metabolites was practically complete. Almost the same resolution was obtained with the equivalent of 900 ml of urine, purified and enriched on the precolumn, as with a 2-ml sample of the original urine. Likewise, the chromatographic metabolite pattern of 650 ml of supernatant from homogenized liver was similar to that of a deproteinized sample of 2 ml. It is suggested that the precolumn is usable for all chromatographic problems involving enrichment of small amounts of substances in large amounts of complex matrices.

Animals↗

PubMedDate not supplied

Fluvoxamine: metabolic fate in animals.

The metabolic fate in animals of the antidepressant compound fluvoxamine was investigated. The 14C-labeled drug was administered orally to dogs, rats, hamsters, and mice, and excretion in urine and feces was measured. Chromatographic patterns of the urines were developed by high performance liquid chromatography. These patterns were used as guides in the isolation of the metabolites, its initial step consisting of concentration of the radioactivity in the urine pools in a conical precolumn, followed by separation in the same HPLC system as used for the metabolite patterns. Altogether, 32 radioactive substances were isolated from the urine pools of the four animal species. They were all identified by the combined use of proton nuclear magnetic resonance and mass spectrometry, and by information obtained from chromatographic behavior and color reactions. Several of the 32 compounds were identical, leaving a total of 11 different metabolites in the four species. In all the animal species, the main focus of fluvoxamine degradation was its aliphatic methoxyl group. In three species, this resulted in the corresponding carboxylic acid as the main metabolite, but in the mouse the corresponding alcohol, in glucuronidated form, was at least as important. In mouse and hamster, the methyl ester was a minor metabolite. Products of acetylation or oxidative removal of the primary amino group accounted for only minor proportions of the metabolite patterns. While fluvoxamine itself has the (E)-configuration, several metabolites occurred both in the (E)- and the (Z)-form. The parent compound was isolated only from the urine of dogs, it accounted for less than 10% of the urinary radioactivity.

Animals↗