Compounds In Human Plasma Research Articles

Gas chromatographic method for the determination of fluoride ion in biological samples. II. Stability of fluorine-containing drugs and compounds in human plasma.

Our gas chromatogrophic method established previusly has been modified to assay fluoride ion which is released from fluorine-containing compounds and drugs in human plasma. A strongly acidic medium was not necessarily required, though fluoride is usually derivatized to trimethylfluorosilane (TMFS) under such acidic conditions. Trimethylsiylation proceeded in pH 2.5 sulfosalicylate (SSA) buffer. Even labile fluorine-containing compounds were stable in SSA buffer, while they were degraded in a strong acid to form fluofide. SSA was effecitive for buffering HCl which was produced by the reaction of excess reagent, trimthylchlorosilane (TMCS), with H2O. At the same time, SSA in plasma sample served as not only a deproteinizing agent but also a buffer agent for biological materials. By means of the present method, released fluoride in human plasma is assayable even in the presence of labile fluorine-containing compounds. More than 5 ng/ml of fluoride can be quantitated. α-Fluoro-β-alanine, 4-fluoroglutamic acid, 3-difluoroalanine and 5-(trifluoromethyl)uracil released fluoride in human plasma at 37°C in vitro. The amount of fluoride increased with time. On the other hand, no fluoride was liberated from 5-fluorouracil of from compounds of drugs studied other than the above ones.

Analysis of vinca alkaloids in plasma and urine using high-performance liquid chromatography with electrochemical detection

The reversed-phase high-performance liquid chromatography with electrochemical detection was used to quantify plasma and urine levels of vinblastine, vincristine, vindesine and a metabolite of vinblastine, desacetylvinblastine. Sample clean-up consisted of solid-phase extraction with a Bond Elut CN column. The extracts were separated on a Hypersil ODS column. The mobile phase consisted of a mixture of methanol and 10 m M phosphate buffer (pH 7.0). The limit of sensitivity using electrochemical detection was 100 pg on-column for all compounds with a signal-to-noise ratio of 3. Quantification of the compounds in human plasma and urine was possible down to 1 ng/ml (ca. 1 pmol). Pharmacokinetic results show that the sensitivity of the method is adequate for drug monitoring in clinical research.

The measurement of plasma vitamin B6 compounds: comparison of a cation-exchange HPLC method with the open-column chromatographic method and the L-tyrosine apodecarboxylase assay

A cation-exchange high-performance liquid chromatographic (HPLC) method was found to be comparable to the open-column (OCC) method for measuring six different B6 compounds in human plasma and the L-tyrosine apodecarboxylase (LTD) assay for pyridoxal-P (PLP). Plasma samples were obtained from 9 subjects before and after 7 days of pyridoxine (PN) supplementation. PLP, pyridoxal (PL) and 4-pyridoxic acid (4-PA) were the major B6 compounds in plasma and the only compounds which increased after supplementation. The coefficients of correlation between any 2 of the 3 methods in measuring plasma PLP were greater than 0.93, and between HPLC and OCC in quantifying PL and 4-PA were 0.82 and 0.63, respectively. With the low plasma levels of pyridoxamine-P, PN and pyridoxamine, the results from OCC were consistently higher than those from HPLC. However, recoveries of spiked B6 compounds in plasma by these methods were between 84 to 105 percent for all the 5 vitamers and 4-PA.

Circulating digitalis-like compounds in essential hypertension.

Inhibitors of the Na+ pump have been proposed as participating in sodium excretion, extracellular fluid regulation, and in the rise of blood pressure. The presence of digitalis-like compounds in human plasma has been investigated by comparing the effects of plasma extracts to those of ouabain in 4 tests. - competition with ouabain for binding to the Na+ pump, - inhibition of Na+ and K+ dependent hydrolysis - inhibition of serotonin uptake by human platelets - central hypertensive effect Plasma fractions exhibited digitalis-like properties in the 4 tests. The effects of plasma extracts of 42 normotensive subjects (21 with family history of hypertension) and 38 patients with essential hypertension (15 with antihypertensive treatment) and 9 patients with chronic renal failure were compared. Plasma from Forty per cent of untreated hypertensive patients and normotensives with hypertensive heredity had a high inhibition level. Inhibition was enhanced in beta-blocker treated patients and decreased in those on diuretics. No digitalis-like activity was observed in uremic plasma. These observations strongly suggest the presence of digitalis-like compound(s) in human plasma and point to its possible association with hypertension.

Analysis of natural corticosteroids in adrenal extracts and in biological fluids by high-performance liquid chromatography

A liquid chromatographic procedure is described for the analysis of the principal natural corticosteroids in extracts of adrenal glands. Microparticulate silicic acid columns and gradients of methanol in chloroform are used: conditions are described for the quantitative analysis of the single principal steroidal components of adrenal extracts for pharmaceutical use and of adrenal extracts of rats. It the last case, the use of a 5-μm silica column with the appropriate gradient allows the determination of corticosterone and of 18-hydroxydeoxycorticosterone, which were identified by means of mass spectromety on their eluates. A single analysis can be performed on the extract of 15 mg of rat adrenal tissue. For the last type of analysis, isocratic conditions on a 10-μm LiChrosorb Diol column are also described. The application of the gradient elution procedure to the analysis of steroidal compounds in human plasma is also described.

Der Metabolismus des Retinoids Ro 10‐9359. Isolierung und Identifizierung der Hauptmetaboliten aus Plasma, Urin und Faeces des Menschen sowie aus der Galle der Ratte Synthese von drei Urinmetaboliten

The Metabolism of the Retinoid Ro 10‐9359. Isolation and Identification of the Major Metabolites in Human Plasma, Urine and Feces Synthesis of Three Urinary MetabolitesAfter oral administration of therapeutic doses of the 3H‐labelled aromatic retinoic acid analog (retinoid) Ro 10‐9359 (ethyl all‐trans‐9‐(4‐methoxy‐2,3,6‐trimethyl‐phenyl)‐3,7‐dimethyl‐2,4,6,8‐nonatetraenoate) to humans 75 and 15% of the 3H‐dose were excreted within the first five days in the feces and the urine, respectively. Using chromatographic procedures including high pressure liquid chromatography 18 metabolites could be isolated from human urine. Their structures were elucidated by mass spectrometry and FT–1H‐NMR. spectroscopy. In these urinary metabolites the tetraene side chain of the parent compound Ro 10‐9359 is shortened. The radioactivity of the identified urinary metabolites accounted for about 11% of the dose. Three urinary metabolites were synthesized. The main part of the radioactivity excreted within the first five days in the feces consisted of unchanged drug (60% of the dose). A smaller (amount 15% of the dose) could not be identified. The unchanged drug and a major metabolite, the corresponding acid, were found in human plasma.In an experiment with bile‐duct cannulated rats the radioactively labelled retinoid Ro 10‐9359 was injected intravenously. About 70% of the 3H‐dose was excreted in the bile, within the first 48 hours. The whole radioactivity of the rat bile consisted of polar metabolites. No unchanged drug could be found. After enzymatic hydrolysis of the bile conjugates three metabolites were isolated. The main metabolite (49% of the i.v. dose) was a conjugate of the corresponding acid of the parent drug, already found as free compound in human plasma. The other bile metabolites (9 and 7% of the i.v. dose) had an intact side chain, too.An enterohepatic recycling of the bile metabolites was observed in the rat.

On the Blood Levels of Organic Iodine Compounds in Various Diseases

Utilization of I181 in clinical investigation has been so prevalent in recent years that a great number of contributions have been made by it toward the clarification of the thyroidal function. But experimental administration of this radioisotope to other patients than those having hyperthyroidism is subjected to certain restrictions. In this paper, a physico-chemical method which can be conveniently used for the separate estimation of organic iodine compounds in human plasma is described. It consists of preliminary separation of the organic iodine compounds in the plasma by paper chromatography and subsequent quantitative estimation of each compound by Heki-Ono's method. The results are as follows. 1. About 85 percent of PBI is recovered by this method. 2. Generally, 85 percent of the organic iodine is present As thyroxine and 15 percent as diiodotyrosine. 3. In hyperthyroidism, the thyroxine fraction increases ; in hypothyroidism, it decreases and the diiodotyrosine fraction shows significant increases. 4. These results are almost identical with those obtained with I131.

UNIDENTIFIED IODINE COMPOUNDS IN HUMAN PLASMA IN ADDITION TO THYROXINE AND IODIDE

UNIDENTIFIED IODINE COMPOUNDS IN HUMAN PLASMA IN ADDITION TO THYROXINE AND IODIDE