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Biomedical subjects

B Kaye

Publications and source records attributed to B Kaye.

At least 19 recordsLinked to original sources
PubMed1992

The sensitive determination of abanoquil in blood by high-performance liquid chromatography/atmospheric pressure ionization mass spectrometry.

A method is described for the determination of abanoquil in human blood. The method is based on high-performance liquid chromatography (HPLC)/atmospheric pressure positive ion chemical ionization mass spectrometry, using (2H3)abanoquil as internal standard. Multiple reaction monitoring is employed for selectivity and sensitivity, which enables quantification over the range 10-500 pg ml-1 with acceptable precision and accuracy. This assay methodology illustrates the versatility of atmospheric pressure ionization/tandem mass spectrometry, in conjunction with HPLC, for the separation and quantification of drugs in the subnanogram per millilitre range.

Adrenergic alpha-Antagonists↗
PubMed1991

Studies on the use of gerbil-derived Babesia divergens antigen for diagnosis of bovine babesiosis.

Babesia divergens antigen obtained from bovine and gerbil erythrocytes was compared for the diagnosis of bovine babesiosis by the indirect immunofluorescence antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA). Using a range of sera from the field and from experimental cattle, it was found that antigen from the two sources did not differ significantly in sensitivity or specificity. Antigen from gerbils may, therefore, be used for serological surveys of bovine babesiosis caused by B. divergens. The IFAT and ELISA were also compared and it was concluded that they are equally effective in the detection of positive samples. For small-scale surveys, the IFAT using gerbil-derived antigen is adequate, but for large surveys the ELISA is preferable.

Animals↗
PubMed1991

Measurement of the class III antidysrhythmic drug, UK-68,798, in plasma by radioimmunoassay.

A sensitive radioimmunoassay (RIA) for the specific determination of 1-(4-methanesulphonamidophenoxy)-2-[N-(4-methanesulphonamido -phenethyl)-N- methylamino]ethane (UK-68,798), a novel class III antidysrhythmic agent, in human plasma is described. Specific antisera were raised in sheep using desmesyl-UK-68,798-succinate-ovalbumin conjugate as the antigenic hapten carrier protein. The antisera produced exhibited high specificity for UK-68,798 compared with known metabolites from animals, other antidysrhythmic agents and co-administered drugs. Good correlation was found in a comparison of the RIA method with a high-performance liquid chromatography (HPLC) method (r = 0.997) and a 10-fold lower limit of determination was observed for the RIA method compared with the HPLC method (0.05 and 0.5 ng ml-1, respectively). The RIA method was applied to the analysis of UK-68,798 in plasma obtained from human volunteers receiving the compound.

Animals↗
PubMed1990

High-performance liquid chromatographic resolution of oxamniquine enantiomers: application to in vitro metabolism studies.

A method is described for the HPLC analysis of oxamniquine enantiomers in liver fraction incubates, using a second-generation alpha 1-acid glycoprotein-based column (Chiral-AGP). Oxamniquine is extracted from the incubation media by liquid-liquid extraction, using diethyl ether. The dried residue is redissolved in eluent, filtered, then injected directly onto the analytical column. The extraction method affords recoveries of oxamniquine of approximately 93%, at concentrations up to 525 micrograms/ml, with an average relative standard deviation of 5.9%. The limit of detection of the method (to give an SNR = 2 at 246 nm) is 0.3 ng on-column for the first eluting, laevorotatory enantiomer and 2.3 ng for the dextrorotatory isomer. The method allowed study of the depletion of oxamniquine enantiomers in liver postmicrosomal incubates. In the rat, a turnover of 21.9% was observed, with no apparent enantioselectivity. Similar observations were made for a mouse liver subcellular fraction incubation. The absence of enantioselectivity in this biotransformation may be attributable to the low substrate specificity of the oxidase or dehydrogenase enzymes involved.

Animals↗
PubMed1989

In vitro metabolism studies on oxamniquine and related compounds by chiral liquid chromatography.

A previously developed method based on alpha 1-acid glycoprotein for the resolution of the enantiomers of the Pfizer antischistosomal drug oxamniquine was used to examine possible enantioselectivity in the in vitro microsomal hydroxylation of a metabolic precursor, UK-3883, but was found to be limited by the poor operational stability of the analytical column ("EnantioPac") employed. As an alternative approach, a "Pirkle" covalently-bonded dinitrobenzoyl leucine column was used, with simple precolumn solute derivatization to the carbamate to improve chromatographic performance. The method allowed preliminary examination of the stereochemistry of the in vitro biotransformation, hydroxylation of UK-3883 to oxaminquine, which yielded evidence for substrate enantioselectivity in favour of the dextrorotatory enantiomer of UK-3883.

Animals↗
PubMed1988

Comparison of the image quality of intravenous urograms using low-osmolar contrast media.

Almost equivalent, intravenous iodine doses of the three new low-osmolar contrast media, ioxaglate (Hexabrix), iopamidol (Niopam) and iohexol (Omnipaque) have been compared for image quality on the intravenous urogram. Generally good radiographic images were obtained. Iohexol gave better results for the nephrogram and pelvicalyceal distension compared with the other contrast media, but only the nephrogram results were statistically significant. Pyelographic density and ureteric distension and density were similar with all three contrast media. In patients where low-osmolality contrast media need to be used for intravenous urography, we suggest that iohexol gives the best radiographic images. Other factors, such as cost and the relative incidence of side-effects of the low-osmolar contrast media also need to be taken into consideration.

Humans↗
PubMed1986

The metabolism and kinetics of doxazosin in man, mouse, rat and dog.

The metabolic fate of doxazosin was investigated in man, mouse, rat and dog using 14C-labelled compound. Bioavailability and pharmacokinetic studies were also conducted with nonlabelled drug, using a specific h.p.l.c. method. Following both oral and intravenous administration, the major route of elimination of drug-related compounds was via the faeces for all species studied. Comparison of the oral and intravenous data show that doxazosin is completely absorbed in man, mouse and rat and is moderately well absorbed in dog. The drug is extensively metabolized, e.g. only about 5% of the dose was excreted unchanged in man. Metabolism in man mainly involves 6- and 7- O-demethylation and 6' and 7'-hydroxylation. These and some minor products were common to the mouse, rat or dog and man. Plasma protein binding was high in all species studied, ranging from 95.3% in the rat to 98.3% in human patients. Oral bioavailability is 60% in dog and approximately 50% in the rat, which is similar to the value of 63% reported for man at therapeutic doses. Mean plasma clearance values were 13 ml min-1 kg-1 (dogs), 30 ml min-1 kg-1 (rats) and 1.2 ml min-1 kg-1 (human subjects). Mean plasma half-life values were 5 h in dogs and 1.2 h in rats: a value of 9 h was reported for human volunteers (cf. 2.5 h for prazosin). The long plasma half-life of doxazosin provides the basis for once-daily dosing.

Adult↗
PubMed1985

Comparison of the serum pharmacokinetics of a long acting and a conventional oxytetracycline injection.

A crossover study was carried out in cattle to determine the serum pharmacokinetics of a standard dose (20 mg/kg bodyweight) of oxytetracycline given either as a conventional injectable formulation or as a long acting formulation. For reference purposes, an intravenous treatment (also given at 20 mg/kg) was included in the trial protocol. A comparison of the two treatment regimes showed that the long acting formulation gave a significantly lower peak oxytetracycline serum concentration, with a significant extension of drug serum concentration. The long acting formulation also showed a longer serum half life and a significantly greater area under the curve value, calculated from 36 hours onwards, together with serum oxytetracycline concentrations which exceeded 0.5 microgram/ml for 86.8 as opposed to 51.5 hours for the conventional formulation. It is concluded that the use of the long acting formulation in cattle leads to a more sustained serum oxytetracycline concentration than does the same dose of conventional formulation.

Animals↗
PubMed1985

Comparison of the side-effects of low-osmolar contrast media in intravenous urography.

The subjective side-effects of almost equivalent intravenous iodine doses of the three new low-osmolar contrast media, ioxaglate (Hexabrix), iopamidol (Niopam) and iohexol (Omnipaque) have been recorded and are found to be generally comparable. Urticaria occurred more frequently with ioxaglate than with the other contrast media and there was a tendency for ioxaglate to cause more nausea. Pain at the injection site occurred less often with ioxaglate than with iohexol. If low-osmolar contrast media are to be used in intravenous urography the relative cost of each is important, there being as yet insufficient data concerning the relative incidences of major reactions.

Contrast Media↗
PubMed1985

Oxidative metabolism of carbazeran in vitro by liver cytosol of baboon and man.

The metabolism of carbazeran has been investigated in vitro using liver cytosol from dog, baboon and man. Carbazeran was not metabolized in cytosol prepared from dog liver but was rapidly metabolized to a single product in baboon- and human-liver cytosol. The product was identified as 4-hydroxy carbazeran. The enzyme responsible for the 4-hydroxylation of carbazeran in vitro was shown by the use of inhibitors to be liver aldehyde oxidase. Species differences in the metabolism of carbazeran in vitro correlate well with studies in vivo; these showed that following an oral dose to man and baboon, the compound was almost completely cleared via pre-systemic 4-hydroxylation, whereas in the dog, this metabolic route appeared unimportant.

Aldehyde Oxidase↗
PubMed1984

A species difference in the presystemic metabolism of carbazeran in dog and man.

The bioavailability of carbazeran and the metabolism of carbon-14 labelled drug have been studied in the dog and man following oral administration. The drug was moderately well absorbed in both species, but there was a marked difference in bioavailability and in routes of metabolism. In the dog, systemic bioavailability was approx. 68% and biotransformation involved mainly O-demethylation. In man, bioavailability was not measurable and carbazeran was almost completely cleared via 4-hydroxylation of the phthalazine moiety. Thus the lack of detectable pharmacological effect in man following oral administration of the drug appears to be due to presystemic metabolism by a particularly active pathway not found in the dog.

Adult↗
PubMed1983

The effect of hyoscine butylbromide on the swallowing of capsules.

Hyoscine butylbromide (20 mg) given intravenously to 48 patients with normal oesophageal motility significantly reduced oesophageal transit of hard gelatin capsules when swallowed in the erect and supine positions with 15 ml and 60 ml water when compared to an age/sex matched group. Delayed capsule transit and possible failed or slowed drug absorption occurring as a consequence of anti-cholinergic drugs on the oesophagus, constitutes a new drug interaction.

Adult↗
PubMed1978

Analysis of cefazolin in serum or urine.

A method was developed to determine cefazolin in serum or urine. The drug is extracted from serum or urine with ethyl acetate, separated by TLC, and determined by fluorescence quenching densitometry. The method was developed to study the pharmacokinetics of the compound in humans.

Cefazolin↗