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Biomedical subjects

J W Hubbard

Publications and source records attributed to J W Hubbard.

At least 127 records · Page 7Linked to original sources
PubMed1983

Improved procedure for the determination of protein binding by conventional equilibrium dialysis.

The binding of drugs to plasma proteins has been studied extensively using a variety of methods, including equilibrium dialysis. Published information on controls used in these studies is frequently inadequate; in other cases, there are deficiencies in the experimental design for the controls. A method is described that eliminates many of the problems associated with artifactual errors in dialysis studies. Multiple replicated controls are performed at the same time as the test, under identical conditions. The controls are used to correct for concentration-dependent binding of drug to the membrane or other equipment. The method was used to determine the binding of sulfadimethoxine to CF-IV-1 alpha-globulin at therapeutic concentrations. The level of binding was low (9-13%), but the stringent control technique permitted statistical analysis which showed each mean test value to be significantly different from its corresponding control. Furthermore, there was a linear relationship between the control-corrected percentage binding values and total drug concentration, whereas there was no correlation between total drug concentration and the uncorrected percentage binding values.

Blood Proteins↗
PubMed1983

A study of the kinetics of chlorpromazine sulfoxide by a specific radioimmunoassay after a single oral dose of chlorpromazine in healthy volunteers.

Antibody specific for chlorpromazine sulfoxide (CPZSO) was produced in rabbits immunized with a hapten-bovine serum albumin conjugate, which was prepared by linking the 10-alkyl side chain of CPZSO to the protein molecule via a 2-carbon bridge. A simple radioimmunoassay was developed which can measure less then 20 pg of CPZSO in plasma. The assay has adequate specificity so that isolation of CPZSO is unnecessary. It was used together with a previously developed chlorpromazine (CPZ) radioimmunoassay to determine the concentrations of CPZ and CPZSO in plasma samples from five healthy volunteers after they had received a single 50-mg oral dose of CPZ. The plasma level data reported here support the previous findings that a significant portion of CPZ is metabolized to CPZSO during presystemic absorption. There are, however, differences to those previously reported in the plasma concentration ratios of CPZSO to CPZ. The possible reasons for these differences are discussed.

Administration, Oral↗
PubMed1982

Identification of phenolic acids in human urine by ion monitoring.

1. Two-different double derivatization techniques and two different g.l.c. systems were used to separate isomeric phenolic carboxylic acids in normal human urine. 2. Carboxylic acids were converted into n-butyl esters and phenolic functions into trifluoroacetic acid esters. 3. n-Butyl trifluoroacetoxybenzoates were separated by g.l.c. and detected by mass spectrometric single-ion monitoring. 4. Trifluoroacetates were hydrolysed under mild conditions, and liberated phenolic groups were subjected to flash methylation. 5. n-Butyl methoxybenzoates were separated by g.l.c. and detected by flame ionization. 6. All derivatives were identified by comparison of retention times and mass spectra with those of authentic reference standards. 7. The urine of a normal vegetarian volunteer was examined. 8. The presence of meta- and para-hydroxybenzoic acids, vanillic acid and isovanillic acid was confirmed by unambiguous techniques.

Chromatography↗
PubMed1981

High-performance liquid chromatographic assay for nanogram determination of chlorpromazine and its comparison with a radioimmunoassay.

A specific and sensitive high-performance liquid chromatographic (HPLC) method for the quantitative determination of plasma chlorpromazine concentrations is described. The procedure is capable of determining 1 ng of chlorpromazine/ml and is adequate for following plasma concentration-time profiles after 7-mg single intravenous doses. After a simple organic extraction of the drug and an internal standard (mesoridazine) from plasma, the organic layer was transferred to a vial and evaporated to dryness at 55 degrees under nitrogen. The residue was dissolved in 200 microliters of HPLC grade acetonitrile. Aliquots (70-100 microliters) were chromatographed, and the drug was quantitated in the range of 1-15 ng/ml of plasma using a fixed-wavelength UV detector. Plasma concentrations determined by the method were compared with those obtained by a previously reported radioimmunoassay specific for chlorpromazine and N-desmethylchlorpromazine. The two methods agreed favorably with a correlation coefficient of 0.993 and a slope of 0.994.

Chlorpromazine↗
PubMed1981

Radioimmunoassay for perphenazine in human plasma.

1 A new sensitive, specific and rapid radioimmunoassay procedure for the determination of plasma concentrations of the neuroleptic drug perphenazine is described. 2 The antiserum developed for perphenazine did not cross-react with most of the major metabolites of perphenazine nor the tricyclic antidepressants and antianxiety agents commonly co-administered with the drug. 3 The assay, based on the above antiserum, enabled the quantitation of 50 pg of the drug in 200 microliters of plasma with a coefficient of variation of about 8% and therefore should be applicable for single dose pharmacokinetic studies, as well as therapeutic monitoring of the drug in patients.

Animals↗
PubMed1981

Radioimmunoassay for trifluoperazine in human plasma.

1 A new sensitive and rapid radioimmunoassay procedure for the determination of the plasma concentrations of the neuroleptic drug trifluoperazine is described. 2 The antiserum developed for trifluoperazine cross-reacted with N-desmethyltrifluoperazine and 7-hydroxytrifluoperazine to the extent of 26 and 24% respectively but its cross-reactivity with commonly co-administered tricyclic antidepressants and antianxiety agents tested was negligible. 3 The assay, based on the above antiserum, enabled the quantitation of 50 pg of the drug in 200 microliters of plasma with a coefficient of variation of about 2% and therefore should be applicable for singly dose pharmacokinetic and bioavailability studies. It should be applicable to therapeutic monitoring of the drug in patients.

Animals↗
PubMed1981

The metabolism of 3-methoxyamphetamine in dog, monkey and man.

1. The metabolism of 3-methoxyamphetamine in vivo was examined in dog, monkey and man. 2. The metabolites identified in all three species were 3-O-methyl-alpha-methyldopamine, 1-(3-methoxy-4-hydroxyphenyl)propan-2-ol, 3-hydroxyamphetamine, 1-(3-hydroxyphenyl)propan-2-one, 1-(3-hydroxyphenyl)propan-2-ol, 1-(3-methoxyphenyl)propan-2-ol and 1-(3-methoxyphenyl)propane-1,2-diol. 3. 1-Hydroxyl-1(3-hydroxyphenyl)propan-2-one was tentatively identified in the urine of all three species. 4. 4-O-Methyl-alpha-methyldopamine was also found in the urine of dog and monkey but not in human urine.

Ammonium Hydroxide↗
PubMed1980

Pathophysiological changes associated with stress-induced hypertension in the borderline hypertensive rat.

1. This study sought to develop an animal model which would be prone to stress-induced hypertension without spontaneously developing it. 2. Eighteen male rats, F1 offspring of spontaneously hypertensive x Wistar-Kyoto rats, had tail-cuff systolic blood pressures of 152 mmHg at 12 weeks of age. Animals were randomly assigned to three groups of six each: experimental (subjected to 'conflict' 2 h daily for 12 weeks), restraint control (placed in conditioning cages but not subjected to conflict) and maturation control (neither restrained nor stressed). 3. Systolic blood pressure rose significantly in experimental animals to 186 mmHg. Experimental animals studied for a 10 week follow-up period without conflict maintained the elevated pressure. In addition, these animals showed myofibrillar degeneration and an elevation in heart weight/body weight ratios. Restraint animals showed a modest elevation in pressure during the study, but not during the 10 week follow-up. Maturation animals showed no changes in blood pressure. 4. The development of a model of hypertension combining genetics with psychological stress may serve as a means for determining the factors involved in triggering and sustaining stress-induced hypertension which may prove relevant to essential hypertension in man.

Animals↗
PubMed1979

Metabolic O-demethylation of 3,4-dimethoxyamphetamine in vivo in dog and monkey.

1. The disposition of the hallucinogen 3,4-dimethoxyamphetamine in vivo was examined in dogs and monkeys. 2. O-Demethylation is important since 3-O-methyl-alpha-methyldopamine (3-methoxy-alpha-methyltyramine) was found in the urine of both species, and traces of alpha-methyldopamine were found in the urine of dogs. 3. Also found in the urine of dogs were 1-(3,4-dihydroxyphenyl)propan-2-one and 3,4-dihydroxybenzoic acid, which are side-chain modified metabolites of alpha-methyldopamine. 4. 1-(3-Methoxy-4-hydroxyphenyl)propan-2-one, a side-chain modified metabolite of 3-O-methyl-alpha-methyldopamine, was present in the urine of both dogs and monkeys. 5. The 3-O-demethylated isomers 4-O-methyldopamine and 1-(3-hydroxy-4-methoxyphenyl)propan-2-one were not detected.

Amphetamines↗
PubMed1979

Radioimmunoassay for chlorpromazine in plasma.

A radioimmunoassay for chlorpromazine in plasma is described. The antiserum was obtained by immunizing rabbits with a conjugate of bovine serum albumin and N-(2-carboxyethyl)desmethylchlorpromazine. It is specific for chlorpromazine and its minor active metabolite, N-desmethylchlorpromazine. Other known active or inactive chlorpromazine metabolites and other psychotropic drugs tested do not cross react with the antiserum. Less than 34 pg of the drug can be detected in 200 muL of plasma. As many as 100 samples can be processed in a day by one technician. Concentrations of chlorpromazine can be measured in 200-muL samples of plasma collected as late as 48 h after a single oral 25-mg dose.

Chlorpromazine↗
PubMed1978

Formation of a cyclic derivative of ethacrynic acid with diazomethane.

Samples of ethacrynic acid were treated with methanol-hydrochloric acid or with diazomethane. GLC and mass spectrometric analysis indicated that the methanol-hydrochloric acid reaction gave the expected methyl ester, whereas diazomethane treatment gave a compound containing an additional 14 mass units. Accurate mass measurement and PMR and IR spectra showed that this product was a cyclic derivative of the methyl ester of ethacrynic acid, methyl 4-(2,3-dihydro-4-ethyl-5-furyl)-2,3-dichlorophenoxyacetate. Either derivatization method can be used for development of an assay for ethacrynic acid.

Chromatography, Gas↗
PubMed1978

Radioimmunoassay for psychotropic drugs I: synthesis and properties of haptens for chlorpromazine.

For the development of radioimmunoassay procedures for chlorpromazine and its active metabolites, three chlorpromazine haptens, 7-(or 8-)(3-carboxypropionyl)chlorpromazine, N-(3-carboxypropionyl)desmethylchlorpromazine, and N-(2-carboxyethyl)desmethylchlorpromazine, were synthesized and characterized by GLC--mass spectrometry, PMR spectrometry, and IR spectrophotometry. Each hapten was coupled to bovine serum albumin, and the number of hapten residues per mole of bovine serum albumin was calculated by UV spectrophotometric methods. Antibodies to each hapten--protein conjugate were obtained in rabbits, and titers of the antiserums were checked by evaluating their binding characteristics to tritiated chlorpromazine.

Animals↗
PubMed1978

Radioimmunoassay for psychotropic drugs II: synthesis and properties of haptens for tricyclic antidepressants.

For the development of radioimmunoassay procedures for tricyclic antidepressants, two drug haptens were synthesized for each of the two amitriptyline--nortriptyline and imipramine--desipramine groups. In one case, nortriptyline or desipramine was treated with succinic anhydride to yield N-(3-carboxypropionyl) derivatives; in the other case, the haptens were novel N-(2-carboxyethyl) derivatives. The hapten and its corresponding ester were characterized by GLC--mass spectrometry, PMR spectrometry, and IR spectrophotometry. Each hapten was coupled to bovine serum albumin, and the number of hapten residues per mole of bovine serum albumin was determined by UV spectrophotometric methods. Antibodies to each hapten--protein conjugate were developed in rabbits, and titers of the antiserums were checked by evaluating their binding characteristics to tritiated drug.

Animals↗
PubMed1976

GLC determination of plasma concentrations of phenprocoumon.

A GLC method for the quantitative estimation of phenprocoumon from plasma is described. Plasma containing phenprocoumon, to which a known amount of phenytoin is added as the internal standard, is acidified and extracted with ethylene dichloride. The drug and the internal standard are then back-extracted into alkali, which is acidified and reextracted with ethylene dichloride. The organic extract is evaporated, and the evaporated residue is mixed with 50 mul of trimethylanilinium hydroxide in methanol. Aliquots (1-2 mul) are injected into a gas chromatography equipped with a flame-ionization detector in which the injection port is held at 325 degrees. The methyl derivatives of phenprocoumon and the internal standard give sharp, well-separated, symmetrical peaks. The method is of sufficient sensitivity to determine 0.125 mug/ml of the drug in plasma with a coefficient of variation of 7%.

Alkylating Agents↗