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Biomedical subjects

J C Loo

Publications and source records attributed to J C Loo.

At least 37 records · Page 2Linked to original sources
PubMed1981

Identification of hydrazone of norethindrone, a metabolic product resulting from the interaction between isoniazid and norethindrone.

Co-administration of isonicotinic acid hydrazide (isoniazid, INH) and 17 alpha-ethinyl-17 beta-hydroxyestr-4-en-3-one (norethindrone, NE) resulted in the formation of the isonicotinyl hydrazone of norethindrone (INH-NE) in rat stomach. Rat liver metabolized the latter compound in vitro. The metabolic product was characterized, following its derivatization with p-methoxy-benzaldehyde (PMBA), by comparison of chromatographic and mass spectral properties with synthetic reference compound. Results showed that INH-NE was cleaved at the amide bond resulting in the formation of the hydrazone of norethindrone. The physicochemical characteristics of synthetic PMBA hydrazone of norethindrone are described.

Animals↗
PubMed1979

A radio-immunological assay for triamcinolone in plasma.

A specific radioimmunoassay for the determination of picogram quantities of triamcinolone in plasma is reported. A rapid chemical separation method was incorporated in the procedure to remove the interfering endogenous hydrocortisone which cross reacts (5%) with the antiserum. Application of this radioimmunoassay to the analysis of triamcinolone plasma concentrations following oral administration of a 5 mg dose of the drug to a human volunteer is described.

Animals↗
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

A specific radio-immunological assay for prednisolone in plasma.

A new, specific radio-immunological assay (R.I.A.) for prednisolone in plasma is described. The R.I.A. incorporates a procedure whereby the endogenous interfering hydrocortisone (in de-proteinized plasma) reacts directly with Girard Reagent T, resulting in a derivative which does not cross react with the specific antibody for prednisolone. The assay is sensitive (quantitation levels are in the 5-10 ng/ml range). The specificity compares favorably with that of a high performance liquid chromatographic procedure.

Animals↗
PubMed1978

The bioavailability of commercial metronidazole formulations.

A bioavailability study of eight commercial pharmaceutically equivalent tablet formulations and a solution of metronidazole was conducted in groups of ten subjects with single oral 250 mg doses. Although the solution gave significantly lower extents of bioavailability, the commercial tablets were not significantly different from the (innovator) reference product. The slow rate of absorption for one formulation (F) was observed to be associated with long dissolution time. Individual elimination half-life differences (probably attributable to metabolism) were reflected in considerable intersubject differences in plasma metronidazole concentrations.

Adult↗
PubMed1977

Analysis of prednisolone in plasma by high-performance liquid chromatography.

A sensitive, specific high-performance liquid chromatographic procedure for the determination of prednisolone in plasma is described. The organic solvent extract from plasma is chromatographed on a silica gel column using a mobile phase of 0.2% glacial acetic acid, 6% ethanol, 30% methylene chloride in n-hexane on a high-performance liquid chromatograph fitted with an ultraviolet dector (254 nm). Quantitation of plasma samples containing 25 ng/ml prednisolone is reported. Metabolites and endogenous hydrocortisone do not interfere with prednisolone. The determination of prednisolone concentration in plasma following administration of a 10-mg single oral dose to a human subject is described.

Chromatography, High Pressure Liquid↗
PubMed1977

Quantitation of digoxigenin in serum following oral administration of digoxin in humans.

Separation of the acid breakdown products from digoxin in serum was accomplished by high performance liquid chromatography (HPLC). The major, less cardioactive, product digoxigenin was quantitated by several different commercial antisera from digoxin radioimmunoassay (RIA) kits. When two normal subjects were given digoxigenin (0.5 mg) orally appreciable concentrations were detected by digoxin RIA kit. Administration of a digoxin (0.5 mg) solution to the same overnight-fasted recumbent volunteers resulted in digoxigenin detection (HPLC-RIA) in serum only in one subject.

Administration, Oral↗