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Biomedical subjects

B G Charles

Publications and source records attributed to B G Charles.

7 recordsLinked to original sources
PubMed1992

Measurement of dothiepin and its major metabolites in plasma by high-performance liquid chromatography.

This paper describes a reversed-phase high-performance liquid chromatographic method which will simultaneously measure dothiepin and its three major metabolites (northiaden, northiaden-S-oxide and dothiepin-S-oxide) in plasma using trimipramine as internal standard. Sample preparation involved a basic extraction using diethyl ether followed by an acid back-extraction. The method we report is linear over the range 50-1000 ng/ml (r = 0.999), for all analytes. Total imprecision is less than 11% (coefficient of variation) and accuracy is greater than 94% (n = 20). Recovery of analytes varied considerably from 51.7% for northiaden-S-oxide to 90.2% for dothiepin-S-oxide.

Chromatography, High Pressure Liquid↗
PubMed1988

A modified assay for cyclosporin in blood using solid-phase extraction with high-performance liquid chromatography.

A modified procedure for measuring cyclosporin in whole blood by high-performance liquid chromatography is described and evaluated for clinical use. Sample preparation uses solid-phase extraction cartridges that can be reused. Life of the reverse-phase analytical column exceeds 1,000 injections at 70 degrees C. Cyclosporins A and D (internal standard) elute after 5.6 and 7.6 min, respectively. Calibration plots are linear from 50 ng/ml to at least 2,000 ng/ml. Within-day and between-day imprecision is less than 9% (coefficient of variation). Minimum measurable concentration is 50 ng/ml.

Chromatography, High Pressure Liquid↗
PubMed1987

Temelastine does not affect theophylline pharmacokinetics in normal subjects.

The pharmacokinetics of theophylline (i.v. aminophylline 250 mg) were studied in a balanced, double-blind crossover following the administration of oral temelastine (100 mg) or placebo, twice daily for 7 days, to 10 normal volunteers. Comparison of volumes of distribution, elimination rate constants, elimination half-lives and areas under the plasma concentration-time curve indicated that temelastine had no significant effect on theophylline pharmacokinetics.

Adult↗
PubMed1977

Action of caffeine and theophylline on staphylococcal penicillinase synthesis.

Both caffeine and theophylline acting in subinhibitory concentrations inhibit the synthesis of penicillinase in Staphylococcus aureus. Neither of these compounds inactivate the enzyme. Inhibition of penicillinase synthesis is attributed to the lack of formation of penicillinase rather than the elimination of the extrachromosomal plasmid.

Caffeine↗