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F T Delbeke

Publications and source records attributed to F T Delbeke.

67 records · Page 4Linked to original sources
PubMed1977

Detection of sympathomimetic central nervous stimulants with special reference to doping. II. Comparative study of two adsorption chromatography methods using different XAD resins.

Recoveries of a series of sympathomimetic central nervous stimulants in human urine are measured using either adsorption chromatography on self-filled columns (method A) or with a special resin method suitable for racehorse urine (method B). The Amberlite resins used are XAD-2, XAD-4, XAD-7 and XAD-8 and elution is performed using chloroform. The reported comparative drug extractabilities indicate that in most instances the recoveries follow the sequence XAD-4 greater than XAD-2 approximately XAD-8 greater than XAD-7 using method A. Based on the recovery and purity of the extracts obtained, XAD-8 is preferred for gas chromatographic analysis while XAD-4 is very suitable for thin-layer chromatographic screening work. Comparing the two methods, equally good or better results were obtained with method A for all of the resins studied except XAD-7. Finally, it was found that the effect of refrigerated storage of the resins on the drug extractabilities for central nervous stimulants could be neglected.

Adsorption↗
PubMed1976

Excretion and metabolism of nikethamide in the horse.

It is well known that nikethamide (N,N-diethylnicotinamide, CoramineR) is metabolized very rapidly to nicotinamide. Hence, there is difficulty in proving that nikethamide has been used as a doping substance because nicotinamide is a normal physiological metabolite in the organism as well as a vitamin preparation. However, an intermediate metabolite (N-ethylnicotinamide) was found by us in the urine of horses treated with CoramineR. This was characterized by gas chromatography/mass spectrometry, and synthesized and identified as being N-ethylnicotinamide. The excretion and metabolism of nikethamide after intramuscular injection in the horse was followed using quantitative gas chromatography of urine extracts over a period of several hours and the results of these experiments are reported. Changes in urinary pH had no significant effect upon either the metabolism or rate of excretion of the drug.

Ammonium Chloride↗
PubMedDate not supplied

Disposition of human drug preparations in the horse. V. Orally administered oxprenolol.

Urinary concentrations of the beta-antagonist oxprenolol and some of its major human metabolites were determined following oral administration of a dose of 160 mg to five fasted horses. Quantitation was performed by gas chromatography-mass spectrometry (GC-MS) in the selected ion mode (SIM) by monitoring ion m/z 466 of the heptafluorobutyric derivatives. As early as 2 h after dosage oxprenolol could be detected in hydrolysed urine and remained detectable up to 24 h. Maximum urinary concentrations and excretion rates were obtained between 2 and 12 h. After 12 h only 2.8% of the administered dose was excreted as conjugates of oxprenolol and major human metabolites including 4-OH-oxprenolol and 5-OH-oxprenolol. These metabolites were detectable up to 48 h.

Administration, Oral↗
PubMedDate not supplied

Detection and metabolism of fencamfamine and the influence of acetazolamide on its urinary excretion.

A gas-chromatographic (g.l.c.) method with electron-capture (e.c.) detection is described for the simultaneous quantitative determination of nanogram concentrations of 2-ethylamino-3-phenyl-norbornane (Fencamfamine, REACTIVAN) and its metabolite 2-amino-3-phenylnorbornane in urine. The renal excretion of fencamfamine and its metabolite after oral administration to humans was followed over a period of several days. The excretion of both substances was affected by urinary pH. Excretion peaks were obtained 2-4 h after ingestion and the total amount excreted during 80 h varied from 11.9 to 33.2 per cent. Based on urinary values, the biological half life of fencamfamine was 16 h. The intake of acetazolamide shortly after fencamfamine resulted in a decrease of the fencamfamine excretion and a suppression of the metabolite output during at least 10 h. Acetazolamide did not influence the percentage of the doses excreted during 80 h. No changes occurred in urinary fencamfamine or metabolite concentrations during storage of urine at -18 degrees for 6 weeks.

Acetazolamide↗
PubMedDate not supplied

Characterization of two metabolites of prethcamide by gas chromatography and mass spectrometry.

Crotethamide and cropropamide, both components of the respiratory stimulant prethcamide, are metabolized in humans by demethylation of the [(dimethylamino)-carbonyl]-propyl moiety. The resulting metabolites are characterized by gas chromatography-mass spectrometry of urinary extracts. The use of HCl to prevent losses by volatilization during the evaporation step, combined with methanol as solvent, complicates gas liquid chromatographic analysis of prethcamide. The resulting artifacts are identified.

Administration, Oral↗
PubMedDate not supplied

The influence of diuretics on the excretion and metabolism of doping agents: Part VI. Pseudoephedrine.

A capillary gas chromatographic method with nitrogen specific detection is presented for measuring pseudoephedrine and its major metabolite norpseudoephedrine in urine after derivatization with trifluoroacetic anhydride. After the oral intake of 49.2 mg pseudoephedrine (ACTIFED) the active substance is nearly quantitatively excreted in urine over a 48 hr period. From 1 to 7 percent is metabolized to norpseudoephedrine. The intake of acetazolamide results in a suppression of the pseudoephedrine concentration for at least 12 h. The diuretic effect after the intake of 1.51 mineral water could be compared with the effect obtained with 1 mg bumetanide and results in a decrease in pseudoephedrine concentration by a factor 4 for several hours.

Acetazolamide↗
PubMedDate not supplied

A liquid chromatographic method for the determination of fenoprofen in equine plasma and urine.

A high performance liquid chromatographic method to measure plasma and urine fenoprofen levels in equine biofluids is described. Liquid-liquid extraction with diethylether was used to isolate the drug from plasma and urine. The accuracy and reproducibility of the method were within acceptable limits over the concentration range 0-10 micrograms/mL and 0-20 micrograms/mL respectively from plasma and urine. Detection limits were 0.05 microgram/mL (2 mL plasma) and 0.2 microgram/mL (0.5 mL urine). This procedure was applied to ascertain the pharmacokinetics of a 3 g dose of fenoprofen calcium in a horse.

Animals↗
PubMedDate not supplied

The influence of diuretics on the excretion and metabolism of doping agents. Part IV--Caffeine.

The urinary excretion of caffeine in humans was followed over a period of 36 h after the oral administration of ANIMINE, a formulation containing caffeine-alpha-naphthylacetate. The excretion of caffeine was not as markedly affected by the urinary pH as was found with stimulant amines. Excretion peaks were obtained 1-2 h after the ingestion and the total amount of unchanged caffeine excreted during 12 h varied from 0.57 to 1.51 per cent. The ingestion of the diuretics acetazolamide or furosemide 2 h after caffeine resulted in a urine-flow dependent and consequently increased caffeine excretion during 2-4 h post-diuretic. This increase paralleled the increase in urine volume resulting in no meaningful differences in caffeine concentration compared to normal conditions.

Acetazolamide↗
PubMedDate not supplied

Influence of hydrolysis procedures on the urinary concentrations of codeine and morphine in relation to doping analysis.

A method is described for the GC-NPD determination of urinary codeine and morphine after derivatization with trifluoroacetic anhydride. The lower limit for accurate quantitative determination was 0.05 microgram ml-1. After the oral administration of Bisolvon Griblettes corresponding to 30 mg codeine phosphate to seven subjects maximum codeine concentrations were obtained after 1-2 h and codeine remained detectable generally 24 h post dosing. The mean maximum level was 5.1 +/- 2.8 micrograms ml-1 found after enzymatic hydrolysis with Suc Helix pomatia juice (SHP). Based on these and previous results (mean 6.3 +/- 3.4 micrograms ml-1) a threshold level for codeine of 16 micrograms ml-1 is proposed. Significant differences were noticed between urinary codeine concentrations found after enzymatic hydrolysis with SHP, beta-glucuronidase from Patella vulgata and acid hydrolysis, respectively. Generally, highest values were obtained after SHP, while beta-glucuronidase and especially acid hydrolysis resulted in much lower levels. No morphine could be detected after acid hydrolysis. Concerning doping analysis, in particular the uniformity of methods and interpretation of the results, it is recommended that the hydrolysis method should be specified in the rules of those sporting federations allowing codeine and/or morphine.

Acetic Anhydrides↗