Biomedical subjects
M Debackere
Publications and source records attributed to M Debackere.
Use of anabolics in beef production.
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Qualitative gas chromatographic and gas chromatographic-mass spectrometric screening for beta-blockers in urine after solid-phase extraction using Extrelut-1 columns.
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Comparative study of extraction methods for the GC and GC-MS screening of urine for beta-blocker abuse.
Comparison is made between conventional liquid-liquid extraction and solid-phase extraction techniques using Extrelut-1, Extrelut-3 and C18-RP cartridges respectively for the screening of several beta-blockers in urine. Generally, using GC with nitrogen specific detection as the screening technique, liquid-liquid extraction and Extrelut-1 solid-phase extraction seem to be the methods of choice. However, when the screening and confirmation are performed by GC-MS, solid phase extractions with C18 or Extrelut-1 are valuable alternatives to conventional extraction. Using the different extraction techniques, detection limits and time periods during which the drugs are detectable in urine after oral administration of subtherapeutic amounts of several beta-blockers are determined.
High-sensitivity determination of nadolol in plasma with mass-selective detection.
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Determination of mofebutazone and its 4-hydroxy metabolite in plasma and urine by high-performance liquid chromatography.
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Pharmacokinetics and diuretic effect of bumetanide following intravenous and intramuscular administration to horses.
Concentrations of the potent diuretic bumetanide were determined by a sensitive high performance liquid chromatographic procedure in plasma and urine from horses following intravenous and intramuscular administration of a dose rate of 15 micrograms/kg. The elimination half-life was found to be 6.3 min, the volume of distribution at steady state 68 ml/kg and the total plasma clearance 10.9 ml/min/kg. The onset of diuresis occurred within 15 min and diuresis was no longer apparent 1 h after i.v. administration. Given by the intramuscular (i.m.) route, bumetanide was rapidly absorbed; bioavailability was 70-80%. i.m. administration of bumetanide prolonged its plasma half-life (11-27 min) and enhanced and prolonged its diuretic effect.
The influence of diuretics on the excretion and metabolism of doping agents. III. Etilamfetamine.
The urinary excretion of etilamfetamine (ethylamphetamine) and its major metabolite amphetamine in humans was followed over a period of several days after the oral administration of two formulations. The excretion of both substances was affected by urinary pH. Excretion peaks were observed 3-4 h after the ingestion of etilamfetamine in a capsule and the proportion of etilamfetamine excreted during 72 h was 22.2 to 54.4%. Excepting a shift in the peak excretion time to 4-5 h, no meaningful pharmacokinetic differences were found when Apetinil-Depot, a retard formulation, was administered. The intake of acetozolamide shortly after etilamfetamine resulted in a decrease of the etilamfetamine excretion during one day and a suppression below the detection limit for periods varying from 2-7 h post-dosing. Although the etilamfetamine excretion was suppressed from 2 to at least 10 h post-dosing, the action of the diuretic clofenamide on the etilamfetamine excretion is generally not so obvious as that of acetazolamide. The administration of furosemide only reduced the etilamfetamine concentrations by a factor of 4 to 5 during a 2-h period.
The influence of diuretics on the excretion and metabolism of doping agents. II. Phentermine.
The urinary excretion of phentermine in humans was followed over a period of several days after the oral administration of two formulations. The intake of phentermine in a capsule generally resulted in an excretion peak 4 h after the administration followed by a second peak 12 or 24 h post dosing. The total amount excreted during 72 h varied from 62.7 to 84.8%. Concerning the administration of Ionamine 15, a sustained release formulation, the maximal excretion rate was spread over 3-9 h, while more than 85% of phentermine were excreted after 72 h. The excretion was affected by urinary pH. The intake of acetazolamide shortly after phentermine resulted in a decrease of the phentermine excretion during one day and in one subject in a suppression below the detection limit 4 h post dosing. The administration of furosemide or bumetanide produced only a diluting effect during 2 h.
Quantitation of caffeine in doping analysis using an automated extractor/concentrator.
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The influence of diuretics on the excretion and metabolism of doping agents - I. Mephentermine.
The urinary excretion of mephentermine and its major metabolite phentermine in human volunteers was followed over a period of several days after oral administration of mephentermine. The excretion of both substances was affected by urinary pH. Maximum excretion was observed 2-4 h after administration and the total proportion of mephentermine excreted during 54 h was 57 to 83%. Based on urinary values, the biological half-life of elimination of mephentermine was 9.9 +/- 2.6 h. The ingestion of acetazolamide shortly after administration of mephentermine resulted in a decrease in excretion of both mephentermine and phentermine during one day; in some instances, the amounts of these substances in the urine were below the detection limit for a period of 3-9 h. The administration of frusemide only produced a urinary diluting effect during 2-4 h after administration.
Caffeine: use and abuse in sports.
The urinary caffeine content was compared between a control group and 775 cyclists checked for doping during the 1982 season. The data for sportsmen demonstrate that the (mis)use of caffeine is more pronounced in both professional and amateur classes than in the younger categories (debutant and junior). Caffeine was also monitored during a 60-h period in the urine of several coffee drinkers. Based on all results, a "maximum level of caffeine" of 15 micrograms X ml-1 in urine for sporting competitions is proposed.
Simple and rapid method for the determination of caffeine in urine using Extrelut-1 columns.
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Pentafluorobenzoyl derivatives of doping agents. I. Extractive benzoylation and gas chromatography with electron-capture detection of primary and secondary amines.
A sensitive and rapid method for the gas chromatographic (with electron-capture detection) confirmation of derivable sympathomimetic amines is described. Extractive derivatization with pentafluorobenzoyl chloride is performed on 2-ml urine or plasma samples. Especially for primary amines, the method appears to be very sensitive. Mass spectral data allowed confirmation of the monobenzoylation of all congeners.
Determination of butanilicaine in horse plasma and urine by extractive benzoylation and gas chromatography with a nitrogen-phosphorus detector.
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Pharmacokinetics of sulfamerazine and antipyrine in neonatal and young lambs.
The disposition of sulfamerazine after oral and after IV administrations was studied in lambs at different times after birth. There was a gradual increase in systemic clearance and plasma binding until the 9th week. After sulfamerazine was given orally, there was a marked evolution in the shape of the concentration-time curves in function of age, strongly suggesting a defective absorption rate in the first weeks after birth. For antipyrine, too, the clearance increased gradually during the period of study, but absorption seemed to be rapid in the very young animals.
Protein binding and pharmacokinetics of sulfamerazine in neonatal and young lambs.
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Detection of some local anesthetics in horse urine and plasma by gas-liquid chromatography.
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