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Biomedical subjects

M G Bogaert

Publications and source records attributed to M G Bogaert.

At least 91 records · Page 5Linked to original sources
PubMed1985

The pharmacokinetics of ciprofloxacin in patients with impaired renal function.

Pharmacokinetics of ciprofloxacin after single oral administration of 250 mg were studied in patients with and without renal failure. Ciprofloxacin concentrations were measured by HPLC. The elimination half-life was 8.7 +/- 0.9 h (mean +/- S.E.M.) in six renal failure patients not on haemodialysis, as compared to 4.4 +/- 0.2 h in six patients with normal renal function. The urinary recovery of unchanged ciprofloxacin was 5.3 +/- 1.7% of dose over 24 h in the renal failure patients, as compared to 37.0 +/- 3.7% in the patients with normal renal function. In haemodialysis patients, the half-life was 5.8 +/- 0.9 h on an interdialysis day, and 3.2 +/- 0.4 h during haemodialysis.

Administration, Oral↗
PubMed1984

Pharmacological characterization of the postjunctional beta-adrenoceptors in the rat gastric fundus.

In order to characterize the postjunctional beta-adrenoceptors in the rat gastric fundus, we studied the influence of beta-agonists and beta-antagonists on methacholine-contracted fundus strips. The mixed beta-agonist isopropylnoradrenaline and the beta 2-selective agonist fenoterol had a concentration-dependent relaxing effect and at higher concentrations completely inhibited the methacholine-induced tone. The reputedly beta 1-selective agonist prenalterol only produced about 50% inhibition and another reputedly beta 1-selective agonist, tazolol, had almost no relaxing effect. The beta-antagonists propranolol (beta 1 + beta 2), practolol (beta 1), H35/25 (beta 2) and ICI 118,551 (beta 2) all shifted the concentration-response curves for isopropylnoradrenaline and fenoterol in a parallel way to the right, but the slope of the Schild plot was not significantly different from 1 only for the antagonism of isopropylnoradrenaline by H35/25. The relaxing effect of prenalterol was only clearly antagonized by ICI 118,551. The results suggest that postjunctional beta 1- and beta 2-adrenoceptors are present in the rat gastric fundus.

Adrenergic beta-Agonists↗
PubMed1984

Binding of oxprenolol and propranolol to serum, albumin and alpha 1-acid glycoprotein in man and other species.

Species differences in binding of basic drugs have only occasionally been studied and we have therefore measured the binding of the beta-adrenergic blockers oxprenolol and propranolol in (1) serum of healthy humans, dogs, rats and rabbits and of rabbits with experimental arthritis, (2) a solution of albumin of these species and (3) a solution of human alpha 1-AGP. In humans, dogs, rats and arthritic rabbits, binding of oxprenolol and propranolol was much higher in serum than in albumin solution; in healthy rabbits serum binding was very low and not different from albumin binding. For both drugs, concentration-dependency was seen in serum of dogs, humans and rats and of arthritic rabbits; a similar concentration-dependency was found for human alpha 1-AGP solution, but not for human albumin and for serum of healthy rabbits. Tris (2-butoxyethyl)-phosphate (TBEP), a known displacer of drugs from alpha 1-AGP in humans, decreased binding in serum of all species except the rabbit. For both beta-blockers, species differences in capacity constants were found; species differences in affinity constants were present only for propranolol. These results suggest that in humans, dog and rat, but much less in rabbits, oxprenolol and propranolol bind mainly to alpha 1-AGP and that binding to alpha 1-AGP is more important for oxprenolol than for propranolol.

Animals↗
PubMed1984

Inhibitory effect of dopamine on canine gastric fundus.

The mechanism of the inhibitory effect of dopamine on canine stomach fundus was studied in longitudinal and circular muscle fundus strips, contracted by transmural electrical stimulation or by methacholine. Results obtained for longitudinal and circular strips were similar. Dopamine (1 X 10(-6)-1 X 10(-4) M) concentration-dependently inhibited frequency-response curves to electrical stimulation; these concentrations did not change the resting tone of the strips. Dopamine (1 X 10(-4) M), tested on contractions of similar amplitude induced in the same strips by electrical stimulation at 0.5 Hz and by methacholine, inhibited the electrically induced contractions but had little influence on the contractions induced by methacholine. The inhibition of the electrically induced contractions by dopamine 1 X 10(-4) M was not influenced by the presence of cocaine 3 X 10(-5) M or hydrocortisone 3 X 10(-5) M. The alpha 1- and alpha 2-adrenoceptor antagonist phentolamine and the alpha 2-adrenoceptor antagonist rauwolscine markedly antagonized the inhibitory effect of dopamine on the response to electrical stimulation at 0.5 Hz. The alpha 1-adrenoceptor antagonist prazosin and the dopamine receptor antagonists haloperidol and domperidone had no effect. The dopamine receptor antagonist metoclopramide decreased the inhibitory effect of dopamine but had a similar effect on the inhibition caused by noradrenaline. These results indicate that the inhibitory effect of dopamine in the dog gastric fundus is mainly mediated by an interaction with alpha 2-adrenoceptors on the intramural cholinergic neurons; this effect is largely direct since it was not influenced by cocaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1984

Pharmacological characterization of alpha adrenoceptors in the rat gastric fundus.

Alpha receptors on the intramural cholinergic neurons and on the smooth muscle cells are involved in the inhibitory effect of catecholamines on rat gastric fundus motility. The pharmacological characteristics of these alpha receptors were assessed using longitudinal muscle strips of the rat gastric fundus, contracted to a similar degree by electrical stimulation and by methacholine. All alpha agonists studied (norepinephrine, phenylephrine, methoxamine, clonidine, UK-14,304 and B-HT 920) concentration-dependently inhibited the stimulation-induced contractions. Norepinephrine, phenylephrine, methoxamine and clonidine also inhibited the methacholine-induced contractions, but for the same concentration of agonist, the inhibition was less pronounced than during electrical stimulation-induced contractions; UK-14,304 and B-HT 920 inhibited the methacholine-induced contractions only in a concentration of 10(-4) M. The effect of clonidine and UK-14,304 on electrical stimulation-induced contractions was antagonized competitively by the alpha antagonists rauwolscine and yohimbine (slope in the Schild plot not different from 1). The effect of norepinephrine and phenylephrine on methacholine-induced contractions was antagonized by the alpha antagonists prazosin, corynanthine and yohimbine; against phenylephrine, the antagonism was competitive (slope in the Schild plot not different from 1). It is concluded that the muscular alpha receptors in the rat gastric fundus are of the alpha-1-type. On the postganglionic cholinergic neurons, alpha-2-like receptors are present; it is not yet clear whether the pronounced effect of alpha-1 agonists on the cholinergic neuron activity is due to interaction with these receptors.

Adrenergic alpha-Agonists↗
PubMed1984

Fate of orally given isosorbide dinitrate in cirrhotic patients.

In 5 out of 7 patients with cirrhosis and extensive shunting, plasma concentrations of isosorbide dinitrate after oral administration of 10 mg of the substance were markedly higher than those found in subjects without hepatic disease. The explanation could be a higher bioavailability and/or a lower systemic clearance, due to shunting and hepatic cell dysfunction. The difference was confirmed by the calculation of the areas under the concentration-time curves.

Administration, Oral↗
PubMed1984

Plasma concentrations of nifedipine in patients with renal failure.

Plasma concentrations of nifedipine were measured after oral administration of a capsule (Adalat) containing 10 mg of the substance in 6 patients with renal failure not on haemodialysis, in 5 patients with renal failure on haemodialysis and in 6 patients with normal renal function. Whereas the presence of renal failure did not influence the plasma concentrations, lower concentrations were found in the patients on haemodialysis than in the other groups.

Administration, Oral↗
PubMed1984

Preliminary pharmacokinetics of intravenous ciramadol in humans.

Plasma concentrations of ciramadol were measured after intravenous administration of 30 mg in 8 healthy volunteers. A high-performance liquid chromatographic method with U.V.-detection for simultaneous determination of the substance and of its desmethyl metabolite was developed. The disposition of the drug in these volunteers could be described by a two-compartment open model. Distribution volume was on average 561, elimination half-life 3.85 hours and mean body clearance 154 ml/min. Desmethylciramadol was not detected in the plasma.

Adult↗
PubMed1983

Determination of nifedipine in human plasma by capillary gas chromatography with nitrogen detection.

A gas chromatographic method for the determination of nifedipine in human plasma is presented. Nifedipine was extracted from plasma at basic pH with toluene, and nitrendipine was used as the internal standard. Chromatography was performed on a cross-linked methylsilicone fused-silica column by on-column injection and with a nitrogen-phosphorus ionization detector. The minimal detectable concentration was approximately equal to 0.5 ng/ml of plasma. The standard curve was linear in the range evaluated, 2-300 ng/ml plasma. The within-analysis coefficient of variation was 3.9-10.4%, and the day-to-day coefficient of variation was 3.8%. A peak with the same retention time as the nitropyridine derivative of nifedipine was detected in the plasma of patients who had taken 10 mg nifedipine orally.

Chromatography, Gas↗
PubMed1983

Toxicokinetics of methyl parathion and parathion in the dog after intravenous and oral administration.

Methyl parathion (20 mg X kg -1 intravenously and orally) and parathion (5 mg X kg -1 intravenously and 10 mg X kg -1 orally) were given to non-anesthetized dogs and the serum concentrations were followed in function of time. For both substances a low bioavailability after oral administration was found. In other dogs radioactivity was followed in urine after oral and after intravenous administration of labeled methyl parathion or parathion. The results suggest a good gastro-intestinal absorption of the substances. In anesthetized dogs which were given methyl parathion or parathion intravenously, high hepatic extraction ratios were found, suggesting that the low systemic availability after oral administration can be explained by an important hepatic first-pass extraction. Binding of methyl parathion and parathion to dog serum, to human serum and to a solution of human albumin was determined with equilibrium dialysis. In both species a high binding (greater than 90%) was found for both substances and there was no concentration-dependency in the concentration range used (0.2-30 micrograms X ml -1). In man and in dog the serum protein binding of parathion was about 5% higher than that of methyl parathion.

Administration, Oral↗
PubMed1983

Effects of dopamine and apomorphine on the response of rabbit isolated atria to sympathetic nerve stimulation.

In isolated rabbit atria, dopamine (10(-6) M to 3 X 10(-6) M), in the presence of cocaine and atropine, inhibits the chronotropic responses to electrical stimulation of the sympathetic nerves without influencing the responses to isoprenaline. The inhibitory effect of dopamine is antagonized by cis-flupenthixol in a concentration (2.5 X 10(-6) M) that does not antagonize the inhibitory effect of clonidine. Phentolamine, in a concentration (10(-5) M) that antagonizes clonidine, does not influence the inhibitory effect of dopamine. Apomorphine (10(-6) M) also produces an inhibition of the nerve stimulation-induced chronotropic responses that can be prevented by cis-flupenthixol. These data suggest that prejunctional dopamine receptors are present in rabbit atria.

Animals↗