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Biomedical subjects

D Hellenbrecht

Publications and source records attributed to D Hellenbrecht.

35 records · Page 2Linked to original sources
PubMed1975

Influence of isoprenaline and salbutamol on the threshold of electrically induced ventricular fibrillation in anaesthetized guinea pigs.

Fibrillation threshold and heart rate were measured after increasing doses of (-)-isoprenaline and (plus or minus)-salbutamol. The initial values of 212 plus or minus 10 muA (x plus or minus SEM) and 211 plus or minus 10muA were decreased to 74 plus or minus 10 muA by low doses of (-)-isoprenaline (10-11- to 10-10 moles/kg i.v.), and to 89 plus or minus 11 muA by (plus or minus)-salbutamol (10-9- to 10-8- moles/kg i.v.). Higher doses, paradoxically, increased fibrillation threshold to initial values, (-)-isoprenaline: 2x10-9- moles/kg; (plus or minus)-salbutamol: 2x10-6- moles/kg. A linear increase in heart rate per 10-fold increase of either drug was observed, (-)-isoprenaline: 25 beats - min-1-; (plus or minus)-salbutamol: 14 beats - min-1-. The apparent beta2-selective property of salbutamol is documented by its low potency in changing fibrillation threshold and heart rate.

Albuterol↗
PubMedDate not supplied

Plasma levels and urinary excretion of lormetazepam in patients with liver cirrhosis and in healthy volunteers.

Plasma levels and urinary excretion of lormetazepam (Noctamid-ampoules; 2 mg/10 ml) were studied after i.v. (0.015 mg/kg b.w.) and after p.o (0.03 mg/kg b.w.) administration of the drug to five patients with cirrhosis of the liver (C) and to five young male volunteers (N). The cirrhotic patients exhibited higher drug plasma levels (Cmax p.o.: 11-43 ng/ml [C] vs. 11-16 ng/ml [N]) and higher AUC0-24 values of the unchanged drug (i.v.: 66-102 ng.h/ml [C] vs. 54-72 ng.h/ml [N]; p.o.: 83-188 ng.h/ml [C] vs. 74-113 ng.h/ml [N]). The absolute bioavailability was increased in the C-group with 57-134% vs. 52-84% [N]. The total plasma clearance of lormetazepam was 3 ml/min/kg in the C-group and 4 ml/min/kg in the N-group and thus within the range known for elderly and young male subjects. Conversely to the parent compound, the AUC-figures of its 3-OH-glucuronide were higher in the N-group (346-434 ng.h/ml) than in the C-group (149-371 ng.h/ml). In 24 h pooled urine samples of both groups, the glucuronide of lorazepam, the N-demethylated metabolite, accounted for approximately 5-14% of the dose fraction excreted as lormetazepam glucuronide. Apart from increased levels of the unchanged drug due to porto-systemic shunt and/or disease-dependent lower glucuronidation rate, the pharmacokinetics of lormetazepam were not altered in cirrhotic patients. It can therefore be concluded that for this group of patients the drug can be administered according to the same dose regimen as that used for normal subjects.

Administration, Oral↗
PubMedDate not supplied

Oral medium-dosed metoclopramide versus placebo as highly effective antiemetic prophylaxis in in- and outpatients on noncisplatin chemotherapy.

The antiemetic effect of oral medium-dosed metoclopramide (MCL, 3.5 mg/kg b.w./cycle) and placebo for chemotherapy-induced emesis of a noncisplatin regimen was assessed for inpatients and outpatients in two double-blind placebo-controlled sequential analyses according to Bross (1952). MCL was given in 5 single doses of 0.7 mg/kg b.w. at 0 h (loading) and at 2 h (i.e. start of chemotherapy) and 6, 10 and 14 h (as maintenance doses). Both studies ended after 8 sequential pairs in favor of MCL (2 alpha = 2 beta = 0.05). Major antiemetic protection (< 2 emetic episodes per 26 h) was achieved for 8/8 of inpatients and 7/8 of outpatients (placebo 0/8 and 0/8). Side effects neither required discontinuation of the antiemetic regimen nor additional therapy. The median of MCL plasma levels ranged from 150 to 750 ng/ml and terminal half-lives from 3.9 to 8.9 h.

Administration, Oral↗
PubMedDate not supplied

Correlations between hydrophobicity and non-specific pharmacological effects of beta-adrenoceptor blocking agents.

It was the aim of this study to test whether the non-specific pharmacological activities of the beta-adrenergic blocking drugs can be predicted by estimation of the hydrophobicity of the compounds. Srong correlations were obtained between the octanol buffer partition coefficients and the ability of the drugs to decrease conduction velocity of the isolated frog heart, to raise the electrically induced ventricular fibrillation threshold in guinea pigs, and to depress ventricular contractility in the cat. The strong correlations between the partition coefficients and the pharmacological actions suggest that estimation of the hydrophobicity of the beta-adrenergic blocking drugs is suitable to predict the non-specific pharmacological properties.

Adrenergic beta-Antagonists↗