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Biomedical subjects

J Kuhlmann

Publications and source records attributed to J Kuhlmann.

At least 127 records · Page 7Linked to original sources
PubMed1978

[Suicide with beta-methyldigoxin (author's transl)].

A 50-year-old woman committed suicide by taking an overdose of beta-methyldigoxin. The interval between swallowing the tablets and death was about 60 minutes. Plasma and tissue samples, taken 163 hours after death, were analysed for glycosides by radioimmunoassay. The plasma-glycoside level was 75.1 ng/ml, in the left ventricular myocardium it was 143.2 ng/g wet-weight. and in the right ventricular myocardium 159.7 ng/g wet-weight. The tissue-plasma ratio for the various parts of the heart varied from 0.8 to 2.1. Death occurred in the early distribution stage.

Digoxin↗
PubMed1977

[Isomerisation and bioavailability of beta- and alpha-acetyldigoxin (author's transl)].

Bioavailability of acetylated derivatives of digoxin tablets have been studied in healthy subjects after a single oral and intravenous dose as well as during maintenance therapy. alpha-acetyldigoxin shows a lower bioavailability than beta-acetyldigoxin even if the alpha-acetylated derivative is incorporated in a matrix of aerosil (SiO2). Moreover, beta-acetyldigoxin can be transferred to alpha-acetyldigoxin in alkaline solutions. This isomerisation leads to a decrease of the bioavailability of such fixed preparations which contain beta-acetyldigoxin and the hygroscopic salts of potassium-magnesium-aspartate. A prevention of the isomerisation is attained by isolating beta-acetyldigoxin from potassium-magnesium-aspartate. The bioavailability of a such new formulation is comparable to that of beta-acetyldigoxin alone. The experiments show the bioavailability of acetylated derivatives of digoxin to be influenced by the physico-chemical properties of a drug and its preparation.

Acetylation↗
PubMed1977

[Pharmacokinetics of cardiac glycosides and clinical consequences].

The purpose of pharmacokinetics of cardiac glycosides is to study the time courses of glycosides in biological fluids, tissues and excreta. The extent of accumulation of a given dose at uniform time intervals depends only from the overall elimination rate constant. By knowing the elimination rate constant the extent to which a cardiac glycoside would accumulate in the body following a fixed dosing regimen can be calculated. The higher accumulation in the central nervous system requires a much longer time. Therefore it may be assumed that the brain is a deep compartment for cardiac glycosides and this compartment cannot be detected by analysis of plasma glycoside concentrations. Central side effects of cardiac glycosides may occur at therapeutic plasma levels. In renal disease a lower maintenance dose of digoxin and methyldigoxin should be administered or the same dose less frequently. Digitoxin does not accumulate in patients with renal failure or in anuria since the extrarenal elimination of digitoxin is much higher compared to digoxin and methyldigoxin.

Biological Availability↗
PubMed1977

Canrenoate disposition in dogs. Tissue distribution and elimination.

The metabolism and tissue distribution of intravenously administered C14-canrenoate-potassium (CR-K) was studied at various time intervals in 10 dogs. After a rapid decline of total radioactivity immediately after injection, the elimination in plasma occurred in two distinct phases with half-lives of 6.8 and 23.6 h. Canrenoate was rapidly converted to lipid- and water-soluble metabolites which were separated by thin-layer chromatography. Most tissues showed similar concentrations of total radioactivity as plasma. An accumulation of radioactivity per g wet weight was detected in the adrenal glands and fat tissue as well as in the metabolic and excretory organs but not in the heart. Taking into consideration that skeletal muscle, fat tissue and liver constitute about 64% of the body weight, it is obvious that the main part of total radioactivity was present in these tissues. In contrast to plasma, urine and feces, where various metabolites could be analysed, the bulk of radioactivity in tissues is represented by canrenone. Thus, the estimation of the parent compound and its metabolites in plasma, urine and feces does not allow final conclusions about the active substance in various tissues. Within 72 h 47% of the dose was recovered in urine and 49% in feces.

Animals↗
PubMed1977

Influence of canrenoate-K and cardiac glycosides on their tissue distribution and elimination.

The combination of cardiac glycosides and canrenoate-potassium (CR-K) produces synergistic effects on hemodynamics. On the other hand, CR-K antagonizes digitalis-induced cardiac arrhythmias. Therefore, it was the purpose of this study to determine interactions between these substances, particularly of their myocardial uptake. The additional administration of CR-K leads to significantly higher concentrations of digoxin and ouabain in heart, liver, adrenal gland and spleen. Contrary to this, additional digoxin reduces the concentration of CR-K in the tissue. Particularly obvious is the reduced concentration in the kidney, adrenal gland, pancreas, brain and spleen. The renal excretion of digoxin and ouabain is reduced by the additional administration of CR-K, while digoxin accelerates the CR-K excretion within the first 60 min after application. Metabolic interference was not detected in the combination of cardiac glycosides and CR-K. The mechanisms for the interactions between cardiac glycosides and CR-K during the distribution phase are discussed. The inhomogenous interference of their myocardial uptake makes a common cardiac receptor for the synergistic effect of cardiac glycosides and CR-K rather unlikely. CR-K does not have a suppressant effect on digitalis-induced arrhythmias due to any diminution of the glycoside uptake by myocardial tissue.

Animals↗
PubMed1976

Bioavailability and pharmacokinetics of beta-methyldigoxin after multiple oral and intravenous doses.

To obtain true half lives, glycoside elimination from six healthy subjects was studied for 14 days after multiple intravenous doses or oral administration of a daily maintenance dose of beta-methyldigoxin 0.3 mg. After oral or intravenous administration of beta-methyldigoxin ceased, the plasma concentrations declined from the 14th to the 16th days with a half life of 1.7 days. From the 16th to the 20th day a change from a shorter to a longer half life of 2.8 and 2.9 days was observed. Similar half lives were found in urine: after the last dose the initial slope from the 14th to the 16th day had a half life of 1.8 days, and the terminal slope had one of 3.2 days. The results indicate release of the glycoside from slowly equilibrating tissues.

Administration, Oral↗
PubMed1976

[Influence of antacids on plasma concentration of digoxin in man (author's transl)].

In a cross-over trial the plasma concentrations of digoxin have been studied in nine healthy subjects given oral doses of digoxin alone and simultaneoulsy with magnesium-aluminium-silicate-hydrate and dimagnesium-aluminium-trisilicate. The administration of 0.75 mg digoxin on each of 3 days and 0.375 mg on each of 2 days caused a 17 percent decrease of digoxin plasma level when given simultaneously with 1100 mg magnesium-aluminium-silicate-hydrate (n=4) and a 24 percent increase when given with 1000 mg dimagnesium-aluminium-trisilicate (n=5), respectively. The differences are not significant. The experiments suggested that antacids containing magnesium-aluminium-silicate do not impair the absorption of digoxin in man.

Administration, Oral↗
PubMed1976

Disposition of digitoxin in renal failure.

The disposition of digitoxin was studied for a period of 8 days in 6 uremic patients given a single oral dose of 1 mg 3H-digitoxin. In plasma, the time-course of radioactivity indicated a diminished absorption velocity of tritium compared to that of control subjects already reported and, after reaching of a pseudostate-equilibrium at 24 hr, an exponential decline with a mean half-life of 8.0 days. In urine, smaller amounts of tritiated compounds were eliminated in uremic patients (8.7% of the dose) than in controls (22.5%). The average fecal excretion of digitoxin and its metabolites was not significantly increased. Chloroform extraction and thin-layer chromatography in plasma, urine and feces suggested no qualitative alteration in the metabolism of digitoxin. Calculations of the total body tritium content (body stores) after each 24-hr interval and its pharmacokinetic behavior showed that the elimination of digitoxin is determined by the transfer constant from tissue to plasma. The differences in elimination kinetics of digitoxin and its metabolites of uremic patients and healthy subjects were not significant.

Chromatography, Thin Layer↗
PubMed1976

Effects of pretreatment with spironolactone of pharmacokinetics of 4'''-methyldigoxin in man.

Pharmacokinetics of 3H-4''' -methyldigoxin (md) were studied in three paired experiments with and without pretreatment with spironolactone (7 mg/kg/day for 7 days) and in one additional test person after pretreatment only. The results were compared with controls after oral (n equals 6) and intravenous (n equals 6) administration of md. In addition the biliary excretion of md and its metabolites was investigated in biliary fistula patients with and without pretreatment with spironolactone. After pretreatment of normal persons maximum plasma levels of tritium were approximately 35% lower and they were reached on average 60 min after oral administration as compared with approximately 15 min without pretreatment. Already 12 hrs after oral administration the plasma concentrations, with and without pretreatment, no longer differed and the biological half lives of radioactivity in plasma were equal. With or without pretreatment, the cumulative excretion of tritium in urine and faeces was nearly identical in the paired experiments within 7 days. It was in the range of the controls which eliminated 55.2 +/- 2.8 and 28.6 +/- 5.7% of the dose in urine and faeces, respectively, after oral, and 62.2 +/- 2.1 and 28.9 +/- 5.2%, respectively, after i.v. administration. Accordingly after pretreatment the radioactivity excreted in bile within 48 hrs (14.9% of the dose) did not differ from controls. Examination of the composition of labelled compounds excreted in urine and bile revealed no significant alterations in the metabolic degradation of md under the influence of spironolactone. Thus the profound effects of spironolactone upon pharmacokinetics of md previously observed in rats are without any significance for human conditions.

Administration, Oral↗
PubMed1975

Concentration of digoxin, methyldigoxin, digitoxin and ouabain in the myocardium of the dog following coronary occulsion.

26 mongrel dogs were given a single dose of 0.03mg/kg tritium-labelled digoxin, beta-methyldigoxin, digitoxin or ouabain 2 hrs or 95 hrs following experimental coronary occlusion. Examination of the epicardial ECG was performed by moving from intact to ischemic or necrotic zones. 60 min after glycoside administration the animals were sacrificed and tissue samples from the marked heart muscles areas and from the skeletal muscle were analysed for glycoside content. The early glycoside uptake in acute ischemic or necrotic myocardium was diminished independently of the physicochemical properties of the glycoside. Significantly higher glycoside concentrations (ng/g wet weight) were measured in the injured myocardium 3 hrs after coronary occlusion than 96 hrs afterward (p less than 0.005). The values in acute ischemic myocardium varied considerably. This nonhomogeneity of glycoside uptake in the acute ischemic heart muscle may partly explain the increased sensitivity to glycosides in myocardial infarction. The decline of glycoside concentration correlates with the alterations in the epicardial ECG. The cardiac effects of cardenolides 60 min after intravenous administration was caused by the unchanged glycoside. In contrast to the myocardium, glycoside accumulation could not be found in the skeletal muscle. The concentrations of digoxin, beta-methyldigoxin and digitoxin in the skeletal muscle were significantly higher than the concentration of ouabain, which was rapidly eliminated via the urine.

Animals↗