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W Doering

Publications and source records attributed to W Doering.

46 records · Page 3Linked to original sources
PubMed1978

[The influence of quinidine on serum digoxin concentrations (author's transl)].

We were able to demonstrate a significant rise of serum digoxin concentrations (SDC) under simultaneous quinidine-glycoside therapy. The reason for this elevation is not yet known. In vitro studies under addition of quinidine showed no influence on the SDC-values measured by a tritium-labelled radioimmunoassay. The mean SDC of 18 patients under simultaneous quinidine therapy was 2.39 +/- 0.84 ng/ml (3.06 +/- 1.08 nmol/l) compared to a mean SDC of 1.23 +/- 0.74 ng/ml (1.57 +/- 0.95 nmol/l) of 11 patients without quinidine therapy (p less than 0.001). Both groups of patients received the same maintenance dose and showed no obvious impairment of renal function and no significant difference in mean body weight. Our results suggest that part of the great number of adverse reactions seen under a combined glycoside-quinidine therapy might be due to the elevated SDC-values. For these patients a low-normal glycoside maintenance dose and an early reduction of the quinidine dose is recommended.

Digoxin↗
PubMed1978

[A simplified radioimmunoassay for digoxin determination using a 125-j-labelled, solid-phase kit (author's transl)].

Our experience with a commercially available kit (Radioimmunoassay DIGOXIN, Boehringer, Mannheim) using (125J)-labelled digoxin and antibody-coated tubes is reported. This simplified method requires only two pepetting steps per sample and results can be obtained in 70 min. The intra- and interassay coefficient of variation ranged between 7% and 8%. The specific digoxin antibody gave no clinical relevant cross-reactions with spironolactone or prednisone (less than 0.0007%). Of the digoxin metabolites the aglucone digoxigenin showed 31% cross-reaction while the more important cardioactive metabolites digoxigenin-bis- and mono-digitoxide had the same binding affinity to the antibody as digoxin, beta-methyldigoxin and beta-acetyldigoxin. Cross-reaction with digitoxin was 6.8%. More than double-fold dilution of serum protein concentration showed little influence on the digoxin values measured. The results obtained by this new kit compare closely with those obtained by our tritium-labelled kit (r = 0.94, p less than 0.001). Therefore, the upper therapeutic limit of 1.9 ng/ml can be adopted for this method.

Antibodies↗
PubMed1977

[Digitalis intoxication: specifity and significance of cardiac and extracardiac symptoms. part I: Patients with digitalis-induced arrhythmias (author's transl)].

In 1164 cases clinical and electrocardiographical findings were correlated with serum digoxin concentrations (SDC). The diagnosis of digitalis intoxication was based on rhythm disturbances which disappeared on withdrawel of the drug. The mean SDC for patients with digitalis-induced arrhythmias was 3.07 ng/ml compared to 1.02 ng/ml for patients with normal Ecg's and 1.01 ng/ml for patients with rhythm disturbances of other origin. Taking 2.0 ng/ml as the lower limit of digitalis intoxication a more than 85% coincidence was found between the diagnosis based on serial Ecg's and on SDC levels. No signs of cardiac toxicity were found in patients with SDC's less than 1.6 ng/ml, some patients, however, showed normal Ecg's despite SDC's up to 4.5 ng/ml. Patients with SDC's greater than 1.9 ng/ml and normal Ecg's were significantly younger than patients with digitalis-induced arrhythmias at comparable SDC's. Although no definite diagnosis of cardiac toxicity could be established in 327 cases, the clinical data of patients with SDC's of 2.0 ng/ml and greater resemble closely those with digitalis-induced arrhythmias while patients with SDC's less than 2.0 ng/ml showed close resemblance to patients with no cardiac evidence of toxicity with regard to: mean age, kidney function, mean digoxin dosage and mean body weight. Patients with elevated SDC's showed a 45% incidence of severely impaired kidney function in contrast to 28% of the patients with SDC's less than 2.0 ng/ml. Even in patients with normal kidney function the correlation between the orally administered digoxin dosage and SDC levels was poor. The correlation was significantly better when dogoxin was administered intravenously. Therefore knowing the amount of digoxin taken (according to the patient's statement) seems of little benefit in the evaluation of digitalis toxicity. In patients with digitalis-induced arrhythmias mean age and mean body weight were significantly lower, mean creatinine concentration and the incidence of severe cardiac insufficency and of typical ST-T-changes were significantly higher. There was no significant difference in mean potassium concentration and incidence of coronary artery disease compared to nontoxic patients. Compared to patients with cardiac arrhythmias of other origin there were no significant differences in mean age, mean potassium and creatinine concentrations and cardiac insufficiency while the incidence of coronary artery disease was significantly higher among patients with rhythm disturbances of other origin. Every type of rhythm disturbance can be digitalis-induced. Among our patients the incidence of digitalis-induced second-degree atrioventricular block (Wenckebach), ventricular bigeminy, nonparoxysmal nodal tachycardia and PAT with block was significantly higher while patients with rhythm disturbances of other origin showed an equally high incidence of PVB's and prolongation of PQ interval...

Arrhythmias, Cardiac↗
PubMed1977

[Digitalis intoxication: specifity and significance of cardiac and extracardiac symptoms. part II. Patients with extracardiac symptoms of digitalis intoxications (author's transl)].

In 1148 cases the serum digoxin concentration (SDC) was correlated with the extracardiac signs of digitalis intoxication. There is a considerably overlap of SDC levels of patients with and without extracardiac signs of toxicity even though the mean SDC's of these two groups differ significantly. An increasing percentage of clinical intoxicated patients with increasing SDC levels was found at digoxin concentrations of 2.0 ng/ml and higher. At lower SDC levels patients with and without extracardiac signs of digitalis intoxication did not differ significantly in their mean SDC but in mean age and in mean creatinine concentration indicating that at least part of the symptoms in these patients might be due to a more severe illness. We could show that many of the extracardiac signs of digitalis intoxication are also seen in patients with impaired kidney function at low SDC levels and may lead to a wrong diagnosis. The most common complaint in patients with SDC's of 2.0 ng/ml and more is nausea (39.4%), followed by tiredness (30.4%), dizzyness (23.7%), vomiting (23.1%), headache (16.0%), visual disturbances (13,5%), colour (yellow) seeing (6;7%), diarrhea (4.2%) and severe neuro-psychiatric disturbances (3.8%). In patients with digitalis-induced arrhythmias the sequence of symptoms is the same only with a somewhat higher percentage rate. Only about one half of the patients with digitalis-induced arrhythmias and SDC values up to 2.5 ng/ml showed also extracardiac signs of intoxication. Therefore these signs are not to be taken as early symptoms of digitalis intoxication. Divided into subgroups (patients with/without digitalis-induced arrhythmias, patients with SDC values of more/less than 2.0 ng/ml) the patients with and without extracardiac signs of digitalis toxicity are compared with each other in regard to: mean body height and weight, concentration of digoxin, potassium and creatinine, digoxin dosage and mean age. The greatest differences were found between patients with combined cardiac and extracardiac signs of intoxication and patients with neither cardiac nor extracardiac signs of intoxication: These intoxicated patients are of significantly higher mean age and lower body weight, their mean concentration of digoxin and creatinine and the digoxin dosage administered are significantly greater, but there is no significant difference in potassium concentration. An important group of patients, namely the elderly with impaired kidney function, are especially prone to develop digitalis intoxication. In this group, however, the extracardial symptoms are of little benefit in the diagnosis of digitalis intoxication. In these patients rhythm disturbances and intoxication-like symptoms are frequently caused by other reasons. In most cases the SDC value can clarify the diagnosis without withdrawal of the drug.

Age Factors↗
PubMedDate not supplied

Effect of quinidine on the intestinal secretion of digoxin in guinea pigs.

Following i.v. injection of digoxin (10 micrograms kg-1) the ratio between digoxin concentrations in the lumen of jejunal loops perfused in situ and in plasma (L/P) of guinea pigs increased linearly with time. After 3 h, L/P was 8.7, indicating net secretion of digoxin against a concentration gradient. In quinidine treated animals (100 mg kg-1 p.o., 2 h before experiment) both the L/P ratio (5.7; p less than 0.01) and the digoxin content of jejunal tissue (-32 per cent; p less than 0.01) were markedly reduced. It is suggested that quinidine reduces the extrarenal clearance of digoxin at least in part by inhibiting the intestinal secretion of this glycoside.

Animals↗