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Biomedical subjects

L Storstein

Publications and source records attributed to L Storstein.

At least 55 records · Page 3Linked to original sources
PubMed1984

Pharmacology of antiarrhythmic drugs for the clinician--medical emergencies and chronic treatment.

Optimal treatment with antiarrhythmic drugs poses difficulties both in acute and chronic treatment situations. Knowledge of clinical pharmacology is helpful in both respects in order to obtain rapid antiarrhythmic activity with minimal side-effects. The pharmacokinetic and pharmacodynamic profiles of antiarrhythmic drugs show marked interpatient variations which are influenced by age and disease. Therapeutic monitoring of drug concentrations is therefore helpful to ensure optimum therapeutic levels, to reduce the risk of side-effects, to detect non-compliance, and to define therapeutic failure.

Age Factors↗
PubMed1984

Pharmacokinetics of calcium blockers in patients with renal insufficiency and in geriatric patients.

Calcium antagonists have been used in the treatment of various medical disorders for more than 10 years, but their pharmacokinetics properties are poorly investigated. Available data on the pharmacokinetics of calcium antagonists in normal men are summarized in the present paper. Information on the influence of renal impairment and old age on the handling of calcium-antagonists are only available for verapamil. Patients with advanced renal disease had a significant reduction in the apparent volume of distribution, a shortened serum elimination half life, a decreased total body clearance of verapamil due to a decrease in the renal excretion of verapamil and its active metabolite norverapamil and also to a decrease in metabolic clearance. Pharmacokinetic parameters obtained after oral administration were not significantly different from those after intravenous dosing. The mean biologic availability (22.8%) was in the same range as reported for normal persons, but individual variations would seem to be greater. Elderly patients with a mean age of 87 years also had a significantly reduced volume of distribution of verapamil and decreased total body clearance of the drug, although this last change did not reach statistical significance. The biologic availability in the elderly was higher than in younger persons with a mean value of 37.69% and a wide range from 9.16 to 82.76%. These findings imply that verapamil dosage should be reduced in patients with impaired renal function and elderly patients.

Administration, Oral↗
PubMed1983

Digitoxin kinetics and renal excretion in children.

Digitoxin kinetics were investigated in 11 children, three girls and eight boys, with a mean age of 7.1 yr (5.9 to 9.2). Five children received digitoxin, 17.5 to 20 micrograms/kg IV, and six other children received 20 micrograms/kg as an oral solution. Digitoxin was given as a single dose 24 to 48 hr after cardiac surgery, and patients were monitored in an intensive care unit for 24 hr. Serum and urine digitoxin concentrations were determined by radioimmunoassay. Children had larger apparent volumes of distribution (1 l/kg) than adults (0.57 l/kg). Mean serum elimination t 1/2 was 6.4 days in children (3 to 11.2) and 8.2 days in adults (5.9 to 11.3). Total body clearance was much greater in children (0.085 ml X min-1 X kg-1) than in adults (0.036 ml X min-1 X kg-1). This was because of an increase in metabolic clearance, although there was no difference in renal clearance in children and adults. Absolute oral bioavailability, measured by comparing serum AUCs after intravenous and oral doses, was complete. Peak serum concentrations of 23 to 50 ng/ml developed 90 to 120 min after the oral dose. A single digitalization dose of 20 micrograms/kg was well tolerated and did not induce arrhythmias.

Administration, Oral↗
PubMed1983

Cluster headache: a computerized analysis of 24 h Holter ECG recordings and description of ECG rhythm disturbances.

Continuous ECG recording has been carried out for at least 24 h in 27 patients suffering from cluster headache. During the study a total of 84 attacks occurred in 25 of the 27 patients who took part. A computerized analysis of the heart rate changes accompanying attacks showed the following: (i) an increase in heart rate at the onset of attacks; the degree of this increase being dependent on the heart rate before attacks, (ii) a relative decrease in heart rate and increased variations in heart rate during attacks, (iii) a relative increase in heart rate at the end of attacks, and (iv) a relative decrease in heart rate after attacks. Five patients (18.5%) showed ECG rhythm disturbances: two frequent premature ventricular beats, one transient attacks of atrial fibrillation, one first degree atrio-ventricular block, and one patient sinoatrial block.

Adult↗
PubMed1983

Diuretics and digitalis in the treatment of chronic heart failure.

The evaluation of the long-term treatment of heart failure is complicated by many biological, clinical and technical problems. Chronic heart failure results from a variety of causes, each resulting in fundamentally different histopathological profiles. Once established chronic heart failure is unremitting, but the speed of progression of the haemodynamic derangement varies widely between different individuals. Moreover, the extent of the haemodynamic disorder correlates poorly with the severity of symptoms. The metabolism of drugs and the response of the damaged myocardium to these drugs is often quite different in the patient with heart failure than in the normal subject. Finally chronic heart failure is a terminal condition of relatively short duration so that clinical trials designed to test the efficacy of a drug treatment will fail if they are continued for more than a brief period, as all patients will die. It is against this complex biological background that the long-term clinical efficacy of diuretics and digitalis in the treatment of chronic heart failure must be evaluated.

Administration, Oral↗
PubMed1981

[Prospective examinations of digitalis poisoning].

Despite many years of using digitalis to treat congestive heart failure, the problem of intoxication has remained unchanged. In nine prospective studies on patients under a maintenance treatment with digoxin the intoxication rate ranged from 15.2% to 27.5%. Other studies have also shown that renal insufficiency was present in 70% of intoxicated patients. In contrast the digitoxin toxicity rate, as shown in two prospective studies from Norway and France on 649 and 2120 patients respectively, resulted in an intoxication rate of 5.8% and 3.2% respectively. The explanation for the discrepancy between the two glycosides seems to be predominantly the influence of renal function on drug elimination. Digoxin is mainly excreted through the kidneys; an impairment of the renal function will therefore lead to a reduced elimination of this drug. In these cases a dose reduction of digoxin is necessary. Digitoxin on the other hand is excreted both through the kidneys and the bile. Impairment of the renal function does, therefore, not lead to any decrease in digitoxin elimination whether in renal disease, during heart failure or in old age. In contrast to digoxin, no dose reduction is necessary with digitoxin when renal function is reduced. Digitoxin is therefore easier to handle in the long term management of cardiac patients with and without renal impairment.

Digitalis Glycosides↗
PubMed1981

The effect of pindolol and isosorbide dinitrate and their combination on exercise tolerance and ECG changes in angina pectoris.

The effect of placebo, isosorbide dinitrate (ISDN) (5 mg orally), pindolol (1.0 mg i.v.) and the combination of ISDN and pindolol was tested in 12 patients with stable, exercise-induced angina pectoris and normal resting ECG. A graded submaximal exercise test was performed on a bicycle ergometer 30 min after medication. All patients had ST depression during and shortly after exercise. ISDN and pindolol increased exercise tolerance to a similar degree but through different mechanisms. Pindolol decreased heart rate and markedly reduced ST depression in the ECG, while ISDN had no effect on ECG changes. The combination of ISDN and pindolol was superior to either drug alone in increasing exercise tolerance in angina pectoris.

Angina Pectoris↗
PubMed1981

Delay of onset of second degree pacemaker block by beta-blockade in patients with P-synchronous pacemakers.

Second degree pacemaker block is a safety mechanism of the synchronous pacer at atrial rates above 120-130. The aim of the present study was to determine the work level at which pacemaker block occurred before and after beta-blockade. Seven patients (mean age 53 y.) were submitted to graded, submaximal exercise on a bicycle ergometer without drug and after 0.8 mg pindolol i.v. (6 pats.) or alprenolol orally (1 pat.). Pacemaker block developed at much higher total work after beta-blockade in 3 patients (5800 vs. 1900 kpm. p less than 0.0005), while 4 patients had to stop work due to exhaustion before pacemaker block occurred. Total work increased significantly after beta-blockade (p less than 0.005). Lack of a stable i.v. atrial electrode has delayed the extensive use of the synchronous pacemaker. The design of the generator, however, is not optimal block occurs is too low for a number of patients. beta-Blockade effectively delays the occurrence of pacemaker block and can be of therapeutic value. It is suggested that the P-synchronous pacer should be redesigned with a programmable basic rate (50-70 beats/min) and a programmable upper rate (130-180 beats/min) to ensure that the obvious physiologic advantages of the atrial triggered pacemaker can be maintained both at rest and during physical exercise.

Adult↗
PubMed1980

Digoxin- and digitoxin-induced changes in monophasic action potential of the right ventricle of the dog heart.

The effects of digitoxin and digoxin on right ventricular monophasic action potentials were studied in intact dogs during an 8 hour observation period. Pentobarbital anaesthesia was used, and monophasic action potential recordings were obtained with the suction electrode technique. Intravenous injection of 2.0 mg digitoxin to six dogs, 2.0 mg digoxin to two dogs and 1.0 mg digoxin to five dogs caused a rapid increase in the time taken for 90% repolarisation with return to control values after 20 to 30 min. A late increase in 50 and 90% repolarisation times was observed 2 to 4 h after digitoxin, while digoxin had no such effect. The late action potential prolonging effect was inversely correlated to serum concentrations in the early elimination phase (2 to 8 h after the injection) since it reached a maximum towards the end of the observation period. Digitoxin and digoxin thus differed in their late effects on ventricular monophasic action potentials in intact dogs and may possess different antiarrhythmic activity.

Action Potentials↗