digoxin and Thyroid-Diseases

Digitalis glycosides continue to place high on the list of prescribed drugs. Digoxin is 8th on prescriptions written in the United States in 1980, digitoxin 16th, and digitalis leaf 23rd. There is little doubt that most physicians continue to believe these drugs are useful. The application of more definite indications, smaller doses, and the recognition of the role of pharmacokinetics and drug interactions make use of the glycosides more challenging than ever before in 1985.

Topics: Administration, Oral; Adrenergic beta-Antagonists; Age Factors; Anti-Arrhythmia Agents; Antihypertensive Agents; Arrhythmias, Cardiac; Biological Availability; Bretylium Tosylate; Deslanoside; Digitalis Glycosides; Digitoxin; Digoxin; Dose-Response Relationship, Drug; Drug Interactions; Heart Failure; Humans; Injections, Intramuscular; Injections, Intravenous; Intestinal Absorption; Kidney Failure, Chronic; Lidocaine; Metabolic Clearance Rate; Myocardial Infarction; Obesity; Phenytoin; Potassium; Pulmonary Heart Disease; Thyroid Diseases

Topics: Animals; Body Weight; Digitalis Glycosides; Digoxin; Heart Failure; Humans; Kidney Failure, Chronic; Liver Diseases; Myocardial Contraction; Protein Binding; Structure-Activity Relationship; Thyroid Diseases; Tissue Distribution

Topics: Administration, Oral; Aged; Digitalis Glycosides; Digitoxin; Digoxin; Feces; Heart Atria; Heart Failure; Humans; Injections, Intramuscular; Injections, Intravenous; Intestinal Absorption; Kidney Diseases; Liver Diseases; Malabsorption Syndromes; Obesity; Tachycardia; Thyroid Diseases; Tritium; Water-Electrolyte Balance

Topics: Administration, Oral; Adult; Arrhythmias, Cardiac; Body Weight; Digoxin; Dose-Response Relationship, Drug; Humans; Kidney; Male; Thyroid Diseases

Topics: Administration, Oral; Age Factors; Attitude to Health; Biological Availability; Body Weight; Digitalis Glycosides; Digoxin; Drug Tolerance; Feedback; Half-Life; Humans; Intestinal Absorption; Kidney; Kinetics; Liver; Quality Control; Tablets; Thyroid Diseases; Time Factors

Topics: Adenosine Triphosphatases; Arrhythmias, Cardiac; Digitalis Glycosides; Digitoxin; Digoxin; Heart; Heart Failure; Heart Rate; Humans; Kidney Diseases; Kinetics; Lanatosides; Lidocaine; Myocardium; Pacemaker, Artificial; Phenytoin; Potassium; Procainamide; Propranolol; Quinidine; Thyroid Diseases

Topics: Acute Kidney Injury; Administration, Oral; Arrhythmias, Cardiac; Digitoxin; Digoxin; Drug Interactions; Electric Countershock; Half-Life; Humans; Injections, Intramuscular; Injections, Intravenous; Liver Diseases; Malabsorption Syndromes; Pharmaceutical Vehicles; Phenytoin; Potassium; Thyroid Diseases

Topics: Age Factors; Arrhythmias, Cardiac; Calcium; Child; Coronary Care Units; Digitalis Glycosides; Digoxin; Electric Countershock; Electrocardiography; Endocrine System Diseases; Heart Diseases; Heart Failure; Heart Rate; Heart Valve Diseases; Humans; Kidney Failure, Chronic; Liver Diseases; Lung Diseases; Magnesium; Obesity; Ouabain; Poisoning; Potassium; Psychophysiologic Disorders; Pulmonary Heart Disease; Thyroid Diseases; Time Factors

Serum digoxin concentrations were measured by radioimmunoassay in 17 hyperthyroid and 16 hypothyroid patients after a seven-day course of oral digoxin. The significantly higher levels of serum digoxin in patients with hypothyroidism and lower levels in those with hyperthyroidism were closely related to the measured changes of glomerular filtration rate and digoxin serum half time in these two groups. Differences in serum digoxin concentration contribute to the altered sensitivity to digoxin shown by patients with thyroid disease.

Topics: Administration, Oral; Adult; Clinical Trials as Topic; Creatinine; Digoxin; Female; Glomerular Filtration Rate; Half-Life; Humans; Hyperthyroidism; Hypothyroidism; Male; Middle Aged; Thyroid Diseases; Time Factors

We surveyed Accident and Emergency (A&E) consultants in England by questionnaire, on their management of patients presenting with AF. Completed questionnaires were received from 124 (45%). Most (42%) would use digoxin as first-line treatment for rate control of AF; 28% would not treat AF acutely but would refer the patient to the medical team; 59% would cardiovert a patient with AF in A&E, if there was evidence of cardiovascular compromise. Some 51% would not routinely initiate any anticoagulation therapy. Faced with a patient in fast AF who was haemodynamically unstable, 67% would immediately opt for electrical cardioversion, 13% would refer the patient directly to the medics and 15% would initially treat with intravenous digoxin. Given a patient in fast AF and cardiac failure, 55% would treat with digoxin. Asked about AF related to Wolff-Parkinson-White syndrome, 37% would initially give adenosine, 23% would opt for immediate DC cardioversion and 25% would refer directly to the medics; however, a minority would still give a rate-limiting calcium antagonist or digoxin. The majority (79%) would not treat AF in a known alcoholic with acute intoxication who was haemodynamically stable. Consultants were more likely to initiate treatment if the patient had signs of shock or heart failure. Where there were underlying medical problems they were more likely to refer the patient directly to the medical team. There was a general reluctance to initiate anticoagulation, and some difference in opinion over how long AF should have persisted for anticoagulation to be necessary in the context of electrical cardioversion. Given the current evolution of A&E as an acute speciality, A&E clinicians should at least initiate management of patients with AF and be prepared to care for them for some time in A&E.

Topics: Alcoholism; Anticoagulants; Atrial Fibrillation; Cardiotonic Agents; Digoxin; Electric Countershock; Emergency Service, Hospital; England; Health Care Surveys; Heart Failure; Humans; Practice Patterns, Physicians'; Referral and Consultation; Surveys and Questionnaires; Thyroid Diseases; Wolff-Parkinson-White Syndrome

The molecular structure is one of the keypoints that govern both the extent of extracardiac action of cardiac glycosides and their different kinetics. The apolar, fat soluble digitoxin is very well absorbed from the intestine, its onset of action is slow, binds to a high degree to albumin and undergoes enterohepatic recirculation which accounts for a long elimination half time and stability of plasmatic levels. Digitoxin is largely excreted via gastrointestinal tract. The absorption of digoxin is less reliable, onset of action occurs earlier and the binding to albumin is considerably less than that of digitoxin. The drawback, however small, of digoxin lies in a lower stability of plasma levels and prevailing renal excretion. The molecule of strophatin is highly polar, its absorption from the intestine negligible and can be administered only intravenously. The onset of action is prompt, elimination half time short and about half the injected amount is excreted extrarenally.

Topics: Cardiac Glycosides; Digitoxin; Digoxin; Gastrointestinal Diseases; Humans; Kidney Diseases; Strophanthins; Thyroid Diseases

Specific binding sites have been demonstrated to exist in the heart for several drugs and hormones such as beta-blocking agents, cardiac glycosides, catecholamines, insulin, glucagon and acetylcholine. The specific binding sites for cardiac glycosides in the human heart have certain properties which make it likely that they are the pharmacological receptors for the therapeutic and toxic actions of digitalis glycosides: they are located in the cell membrane and bind cardioactive steroids reversibly with high affinity: half-maximal receptor binding occurs at approximately 2 nM (approximately 1.5 ng/ml) for digoxin; potassium decreases receptor affinity, calcium increases it; specific binding of ouabain, digoxin or digitoxin is related to inhibition of (Na+ + K+)-ATPase activity--which is supposed to be the receptor enzyme for cardiac glycosides. Human left ventricle contains approximately 1.5 x 10(14) binding sites/g wet weight, right ventricle approximately 0.9 x 10(14). In disease the number of receptors may decrease (hypothyroid states, myocardial infarction) or increase (hyperthyroidism, chronic hypokalaemia). Certain drugs (such as phenytoin) or different temperatures or pH changes cause a change in digitalis-receptor affinity. Thus, the number of receptors and possibly their properties are subject to regulation in clinically relevant situations. Further investigations will probably reveal those pathophysiological states, which allow the explanation of toxicity or digitalis refractoriness.

Topics: Animals; Binding Sites; Cats; Cell Membrane; Cells, Cultured; Digitoxin; Digoxin; Guinea Pigs; Humans; Hypokalemia; Myocardial Infarction; Myocardium; Ouabain; Receptors, Drug; Sodium-Potassium-Exchanging ATPase; Thyroid Diseases

Topics: Biological Availability; Cardiac Glycosides; Creatinine; Deslanoside; Digitalis Glycosides; Digitoxin; Digoxin; Drug Interactions; Humans; Hypokalemia; Kidney Diseases; Liver Diseases; Malabsorption Syndromes; Obesity; Ouabain; Thyroid Diseases

Topics: Administration, Oral; Adult; Aged; Creatinine; Digoxin; Female; Glomerular Filtration Rate; Humans; Hyperthyroidism; Hypothyroidism; Injections, Intravenous; Kinetics; Male; Metabolic Clearance Rate; Middle Aged; Models, Biological; Thyroid Diseases

The pharmacokinetics of digoxin, the most frequently used digitalis preparation, are reviewed. The dominate serum turnover time is about 34 hours, and is not affected by the route of administration. Excretion is largely as unchanged digoxin in the urine and this excretion is compromised in renal failure. Serum levels of digoxin (determined by radioimmunoassay) are generally available and are useful clinically in assessment of both toxicity and the state of underdigitalization, even though significant overlap exists. Special problems are presented in patients with myocardial infarction, pulmonary heart disease, and thyroid disease.

Topics: Acute Kidney Injury; Aging; Digitalis Glycosides; Digoxin; Heart Rate; Kidney; Kinetics; Myocardial Contraction; Myocardial Infarction; Obesity; Pulmonary Heart Disease; Structure-Activity Relationship; Thyroid Diseases; Water-Electrolyte Balance

Topics: Aminophylline; Digitalis Glycosides; Digoxin; Diuretics; Heart Failure; Heart Rate; Humans; Hypokalemia; Hyponatremia; Intermittent Positive-Pressure Breathing; Mineralocorticoid Receptor Antagonists; Oxygen; Potassium Deficiency; Pulmonary Edema; Tachycardia; Thyroid Diseases

Topics: Digitalis Glycosides; Digoxin; Humans; Thyroid Diseases