digitoxin and Hypokalemia

Ventricular fibrillation is the most common mechanism of sudden unexpected cardiac death in persons with asymptomatic or symptomatic coronary artery disease. The electrophysiologic mechanisms reviewed in this article include: automaticity of pacemaker fibers, transformation of nonpacemaker into pacemaker fibers, "injury" currents and reentry. Some of the conditions facilitating ventricular fibrillation include bradycardia, long QT syndrome, electrocution, electrolyte imbalance, drugs, sympathetic stimulation and myocardial ischemia. Electrophysiologic studies during acute myocardial ischemia suggest that the earliest activity at the onset of arrhythmia may originate at the sites of the surviving Purkinje fibers or at the epicardial rim. Reentrant arrhythmias arising in ischemic myocardium are attributed to nonhomogeneous distribution of local hyperkalemia and acidosis.

Topics: Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Coronary Disease; Death, Sudden; Digitalis; Electric Stimulation; Electrocardiography; Electrophysiology; Heart Conduction System; Heart Rate; Heart Ventricles; Humans; Hypokalemia; Membrane Potentials; Pacemaker, Artificial; Phenothiazines; Plants, Medicinal; Plants, Toxic; Sympathetic Nervous System; Syndrome; Vagus Nerve; Ventricular Fibrillation

Topics: Age Factors; Calcium; Digitalis Glycosides; Digitoxin; Digoxin; Drug Interactions; Humans; Hypercalcemia; Hypokalemia; Intestinal Absorption; Methods; Potassium; Saliva; Suicide

Topics: Age Factors; Creatinine; Diet; Digitalis; Digitalis Glycosides; Digitoxin; Digoxin; Diuretics; Heart Failure; Humans; Hypercalcemia; Hypokalemia; Kidney; Kinetics; Liver; Magnesium; Ouabain; Plants, Medicinal; Plants, Toxic; Rest; Thyroid Gland; Time Factors

Topics: Aldosterone; Digitalis; Digitalis Glycosides; Diuretics; Edema; Electrolytes; Heart Failure; Hypokalemia; Physiology; Potassium; Sodium; Toxicology; Vasopressins

Topics: Digitalis; Humans; Hypokalemia; Poison Control Centers; Referral and Consultation; Renal Dialysis; Treatment Outcome

Topics: Adrenergic beta-Antagonists; Amiodarone; Digitalis; Education, Medical, Continuing; Electrocardiography; Humans; Hypercalcemia; Hyperkalemia; Hypocalcemia; Hypokalemia; Plants, Medicinal; Plants, Toxic; Quinidine

We examined the frequency of hypokalemia and hypomagnesemia in patients receiving digitalis. Serum sodium, magnesium, and potassium levels were determined in 136 serum samples sent to the laboratory for digoxin assay. Hyponatremia (less than or equal to 130 mEq/L) occurred most frequently (21%), followed by hypomagnesemia (less than or equal to 1.25 mEq/L) in 19%, hypokalemia (less than or equal to 3.5 mEq/L) in 9%, and hypermagnesemia (greater than or equal to 2.25 mEq/L) in 7%. The twofold frequency of hypomagnesemia (19%) contrasted with hypokalemia (9%) indicates that clinicians are more attuned to avoiding hypokalemia than hypomagnesemia in patients receiving digitalis. Because hypokalemia and/or hypomagnesemia may contribute to the toxic effects of digitalis, our observation suggests that hypomagnesemia may be a more frequent contributor than hypokalemia to induction of toxic reactions to digitalis. Routine serum magnesium determination in patients receiving digitalis, who often are also receiving potent diuretics, may assist in identifying additional patients at risk for the toxic effects of digitalis.

Topics: Digitalis Glycosides; Digitoxin; Digoxin; Hospitalization; Humans; Hypokalemia; Hyponatremia; Magnesium

Kidney independent glycosides offer a high measure of therapeutic safety in comparison with kidney dependent glycosides. The intoxication rate lies between 4 and 6%. The pharmacokinetic properties of pentaformylgitoxin (INN: gitoformate) are comparable with those for digitoxin. The active glycoside 16-formylgitoxin (INN: gitaloxin) is formed by rapid deformylation of the formyl residue on the sugar chain. The maintenance dose of 0.06 mg daily, based on the half-life, produces therapeutic concentrations in the range 6-30 ng/ml. The required loading dose, as for digitoxin, amounts to 10 times the maintenance dose.

Topics: Cardiac Glycosides; Digitoxin; Digoxin; Heart Failure; Humans; Hypokalemia; Kidney; Protein Binding; Risk; Serum Albumin

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: Arrhythmias, Cardiac; Barbiturates; Digitalis Glycosides; Digitoxin; Digoxin; Diuretics; Drug Interactions; Humans; Hypokalemia; Phenylbutazone; Potassium; Quinidine

Two case reports describing the treatment of digitoxin toxicity with cholestyramine resin are presented. Both female patients were receiving 100 microgram/day of digitoxin when toxicity occurred. In both patients, digitoxin was discontinued and hypokalemia was corrected. In patient 1, lidocaine hydrochloride and phenytoin sodium also were administered. Serum digitoxin levels were decreased from 43 ng/ml to 21.8 ng/ml and from 42 ng/ml to 29 ng/ml in patients 1 and 2, respectively, following administration of three 4-g doses of cholestyramine resin over a one-day period. Previous studies on the treatment of digitoxin intoxication with potassium chloride, phenytoin sodium, lidocaine hydrochloride, digitoxin-specific antibodies, colestipol hydrochloride and cholestyramine resin are discussed. Ion-exchange resins may be valuable adjuncts in the treatment of digitoxin intoxication but further studies of their utility are needed.

Topics: Aged; Arrhythmias, Cardiac; Cholestyramine Resin; Digitoxin; Female; Humans; Hypokalemia

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: Chlordiazepoxide; Digitoxin; Drug Hypersensitivity; Drug Interactions; Drug-Related Side Effects and Adverse Reactions; Female; Humans; Hydrochlorothiazide; Hyperkinesis; Hypokalemia; Iatrogenic Disease; Male; Medication Errors; Middle Aged; Nausea; Trifluoperazine

Topics: Aspartic Acid; Coronary Disease; Digitoxin; Diuretics; Female; Glomerulonephritis; Humans; Hypokalemia; Magnesium; Male; Potassium; Pyelonephritis

Topics: Adult; Arrhythmias, Cardiac; Atrial Fibrillation; Atrial Flutter; Bradycardia; Cardiac Complexes, Premature; Digitoxin; Electric Countershock; Electrocardiography; Electrolytes; Embolism; Female; Heart Failure; Heart Septal Defects, Atrial; Heparin; Humans; Hypokalemia; Intracranial Embolism and Thrombosis; Male; Middle Aged; Mitral Valve Stenosis; Postoperative Complications; Pulmonary Embolism; Quinidine; Spironolactone; Water-Electrolyte Balance

Topics: Animals; Digitalis; Dogs; Hyperkalemia; Hypokalemia; Insulin; Isoproterenol; Membrane Potentials; Plants, Medicinal; Plants, Toxic; Ventricular Fibrillation

Topics: Acute Kidney Injury; Animals; Digitalis; Digoxin; Hypokalemia; Membrane Potentials; Mice; Myocardium; Plants, Medicinal; Plants, Toxic; Potassium Deficiency; Tritium

Topics: Arrhythmias, Cardiac; Chlorthalidone; Digitoxin; Drug Synergism; Heart Function Tests; Humans; Hypertension; Hypokalemia; Methyldopa; Myocardial Infarction; Quinidine; Reserpine

Topics: Arrhythmias, Cardiac; Blood; Carbon Dioxide; Digitalis; Dogs; Electrocardiography; Extracorporeal Circulation; Heart, Artificial; Hypokalemia; Lactates; Phosphates; Research; Toxicology

Topics: Digitalis; Electrolytes; Guinea Pigs; Heart Failure; Hemodynamics; Hyperkalemia; Hypokalemia; Metabolism; Myocardium; Pharmacology; Potassium; Sodium; Strophanthins; Toxicology

Topics: Digitalis; Electrocardiography; Geriatrics; Humans; Hypokalemia; Tachycardia; Toxicology

Topics: Adrenal Cortex Hormones; Aortic Diseases; Arrhythmias, Cardiac; Digitalis; Digitalis Glycosides; Diuretics; Electrocardiography; Female; Humans; Hypokalemia; Iatrogenic Disease; Mitral Valve Stenosis; Potassium Deficiency; Pregnancy; Pregnancy Complications; Pregnancy Complications, Cardiovascular; Toxicology

Topics: Diet; Diet Therapy; Digitalis; Digitalis Glycosides; Diuretics; Electrocardiography; Heart Failure; Humans; Hyperthyroidism; Hypokalemia; Hyponatremia; Radiography, Thoracic

Topics: Arrhythmias, Cardiac; Cardiomegaly; Digitalis; Digitalis Glycosides; Heart Valve Prosthesis; Humans; Hypokalemia; Mitral Valve; Toxicology; Ventricular Fibrillation

Topics: Diagnosis; Digitalis; Digitalis Glycosides; Diuretics; Drug Prescriptions; Humans; Hypokalemia; Prescriptions; Toxicology

Topics: Digitalis; Digitoxin; Humans; Hypokalemia; Kidney Diseases

The concentration of potassium in the extracellular fluid, and presumably in the cell membrane and intracellular contents of the myocardial fibre, has a significant influence on the contractibility, irritability, conduction and rhythmic tendency of the heart muscle. The therapeutic and toxic dosage of digitalis is clinically affected by the variations in potassium concentrations. The range between therapeutic and toxic dosages of digitalis and sensitivity to bodily potassium depletion varies with the degree of failure of the myocardium and passive congestion of the liver.

Topics: Cell Membrane; Cytoplasm; Digitalis; Digitalis Glycosides; Heart Rate; Hyperemia; Hypokalemia; Liver; Myocardium; Myocytes, Cardiac; Potassium

Topics: Arrhythmia, Sinus; Arrhythmias, Cardiac; Digitalis; Digitalis Glycosides; Electric Countershock; Heart Block; Heart Failure; Humans; Hypokalemia; Potassium; Procainamide; Resuscitation; Tachycardia; Tachycardia, Paroxysmal; Toxicology

Topics: Blood Chemical Analysis; Calcium; Calcium, Dietary; Digitalis; Digitalis Glycosides; Electrocardiography; Electrolytes; Humans; Hypercalcemia; Hyperkalemia; Hypernatremia; Hypokalemia; Metabolism; Myocardium; Potassium; Sodium

Topics: Calcium; Calcium Metabolism Disorders; Digitalis; Digitalis Glycosides; Heart; Hypocalcemia; Hypokalemia; Myocardium; Potassium

Topics: Animals; Digitalis; Digitalis Glycosides; Hypokalemia; Incidence; Plant Extracts; Potassium; Potassium Deficiency; Rats

Topics: Animals; Desoxycorticosterone Acetate; Digitalis; Digitalis Glycosides; Dogs; Hypokalemia; Lanatosides; Myocardium; Potassium; Potassium Deficiency