Gary Brooker

A Nomogram for Digoxin Therapy

Abstract A nomogram is described for developing loading and maintenance dosage regimens of digoxin for adult euthyrold patients with reasonably normal hepatic function, in normal electrolyte balance, who have no obvious abnormality of gastrointestinal absorption. The nomogram relates observed data of risk of adverse reactions, risk of arrhythmias, serum digoxin levels, calculated maximum total body digoxin concentrations, body weight, total oral loading dose, data of renal function and daily maintenance dose. Physicians may select an acceptable risk or peak serum level depending upon each patients clinical status, and then develop a loading and maintenance dosage regimen to consider giving, adjusted to the patients body weight and renal function, to achieve ones selected therapeutic goals with reasonable accuracy for most patients most of the time.

Chlorpropamide and tolbutamide inhibition of adenosine 3′5′ cyclic monophosphate phosphodiesterase☆

Abstract These sulfonylurea agents inhibit the cyclic AMP phosphodiesterase, and thereby could increase the steady state level of cyclic AMP in various tissues, depending upon the tissue concentrations achieved after oral or parental administration.

Serum Cardiac Glycoside Assay Based upon Displacement of 3H-Ouabain from Na-K ATPase

An assay of serum digoxin and other cardiac glycosides by displacement of 3H-ouabain from Na-K ATPase is described. It is rapidly set up by any laboratory with a liquid scintillation counter. It can also assay digitalis leaf, digitoxin, and gitalin (Gitaligin), and has uncovered unsuspected administration of them.The assay takes less than 1 hour. No quench correction of counts is required. One technician can assay 30 samples/day with results that afternoon. No interfering compounds have been found in over 1,800 assays. It is unaffected by lung scans.Incidence of toxicity from digoxin is 10%, 25%, and 50% at serum levels of 1.4, 2.0, and 2.9 ng/ml, respectively. Toxic levels of digitalis and digitoxin are usually over 40 ng/ml.Serum digoxin levels are also highly correlated with computed total-body concentrations of digoxin, obtained from data of dosage, route of administration, and the patients weight and renal function.Physicians may now select a serum digoxin level and computed total-body concentration of digoxin which are associated with an incidence of arrhythmias which they feel is reasonable for the urgency of each patients clinical situation. These selected serum levels are associated with specific loading and maintenance dosage regimens, individualized to that patients body weight, renal function, and route of digoxin administration.

ACTH activation of glycolysis in the rat adrenal gland

Abstract A number of substrates of glycolysis, the pentose phosphate pathway, the Krebs cycle and the pyridine and adenine nucleotides (including cyclic AMP) have been measured before and after ACTH stimulation in hypophysectomized rats. Crossovers in substrate concentrations at the level of phosphofructokinase and glyceraldehyde phosphate dehydrogenase were found, indicating an activation of these enzymes in the stimulated adrenals. Elevations in cyclic AMP and a decrease in the ATP ADP · AMP ratio were also found, either of which could explain phosphofructokinase activation.