antimicrobial agent. Since only 10% of subjects produce large amounts of these reduced derivatives, this increase in digoxin levels due to antibioticsshould occur in only a minority of patients . Thus, the increase in bioavailability during administration of these antibiotics should be minimized with the use of the capsule forms of digoxin. Drugs that alter gut motility. Digoxin absorption is not affected by medications that alter gut motility, such as propantheline (Probanthine) or metoclopramide Cancer chemotherapeutic agents: Digoxin absorption and steady state levels may be markedly decreased by cancer chemotherapy

– Interaction of Digoxin With Antiarrhythmic Drugs

Quinidine It is clear that the elevation of digoxin levels by concurrent quinidine administration results in enhanced electro physiologic effects demon started on the surface electrocardiogram as a prolongation of the PR interval , by central nervous system manifestation s of toxicity such as anorexia , nausea and vomiting also by enhanced ventricular ectopic activity . The elevated serum digoxin levels induced by concurrent administration of digoxin and quinidine have been reported not to show an enhanced inotropic effect as measured by systolic time intervals . Clinical evidence indicates that there are increased electro physiologic and inotropic effects associated with the elevation of serum digoxin as a result of concurrent quinidine administration . In 1978, Ejvinsson reported that the concurrent administration of quinidine to 12 patients increased average serum digoxin concentrations from 0.9 to 1.6 ng/ml. Decisive evidence for a decrease in the nonretail excretion of digoxin under the influence of quinidine was established by comparing the kinetics of digoxin in anuric patients on chronic hemodialysis when given digoxin alone and concomitantly with quinidine . However, in patients with a glomerular filtration rate of less than 50 ml/rnin , the time required for digoxin to reach a new steady state with the addition of quinidine may be considerably longer. , however, measured inotropic effects of digoxin at steady state during digoxin administration alone and during digoxin and quinidine administration . Since glornerular filtration rate is unchanged during concurrent digoxin quinidine administration, it is clear that the decreased renal elimination of digoxin in