Digoxin renal elimination

Renal elimination of foreign compounds may change dramatically with increasing age by factors such as reduced renal blood flow, reduced glomerular filtration rate, reduced tubular secretory activity, and a reduction in the number of functional nephrons. It has been estimated that in humans, beginning at age 20 years, renal function declines by about 10% for each decade of life. This decline in renal excretion is particularly important for drugs such as penicillin and digoxin, which are eliminated primarily by the kidney. 

Amiodarone increases the hypoprothrombinemic response to warfarin (an oral anticoagulant) by reducing its metabolism. Patients receiving digoxin may undergo an increase in serum digoxin concentrations when amiodarone is added to the treatment regimen. Amiodarone interferes with hepatic and renal elimination of flecainide, phenytoin, and quinidine. 

Repeated dose of activated charcoal administered by oral route have been shown to enhance the non-renal elimination of carbamazepine, salicylates, phenobarbitone, phenytoin, digoxin, theophylline and meprobamate. In severe cases activated charcoal is to be administered via a nasogastric tube. 

Although great focus is naturally concentrated on the neonate, it is important to remember that toddlers may have shorter elimination half-lives of drugs than older children and adults, due probably to increased renal elimination and metabolism. For example, the dose per kilogram of digoxin is much higher in toddlers than in adults. The mechanisms for these developmental changes are still poorly understood. 

DIGOXIN CICLOSPORIN t plasma digoxin levels, with risk of toxicity. Digoxin may t cidosporin bioavailability (by 15-20%) Attributed to inhibition of intestinal P-gp and renal P-gp, which t bioavailability and t renal elimination. Digoxin t bioavailability of cidosporin due to substrate competition for P-gp Watch for digoxin toxicity. Monitor plasma digoxin and cidosporin levels... 

In addition to its effect in reducing the elimination of digoxin, renal insufficiency may be associated with an increased sensitivity to the actions of digitalis (149). 

Once the cardiac glycosides are absorbed, they bind to plasma proteins digoxin has only 30% binding. The half-life of digoxin in patients with normal renal function is 1.5 to 2.0 days. Biliary excretion of digoxin is minimal. Digoxin is eliminated primarily unchanged by renal tubule excretion. 

Not fully understood. The authors of the studies concluded that ciclosporin has no specific inhibitory effect on the renal elimination of digoxin, but that it causes a non-specific reduction in renal function after acute administration, which reduces digoxin elimination. Conversely, another study in animals suggested that ciclosporin can reduce the secretion of digoxin by the kidney tubular cells by inhibiting P-glycoprotein. ... 

Rofccoxib 75 mg once daily did not cause significant changes in the plasma pharmacokinetics or renal elimination of single 500-microgram doses of digoxin elixir. ... 

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