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Digitalis therapy is complex in renal failure due to altered drug handling and cardiac effects. Digitoxin is often preferred by nephrologists due to its stability despite altered pharmacokinetics in uremia.
Area of Science:
- Nephrology
- Cardiology
- Clinical Pharmacology
Background:
- Cardiac dysfunction is prevalent in end-stage renal disease.
- The use of digitalis glycosides in uremic patients lacks a clear consensus.
- Potential mechanisms for cardiac dysfunction include toxic factors and altered catecholamine response.
Purpose of the Study:
- To review the challenges and considerations for digitalis therapy in patients with renal failure.
- To discuss the altered pharmacokinetics and pharmacodynamics of digitalis glycosides in uremia.
- To evaluate the rationale behind the choice of specific digitalis preparations in this population.
Main Methods:
- Review of existing literature on digitalis use in renal failure.
- Analysis of pharmacokinetic and pharmacodynamic alterations of digitalis glycosides.
- Comparison of different digitalis preparations regarding their suitability for uremic patients.
Main Results:
- Uremia significantly alters the pharmacokinetics of some digitalis glycosides, prolonging elimination half-lives of strophanthin and digoxin.
- Digitoxin's elimination half-life remains largely unchanged in uremia.
- Altered protein binding and volume of distribution affect digitalis disposition in renal failure.
Conclusions:
- Digitalis therapy requires careful consideration in patients with terminal renal failure.
- Digitoxin is frequently favored by nephrologists due to its pharmacokinetic stability in the context of renal impairment.
- Understanding altered drug metabolism and distribution is crucial for safe and effective digitalis use in uremia.
Abstract:
Cardiac dysfunction is common in patients with terminal renal failure. However, no consensus has been reached with respect to the indications for digitalis therapy. Depression of myocardial contractility may occur as a result of circulating toxic factors, parathyroid hormone, and altered catecholaminergic responsiveness. On the other hand, paradoxical positive inotropic effects have been observed possibly as a result of a circulating natriuretic factor (an endogenous digitalis analogue) which inhibits Na,K-ATP'ase. Pharmacokinetics and pharmacodynamics of digitalis steroids are altered in uremia. Elimination half-lives of strophanthin and digoxin are prolonged, whereas the elimination half-life of digitoxin is unchanged. Altered protein binding and volume of distribution have been noted. Despite its long elimination half-life, most nephrologists favor administration of digitoxin because of its insensitivity to changes in renal function.