Understanding digoxin use in the elderly patient.

There are many disease states in the elderly that mandate the use of drugs with extremely narrow therapeutic indexes and potentially fatal toxicity. Digoxin is one example of such drugs. It is extensively used for the treatment of congestive heart failure of diverse origin and of cardiac arrhythmias of supraventricular origin. Aging can produce changes in essentially all organ systems, which as a whole render geriatric patients particularly vulnerable to the toxic effects of digoxin. Among all age-related pharmacokinetic and pharmacodynamic changes, declining renal function is perhaps the most important factor that must be considered. This often means a significantly less efficient renal digoxin clearance, which necessitates a reduction in dosage. The geriatric population tends to consume more drugs and are more at risk for undesirable multidrug interactions than their younger counterparts. To name a few, quinidine, verapamil, amiodarone, and non-K(+)-sparing diuretics are notorious for predisposing the patient to digoxin toxicity when administered concurrently with digoxin. Therefore, digoxin must be prescribed to elderly patients with great judiciousness, with careful interpretation of serum digoxin assay, and due consideration of its intrinsic limitations.