Risk factors and manifestations of digoxin toxicity in the elderly.

The incidence of digoxin toxicity increases with age, largely because the two most common conditions that benefit from use of digoxin, congestive heart failure and atrial fibrillation, are markedly more prevalent in old age. Whether the elderly are more sensitive to the effects of digoxin because of age per se is unclear. However, several other factors render the elderly more susceptible to digoxin toxicity. These include an age-related decline in renal function and a decrease in volume of digoxin distribution. There is also an increase in the number of comorbid conditions, including cardiovascular and chronic obstructive pulmonary disease, which heighten susceptibility to digoxin toxicity. Moreover, treatment of these diseases with such interactive medications as quinidine and calcium channel blockers may increase the serum level of digoxin. Similarly, such electrolyte imbalances as hypokalemia and hypomagnesemia occur more frequently in the elderly as a result of diuretic therapy. However, recent data suggest that manifestations of digoxin toxicity among younger and older patients do not differ. Similar incidences of cardiac toxicity, gastrointestinal toxicity, and altered mental status are found in both patient populations. Treatment of digitalis toxicity in the elderly is the same as for younger patients. Response rates to Digibind are not diminished in the elderly.