Comparative study of the absorption, plasma levels, and urinary excretion of the "new" and the "old" Lanoxin.

A comparative study was performed of the absorption, the plasma level at equilibrium, and the urinary excretion of digoxin using two types of Lanoxin tablets, those produced before and after the 1972 alteration of the tablet manufacture.After a single dose the absorption rate of the new tablets was about twice as great as the old, both in young subjects and in the elderly patients. There were no significant differences in the plasma levels of digoxin for the two tablets 15 hours after the last administration in patients on an equal maintenance dose. The urinary excretion of digoxin increased about 40% when the "old" Lanoxin was replaced by the "new." In elderly patients a daily dose of 0.125 mg twice daily of the new tablets should be sufficient to reach the therapeutic range. Young people need a higher dosage. If the kidney function is reduced by as much as 50% the dose should be reduced.