Effect of urapidil on steady-state serum digoxin concentration in healthy subjects

In an open, randomized, two-period change-over study the effect of urapidil, an antihypertensive agent, on steady-state serum digoxin levels was investigated in 12 healthy male volunteers. The subjects were given digoxin 0.25 mg once daily for 4 days to produce a steady-state digoxin level in serum. At the end of that time the subjects received either digoxin monotherapy or digoxin and concomitant treatment with urapidil 60 mg b.d. for a further 4 days. Subsequently the treatments were changed over. The absorption characteristics Cmax and tmax of digoxin were not altered by concomitant urapidil treatment. The geometric mean and nonparametric 95% confidence limits of digoxin relative bioavailability were 97% (93%-103%). Therefore, concomitant administration of urapidil with digoxin treatments did not appear to alter the rate and extent of absorption of the glycoside.