Digoxin binds to muscle tissue, Vd=400.

If something else binds to muscle tissue, digoxin is displaced, leading to higher blood levels and lower Vd. = Digoxin toxicity. (eg, quinidine)

Also: Can cause increased bleeding if taken with Warfarin.

Also: Cholestyramine causes decreased absorption. Also: Erthromycin increases bioavail by 3 mechanisms.