Decreased bioavailability of digoxin due to hypocholesterolemic interventions.

This study tested the hypothesis that hypocholesterolemic interventions interfere with the bioavailability of orally administered digoxin. Using single dose studies of bioavailability, cumulative six-day urinary digoxin excretion (ex- pressed as a percentage of each individual's control value) was 103% with a normal fiber diet, 82% with a high fiber diet, 83% with 4 g of cholestyramine, 69% with 8 g of cholestyramine, 80% with 8 g cholestyramine administered eight hours before digoxin, 92% with 8 g of cholestyramine administered eight hours after digoxin and 80% after completion of two weeks of treatment with para-aminosalicylic acid.