Effect of Attapulgite on the Bioavailability of a Model Low Dose Drug (Riboflavine) in Humans

Abstract

In human volunteers, both the rate and extent of urinary excretion of riboflavine were significantly reduced (p<0.05) when attapulgite was co-administered with the drug. About 50% reduction occurred in the cumulative amount excreted following the concurrent administration of 10 mg riboflavine in solution form and 2 g of regular attapulgite. The co-administration of the drug with a 30 ml dose of a commercial antidiarrheal suspension containing 10% activated attapulgite and 3% colloidal attapulgite produced a relatively lesser effect; the reduction in extent of absorption being 40%. No statistically-significant effect was found when the adsorbent was ingested 2 h prior to the drug. The observed reduction in drug bioavailability in the presence of attqapulgite to the significant uptake of the drug by the adsorbent.