Absorption, distribution and excretion of beta-cyclodextrin and glucosyl-beta-cyclodextrin in rats

The absorption, distribution and excretion of intravenously and orally administered beta-cyclodextrin (beta-CD) and glucosyl (G)-beta-CD in rats were studied using HPLC with pulsed amperometric detection. Within 10 h after intravenous administration, unchanged beta-CD and G-beta-CD recovered in urine were about 90% of each dose. The nephritic accumulation of G-beta-CD after the intravenous administration of G-beta-CD was slightly lower than that of beta-CD using the same treatment. The maximum plasma concentrations of beta-CD and G-beta-CD after the oral administration of CDs (500 mg/kg) were observed within 40 min. After oral administration, 0.6% of beta-CD and 0.3% of G-beta-CD were excreted in urine. The pharmacokinetic behaviour of both CDs after the intravenous administration of CDs (50 mg/kg) was almost the same. Furthermore, the inclusion complexes of estriol and betamethasone with CDs were prepared, and their absorption was evaluated after oral administration in rats. The plasma concentrations of CDs after oral administration of drug-CD complexes were significantly decreased in comparison with those after the oral administration of CDs alone. On the other hand, the plasma concentrations of drugs after the oral administration of drug-CD complexes were higher than those after the administration of drugs alone.