Per-thiolated cyclodextrins: Nanosized drug carriers providing a prolonged gastrointestinal residence time.

Oral delivery is one of the most advantageous routes for drug administration, but due to the short gastrointestinal (GI) residence time, the systemic uptake of poorly absorbed drugs is too low to reach the desired therapeutic effect. In order to prolong the GI residence time of orally given drugs, we synthesized per-thiolated β-cyclodextrin (CD) as mucoadhesive drug carrier. Due to thiolation, the mucoadhesive properties of CD on porcine intestinal mucosa were increased 2-fold. In vivo studies showed 4 h after oral administration, a 19.4-fold, 2.1- fold, and 4.5-fold higher quantity of per-thiolated β-CD vs. unmodified β-CD in the stomach, duodenum/jejunum, and the ileum of rat model, respectively. Eight hours after oral administration, still, 60 % of per-thiolated CD, but no native CD remained in the GI tract. These results provide evidence that due to thiolation of β-CD, GI-residence time can be essentially prolonged.