Oral colon targeted delivery systems for treatment of inflammatory bowel diseases: Synthesis, in vitro and in vivo assessment

The aim of this study was to investigate the potential of prodrugs of some non-steroidal anti-inflammatory drugs (NSAIDs) as colon targeted delivery systems for treatment of inflammatory bowel diseases. Naproxen, sulindac and flurbiprofen (Fbp) were used. The carboxylic group of those drugs was conjugated onto the amino group of l-aspartic acid or the hydroxyl group of α- or β-cyclodextrin (CyD). Prodrugs hydrolysis in buffers of pH range 1.2–7.2 and in rat gastrointestinal tract homogenates and the effect of oral pretreatment of rats with clindamycin on the hydrolysis of the prodrugs was examined. Additionally, the effect of oral administration of Fbp-β-CyD prodrug on the experimentally induced colitis in rats was evaluated. The in vivo inflammatory response was assessed macroscopically, histologically and by measurement of reduced glutathione (GSH) levels in colon tissues. No significant hydrolysis of the proposed seven prodrugs in buffers having pH range of 1.2–7.2 was observed over 72 h. Negligible % of drug released from Fbp-α-CyD or Fbp-β-CyD prodrugs was detected in rat stomach contents, intestinal tissues and intestinal contents homogenates. On the other hand, Fbp-α-CyD and Fbp-β-CyD prodrugs released about 60% Fbp within 4 h in rat colon homogenate. Oral pretreatment of rats with clindamycin significantly reduced % Fbp released from Fbp-α-CyD or Fbp-β-CyD prodrugs. Oral administration of Fbp-β-CyD to rats after induction of colitis significantly attenuated the severity of the colonic injury and reduced the score of the macroscopic and microscopic damage. Additionally, there was a significant increase in the level of GSH. The present study provided an evidence that Fbp-β-CyD prodrug may be beneficial in treatment of inflammatory bowel disease.