Dextran Carrier Macromolecule for Colon Specific Delivery of Celecoxib

The colon specific polymeric conjugates of celecoxib were prepared with dextran of different molecular weight Mr ∼40 000, 70 000, and 100 000 (CSD-40, CSD-70 and CSD-100). Succinic acid was used as linker between the drug and dextran. The prepared conjugates were characterized by UV, IR, 1H NMR and HPLC. The maximum degree of substitution 3.9±0.20 %was found with the dextran CSD-100 conjugate. The percent release of drug obtained by in-vitro hydrolysis studies, was found to be 24.37± 0.6, 23.0 ± 0.5 and 20.13± 0.8 in simulated colonic fluid (SCF) pH 6.8 while 17.90 ± 0.4, 16.8± 0.75 and 15.47 ± 0.5 in simulated intestinal fluid (SIF) pH 7.4 for CSD-40, CSD-70 and CSD-100, respectively, in both medium. The drug release from the conjugates was observed for 24 h in 3% w/v rat caecal content and found to be 41.77 ± 1.2, 39.03 ± 1.0 and 35.26 ± 1.09 for CSD-40, CSD-70 and CSD-100 conjugates, respectively. The half life of conjugates was determined and was found to be short in 3% w/v rat caecal content. No amount of drug was released in simulated gastric fluid pH 1.2 and stomach homogenate in 2 h. The amount of drug released from small intestine homogenate was 3.4± 0.1 percent in 12 h for the CSD-40. The above result suggests that dextran could be used as a macromolecular carrier for colon specific drug delivery of celecoxib.