In vivo evaluation of guargum-based colon-targeted oral drug delivery systems of celecoxib in human volunteers.

The present study involved the in vivo evaluation of orally administered guar gum-based colon-targeted tablet formulations of celecoxib (colon-targeted tablet-20 or colon-targeted tablet-30) as compared with an immediate release capsule in 15 human volunteers. Blood samples were obtained at different time intervals and the plasma concentration of celecoxib was estimated by reversed phase HPLC. The immediate release capsules of celecoxib might have disintegrated very fast in GI tract and absorbed quickly from stomach and small intestine thereby producing peak plasma concentration (Cmax of 478 +/- 57 ng/ml) within 3.8 +/- 0.1 h (Tmax). Though celecoxib could be seen in plasma after oral administration of colon-targeted tablet-20 or colon-targeted tablet-30 between 1 and 2 h, low levels of drug were observed upto 8 h resulting in peak concentration (Cmax) of 78 +/- 6 ng/ml or 88 +/- 15 ng/ml at 10.5 +/- 1.9 h or 13.5 +/- 1.4 h (Tmax) respectively, whereas the immediate release capsules produced peak plasma concentration (Cmax) of 478 +/- 57 ng/ml at 3.8 +/- 0.1 h (Tmax). Colon-targeted tablets showed decreased AUC(0-infinity), Cmax and absorption rate constant, prolonged absorption time (ta), and increased t1/2 in comparison with the immediate release capsules. The results of the study indicated that the guar gum-based colon-targeted tablets of celecoxib did not release the drug significantly in stomach and small intestine, but delivered to the colon resulting in a slow absorption of the drug and making it available for local action in the colon.