In vivo evaluation of guar gum-based colon-targeted drug delivery systems of ornidazole in healthy human volunteers

The aim of the present study was to find the in vivo performance of guar gum-based colon-targeted tablets of ornidazole (dose 250 mg) in comparison with an immediate release tablet of ornidazole (250 mg) in human volunteers. Six healthy volunteers participated in the study, and a cross over design was followed. The plasma concentration of ornidazole was estimated by HPLC. The immediate release tablets of ornidazole produced peak plasma concentration (C-max of 2171.33 +/- 278.15 ng/ml) at 2.91 +/- 0.14 h (T-max) whereas colon-targeted tablets produced peak plasma concentration (C-max of 1716.66 +/- 125.83 ng/ml) at 11.91 +/- 0.14 h. The delayed T-max, decreased C-max, and decreased k(a) of ornidazole from guar gum-based colon-targeted ornidazole tablets, in comparison with the immediate tablets, indicated that the drug was not released in stomach and small intestine, but targeted to colon. Slow absorption of ornidazole from the less absorptive colon might result in the availability of drug for local action in the colon.