Pharmacokinetic evaluation of guar gum-based colon-targeted drug delivery systems of tinidazole in healthy human volunteers

The aim of the present investigation was to determine the in vivo availability of guar gum-based colon-targeted tablets of tinidazole in comparison with immediate release tablets of tinidazole in human volunteers. Six healthy volunteers participated in the study, and a cross-over design was used. The plasma concentration of tinidazole was estimated by HPLC. The pharmacokinetic parameters were calculated from the plasma concentration of tinidazole versus time data. The immediate release tablets of tinidazole produced a peak plasma concentration (C-max of 3239 +/- 428 ng/ml) at 1.04 +/- 0.32 hr (T-max), whereas colon-targeted tablets produced peak plasma concentration (C-max of 2158 +/- 78 ng/ml) at 14.9 +/- 1.6 hr. The delayed T-max, decreased C-max, and K-a, and unaltered bioavailability and elimination half-life of tinidazole from guar gum-based colon-targeted tinidazole tablets, in comparison with the immediate tablets, indicated that the drug was not released in the stomach and small intestine but delivered to the colon. Slow absorption of the drug from the less absorptive colon might result in the availability of the drug for local action in the colon. The guar gum-based colon-targeted tablets of tinidazole may be useful in providing an effective and safe therapy of intestinal amoebiasis.