Effects of herbal drugs prescribed in wood creosote pills on the dissolution profile of guaiacol.

Wood creosote pills (P4) containing wood creosote and four herbal drugs, Gambir, Phellodendri Cortex, Glycyrrhizae Radix, and Citri Unshiu Pericarpium (CUP), have been used to treat food poisoning and diarrhea through self-medication in Japan. The mean dissolution time (MDT) of guaiacol, one of the active constituents of wood creosote, from P4 (138.3+/-3.3 min) was significantly longer than that (42.6+/-4.3 min) from pills (P0) containing only wood creosote. The MDT of the variant pills prepared from P4 without CUP (54.3+/-12.5 min) was found to be significantly shorter than that of P4. These findings suggest that CUP plays an important role in sustaining the dissolution of guaiacol from P4. The long MDT of guaiacol is considered one of the most important factors affecting the duration of efficacy after oral administration of wood creosote pills. The present findings are considered proof that CUP has been prescribed in traditional as well as new formulations of wood creosote pills.