Iga Katsumi

Assessment of local and systemic availability of tribenoside after rectal administration in rats

Abstract The local and systemic availability of tribenoside administered rectally as a suppository was studied in comparison with those in the oral administration in rats, using [ 14 C]-labelled tribenoside. In the rectal administration, the systemic bioavailability calculated with the orally administered solution as the reference standard was almost 60%. On the other hand, high concentration of tribenoside was retained for a prolonged period of time in the tissues of the rectum and anus, particularly in the lamina propria without being metabolized after rectal administration. The average concentration of the drug in those tissues for 1–24 h was almost 50 times higher than that in the oral administration. These findings suggested that the rectal application of tribenoside suppositories for treatment of hemorrhoids could offer a greater advantage with regard to direct delivery of the drug close to the actual site of the action before diluted in the systemic circulation and metabolized by the liver passage, or with regard to the duration of the drug action.