Preparation and evaluation of Eudragit gels. VIII. Rectal absorption of 5-fluorouracil from Eudispert hv gels in rats.

Rectal absorption of the hydrophilic 5-fluorouracil (5-FU) in rats was studied with Eudispert hv gels with or without fatty acids as the rectal bases. In the absence of fatty acids, absolute bioavailabilities of 5-FU for Eudispert hv hydrogel and xerogel preparations increased approximately 2.5 times compared with those of Witepsol H-15 and PEG 2000 suppositories. When n-capric acid or linolenic acid was used as an absorption enhancer, absolute bioavailabilities of 5-FU were, respectively, 25.5 and 30.9% for Witepsol H-15 and 64.4 and 66.1% for PEG 2000. Furthermore, the absolute bioavailabilities of 5-FU for Eudispert hv hydrogel with n-capric acid or linolenic acid were 95.6% and 81.7%. The addition of capric acid or linolenic acid to the hydrogel was a useful method for increasing 5-FU permeability through the rectal membranes. These results are consistent with the observation that the total amounts of 5-FU remaining in the lumenal contents of the rectum and that accumulated in the rectal tissue decreased in relation to the increase in the bioavailabilities. Thus, the Eudispert hv hydrogel containing 5-FU with capric acid may be a useful rectal preparation for increasing the maximum plasma level and improving the absolute bioavailability of 5-FU.