[Croton oil-induced hemorrhoid model in rat: comparison of anti-inflammatory activity of diflucortolone valerate with other glucocorticoids].

A hemorrhoid model was prepared by means of application of croton oil onto the recto-anus of rats. Cotton swab soaked with the inducer, which consisted of water, pyridine, diethylether and 6% croton oil in diethylether, was inserted into the anus. The following conditions were found to be optimal for preparing the model: cotton swab containing 0.16 ml of the inducer solution was applied to the anus of a 6 week-old rat (body wt. about 140 g) for 10 sec. The edema developed linearly until 7-8 hr after application, and the severity of the edema was sustained almost constantly for more than 24 hr. Macroscopic observations at 6 hr p. a. revealed homogeneous and consistent inflammation in the recto-anus applied region. Histological observation showed appearance of edema, infiltration of fibrin, inflammatory cells, vasodilation, blood congestion and medium to high degrees of necrosis in the mucosal epithelium. Thus this model was useful for evaluating the effect of anti-hemorrhoidal drugs on intumescence and vasodilatation. The efficacy of diflucortolone valerate, hydrocortisone caproate and hydrocortisone was evaluated in this model. Wet weight and vasopermeability increased by the inducer was suppressed strongly by simultaneous application of the corticoids, and the degree of suppression was parallel with the potency of the glucocorticoid activity. Compared to Scheriproct, Posterisan forte, Posterisan and Borraginol N, Neriproct showed the strongest effects in the protection against and treatment of the experimental hemorrhoid. Scheriproct, which was less active than Neriproct, was also found to have higher efficacy than the others.