Aluminum Potassium Sulfate Hydrate/Tannic Acid

Clinically, hemorrhoidal bleeding and prolapse disappeared immediately after injection of the sclerosing agent OC-108 into submucosa of hemorrhoids. The aim of this study was to elucidate the mechanism of action responsible for the immediate hemostatic effect of OC-108 using anesthetized rats. Subcutaneous injection of OC-108 in rats decreased blood flow at the injection site within 5 min. Aluminum potassium sulfate, one of the main ingredients of OC-108, reduced the skin blood flow. However, tannic acid, another main ingredient, did not. By perfusion of OC-108 on the mesenteric surface, microcirculatory blood flow was arrested without remarkable change in blood vessel diameter, accompanied by increased vascular permeability and venous hematocrit. These results indicate that OC-108 induces regional blood flow arrest with rapid onset, this effect being attributed to the action of aluminum potassium sulfate, and that hemoconcentration due to increased vascular permeability (plasma extravasation), an acute inflammatory reaction, is involved in the mechanisms of the immediate hemostatic action of OC-108.

OC-108 is a novel sclerosing agent for hemorrhoids, containing aluminum potassium sulfate (alum) and tannic acid as its main ingredients. In clinical studies, OC-108 injection therapy for severe internal hemorrhoids proved to be highly effective, not only on bleeding but also for prolapse, and the effects were comparable to hemorrhoidectomy. The aim of this study was to elucidate the mode of action by administrating the agent s.c. to mice and rats. In response to OC-108 injection, inflammation with necrosis developed at an early stage followed by granuloma formation with fibrosis at the injection site. Necrotic debris with aluminum was observed in the granuloma for a long period. Alum, as well as OC-108, induced vascular permeability, leukocyte infiltration, and granuloma formation; however, tannic acid did not. On the other hand, tannic acid inhibited leukocyte infiltration induced by alum but did not inhibit granuloma formation. These results indicate that OC-108 causes sclerosis and retraction of hemorrhoids through fibrosis associated with granulomatous chronic inflammation induced by the main active ingredient alum and that the adjunct ingredient tannic acid reduces excessive acute inflammation induced by alum.