Mohs paste (MP) is a hospital preparation containing zinc hydrochloride and zinc oxide starch. It is a topical medication used to fixate tissues for the removal of inoperable skin tumors and the management of hemorrhage and exudates, and to prevent foul odor resulting from secondary infections. However, it has problems, such as changes in hardness and viscoelasticity with time and liquefaction by exudate. It has been reported that the modified MP with D-sorbitol (S-MP) and the modified MP using the cellulose instead of starch (C-MP) have excellent physicochemical stability and better handling than original MP (O-MP). In this study, the effect of prescription improvement of MP on the pharmacological effect was examined with reference to water absorbing property, and its tumor tissue invasion fixation depth as an indicator. In the S-MP and C-MP, the amounts of water absorption did not differ significantly from those in the O-MP. The hardness of S-MP was decreased and liquefied like O-MP after absorbing water. In contrast, C-MP retained its form even after water absorption. The subcutaneous tumors in mice treated with modified MP formulations were measured for invasion fixation depth at 6 and 24 h after application. And the tissue status was observed using computed tomography. In all MPs, invasion fixation depth increased depending on application time. S-MP and O-MP depths did not differ significantly. The invasion depths of the C-MP significantly increased compared with those in the O-MP. These results suggest that C-MP had a high tissue fixation rate.
Keywords: Mohs paste; modified prescription; subcutaneous tumor; tissue invasion depth; water absorbing property.