Formulation Study of Mohs Paste for Chemosurgery

Abstract

Mohs paste is using for chemosurgery to treat local recurrence of breast cancer tumors and other tumors. However, physicochemical properties of Mohs paste such as hardness, viscosity, stickiness, and spreadability, change signifi cantly during storage after preparation. We investigated the mechanism of change in these physicochemical properties and reformulated Mohs paste. Mohs paste was very hard immediately after preparation and then gradually became soft and sticky during storage. We found that starch particles in the formulation caused the change in physicochemical properties. The initial hardening of the paste was caused by water adsorption and swelling of starch granules. The ensuing softening and tackifying were caused by gelatinization of the starch. The change in physicochemical properties could be restricted by reduction of free water in the formulation by adding a sugar alcohol. Sorbitol was the most effective material among additives because sorbitol can interact strongly with hydration water.