Optimization of HPMC and Carbopol 940 as Gelling Agents on The Physical Properties and Stability in Anti-Acne Gel of Binahong Leaves (Anredera cordifolia (Ten.) Steenis Extract

Binahong (Anredera cordifolia (Ten.) steenis) is recognized as a widespread plant species in Indonesia and is known to possess strong antibacterial properties against P. acnes. This study aims to determine the effect and optimum proportion of hydroxypropyl methylcellulose (HPMC) and carbopol 940 as the gelling agent on the physical properties of binahong anti-acne gel. The Simplex Lattice Design (SLD) method was performed to optimize the gel base with Design-Expert® version 13.0.0 with a total run of 8 formulas. The evaluated parameters were organoleptic, homogeneity, pH, viscosity, spreadability, adhesion, stability, and irritation test. The independent variables in SLD were the amount of HPMC and carbopol 940, while the responses included pH, viscosity, spreadability, and adhesion. The optimal formula proposed by SLD is a combination of 1.96% HPMC, and 0.53% carbopol 940 that showed no significant difference when compared to the test results. The optimal formula has a pH of 6, a viscosity of 18,130 cP, a spreadability of 4.7 cm, and an adhesion of 10 second. The optimum formulation proved to be physically stable after three freeze-thaw cycles and showed no irritation after in vivo application.