Carbopol-Based Clove Oil (Syzygium aromaticum) Emulgel: Formulation, Physical Characterization, and Thermodynamic Stability

Abstract

Clove oil from Syzygium aromaticum contains eugenol with well-documented anti-inflammatory potential, but its use as a topical liquid is limited by volatility, low physical stability, and short skin contact time. This study aimed to formulate and characterize Carbopol-based clove oil emulgels as candidate topical delivery systems. Emulgels containing 10% (w/w) clove oil were prepared with Carbopol 940 at 1%, 2%, and 3% (w/w) and evaluated for organoleptic properties, spreadability, adhesion, pH, and thermodynamic stability using freeze–thaw cycling and centrifugation. All formulations showed acceptable appearance and homogeneity, with pH values of approximately 5.3–5.5, within the physiological skin range. Increasing Carbopol concentration decreased spreadability but significantly increased adhesion, reflecting higher viscosity and a denser gel network. After six freeze–thaw cycles, the 3% Carbopol formulation (F3) showed the smallest change in spreadability and adhesion and no evidence of phase separation, while maintaining skin-compatible pH. These findings indicate that the 3% Carbopol emulgel provides the most favourable balance between handling properties and thermodynamic stability and represents the most promising formulation among those tested for further development as a topical clove oil delivery system.