Optimization of the Formulation for a Transdermal Hydrogel Patch Containing Basil Leaf Essential Oil (Ocimum basilicum) using the Factorial Design Method

Background: Fever is a physiological response to infection or inflammation associated with increased prostaglandin E2 (PGE2) synthesis. Basil (Ocimum basilicum) leaf essential oil contains bioactive compounds with potential for development in a transdermal drug delivery system. The development of a transdermal hydrogel patch requires optimization of the polymer composition to achieve appropriate physical characteristics. Objective: This study aimed to optimize a transdermal hydrogel patch formulation containing basil (Ocimum basilicum) leaf essential oil using a combination of polyvinyl alcohol (PVA) and hydroxyethyl cellulose (HEC) through a factorial design approach. Methodology: This experimental study prepared basil leaf essential oil as an emulsion, which was subsequently incorporated into a transdermal hydrogel patch. Optimization was performed using a two-factor, two-level factorial design with PVA and HEC concentrations as independent variables and folding endurance and moisture absorption as response variables. The data were analyzed using Design Expert version 13 Trial. The optimum formulation was selected based on the optimization results and subsequently verified through physical characterization tests. Results and Discussion: The optimum formulation consists of 20% basil leaf essential oil emulsion, 10.65% PVA, 3.35% HEC, 10% PEG 400, 10% Transcutol, 10% ethanol, and purified water up to 100 mL. The optimum formulation shows a folding endurance of 301 ± 24.19 folds and moisture absorption of 7.24 ± 0.30%. The statistical models show R² values of 0.9006 for folding endurance and 0.9855 for moisture absorption, indicating the models' ability to explain variation in the responses. The combination of PVA and HEC concentrations contributes to the physical characteristics of the patch, particularly its folding endurance and moisture absorption.Conclusion: The combination of PVA and HEC can be used to optimize a transdermal hydrogel patch containing basil leaf essential oil. The formulation containing 10.65% PVA and 3.35% HEC provides optimum physical characteristics based on folding endurance and moisture absorption responses.