Objective: The objective of the study was to develop, create, and optimize a microemulgel based on thujone oil for the treatment of psoriasis and bacterial skin infections. Using a Quality by Design (QbD) methodology, the objective was to improve topical drug administration by increasing spreadability, pH stability, and viscosity. Methods: A micro-emulgel was developed using thujone oil, liquid paraffin, Tween 80, Span 80, and Carbopol-934 as the gelling agent. The central composite design (CCD) was employed to optimize three independent formulation variables —oil concentration (4-12%), surfactant concentration (1.5–2.5%), and gelling agent concentration (1.5-2.0%) —with respect to three key responses—pH, viscosity, and spreadability. The optimized formulation (F2) was further evaluated for particle size, in vitro drug release, antimicrobial activity, and various physicochemical parameters. Analytical characterization was performed using Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography–Mass Spectrometry (GCMS) to confirm compatibility and identify the major constituents of thujone oil. Results: The more effective formulation (F2) has a spreadability of 7.98 g·cm/s, a pH of 6.76, and a viscosity of 4023 cps. A mean droplet diameter of 6.7 μm, which indicates micro-range globules, has been confirmed by particle size analysis. According to zero-order and Korsmeyer–Peppas kinetics, in vitro release tests demonstrated 60% drug release in 7 hours (R2 = 0.99). A zone of inhibition of 18.8 mm against E. coli was shown by antimicrobial assessment, which was similar to that of conventional medications. The existence of important bioactive substances, such as copaene, cedrol, and thujopsene, was verified by GC-MS analysis. Discussion: A thujone oil-based micro-emulgel with advantageous physicochemical characteristics, prolonged drug release, and significant antibacterial action was developed and refined during this study. As a topical therapy for skin infections, the improved formulation (F2) proved to be effective. The possible use of thujone oil micro-emulgels in dermatological treatment is supported by this study. Conclusion: The outcomes demonstrate that thujone oil-based microemulgel may deliver topical drugs in a stable, effective, and controlled manner. By effectively optimizing formulation parameters, the CCD method ensured the required spreadability, viscosity, and pH. Drug release was improved by smaller particle sizes, and antimicrobial testing revealed potent antibacterial action. The results demonstrate thujone oil's potential as a natural treatment for psoriasis and bacterial skin infections. However, a direct comparative assessment with simple emulsion and gel formulations was not performed and will be included in future studies to further substantiate the advantages of the micro-emulgel system.
Bahmani et al. (Tue,) studied this question.