Development and Optimization of a Polyherbal Anti-Acne Emulgel Containing Aloe vera, Tea Tree Oil, Rosemary Oil, and Turmeric Oil Using a Quality by Design Approach

Abstract

Acne vulgaris is a common inflammatory skin disorder associated with excessive sebum production, follicular blockage, microbial colonization, and inflammation. Conventional therapies may cause irritation and antimicrobial resistance, creating a need for safer and more effective alternatives. Polyherbal topical systems offer a promising approach due to their antimicrobial, antioxidant, and anti-inflammatory properties. Objective: The present study aimed to develop and optimize a polyherbal anti-acne emulgel containing Aloe vera, tea tree oil, rosemary oil, and turmeric oil using a Quality by Design (QbD) approach to improve topical delivery and therapeutic efficacy against acne. The emulgel was prepared using an emulsion-incorporation technique and optimized through Response Surface Methodology. Formulations were evaluated for physicochemical characteristics, drug content, pH, viscosity, spreadability, extrudability, particle size, in-vitro drug release, antioxidant activity, and antimicrobial efficacy against Cutibacterium acnes. Compatibility studies were performed using FTIR and DSC analyses. Compatibility studies confirmed the absence of significant interactions between herbal actives and excipients. The optimized formulation (F5) exhibited satisfactory physicochemical properties, including pH (5.81 ± 0.04), viscosity (5018 ± 60 cP), spreadability (18.03 ± 0.29 g·cm/s), and extrudability (146.07 ± 1.76 g/cm²). Particle size analysis showed a Z-average size of 616.0 nm with acceptable dispersion characteristics. The formulation demonstrated sustained drug release (86.5 ± 2.3% at 300 min), significant antioxidant activity, and pronounced antimicrobial activity against Cutibacterium acnes, producing a zone of inhibition of 17.8 ± 0.35 mm, corresponding to 90.8% activity relative to marketed clindamycin gel. Statistical optimization showed strong model predictability (R² = 0.958). Conclusion: The QbD-optimized polyherbal emulgel demonstrated favorable pharmaceutical characteristics, sustained release behavior, and significant anti-acne potential. The synergistic action of Aloe vera, tea tree oil, rosemary oil, and turmeric oil suggests that the developed formulation may serve as a promising alternative or adjunct to conventional acne therapies.