FORMULATION AND EVALUATION OF HERBAL AROMATHERAPY HYDROGEL PATCH USING ORANGE PEEL ESSENTIAL OIL

Aromatherapy is a complementary therapeutic approach that utilizes volatile plant-derived essential oils to promote physical and psychological well-being through olfactory and transdermal pathways. Orange peel (Citrus sinensis / Citrus reticulata), a widely available agro-industrial by-product, is rich in D-limonene and other monoterpenes that exhibit anxiolytic, antimicrobial, antioxidant, and mood-elevating properties. The present study was undertaken to formulate and evaluate a herbal aromatherapy hydrogel patch incorporating orange peel essential oil as an alternative, sustained-release, non-invasive delivery system for topical and ambient aromatherapy application. Orange peel essential oil was extracted by steam distillation and characterized for physicochemical parameters. Hydrogel patches (F1–F5) were prepared by the solvent-casting method using varying concentrations of hydrophilic polymers (sodium carboxymethyl cellulose, polyvinyl alcohol, and carbopol 934) as the gel-forming matrix, propylene glycol as a plasticizer, and orange peel essential oil as the active aromatic and therapeutic component. The formulated patches were evaluated for physical appearance, thickness, weight uniformity, folding endurance, percentage moisture content, percentage moisture uptake, oil content uniformity, in-vitro diffusion/release profile, and skin irritation potential. Among the formulations, batch F3 exhibited optimum thickness, satisfactory folding endurance, uniform oil distribution, and a controlled, sustained release profile over 8 hours, along with a pleasant and stable orange fragrance and no signs of skin irritation. The results indicate that orange peel essential oil can be successfully incorporated into a hydrogel patch matrix to deliver a stable, cost-effective, and eco-friendly herbal aromatherapy product suitable for stress relief and topical aromatherapeutic use.