Gallic Acid–Loaded Nanosponge Hydrogel for Targeted Topical Delivery in Seborrheic Dermatitis: Formulation, Characterization and Evaluation

Background Seborrheic dermatitis (SD) is a chronic inflammatory skin disorder requiring prolonged topical therapy. Conventional formulations often suffer from poor retention, inadequate penetration, and dose-related irritation. Gallic acid, a natural polyphenolic compound with antioxidant and anti-inflammatory properties, presents therapeutic potential; however, its clinical utility is limited by instability and rapid release. Objective To develop and evaluate a gallic acid-loaded nanosponge-based hydrogel for controlled topical delivery aimed at improving therapeutic efficacy and patient compliance in seborrheic dermatitis. Methods Gallic acid-loaded nanosponges were prepared using the quasi-emulsion solvent diffusion method and incorporated into a hydrogel base. The formulation was evaluated for physicochemical properties including viscosity, pH, spreadability, extrudability, and drug content. In vitro drug release studies were performed over 12 hours. Stability studies were conducted under different temperature and humidity conditions (25°C/60% RH, 30°C/65% RH, and 40°C/75% RH). Results The optimized formulation (B4) exhibited a viscosity of 13,453 ± 209 cP, indicating suitable consistency for topical application. The pH range (5.0–5.5) was compatible with skin physiology, minimizing irritation risk. The gel showed good spreadability and extrudability (80–85%), ensuring ease of application. Drug content was found to be 97.38%, indicating uniform drug distribution. The in vitro release profile demonstrated a controlled and sustained drug release over 12 hours, with an initial slow release phase (6.77–22.02% within 0.5–2 h), followed by a moderate release phase (22.02–56.99% within 2–6 h), and a sustained release reaching 82.94% at 12 hours. This biphasic release pattern suggests diffusion-controlled drug release from the nanosponge-hydrogel system. Stability studies revealed no significant changes in physical parameters, including clarity, color, odor, pH, viscosity, spreadability, and extrudability under all tested conditions, confirming formulation stability. Conclusion The developed gallic acid-loaded nanosponge hydrogel demonstrated desirable physicochemical properties, high drug content, controlled release behavior, and excellent stability, making it a promising topical delivery system for seborrheic dermatitis. The sustained release profile and stability of the formulation may enhance therapeutic efficacy, reduce dosing frequency, and improve patient compliance.