Design, optimization, and evaluation of nanostructured lipid carriers loaded prepared by microemulsion technique prepared topical gel for atopic dermatitis

Curcumin, a hydrophobic polyphenol from Curcuma longa, possesses anti-inflammatory, antioxidant, and antimicrobial activities but suffers from poor aqueous solubility, chemical instability, and limited dermal penetration. This study aimed to develop and optimize curcumin-loaded nanostructured lipid carriers (Cur-NLCs) using the microemulsion technique and incorporate them into a salicylic acid-based topical gel. Independent variables (lipid and emulsifier concentrations) were evaluated using a factorial design to determine their effects on particle size and entrapment efficiency. Optimized Cur-NLCs exhibited nanoscale particle size, narrow distribution, high entrapment, and good stability. Cur-NLC dispersion was embedded in a carbopol gel containing salicylic acid to enhance stratum corneum permeability. The combined system offers promise for improved topical delivery of curcumin in inflammatory and hyperkeratotic skin conditions.