Skin targeting of curcumin solid lipid nanoparticles-engrossed topical gel for the treatment of pigmentation and irritant contact dermatitis

Irritant contact dermatitis (ICD) and hyperpigmentation are the problems associated with skin. Topical curcumin (CUR) although effective in hyperpigmentation and ICD, is a challenging molecule due to low-solubility. Encapsulation of CUR into solid lipid nanoparticles (SLNs) makes it amenable to topical dosing as their small size promotes its penetration into the skin. CUR-SLNs were prepared using Precirol ATO5 and Tween-80 by probe ultrasonication method. Further, CUR-SLNs were incorporated into Carbopol gel and investigated for ex-vivo skin permeation, skin deposition and skin irritation studies. The potential of CUR-SLN gel was checked against hyperpigmentation through the inhibition of tyrosinase enzyme. It was further evaluated for possible effects on ICD using BALB/c mice. The optimized CUR-SLN showed the particle size of 51 nm and 93% EE. Ex vivo permeation of CUR-SLN gel exhibited controlled drug release up to 24 h, similarly in vitro drug deposition studies showed potential for skin targeting. In vitro tyrosinase inhibition assay indicates that the formulated gel has potential in skin depigmentation. The gel also confirmed proficient suppression of ear swelling and reduction in skin water content in the BALB/c mouse. Thus, the CUR-SLN gel would be a safe and effective alternative to conventional vehicles for treatment of ICD and pigmentation.