Fabrication of Thymoquinone and Ascorbic Acid-Loaded Spanlastics Gel for Hyperpigmentation: In Vitro Release, Cytotoxicity, and Skin Permeation Studies

This study developed a spanlastic gel loaded with thymoquinone (TQ) and ascorbic acid (AA) for treating hyperpigmentation, demonstrating high entrapment efficiency (97.18% for TQ and 93.08% for AA) and effective skin permeation. The gel showed controlled release, with 44.76% of TQ and 48.20% of AA released after 4 hours, and maintained stability over 2 months at 4°C. Cytotoxicity tests confirmed the gel's non-toxic nature, and tyrosinase inhibition tests indicated TQ's primary role in inhibitory activity. The study concludes that the spanlastic gel is a promising, safe, and effective delivery system for TQ and AA in hyperpigmentation treatment.