Nanocrystals in Dermal Drug Delivery: A Breakthrough for Enhanced Skin Penetration and Targeted Skin Disorder Treatments.

One of the major challenges in dermal drug delivery is the adequate penetration of the active compound into the skin without causing any skin irritation and inflammation. Nanocrystals (NCs) are nanoscale particles, and their sizes are below 1000 nm. NCs are made up of drug particles only, which are used to improve the aqueous solubility and bioavailability of poorly water-soluble drugs. NCs are typically prepared either by bottom-up or top-down techniques. The advantages of using NC-based formulations in enhancing dermal drug delivery include increased drug loading capacity, easier and deeper penetration into the skin tissue, and increased passive diffusion. NC-based formulations with the capacity of enhanced dermal drug delivery can be effectively used to treat a wide range of skin disorders, including melanoma, inflammation, psoriasis, acne vulgaris, bacterial infections, fungal infections, eczema, skin aging, herpes simplex virus infections, skin manifestations of tick bites, frostbite-related infections, hyperpigmentation, and diabetic foot ulcer. In this review, major challenges in dermal drug delivery across the skin barrier, mechanism of action of dermal NCs, advantages of using NCs in enhancing dermal drug delivery, NC preparation methods, and applications of NCs in the treatment of various skin disorders have been discussed.