Table 8.

Methods to improve penetration of topical antifungal therapy in onychomycosis

Penetration enhancement method	Examples
Transungual drug delivery systems (TUDDS)	Water-insoluble polymers, which create a film on the nail surface. They need daily or weekly application and removal with organic solvents or nail filing
	Water-soluble solutions like hydroalcoholic solutions of hydroxypropyl chitosan. Their invisible non-irritating film can also be easily removed.
Chemical penetration enhancers[43]	Dimethyl sulfoxide
	Urea
	Bioadhesive polymers like Carbopol 971P, Klucel MF
	Surface modifiers like tartaric acid and phosphoric acid gel
Physical methods	Ultrasound-mediated drug delivery system
	Lasers
	Photo-dynamic therapy (PDT)
	Iontophoresis
Mechanical methods	Nail avulsion
	Nail abrasion
Novel drug delivery systems[44]	Nanoparticles
	Liposomes
	Microemulsions
	Hydrogels and in situ gels.