Transfollicular drug delivery: current perspectives

Figures & data

Figure 1 Skin layers and possible routes of drug delivery to skin layers.

Notes: (A) Transepidermal route, (B) Transappendageal route.

Figure 2 Factors affecting sebum production in humans.

Table 1 Potential barriers and resolving schemes combined with drug delivery into pilosebaceous glands

Potential barriers	Resolving scheme	Bioactive	References
Size selectivity	Optimize microparticle diameter	–	12, 47–49
	1.5–7 μm
	2.2–40 nm
Sebum	Utilize a lipophilic penetrant	Curcumin	7
	Utilize a vehicle miscible with sebum	Propylene glycol	50
Hair cycle	Apply penetrant during anagen	DNA	51
		Curcumin	7

Table 2 Microparticulate systems intended for follicular drug delivery

Skin model(s)	Microparticulate fabrication with size range in nm	Reference
Human and rhino mouse	PLGA with adapalene; 5,000	12
Human	Titanium dioxide; 17 Polystyrene; 1,000–24,000 and 750–6,000	38,47
Pig	Polystyrene, 20–200	48
Hairy guinea pig	PCL block-PEG with minoxidil; 40–130	49
Hairless rat	Porous nylon with methylene blue; 5,000	52
Pig; regrown human epidermis	Solid-lipid nanoparticles with Nile red and silver; 150–500	53

Abbreviations: PEG, polyethylene glycol; PLGA, poly(lactic-co-glycolic acid).

Table 3 Suitable candidates for transfollicular drug delivery

Drug candidate	Reference
Tacrolimus	62
Dithranol	63
5-Aminolevulinic acid	64
Caffeine	65
Cyclosporine	66
Triamcinolone acetonide	67
Enoxacin	68
Trihexyphenidyl HCI	69
Corticosteroid	70
Low-molecular-weight heparin	71
Unfractionated heparin	71
Progesterone	72
Paromomycin	73
pDNA	74
Adriamycin	75
Estradiol	76
Levonorgestrel	77