Site-specific methylene blue delivery to pilosebaceous structures using highly porous nylon microspheres: an experimental evaluation.
OBJECTIVE
This study aimed to evaluate the penetration of methylene blue (MB)-loaded microspheres into pilosebaceous structures of rats.


METHODS
MB was incorporated into 5 microm highly porous nylon microspheres. The microspheres were dispersed into fluid silicone. Male hairless rats were used to evaluate the penetration of MB into hair follicles. After formulation application, MB diffusion was induced and skin biopsies were realized immediately, 2 and 26 hours after MB loaded microspheres application. MB fluorescence was observed with a microscope expanded for fluorescence microscopy.


RESULTS
Position of microspheres and MB diffusion was dependent on delay between microspheres application and harvest. Inside the skin, MB was seen exclusively in the hair follicle and the sebaceous glands. MB diffusion varied from 160+/-50 microm (2 hours after application) to 410+/-70 microm (26 hours after application). MB was also found in the sebaceous glands.


CONCLUSIONS
This study confirms that 5 micro m microspheres are optimally deposited deep within the pilosebaceous structure. In agreement with the literature, when microspheres are topically applied on the skin, they penetrate via a "lipid-rich channel" coating the hair follicles. MB is exclusively distributed in the hair follicles and their accessories.


CONCLUSIONS
This report presents evidence of MB pilosebaceous delivery through the use of microsphere formulation. This is obtained thanks to topical enhancement via the follicular route. This drug delivery system aims to transport MB into the pilosebaceous unit specifically and deeply. Various other applications could derive from this work. For example, such a method might be used to increase the therapeutic index of drugs directed at hair sebaceous gland disorders. Laser treatment of acne or laser hair removal could also benefit of this technique.
Mordon
Serge
S
UPRES EA 2689 INSERM-IFR 114, Pavillon Vancostenobel, Lille University Hospital, 59037 Lille, France. mordon@lille.inserm.fr
Sumian
Chryslain
C
Devoisselle
Jean Marie
JM
D000818:Animals; D016503:Drug Delivery Systems; D018859:Hair Follicle / Q000187:drug effects*; D007202:Indicators and Reagents / Q000008:administration & dosage*; D008297:Male; D008751:Methylene Blue / Q000008:administration & dosage*; D008863:Microspheres; D009757:Nylons; D051381:Rats; D012627:Sebaceous Glands / Q000187:drug effects*
D007202:Indicators and Reagents; D009757:Nylons; D008751:Methylene Blue