Penetration Profile of Microspheres in Follicular Targeting of Terminal Hair Follicles

Abstract

The transfollicular administration of pharmacologically active molecules is of current therapeutic interest, mainly with regard to delivery to specific sites of the hair follicle (HF) and the reduction of hepatic metabolism and systemic toxicity. HF are privileged pathways for specific molecules depending on formulations, which enter faster into these shunts than through the stratum corneum. The aim was to optimize the delivery of fluorescent microspheres into the HF, thereby, developing a standardized protocol for follicular targeting with microspheres. The number of HF showing penetration, as well as the depth of penetration, was determined. Freshly excised skin samples with terminal HF were divided into groups, with or without prior treatment with cyanoacrylate skin surface stripping-technique (CSSS). Thereafter microspheres at a size of 0.75-6.0 microm were applied according to the developed standardized protocol. Skin biopsies were obtained, shock-frozen, and sectioned in 5 microm slices. We demonstrated a selective penetration route of the microspheres into the HF. Optimal microsphere size proved to be approximately 1.5 microm, with a 55% rate of all HF, and with a maximum penetration depth of >2300 microm. Without previous CSSS treatment of the skin, the transfollicular microsphere penetration was below 27% with a maximum penetration depth of 1000 microm. Thus, the basis for follicular targeting of essential structures containing stem cells for keratinocytes, melanocytes, and mast cells has been laid.

Noninvasive and persistent transfollicular drug delivery system using a combination of liposomes and iontophoresis

“…There are some reports for follicular drug delivery using the nano-or microparticulate systems (several hundreds nm -several µm) (Alvarez-Roman et al, 2004;Mordon et al, 2003;Rolland et al, 1993;Toll et al, 2004). While the follicular opening constitute only about 0.1% of the total skin area (Meidan et al, 2005), the hair follicle represents an invagination of the epidermis extending deep into the dermis and thus provides a greater actual area for potential absorption (Agarwal et al, 2000;Singh et al, 2000).…”

DETERMINATION OF PERMEATION PATHWAY OF GENTAMICIN INTO PIG’S EAR SKIN

“…Limitation of follicular penetration is there might be a possibility that the follicle orifice is blocked by a plug. This limitation however, can be overcome by peeling the skin or by surface skin stripping with cyanoacrylate tapes 27 . Besides that, the analysis instrumentation used for the study can be improved by using a new surface ionization mass spectrometry (SI/MS) technique, which is able to show clear differences between interfollicular and follicular penetration of a topically applied substance as compared to UV Spectrometry 19 .…”

Desenvolvimento, caracterização e avaliação de sistemas microestruturados para veiculação de ácido retinóico na pele

“…Sabe-se que as micropartículas podem entrar via folículo piloso e oferecer a possibilidade de criar altas concentrações do fármaco dentro deste (ROLLAND et al, 1993;ILLEL, 1997;LADERMAN et al, 1999, TOLL et al, 2004VOGT et al, 2005). O tamanho das micropartículas tem sido de grande importância no direcionamento folicular conforme foi apresentado na figura 14 (SHAEFER et al, 1990;ROLLAND et al, 1993 …”