Intradermal drug delivery by low-frequency sonophoresis (25 kHz)

Ultrasound waves (US) have been proposed to facilitate the absorption of active compounds (transdermal delivery) stimulating some disaggregation of the horny layer and promoting convective movements within the epidermis. Drugs used for alopecia areata, melasma, and lentigo, although proved effective, have limited effects resulting from only partial penetration into the skin. This study has evaluated the efficacy of low-frequency sonophoresis (LFS) at 25 kHz produced by a sonicator apparatus for treatment of alopecia areata, melasma, and solar lentigo. Thirty patients affected by alopecia areata were treated by application of methylprednisolone or cyclosporine solution followed by LFS. In a case-control study 48 women with melasma and 48 with solar lentigo were also treated by depigmenting emulsion and LFS application. For alopecia areata after 36 applications with LFS and 3-month treatment, the results were 57 percent partial regrowth and 29 percent total with methylprednisolone, and 33 percent partial regrowth and 34 percent total when cyclosporine was used. For melasma and solar lentigines the results when the drug application was followed by LFS, were (after twice-a-week application for 3 months) 75 percent complete depigmentation and 25 percent partial for melasma, 43 percent total regression and 57 percent partial for solar lentigo.

This is the first report of sonophoresis at a frequency of 25 kHz in dermatocosmetology. The study shows that LFS, a not aggressive technique, enhance penetration of topic agents obtaining effects at the level of the epidermis, dermis and appendages (intradermal delivery), giving better results in the treatment of some cosmetic skin disorders.