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Intradermal drug delivery by low frequency sonophoresis (25KHz)

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Intradermal drug delivery by low frequency sonophoresis (25KHz)
Pietro SantoiannI, Massimiliano Nino, and Gabriella Calabro
Dermatology Online Journal 10 (2): 24

Department of Dermatology, University "Federico II" of Naples, Italy


Ultrasound waves (US) have been proposed to facilitate the absoption 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, though proved effective, have limited effects due to only partial penetration into the skin. This study has evaluated the efficacy of low frequency sonophoresis (LFS) at 25KHz 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 lentigo the results when the drug application was followed by LFS, were after 3-month and twice a week application: 75 percent complete depigmentation and 25 percent partial for melasma, 43 percent total regression and 57 percent partial for solar lentigo. Conclusion: This is the first report of sonophoresis at a frequency of 25 KHz in dermatocosmetology. The study shows that LFS, a not aggressive tecnique, 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.


Corticosteroids are actually used successfully for the treatment of alopecia areata. Azelaic and kojic acids have been shown to have some depigmenting activity for melasma and solar lentigo. Biodisposability of most topical formulations is extremely low (about 1-5 % of applied dose) and, ineffective drug delivery into the skin may be a problem with poor results.

Experimental studies have shown that ultrasound waves (US) high low frequencies bring about a sort of disaggregation of the horny layer and stimulate convective movements within the epidermis, facilitating the absorption of the active compounds (transdermal delivery) [1, 2]. To potentiate the epidermal penetration of the drugs used the study aimed to prove the efficacy of an enhancing delivery system with a sonicator apparatus using low frequency sonophoresis (LFS) at 25 KHz to obtain intradermal delivery.


US waves (25 KHz) were obtained by a sonicator apparatus with a power intensity ranging from 50 to 100 mW/cm2.

Alopecia areata

Methylprednisolone ointment and cyclosporine solution were used for treatment of alopecia areata.

Thirty patients (median age: 23.6 years) were divided into 2 subgroups: group A treated by methylprednisolone+LFS; group B by cyclosporine+LFS. The drug was applied three-times a week for a 3-month period. Prior of drug application a superficial peeling by US waves was performed for 10 minutes, and methylprednisolone in w/o vehicle was applied (at 0.05mg/cm2.; cyclosporine dissolved in seed-oil was applied at 5mg/cm2. At the beginning and at the end of treatment usual laboratory tests were performed. Cyclosporinaemia was evaluated at day 0, and at days 30 and 60 and at the end of the treatment. Arterial pressure was monitored and HPLC analysis showed that US waves treatment does not induce cyclosporine degradation or structural modifications.

Melasma and solar lentigo

A depigmenting emulsion containing ascorbic, azelaic, and kojic was used for the treatment of 48 women with melasma and for 48 with solar lentigo. Each group of patient was divided into 3 subgroups: group A treated by emulsion +LFS; group B by depigmenting emulsion only; group C by placebo+LFS.

Patients underwent two weekly treatments for 5 consecutive weeks (average 10 applications). The skin color was converted into numeric code (by a spectrocolorimeter X-Rite 968) and results misured by an increase in the luminosity index (L).


Alopecia areata

Figure 1
Results of patients treated with Methylprednisolone (Group A).

Figure 2 Figure 3
Treatment by methylprednisolone+application of US waves: results in a patient. Before treatment (Fig. 2). After 2-months treatment (Fig. 3)

Figure 4
after 3-months treatment

Both methylprednisolone and cyclosporine in combination with US have shown remarkable hair regrowth. The results obtained by methylprednisolone+LFS were: 57 percent partial regrowth and 29 percent total (Fig. 1). Figures 2-4 show clinical results in a patient with partial regrowth after 2-month and total after 3-month treatment (36 applications). Results by cyclosporine+LFS were: 33 percent partial regrowth and 34 percent total (Fig. 5); Figures 6-8 show clinical results in a patient with total regrowth after 3 months. No patient showed arterial pressure modifications or blood tests alterations. Only two patients presented a limited increase of cyclosporinaemia (220 ng/ml -N. V. 20-200 ng/ml).

Figure 5
Results of patients treated with Cyclosporine (Group B).

Figure 6 Figure 7
Treatment by cyclosporine+application of US waves: results in a patient. Before treatment (Fig. 6). after 1-month treatment (Fig. 7).

Figure 8
After 3 months treatment.

Melasma and solar lentigo

The results showed for melasma and lentigo a good degree of depigmentation, compared to controls (group B and C). The more remarkable results were obtained for melasma treated with emulsion and LFS (group A): 3 cases out of 4 obtained complete depigmentation (Figs. 9, 10), and 1 only partial. Depigmentation occurred to a lesser extent in group B (total in 25 percent and partial in 75 percent), and in group C (total depigmentation in 81 percent and partial in 19 percent).

Figure 9 Figure 10
Treatment by emulsion +US waves: results in a patient with melasma (group A). Before treatment (Fig. 9). After 5-weeks treatment (Fig. 10).

For solar lentigo, in group A total remission was obtained for 43 percent patients and partial regression for 57 percent (Figs. 11, 12). In group B, total depigmentation occurred in 12 percent of cases, partial in 50 percent while in the remaining 38 percent no result was achieved. Fifty percent of patients in group C experienced a very limited regression, while no result was achieved for the other 50 percent.

Figure 11 Figure 12
Treatment by emulsion +US waves: results in a patient with solar lentigo (group A). Before treatment (Fig. 11). After 5-weeks treatment (Figure 12).


Effects induced by US at 25 KHz are: micromechanical, thermic and cavitation effects. The micromechanical effect with microvibrations induced by US waves at 25 KHz stimulate the disaggregation of the horny layer of the epidermis [3], and the molecular movements of the solute increase their kinetic power and temperature (thermic "Joule effect") [4]. Moreover, the increased temperature with pressure modifications increase the permeability of membranes ("pushing" function). The movements promoved by US and transmitted to the vehicle applied on skin induce pressure modifications resulting its transformation to vapour state as microbubbles that break into surface (cavitation effect) [5]. Wave induced depression and pressure bring about deformation and explosion of microbubbles, generating a very high push between liquid and skin surface; and explosion increases horny layer disaggregation ("peeling" effect).

This study shows that US, with a not aggressive technique, enhance penetration of topic agents giving better results in the treatment of some cosmetic skin disorders. Combination of drugs in a suitable vehicle with LFS allows good penetration also of high molecular wheight compounds.


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4. Joshi A, Raje J, Sonicated transdermal drug transport, J Control Release. 83:13-22, 2002.

5. Tang H, Wang CC, Blankschtein D, Langer R, An investigation of the role of cavitation in low-frequency ultrasound-mediatedtransdermal drugtransport, PharmRes. 19:1160-1169, 2002

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