Recipient Human Skin

FIELD OF THE INVENTION

This invention relates to the delivery system and method for delivery of solutions into the human skin via pores.

BACKGROUND OF THE INVENTION

Improvement of the appearance of the skin and slowing down its aging process is achieved using different procedures and technologies. The effect of supplements to eliminate wrinkles, pigmentation unevenness, sun damage and protect the skin from environmental hazards is based on their penetration through the skin. The main obstacle for the penetration of supplements through the skin is the stratum corneum which is only about 50 - 300 μηι thickness. This thin barrier prevents passage of any substance whose size is bigger than a water molecule.

US Patent Nos. 6,607,508 and 7,025,774 disclose devices and methods for drug delivery by injection, wherein the skin is punctured by a needle and medicine is injected to the required depth. Injections allow for flexible local treatment, direct absorption of the solutions and their delivery to the intercellular fluids by using a minimal substance amount. Disadvantages of such an approach are the sophisticated technique required, the risk of infection, cross-contamination, pain, difficulty of injection depth control, and the danger of harming blood vessels. Another syringe type, the so-called needle-free injector, has the additional drawback that it does not allow for adequate control of the drug injection depth. Such devices are described in "Comparison of a needle-free high- pressure injection system with needle-tipped injection of intracavernosal alprostadil for erectile dysfunction", L. M. Harding, A. Adeniyi, R. Everson, S. Barker, D. J. Ralph and A. P. Baranowski, in International Journal of Impotence Research (2002) 14, 498- US Patent Nos. 6,652,483, 5,947,928 and 7,226,439 disclose methods and devices for transdermal medicine delivery into the skin. The delivery is controlled by the solutions' physical and chemical parameters: diffusion, solubility and affinity. Diffusion depends on the molecule size. As molecule size decreases, permeability improves. US Patent No. 7,315,758 proposes additional physical means to increase diffusion, for example, electrical, magnetic and sonar. Transportation of hydrophilic or charged molecules is a particularly difficult process because of the low water content in the stratum corneum which is lipids-based: the skin (epidermis) layer is composed of about 40% lipids, 40% protein and only 20% water. This makes the diffusion method of medicine delivery slow and inefficient.

Delivery of cosmetic and medical solutions via pores could possibly be efficient since pores cover the majority of the skin surface. The pores enable water transfer vital for thermoregulation and for the transfer of the products of metabolism only from the dermis to the surface and not vice versa. These channels contain structured hydrophilic and lipophilic domains that feature exclusively unilateral conductivity toward the outside.

A square millimeter of skin surface contains not less than 3 pores. Pore size depends on pore condition and activity. On average, pore diameter is from 50 to 300um. Pores are tubular twisting capillaries that arrive from the depth of the dermis and gradually become cylindrical tubes that open onto the surface of the stratum corneum. The total surface area of pores is less than 1% (0.1% to 1%) of the entire surface area of the skin; hence pores cannot facilitate the delivery of a sufficient amount of material through diffusion. The inventor is not acquainted with methods and devices for delivery of cosmetic and medical solutions via pores that are not based on molecular diffusion.

The delivery of medical or cosmetic solutions through the skin would be facilitated if it were possible to inject solutions directly into the pores.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to facilitate the delivery of solutions through the skin by injection directly into the pores.

This object is realized according to the invention by a method and system having the features of the respective independent claims herein. Human skin has at least three types of pores, i.e., hair follicles, sebaceous glands and sweat glands. The proposed method of delivery of cosmetic and medical material exploits the fact that these skin appendages bypass stratum corneum defense and provide access to the dermis. The modality of the method is that the device for medical solution delivery has a tip with one or more nozzles that are smaller than pore size. Negative pressure is applied in order to ensure that the outlets of the device nozzles coincide with the inlets of the pores. In order to deliver the material through a larger number of pores on the treated skin surface, the device is shifted relative to the pores.

Since the outlet diameter of the nozzle is smaller than the size of a pore opening, the pressure of the jet superposed with the pore does not meet any skin resistance and does not cause skin damage in the flow direction. The negative pressure causes the treated skin area to adjoin the inner surface of the nozzle tip. As the device is shifted over the skin surface the nozzle orifices and the pore inlets become connected for short periods of superposition and the pore channel is filled with the medicine or cosmetic. As a result of filling, the pore inlet is widened and filled with even more medicine or cosmetic. If the orifice of the nozzle were larger than that of the pore inlet, the jet pressure would also affect the skin region surrounding the pore, causing compressive deformation of the skin inward and consequently closing the pore and preventing the medicine or cosmetic from permeating into the skin. Moving the device over the skin surface allows for skin treatment by means of medical or cosmetic solution delivery to a large number of pores.

A device implementing the proposed method of medicine or cosmetic solution delivery into the human skin consists of a compressor, ejector, separation container (separator), container for medical or cosmetic solution storage, pumping unit, operational handpiece with a port for the solution supply under pressure and waste evacuating port.

Although pores occupy only a small portion of the entire skin surface the present invention enables the use of their macro-structure for transportation of medical or cosmetic solutions to a uniform depth over the treated skin surface. BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure 1 illustrates a system for the delivery of medicine or cosmetic solutions to the skin via pores;

Figure 2 is a partial section of an operational handpiece for use in the system shown in Figure 1 ; and

Figures 3a and 3b are enlarged schematic drawings showing a detail of the handpiece during delivery of medicine or cosmetic via human skin pores.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to Figure 1, there is shown a system 10 comprising a compressor 11 connected to a gas ejector 12 by a tube 13. A vacuum pump can be used instead of the compressor 1 1 and ejector 12. The ejector 12 is connected to a separation container 14 which is connected to an operating handpiece 15. The handpiece 15 is connected to a pumping unit 16 which is in turn connected to a storage container 17 for storing a liquid such as a medical or cosmetic solution.

The compressor 1 1 is used for the air compression needed to generate negative pressure in the gas ejector 12. The gas ejector 12 does not contain moving parts, which makes it preferable for negative pressure generation in humid media. The separation container 14 provides liquid separation of the liquid-gas mixture. The storage container 17 is used for solution storage and its delivery to the pumping unit 16, which provides the high pressure used for the solution delivery.

Figure 2 shows in enlarged scale that the operating handpiece 15 includes an outer casing 20 accommodating a motor 21, which is coupled to a rotary drive 22 that is rotatably coupled to a tip 23. A suction port 24 in the casing 20 is used for applying the negative pressure inside the handpiece 15 and for the evacuation of waste into the separation container 14. A supply port 25 in the casing 20 is used to supply solution under pressure from the pumping unit 16 to the tip 23. The tip 23 comprises two assembled parts which form the unit with two channels. An external channel 26 is used to supply the cosmetic or medical solution under pressure via the supply port 25 to one or more nozzles 27 positioned in the distal part of the tip 23, which contact the skin surface. The nozzles 27 face toward the longitudinal axis of the tip 23 and perpendicular to its inside surface. An internal channel 28 of the tip 23 is designated for the waste evacuation via the suction port 24 and for gripping the treated skin area.

The operation of the system 10 will now be described. First the compressor 11 is activated, which applies air under high pressure to the ejector 12. The ejector 12 generates negative pressure i.e. vacuum in the separation container 14 and the handpiece 15. When the distal part of the tip 23 of the handpiece 15 contacts the skin surface, limited deformation of the skin region 29 within the perimeter of the tip 23 occurs. Owing to the negative pressure, the skin is drawn into the open chamber 28 of the tip 23 to a level that overlaps the nozzles 27 and is seated along the internal contour of the tip 23, thereby adopting its shape 29 along the points of contact as shown in Figure 3a. The pumping unit 16 is then activated which supplies the medicine or other liquid under pressure to the handpiece 15 via the supply port 25 from the storage container 17. At the same time, the motor 21 is activated and starts to rotate the tip 23 via the rotary drive 22. The medical or cosmetic solution ejected by the nozzles 27 of the rotating tip 23 flow to the skin surface 29 (shown in Figures 3a and 3b) located inside the open chamber 28 of the tip 23.

A jet of the medical or cosmetic solution under pressure (of about 1-2 bar) is delivered via the nozzles 27 and circulates over the deformed skin region (shown in Figure 3a) during rotating contact of the tip 23. At the moments when, as shown in Figure 3b, the outlet of a nozzle 27 in the tip 23 is located wholly within an inlet 30 of a pore, sluicing occurs, whereby the channel of the nozzle 27 is momentarily connected to the pore channel 31. Since the exit diameter of the nozzles 27 is smaller than that of the pore inlet 30, the liquid jet permeates into the pore interior without any resistance. Thus, during coincidence of the nozzles 27 and the pore inlet 30, the pore channel 31 is filled with the medical or cosmetic solution.

Pores contain structured hydrophilic and lipophilic domains with unilateral conductivity only toward the outside. However they are not protected against propagation of a single jet of solution flowing centrally toward the channel depth. During coincidence between the nozzle and the pore inlet, the pore channel is filled with a certain amount of medicine or cosmetic solution. The pore channel 31 continues filling as long as the moving nozzles 27 of the head portion 23 and the pore inlets 30 remain coincident. The amount of medicine permeating into the pores depends on the difference between the size of the solution delivery nozzle 27 and that of the pore inlets 30, i.e. as the pore size increases so too does the sluicing time with the nozzle. On the other hand the faster the tip rotation velocity, the shorter the sluicing duration. As the pressure of the medical or other solution rises, the quantity of liquid entering the pore increases. When motion of the orifice of the nozzle 27 overlaying the pores inlet 8 is arrested, the stretched throat of the pore contracts and encapsulates the residual solution in the pore channel 31. Treatment is performed by moving the handpiece 15 over the skin surface. When used medically, it has been demonstrated experimentally that a head portion 23 with an outer diameter of 5 mm with a nozzle diameter of 50 μηι provided the best medical effect. The optimal rotation velocity of the head portion 23 was found to be 160 rpm with a solution pressure of 1-3 bars.

The average liquid volume permeating inside an individual pore depends on jet pressure, the rotation velocity of the head portion 23 and its geometry, and should reach 0.05 - 0.3 mm ³ . The maximum estimated amount of liquid spread over all the affected skin appendages is about 2 ml/200 cm ² .

For example in the case of an aesthetic procedure, the delivery of mild Alpha Hydroxy Acids (2-5%) via the pores extends to the depth of the dermis without damaging the skin. Usually this is possible only if skin integrity has been disrupted, i.e. the epidermis and dermis are damaged. In response to what appears as a threat, namely penetration of foreign solutions into the skin, the immune and nervous systems activate to repair potential damage from what is perceived as possible irritant penetration inside the skin. Thus, a real inflammatory response is generated by the extremely mild irritants that have permeated through the pores. The body's natural immune and infection protection systems promptly go into action to heal the non-existent damage to the skin. As a result cell multiplication rate is increased and new epidermis cells are generated. The gross factors responsible for natural collagen production are activated in the dermis.

The method in the aesthetic application case, cosmetic solution delivery via pores under pressure, causes thickening of the epidermis. Production of additional natural collagen improves skin density and causes smoothing of small wrinkles. As a result of sufficiently deep penetration into the dermis, a process of neurocosmetic and regenerative effect on the skin is steadily developed and persists for months. The delivery of non-damaging solutions via pores enables all the natural functions of skin protection and interaction with the environment. It is to be understood that while the invention has been described with particular regard to the injection of a medicinal solution through the pores of a human patient, it is equally applicable to the injection of non -medical solutions such as cosmetics in non- therapeutic treatment of the human body.

It is also to be understood that typically the nozzles are circular in cross -section, such that the nozzle diameter is less than the inlet size of the pores. However, the nozzles need not be circular in cross-section provided that their outlet produces a stream whose cross-section at its widest point is smaller than the narrowest point in the inlet opening of a human skin pore.