fig1 shows the structure of the skin . the skin comprises 4 principal layers . the superficial region of the skin ( first layer ) is stratum corneum 1 . underlying this region is epidermis 2 , dermis 3 , and hypodermis 4 . fig1 also shows the structure of a pilosebaceous unit . the pilosebaceous unit is composed by hair follicle 5 and sebaceous gland 6 . each hair follicle 5 is a discontinuity in stratum corneum 1 . the hair growing begins in hair bulb 7 , located at the root of hair follicle 5 . hair follicle 5 is a tubular structure composed with five concentric layers of epithelial cells . in hair growth stage , epithelial cells proliferate to form the four internal hair follicle layers . during the progression from hair bulb to skin surface , three layers ( in the center ) are subjected to keratinization to form hair 8 . the fourth layer disappears at the sebaceous gland level to leave a space , which is named inner lumen 9 . the present invention is further illustrated by the following examples , but is not limited thereby . a method for enhancing compound / drug penetration into hair follicles on the body areas of an animal or a human , wherein a composition is topically applied to cause the opening of hair follicles and prevent the follicles from collapsing . the following steps characterise this method : ( 1 ) a preliminary epilation is performed , since hair is generally present in the body areas to which composition will be applied ,. ( 2 ) topical application of a swellable composition to said body areas with stratum corneum intact where compound / drug penetration enhancement is desired and where there are hair follicles . ( 3 ) volume swelling of the composition applied in step ( 2 ) to prevent closure of said hair follicle and to enlarge where possible said depth of said hair follicle ; and ( 4 ) application of a cosmetically and / or pharmaceutically acceptable compound / drug the term “ epilation ” as defined herein means that hair is removed from its hair follicle . epilation can be performed using methods such as cold waxing , warm waxing , and the use of mechanical devices . as used herein “ topical application ” means directly laying on or spreading on the skin of a mammal . this application could be performed with massaging . after this application , a substance , a film , a dressing and the like can be applied to achieve an occlusion . the term “ cosmetically and / or pharmaceutically acceptable composition ” as defined herein can be salts , drugs , medicaments , inert ingredients or other materials which are suitable for use in contact with the tissues of humans or other animals without inducing toxicity , incompatibility , instability , irritation , allergic response , and the like reactions , commensurate with a reasonable benefit / risk ratio . the term “ swellable composition ” relates to composition containing specific kinds of substance which swells . examples of swellable composition or chemical cross - linked structures are disclosed in u . s . pat . no . 5 , 770 , 229 , 5 , 236 , 965 , 5 , 026 , 596 , and 4 , 596 , 858 as well as in wo 99 / 31167 and wo 99 / 08868 , the disclosures of which are hereby incorporated by reference . the composition is a form of ointment , cream , lotion , gel , spray , tonic , mousse , paste and the like . in one preferred embodiment , the substance is a form of microsphere or liposome . as disclosed in ep 03750520 and wo 98 / 48716 , formulations containing specific size of ingredients ( e . g . microspheres or liposomes ) may target compounds to follicles . as used herein “ target ” means specific penetration into hair follicles . by using this particular form of substances , hair follicles open without composition presence under the skin surface . as used herein “ compounds / drugs ” mean any molecules used in cosmetic and / or pharmaceutics fields , including all photosensitizer molecules , their derivatives , and their precursors used in photodynamic therapy . as used herein “ photosensitizer molecules ” include hematoporphyrin , indocyanine green , microcyanine , clorin , chlorophyll , dyes , carbon , ala ( aminolevulinic acid ), benzoporphyrin , protoporphyrin and their derivatives . the list of photosensitizer molecules given here is non - limiting and is only for exemplification . as used herein “ penetration enhancement ” means increasing the quantity of compounds / drugs into hair follicles or increasing compound / drug flux through hair follicles . the term “ volume swelling ” relates actions that increase physical volume occupied by the composition . this swelling is induced by any known processes . the choice of the process used is carried out by the substance incorporated into the composition . these processes include solvent evaporation , pressure changing , physiological reactions , thermal reactions with or without external power supply , reactions induced by radiation such as photochemical , photothermal reactions , chemical reactions with another compound like water , and physical process such as ultrasound or pressure . the list of processes given here is non - limiting and is given only for exemplification . preferentially , a plate , a film , a dressing and the like are applied above the composition during swelling process to favor horizontal swelling against vertical swelling . after swelling process , compositions are permeable and permit compounds / drugs passing through or around it ( if composition is in a form of microsphere or liposome ). eventually , a skin barrier restoration can proceed after compound / drug application . as used herein “ restoration ” relates to closing up hair follicles after treatment . this is achieved by canceling forces exerted to hair follicles from composition swelling . this cancellation is obtained by any known means choosing according to composition used . it can be biodegradation , stripping , dissolution in situ , optical reactions , temperature changing , chemical reactions , physical processes , or physiological reactions . the list of processes given here is non - limiting and is given only for exemplification . the dermis is composed of elastic and collagen fibers . these fibers provide the principal mechanical resistance of the skin and exert pressure on hair follicle . as it is depicted in fig2 a , hair follicle collapse 10 appear when hair is removed or when there are no “ normal ” growing ( such as in alopecia ). however , the difference on the structure along the hair follicle produce different mechanical reactions 11 and hair follicle collapses 10 only on the superficial part . thus , compound / drug enhancement could be obtained by exerting strengths against the collapse for opening hair follicle . fig2 b shows an enlarged view of a hair follicle after topical application of cosmetically and / or pharmaceutically acceptable and swellable composition 12 . after topical application with light massaging , composition penetrates into the hair follicle down to collapsing position 13 . fig2 c shows the hair follicle reaction after inducing composition volume swelling . swelling forces 15 exert pressure on hair follicle against the collapse . the result of this step is the hair follicle opening . fig2 d shows topical application of compound / drug solution 17 . because of the permeability of swelled composition , compounds / drugs 17 pass through the composition and penetrate the skin . if there are no stratum corneum alterations , compounds / drugs 17 penetrate preferentially into hair follicle to increase flux 18 through it . this flux increasing induces even deeper penetration 19 . fig2 e shows the step of skin restoration . to prevent penetration of unwanted foreign compound after the treatment , skin barrier is restored by cancellation of the forces exerted by swelled composition . this step is accomplished by either a single or a combination of different methods , such as stripping composition , composition solubilization , and composition biodegradation 20 . as used herein generally “ skin barrier restoration ” means hair follicle 21 collapse . as shown in fig2 f , the compounds / drugs can diffuse inside and / or outside hair follicle 22 after the penetration . as used herein “ outside diffusion ” means into dermis 23 and / or into the blood by systemic passage 24 . a method for enhancing compound / drug penetration into hair follicles on body areas of an animal or human is provided wherein a composition is topically applied and therefore causes depth of the inner lumen space of hair follicles to increase . the method comprises the steps of : ( 1 ) topical application of cosmetically and / or pharmaceutically acceptable and swellable composition on the skin areas where compound / drug penetration enhancement is desired and where there are hair follicles ; and ( 2 ) volume swelling of the composition applied in step ( 1 ) before the first step , hair on body areas where composition is going to be applied should be clipped . the term “ clip ” as defined herein means that hair is cut . the cutting is performed by using different methods , such as a manual or electrical razor , a pair of scissors , and manual or electrical clippers . as used herein “ topical application ,” “ cosmetically and / or pharmaceutically acceptable composition ,” “ swellable composition ,” “ compound / drug ,” “ photosensitizer molecules ,” “ penetration enhancement ,” “ volume swelling ” are the same as defined in example 1 . the swellable composition may target drugs to inner lumen of hair follicles . by using a particular form of composition , inner lumen is opened without composition presence under the skin surface . eventually , a skin barrier restoration can proceed after compound / drug application . as used herein “ restoration ” relates to cancel forces exerted to inner lumen of hair follicles by composition swelling . this cancellation is obtained by any known means choosen according to the composition used . it can be biodegradation , stripping , dissolution in situ , optical reaction , temperature changing , chemical reaction , physical process , and physiological reaction . the list of processes given here is non - limiting and is given only for exemplification . in this example , there is no hair removal and no hair follicle collapse . the fourth layer of the hair follicle provides a junction between external and internal layers to prevent any foreign compound penetration . by exerting forces at the inner lumen of hair follicle , the space is enlarged because of the alteration of the layer , and compounds / drugs can diffuse through the layer . fig3 a shows an enlarged view of a hair follicle after topical application of cosmetically and / or pharmaceutically acceptable and swellable composition 24 . after topical application with a light massaging , composition penetrates into the inner lumen 25 of the hair follicle . fig3 b and fig3 c ( enlarged view of inner lumen ) show hair follicle reaction after inducing swelling of composition 26 . forces 27 created by swelling exert pressure on external layer 28 of the hair follicle . the result of this step is alteration of the junction between fourth 28 and third 29 hair follicle layers . fig3 d and fig3 e ( enlarged view of inner lumen ) show topical application of compound / drug solution 30 . because of permeability of swelled composition , compounds / drugs 30 pass through the composition to penetrate the skin . if there are no stratum corneum alterations , compounds / drugs penetrate preferentially into hair follicle to increase flux 31 through it . this flux increasing induces an increasing of penetration depth . fig3 f shows the removal of swelled composition . this step is accomplished by a single method or a combination of different methods , such as stripping composition , composition solubilization , and composition biodegradation 32 . fig3 g shows compounds / drugs can diffuse inside and / or outside hair follicle 33 after the penetration . having described preferred embodiments of the invention with reference to the accompanying drawings , it is to be understood that the invention is not limited to the precise embodiments , and that various changes and modifications may be effected therein by skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims .
methods for enhancing penetration of compounds / drugs into an animal or human through their hair follicles are provided . the methods employ topical application of swellable compositions which can maintain a passage for desired drugs by either opening hair follicles and preventing them from collapsing or increasing the depth of inner lumen space of the hair follicles . the swellable composition can be polymers that are biodegradable , bioactive , encapsulated in microspheres or liposomes , and / or form microspheres . the method is useful to increase compound / drug penetration deep into a patient , to increase flux of compounds / drugs through the hair follicle , to obtain release of compounds / drugs in the tissues surrounding hair follicle or under the skin surface , and to obtain a systemic effect of the compounds / drugs after topical application . the method is also useful to increase therapeutic effects of compounds / drugs in the treatment of a wide variety of skin disorders . the method can further used to obtain permanent removing of unwanted hair by permitting the diffusion of compounds / drugs deeply into hair follicles .