the object of the present invention is represented by the use of chitosan , chitosan derivatives , and / or of a physiologically acceptable salt thereof , for the acceleration of nail growth . the preferred chitosan derivatives are selected from chitosan amino - polysaccharides , preferably water soluble , having a molecular weight higher than 50000 da , preferably of from 100000 to 500000 da ; among them hydroxyalkyl chitosans , such as hydroxypropyl chitosan , and carboxyalkyl chitosans are particularly preferred . more particularly , it is represented by the use of chitosan , a chitosan derivative or of a physiologically acceptable salt thereof , for the acceleration of nail growth , during treatment not only of nail illnesses , such as onychomycosis , nail psoriasis , lichen planus , or atopic dermatitis , but also of nail dystrophy and nail growth disturbances of various origin . liquid or semi - solid preparations of chitosan or of a chitosan derivative , in the form of nail lacquer , cream , ointment , gel , lotion , foam , with a content in chitosan from 0 . 1 to 10 wt . %, more preferably from 0 . 2 to 5 wt . %, most preferably from 0 . 3 to 2 %, are suitable to accelerate nail growth when regularly applied on the nail surface . pharmaceutical compositions will be prepared according to conventional techniques , using compatible excipients and pharmaceutically acceptable carriers , and may contain , in combination , one o more active principles with complementary or , in any case , useful activity . the active agents which may be used in the compositions in combinations with the chitosans of the present invention include , but are not limited to , corticosteroids , antipsoriatic agents , immunosuppressive agents , antimycotic agents , antiseptic agents , moisturizers , and / or nail strengthening agents . examples of corticosteroids include 21 - acetoxypregnenolone , alclometasone or its dipropionate salt , algestone , amcinonide , beclomethasone or its dipropionate salt , betamethasone and salts thereof , including , for example , betamethasone benzoate , betamethasone dipropionate , betamethasone sodium phosphate , betamethasone sodium phosphate and acetate , and betamethasone valerate ; clobetasol or its propionate salt , clocortolone pivalate , hydrocortisone and salts thereof , including , for example , hydrocortisone acetate , hydrocortisone butyrate , hydrocortisone cypionate , hydrocortisone phosphate , hydrocortisone sodium phosphate , hydrocortisone sodium succinate , hydrocortisone tebutate and hydrocortisone valerate ; cortisone acetate , desonide , desoximetasone , dexamethasone and salts thereof , for example , acetate and sodium phosphate ; diflorasone diacetate , fludrocortisone acetate , flunisolide , fluocinolone acetonide , fluocinonide , fluorometholone , flurandrenolide , halcinonide , medrysone , methylprednisolone and salts thereof , e . g . acetate , sodium succinate ; mometasone furoate , paramethasone acetate , prednisolone and salts thereof , e . g ., acetate , diethylaminoacetate , sodium phosphate , sodium succinate , tebutate , trimethylacetate ; prednisone , triamcinolone and derivatives thereof , e . g . acetonide , benetonide , diacetate , hexacetonide . examples of antipsoriatic agents include : anthracene derivatives , such as dithranol ; psoralens , like trioxsalen or methoxsalen ; vitamin d3 analogues , like calcitriol , calcipotriol or tacalcitol ; retinoids , like tazarotene , acitretine or etretinate ; fumaric acid and esters thereof , e . g . monomethyl ester , dimethyl ester . examples of antimycotic agents include : 1 - hydroxy - 2 - pyridone compounds and their salts , e . g . ciclopirox , rilopirox , piroctone , ciclopirox olamine ; imidazole derivatives and their salts , e . g . clotrimazole , econazole , isoconazole , ketoconazole , miconazole , tioconazole , bifonazole , fenticonazole and oxiconazole ; polyene derivatives and their salts , e . g . nystatin , natamycin and amphotericin ; allylamine derivatives and their salts , e . g . naphtifine and terbinafine ; triazole derivatives and their salts , e . g . fluconazole , itraconazole , terconazole and voriconazole ; morpholine derivatives and their salts , e . g . amorolfine and morpholines disclosed in u . s . pat . no . 5 , 120 , 530 ; griseofulvin and related compounds , e . g . griseofulvin ; undecylenic acid and its salts , in particular , the zinc and calcium salts of undecylenic acid ; tolnaphtate and its salts ; and flucytosine and its salts . the antimycotic agent may also be selected from natural sources , in particular plant extracts . examples of these extracts include tea tree oil ( melaleuca attemifolia ), lavender oil ( lavandula officinalis chaix ) and the leaf extract of the neem tree ( azadirachta indica ). examples of the antiseptic agents include : benzalkonium - chlorid , benzethonium - chlorid , cetrimoniumbromid , chlorhexidin , dequaliniumchlorid , triclocarban , triclosan , salicylic acid , benzoic acid and their salts , p - hydroxybenzoic acid and its esters . examples of the compositions prepared according to the present invention include : nail lacquer , cream , ointment , gel , lotion , foam , for application to the nail surface freely or under semi - occlusive or occlusive medication . the pharmaceutical compositions and the uses of the present invention will now be more fully described by the following examples . it should , however , be noted that such examples are given by way of illustration and not of limitation . 1 . purified water 21 . 0 % 2 . ethanol 73 . 0 % 3 . ethyl acetate 4 . 0 % 4 . hydroxypropyl chitosan ( hpch ) 1 . 0 % 5 . cetostearyl alcohol 1 . 0 % the formulation is prepared by using a closed vessel with a stirrer . to this vessel are added ethanol , deionized water and ethyl acetate to form a mixture . thereafter , cetostearyl alcohol is added . finally , hydroxypropyl chitosan is added and the resulting mixture is stirred for 24 hours or until dissolution . the obtained composition has a clear and homogenous appearance even after prolonged storage . moreover , when applied on the nails , the liquid is able to form a non - sticky and elastic film which could strongly adhere to the nail surface . an open , comparative clinical study was performed to assess the nail growth accelerating efficacy and the safety of the solution according to the example 1 on the nails of healthy volunteers . the trial was conducted by a single centre , under dermatological control for 4 weeks of treatment . in particular the study product was applied , once daily , on 5 nails of the left or right hand according to a randomisation list and following the investigator &# 39 ; s instructions ; the study product application side was assigned by the investigator at each included subject during the baseline visit . nails of the opposite hand were used as control area ( untreated nails ). baseline — t0a ( before product use ) baseline extension visit — t0b ( 3 days after t0a ) final visit — t4a ( after 25 days of treatment ) final extension visit — t4b ( at the end of 4 week treatment ). the study was conducted on 22 healthy volunteers ( 1 male and 21 female ), whose informed consent had been obtained , age range 18 - 50 ( mean = 43 ). all subjects ended the trial as per the protocol direction . no important event which may have interfered to the test results occurred during the study period . the activity of the product was expressed in absolute values and in relative terms with respect to an untreated control area . in particular statistical analysis of experimental data was performed as follows : comparison of t4 results of treated and untreated nails versus basal conditions ( student t test ). comparison of treated vs untreated nails time by time ( variance analysis ). nail growth speed ( mm / day ) was determined for each subject comparing the digital images of the thumb nail of both treated and untreated hands , taken in baseline conditions ( t0a vs t0b ) and at the end of the trial ( t4a vs t4b ). the obtained results showed that the study product determined a statistically significant increase ( student t test p & lt ; 0 . 01 vs t0 ) of nail growth speed corresponding to 15 % ( from a basal mean value of 0 . 071 mm / day to a final mean value of 0 . 082 ). no variation of nail growth speed was highlighted for the untreated nails ; in fact the mean value obtained at t0 and at t4 was 0 . 075 mm / day . besides the increase of nail growth speed , an important increase of nail smoothness was measured in the treated nails , significant vs control , untreated nails . moreover , the treatment was very well tolerated and no side effect was reported . 1 . purified water 13 . 0 % 2 . ethanol 73 . 0 % 3 . ciclopirox 8 . 0 % 4 . ethyl acetate 4 . 0 % 5 . hydroxypropyl chitosan ( hpch ) 1 . 0 % 6 . cetostearyl alcohol 1 . 0 % the formulation is prepared by using a closed vessel with a stirrer . to this vessel are added ethanol , deionized water and ethyl acetate to form a mixture . thereafter , cetostearyl alcohol and ciclopirox are added . finally , hydroxypropyl chitosan is added and the resulting mixture is stirred for 24 hours or until dissolution . the obtained composition has a clear and homogenous appearance even after prolonged storage . moreover , when applied on the nails , the liquid is able to form a non - sticky and elastic film which could strongly adhere to the nail surface . the nail growth accelerating efficacy of the solutions according to the examples 3 ( named p - 3051 ) and 1 ( used as a placebo ) was measured in the frame of a controlled clinical study on patients with onychomycosis due to dermatophyte fungi . the study was multicentre , randomized , long - term , double blind / blinded assessment , parallel groups , three arms : the p - 3051 solution as in the example 3 , containing hydroxypropylchitosan as an ingredient and ciclopirox as active antifungal agent ; the placebo solution as in example 1 , containing hydroxypropylchitosan as an ingredient , but devoid of any active antifungal agent , and a reference nail lacquer from the us market ( penlac ®), containing ciclopirox 8 % as antifungal agent , and water , isopropanol , monoester resin as other ingredients . the reference solution differed from the test p - 3051 solution in that no chitosan was contained in the reference . overall , 467 patients were randomized in a 2 : 2 : 1 ratio among p - 3051 , reference product and placebo . they underwent a 4 - 8 week run in , 48 week treatment and 12 week follow up . among efficacy endpoints , conversion to negative of fungal culture , percentage of patients with ≧ 90 % clear nail , growth rate of healthy nail were measured during treatment and follow up . growth rate of healthy nail is a parameter in which contribution of both the antimycotic effect and the nail growth accelerating effect plays a specific role . as expected , the effect of p - 3051 and reference active treatments on mycological findings was similar , with about 90 % conversion to negative of fungal culture at end of treatment . the rate of conversion to negative of mycological culture was significantly lower ( 70 %) in placebo arm , and this result was also expected . the results in terms of nail growth rate are summarized in the table 1 . the market reference , containing 8 % ciclopirox , but not chitosan , had a continuous increase of growth of healthy nail , at 24 , 36 and 48 week of treatment . placebo , containing hydroxypropylchitosan , but not the active antifungal agent , showed also a continuous increase of growth of healthy nail , similar to that of the market reference . as it shall be appreciated , p - 3051 , containing both the chitosan and 8 % ciclopirox ( the active antifungal agent ), was definitely more active than market reference penlac ®, in healthy nail growth rate . it is concluded that the presence of chitosan derivative , having a direct effect on the nail growth rate , in the composition of p - 3051 , made according to the example 3 , improved the effect of the antimycotic agent in terms of growth of healthy nail . 1 . purified water 29 . 375 % 2 . ethanol 96 ° 70 . 0 % 3 . budesonide 0 . 025 % 4 . hydroxypropyl chitosan ( hpch ) 0 . 5 % 5 . peg - 40 hydrogenated castor oil 0 . 1 % the formulation is prepared as per the examples 1 and 3 , by adding hydroxypropyl chitosan as the final ingredient and stirring for 24 hours or until dissolution . 1 . propylene glycol 13 . 0 % 2 . isopropanol 82 . 497 % 3 . calcitriol 0 . 003 % 4 . ethyl acetate 4 . 0 % 5 . chitosan 0 . 5 % chitosan is dissolved in propylene glycol , then calcitriol previously dissolved in isopropanol is added . then ethyl acetate is added and the resulting mixture is stirred until dissolution . an open , comparative clinical study was performed to assess the nail growth accelerating efficacy of the solution according to the example 3 on the nails of 24 healthy male volunteers , aged 21 - 40 years ( mean 31 . 8 ± sd 4 . 6 yrs ) who gave their informed consent . in this experiment , the nail growth accelerating efficacy of the solution according to the example 3 was compared with that of a commercial nail lacquer ( loceryl - france ) as a reference , containing the following ingredients : amorolfine hcl 5 . 574 %, metachrilic acid copolymer , triacetine , buthyl acetate , ethyl acetate , ethanol . test and reference products were randomly self - applied to all fingernails of either hand for a period of 28 days . the test product was applied once daily by a brush ; the commercial reference was applied twice weekly as per the approved labelling , by using a spatula . both test and reference products were applied in the evening . before each test application the subjects were instructed to wash their hands with water and soap and dry accurately ; before each reference application the subjects had to remove the previous product layer with an isopropyl alcohol swab . the accelerating nail growth activity was assessed at the same timing and with the same method as per the example 2 . the obtained results showed that the test solution according to the example 3 determined a statistically significant increase ( student t test p & lt ; 0 . 01 vs t0 ) of nail growth speed corresponding to 34 % ( from a basal mean value of 0 . 094 mm / day to a final mean value of 0 . 126 ). on the contrary , the growth of the nails applied the reference nail lacquer did not significantly differ from baseline ( 0 . 104 mm / day ) to the end of the experiment ( 0 . 117 mm / day , not significant ). 1 . propylene glycol 13 . 0 % 2 . isopropanol 82 . 5 % 3 . ethyl acetate 4 . 0 % 4 . chitosan 0 . 5 % chitosan is dissolved in propylene glycol , then isopropanol and ethyl acetate are added and the resulting mixture is stirred until dissolution . an open , comparative clinical study was performed to assess the nail growth accelerating efficacy of the solution according to the example 8 on the nails of 6 healthy male volunteers , aged 22 - 40 years ( mean 32 . 2 ± sd 7 . 9 yrs ) who gave their informed consent . in this experiment , the nail growth accelerating efficacy of the solution according to the example 8 was randomly self - applied in the evening , before going to bed , to all fingernails of one hand for a period of 28 days . before each test application the subjects were instructed to wash their hands with water and soap and dry accurately . the accelerating nail growth activity was assessed at the same timing and with the same method as per the example 2 . untreated fingernails served as reference nails . the obtained results are summarized in fig1 . the test solution according to the example 8 determined a statistically significant increase ( student t test p & lt ; 0 . 01 vs to ) of nail growth speed by about 48 % ( from a basal mean value of 0 . 083 mm / day to a final mean value of 0 . 123 ). on the contrary the growth of the reference untreated nails did not significantly differ from baseline ( 0 . 087 mm / day ) to the end of the experiment ( 0 . 081 mm / day ). a liquid formulation having the following w / w % composition was prepared : 1 ) equisetum arvense ( horsetail ) glycolic extract 5 . 00 % 2 ) methylsulfonyl methane ( msm ) 5 . 00 % 3 ) ethyl alcohol 96 ° 36 . 50 % 4 ) diethyleneglycole monoethyletere 1 0 . 50 % 5 ) chitosan 1 . 00 % 6 ) purified water 52 . 00 % 1 transcutol ® p chitosan was dissolved in water after acidification with acetic acid at ph 3 . 0 . then , ethyl alcohol was added and the mix was stirred till to obtain a clear viscous solution . at this point , the ph rose till to 5 . 5 . diethyleneglycole monoethyletere , msm and the glycolic extract were added and mixed till to obtain a clear slightly viscous solution . the obtained formulation was a clear and yellow - pale solution , homogenous in appearance and slightly viscous . an open , comparative clinical study was performed to assess the nail growth accelerating efficacy of the solution according to the example 10 on the nails of 5 healthy female volunteers , aged 28 - 50 years , who gave their informed consent . in this experiment , the nail solution according to the example 10 was randomly self - applied in the evening , before going to bed , to all fingernails of one hand for a period of 28 days . during the whole study the subjects were requested not to apply nail polishes nor to undergo treatments that could interfere with the assessment of the results . the accelerating nail growth activity was assessed at the same timing and with the same method as per the example 2 . untreated fingernails served as reference nails . the obtained results are summarized in fig2 . the test solution according to the example 10 determined a statistically significant increase ( student t test p & lt ; 0 . 05 vs to ) of nail growth speed by 13 . 73 % ( from a basal mean value of 0 . 1085 mm / day to a final mean value of 0 . 1234 ). on the contrary the growth of the reference untreated nails did not significantly differ from baseline ( 0 . 1097 mm / day ) to the end of the experiment ( 0 . 1106 mm / day ).
the present invention is directed to the use of chitosan , a chitosan derivative or a physiologically acceptable salt thereof , to increase nail growth rate . the invention is further directed to the use of chitosans to accelerate nail growth rate during treatment of nail illnesses , nail dystrophy or other nail conditions , in order to shorten considerably the specific treatments of said nail illnesses , nail dystrophy or other nail conditions .