alcohols used in the formulation experiments were ethanol 99 . 9 % (“ etoh ”, vwr ), 2 - propanol hplc grade (“ ipa ”, rathburn ), glycerol 99 . 5 % (“ gro ”, vwr ) and 1 , 2 - propanediol , ph . eur . (“ pd ”, fluka / sigma - aldrich ). the materials used in the formulation experiments were provided by the following suppliers : dow corning corp ., midland , mich ., usa ; lipoid gmbh , ludwigshafen , germany ; aarhus karlshamn sweden ab , karlshamn , sweden ; ltp lipid technologies provider ab , karlshamn , sweden ; swedish oat fiber ab , väröbacka , sweden ; sigma - aldrich , st . louis , mo ., usa ; croda , goole , east yorkshire , uk ; rathburn chemicals ltd , walkerburn , scotland , uk ; vwr international ab , spånga , sweden ; polypeptide laboratories a / s , hillerød , denmark ; dermagen ab , lund , sweden . the phospholipid was dissolved in absolute ethanol at a concentration of 50 . 0 % ( w / w ). complete dissolution of the phospholipid was promoted by short ultrasonication in a bath - type sonicator at about 40 ° c . to a pre - weighed amount of lidocaine and lidocaine hydrochloride , respectively , was added the ethanolic phospholipid solution . the mixtures were gently heated and sonicated until clear solutions had been formed . the solutions were diluted with volatile silicone oil to obtain light brown to yellow solutions , which were stored in air - tight glass vials at room temperature . the appearance of compositions ( compositions a and b ) was unchanged for more than a month at room temperature . no signs of phase separation or precipitation and subsequent sedimentation were observed . this indicates excellent physical stability . a pre - weighed amount of benzocaine was dissolved in a 50 % ( w / w ) ethanolic phospholipid , prepared as described in example 1 . the solution was diluted with the volatile silicone oil . the resulting clear , light brown to yellow solution was stored in an air - tight glass vial at room temperature . the appearance of the composition ( composition c ) was unchanged for more than a month at room temperature . no signs of phase separation or precipitation and subsequent sedimentation were observed , which indicates excellent physical stability . to a pre - weighed amount of deet was added 50 % ( w / w ) ethanolic phospholipid prepared as described in example 1 . the obtained clear solution was diluted with the volatile silicone oil . the resulting clear , light brown to yellow solution was stored in an air - tight glass vial at room temperature . the appearance of the composition ( composition d ) was unchanged for more than a month at room temperature . no signs of phase separation or precipitation and subsequent sedimentation were observed , which indicates excellent physical stability . three compositions ( e , f , g ) were prepared . to pre - weighed amounts of econazole nitrate was added 50 % ( w / w ) ethanolic phospholipid prepared as described in example 1 . after treatment in a bath - type sonicator at about 37 ° c ., the obtained clear golden brown solutions were diluted with the volatile silicone oil . the resulting clear , light golden brown solutions were stored in air - tight glass vials at room temperature . composition f was prepared by diluting a portion of composition e with volatile silicone oil . the appearance of compositions e and f changed within a few days ( slight sedimentation was observed in both samples ) and therefore cannot be considered stable . on the other hand , the appearance of composition g was unchanged for more than a month at room temperature . no signs of phase separation or precipitation and subsequent sedimentation were observed , indicating excellent physical stability . three compositions ( h , i , j ) were prepared . to pre - weighed amounts of betamethasone 17 - valerate was added 50 % ( w / w ) ethanolic phospholipid prepared as described in example 1 . after treatment in a bath - type sonicator at about 37 ° c ., clear golden brown solutions were obtained . the solutions were diluted with the volatile silicone oil and the resulting mixtures stored in air - tight glass vials at room temperature . composition i was prepared by diluting a portion of composition h with volatile silicone oil . composition i was unstable since it formed immediately a milky dispersion , which separated within a few days . compositions h and j formed clear , light golden brown solutions . they showed no signs of phase separation or precipitation and subsequent sedimentation after storage for one month at room temperature . this indicates excellent physical stability . to a pre - weighed amount of cyclosporin a was added a 50 % ( w / w ) ethanolic phospholipid solution , prepared as described in example 1 . after treatment in a bath - type sonicator at about 35 ° c ., a clear solution was obtained . the solution was diluted with the volatile silicone oil to form a clear , light brown to yellow solution , which was stored in an air - tight glass vial at room temperature . the appearance of the composition ( composition k ) was unchanged for more than a month at room temperature . no signs of phase separation or precipitation and subsequent sedimentation were observed . this indicates excellent physical stability . three compositions ( m , n , o ) were prepared . to pre - weighed amounts of minoxidil was added a 33 % ( w / w ) ethanolic phospholipid solution , ethanol , and 50 % ( w / w ) ethanolic phospholipid . after treatment in a bath - type sonicator at about 35 ° c ., the resulting mixtures were diluted with the volatile silicone oil and stored in air - tight glass vials at room temperature . the appearance of composition o stayed unchanged for more than two months at room temperature , i . e ., no signs of phase separation or precipitation and subsequent sedimentation were observed . this indicates excellent physical stability . composition m did not show complete dissolution of minoxidil , whereas composition n started to precipitate shortly after preparation . thus compositions m and n did not meet the criteria of one - month stability when stored in a closed container at room temperature . presented in table 3 are miscibility data of ethanolic phospholipid solutions with either volatile silicone oil or water . the mixtures with a low content of pl / ethanol in the silicone oil had a clear appearance immediately after preparation , but separated within a month at room temperature . the composition with a concentration of pl / ethanol of 20 % was miscible with the volatile silicone oil , did not change in appearance during this time period and can thus be considered to be physically stable . the phospholipid of table 1 is lipoid s75 manufactured by lipoid gmbh , ludwigshafen , germany . this phospholipid material from soybean contains about 68 - 73 % of phosphatidyl choline ( pc ). other suitable phospholipid materials are , for example , lipoid s45 , phospholipon 50 , and lipoid s100 , all made from soybean and manufactured by lipoid gmbh , covering a range of pc content of about 50 % up to 100 % further suitable phospholipids are the synthetic dioleyl phosphatidylcholine ( dopc ), dimyristyl phosphatidylcholine ( dmpc ), and dipalmitoyl phosphatidylcholine ( dppc ). fig1 illustrates an exemplary phase diagram of the ternary system of the polar lipid carrier composition of the invention : polar lipid ( lipoid s75 )/ c 2 - c 4 alcohol ( ethanol )/ silicone oil ( dc 345 ). incorporation of small amounts of a pharmacologically or cosmetically active agent of the invention or of a protective agent of the invention will only insignificantly affect the area of stability . carrier composition cc consisting of 40 % by weight of polar lipid lipoid s75 , 30 % by weight of ethanol and 30 % by weight of silicone oil dc 345 is an example of a stable carrier composition . phospholipid was dissolved in mixtures of dc 345 volatile silicone oil and alcohol . the lipid was accurately weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless or slightly yellow liquid was obtained . table 4a shows examples of compositions based on phosphatidyl cholines and table 4b compositions based on phosphatidyl ethanolamines . commercially available monoglyceride products are mixtures of monoacyl -, diacyl - and small amounts of triacylglycerols . the acylglycerol products were dissolved in mixtures of dc 345 volatile silicone oil and alcohol . the lipid was accurately weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless liquid was obtained . table 5 shows examples of compositions based on acylglycerols . compositions comprising cholesterol were prepared by mixing with dc 345 volatile silicone oil and alcohol . the lipid was accurately weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless liquid was obtained . table 6 shows examples of compositions based on cholesterol . two examples of galactolipid rich materials were used to prepare mixtures with dc 345 volatile silicone oil and alcohols . the lipid was accurately weighed and mixed with silicone oil and alcohols . the mixture was gently agitated at 40 ° c . until a homogenous , clear and slightly yellow to brownish yellow liquid was obtained . table 7 shows examples of compositions based on galactolipid rich lipids . the ability to combine lipids with different properties in volatile silicon oil / alcohol mixtures was tested . the lipid materials were accurately weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless or slightly yellow liquid was obtained . table 8 shows examples of compositions based on various combinations of lipids . commercially available lecithin products are in mixtures of polar lipids ( mainly phospholipids ) and non - polar lipids ( mainly triglycerides ). the materials used in the following examples are all obtained from soy beans and contain phosphatidyl choline as the main polar lipid . the lipid was accurately weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and yellow or brownish yellow liquid was obtained . table 9 shows examples of compositions based on lecithins . the possibility to use different volatile silicone oils was tested by replacing dc 345 by two other silicone oils , dc 245 and dc 246 . the lipid was weighed and mixed with silicone oil and alcohol . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless liquid was obtained . table 10 shows examples of compositions comprising dc 245 and dc 246 . the possibility to add small amounts of water to the vehicles of the invention was tested . the lipid was accurately weighed and mixed with silicone oil and alcohol . a small amount of water and optionally isopropanol was added . the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless or brownish yellow liquid was obtained . table 11 shows examples of compositions with small amounts of water . accurately weighed amounts of the peptide dpk - 060 were dissolved in mixtures of lipid , glycerol , 1 , 2 - propanediol and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless to brownish yellow liquid was obtained . table 12 presents representative examples of dpk - 060 compositions . accurately weighed amounts of the peptide ll - 37 were dissolved in mixtures of lipid , glycerol and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and slightly yellow to brownish yellow liquid was obtained . table 13 presents representative examples of ll - 37 compositions . accurately weighed amounts of oxytocin were dissolved in mixtures of lipid , glycerol and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and optionally isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless to brownish yellow liquid was obtained . table 14 presents representative examples of oxytocin compositions . an accurately weighed amount of hydrocortisone was dissolved in a mixture of lipid and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and yellow liquid was obtained . table 15 presents a representative example of hydrocortisone compositions . an accurately weighed amount of dihydroxyacetone was dissolved in a mixture of lipid and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and yellow liquid was obtained . table 16 presents a representative example of dihydroxyacetone compositions . an accurately weighed amount of lidocaine was dissolved in a mixture of lipid and ethanol at 40 ° c . under agitation . silicone oil ( dc 345 ) and optionally isopropanol was added and the mixture was gently agitated at 40 ° c . until a homogenous , clear and colourless to yellow liquid was obtained . table 17 presents representative examples of lidocaine compositions . three lipid layer forming compositions of the invention termed a , b , c ( table 18 ) were tested for their effect on transepidermal water loss ( tewl ) from a skin surface . their effect was compared with that of white vaseline ( aco hud , sweden ), a conventional agent for tewl . the compositions were applied to the skin of ten healthy individuals , 5 women and 5 men ; mean age 34 years , sd 18 years , who showed no evidence of skin disease . prior to application , the volar aspects of their forearms were rapidly cleansed with paper tissue soaked in pure alcohol . five rectangular areas of 2 × 2 cm were marked on the volar forearm with a pencil and measured for basal tewl . the compositions and vaseline were applied to the areas in a randomized manner ; one of the areas was left as an untreated control . two dosages were studied , 3 μl / cm 2 and 6 μl / cm 2 . vaseline was used in half of the amount , i . e . 1 . 5 μl / cm 2 and 3 μl / cm 2 . the high dose was applied on the right forearm , and the low dose on the left forearm . the products were dispensed onto the surface by means of a displacement micro - pipette ( gilson ). the compositions were applied in small droplets onto the area ; evaporation was facilitated by slightly blowing at the surface . vaseline was spread by fingertip . tewl was measured before application and 30 min after application by use of dermalab equipment ( open chamber ; cortex technology , hadsund , denmark ). the recorded reduction of transepidermal water loss is shown in fig2 . the composition 1 of the invention was comparable in effect to vaseline while compositions 2 and 3 of the invention exerted no significant effect on tewl .
a lipid layer forming composition comprises a volatile silicone oil of a boiling point above 180 ° c ., a polar lipid , optionally a c 2 - c 4 aliphatic alcohol , optionally a pharmacologically or cosmetically active agent or a protective agent . the lipid layer forming composition can be applied to a biological surface by spraying , dipping or brushing to form a stable polar lipid layer on the surface .