according to the present invention , it has now been found that important advantages and improvements over prior art compositions and pharmaceutical presentation forms containing nicotine and methods of topical application thereof can be obtained by admixture with an uncrosslinked , water - insoluble vinylpyrrolidone copolymer . water - insoluble copolymers of vinylpyrrolidone , which can be used in the practice of this invention , may be prepared by the copolymerization of vinylpyrrolidone with one or more appropriate comonomers in the proportions which yield water - insoluble , uncrosslinked copolymers . suitable comonomers include acrylic esters , methacrylic esters , vinyl esters , crotonic esters , vinyl ethers , maleic half esters and diesters , vinylene carbonate , styrene , allyl esters , allyl ethers , etc . other comonomers which are capable of copolymerizing with vinylpyrrolidone and are well known to those skilled in the art may also be used . toxicological considerations restrict the choice of monomers to those which yield copolymers having a demonstrated lack of toxicological side - effects on topical application to the skin , good drug compatibility , good adhesion to the skin and film - forming properties . the acrylic , methacrylic , crotonic and maleic esters which may be used in the preparation of the water - insoluble vinylpyrrolidone copolymers which are effective in the practice of the present invention , include the esters of c 1 - c 40 linear , branched or cyclic alkanols , aralkanols , phenols and substituted phenols . the co - polymers of vinylpyrrolidone and the acrylic , methacrylic , crotonic and maleic esters may be made by copolymerization of vinylpyrrolidone with the appropriate ester or by esterification of copolymers of vinyl ˜ pyrrolidone and acrylic , methacrylic , crotonic and maleic acid or anhydrides , with the appropriate hydroxylcontaining compound ˜ unesterified carboxylic acid functionality may be retained in the copolymer . the vinyl esters and allyl esters which may be used in the preparation of the water - insoluble vinylpyrrolidone copolymers which are useful in the practice of this invention , include the esters of c 1 - c 40 linear , branched or cyclic aliphatic , araliphatic or aromatic carboxylic acids . the copolymers of vinylpyrrolidone and the vinyl esters may be prepared by copolymerization of vinylpyrrolidone with the appropriate vinyl ester or by transesterification of copolymers of vinylpyrrolidone and vinyl acetate or other vinyl esters or by esterification of hydrolyzed copolymers of vinylpyrrolidone and vinyl acetate or other vinyl esters . the copolymers of vinylpyrrolidone and allyl esters may also be prepared either by direct copolymerization or by transesterification or esterification , analogous to the preparation of vinyl ester copolymers with vinylpyrrolidone . graft copolymers made by grafting vinyl monomers onto polyvinylpyrrolidone may also be used , e . g . graft copolymers of polyvinylpyrrolidone with acrylic esters , methacrylic esters , styrene , vinyl acetate and the like . the water - insoluble copolymers of vinylpyrrolidone which be used in the practice of the present invention , may be prepared by any of the conventional methods known in the art , including bulk , solution , emulsion , suspension or dispersion polymerization , with appropriate free radical catalysts such as peroxygen compounds , azo compounds , redox systems , radiation and other catalytic techniques for initiating free radical polymerization . since the method of polymerization is not an integral part of the practice of the present invention , any suitable method known to those skilled in the art may be used . the amount of one or more comonomers in the water - insoluble vinylpyrrolidone copolymers which are useful in the practice of the present invention may be varied from 20 % to 80 % by weight . the actual amount is determined by the nature of the comonomer and the concentration necessary to produce a water - insoluble copolymer . the drug used in the practice of the present invention may be nicotine or its salts and also cotinine . the preferred drug is nicotine . the compositions described in this application are particularly effective as aids in smoking - cessation programs . they can also be potentially useful in the treatment of attention deficit hyperactive disorder , tourette &# 39 ; s syndrome , schizophrenia , anxiety and depression . the nicotine compositions which are useful in the practice of the present invention and provide sustained release of the drug , may be prepared by dissolving or dispersing the water - insoluble vinylpyrrolidone copolymer in a solvent such as ethanol , isopropanol , vegetable oils and petrolatum and admixing the polymer solution or dispersion with nicotine . the solution , or dispersion , of the uncrosslinked water - insoluble vinylpyrrolidone copolymer and nicotine , in the presence or absence of an excipient , may be cast on a suitable surface and the solvent evaporated under ambient pressure or in vacuo , at ambient or slightly elevated temperature . the resultant film on the substrate surface or after removal from the substrate , contains nicotine and may be cut into strips or tapes which can be affixed to the skin of a patient for sustained release of the medicament . the solution or dispersion of uncrosslinked , water - insoluble vinylpyrrolidone copolymer and nicotine may be applied directly to the skin of the patient and permitted to evaporate to form a film thereon , containing nicotine . the latter is slowly released from the film and absorbed into the skin of the patient . a gel or thickened solution of nicotine and water - insoluble vinylpyrrolidone copolymer may be applied with greater control to a restricted area of skin than a low viscosity solution . the solution may be thickened by the addition of a small amount of a soluble high molecular weight natural or synthetic thickener or a cellulose derivative thickener of the type well known to those skilled in the art . high surface area inorganic materials such as finely divided fumed silica are also effective thickeners . the addition of a small amount of such a material results in a marked increase in the viscosity of the solution . the resultant gel or thickened solution is thixotropic and flows readily during application but does not run after application to the skin . the large surface area of the silica thickener increases the rate of evaporation of the solvent and contributes to rapid drying and film formation . nicotine in the formulation is slowly released and absorbed into the skin of the patient . at the end of the treatment time , the film may be removed by washing with soap and water . the gel or thickened solution may be applied to the skin in a pre - measured amount from a tube , a roll - on dispenser , a graduated spatula or via a dosifying pump . the solution of nicotine and water - insoluble vinylpyrrolidone copolymer in ethanol may be pressurized in an aerosol can and nicotine may be conveniently applied to the skin using an aerosol formulation containing one or more low boiling propellants . in order to control the amount of polymer and nicotine applied to the skin , it is advantageous to use a metering valve which delivers precise quantities of solution . when applied in this manner , the propellant and solvent quickly evaporate leaving a dry film of controlled nicotine content covering the desired area of skin . a solution or dispersion of uncrosslinked , water - insoluble vinylpyrrolidone copolymer and nicotine , in the absence or presence of an excipient , may be applied to a porous or open - structured substrate such as gauze , bandage tissue or paper , and upon evaporation of the solvent , provides an impregnated structure containing nicotine , which is released over an extended period of time when applied topically to the skin of a patient . the solution or dispersion of water - insoluble vinylpyrrolidone copolymer and nicotine may be mixed , with stirring , with one or more ointment bases , such as petrolatum , vasoline , lanolin , stearin , spermaceti wax or other waxy or fatty material . the ointment may be applied directly to the skin of a patient or may be coated on a carrier such as a bandage or polymeric tape for topical application to the skin of a patient . the nicotine is slowly released and absorbed into the skin of the patient over an extended period of time . although the vinylpyrrolidone copolymer is water - insoluble , the hydrophilicity of the vinylpyrrolidone units contained therein results in moisture absorption , e . g . from perspiration on the skin of the patient , and facilitates release of the nicotine from the composition into the skin . the rate of release may be varied over a wide range and is dependent upon the percentage of vinylpyrrolidone in the copolymer and the ratio between the copolymer and nicotine . the concentration of water - insoluble vinylpyrrolidone copolymer and nicotine in the compositions of the present invention , may be varied over a wide range , depending upon the desired release rate . the nicotine concentration may range from about 0 . 1 % to about 10 % of the total weight of the composition , while the concentration of the water - insoluble vinylpyrrolidone copolymer may range from about 3 to about 20 % of the weight of the formulation . the following examples are non - limiting illustrative embodiments of the compositions and methods of the present invention . variations thereof will be obvious to those skilled in the art . the emulsion copolymerization of 66 . 7 parts of n - 30 vinylpyrrolidone ( vp ) and 28 . 6 parts of lauryl methacrylate ( lm ) was carried out in 200 parts of water containing 5 parts of sodium stearate and 1 . 25 parts of 30 % hydrogen peroxide as catalyst . the mixture was heated with stirring and the polymerization was carried out at 75 ° c . for about 10 hours . the conversion was 92 %. the emulsion was spray dried at about 210 ° c . to yield a fine , off - white powder . the nitrogen content of the copolymer was 8 . 6 %, indicating a vp content of 68 %. an emulsion polymerization was carried out using the following ingredients , in parts by weight : in this formulation ammonium stearate is the emulsifier although other emulsifiers may be used . all the ingredients , except the sodium metabisulfite solution , were charged into a stainless steel reactor equipped with heating jacket , condenser and mechanical stirrer . the bisulfite solution was added slowly over 5 hours while maintaining the temperature at 75 ° c . with stirring . the reaction was then continued with stirring for an additional 4 hours at 75 ° c . and then the emulsion was allowed to cool to room temperature . the solids content was 32 . 5 %, representing 94 % conversion . the emulsion was diluted to 20 % solids and spray dried at 210 ° c . to yield a fine off - white powder which had a nitrogen content of 8 . 7 %, equivalent to a vp content of 69 %. after completing the reaction and drying , as described in example ii , the material had a nitrogen content of 8 . 3 %, as shown by the kjeldahl method , equivalent to a vp content of 65 . 8 %. the completion of the reaction was checked by the free monomers content , which was : vinyl pyrrolidone 0 . 22 % free monomer and lauryl methacrylate also 0 . 22 % free monomer , both determined by gas chromatography . a gel base was prepared by vigorously mixing the following ingredients ( in parts by weight ): the resultant gel had a viscosity of 12 , 000 cps and a specific gravity of 0 . 8 . to 40 g of gel of example iv were added 140 mg of nicotine . mixed thoroughly to obtain a composition containing 3 . 5 mg / g ( 2 . 8 mg / ml ). this composition was used for pharmacokinetic trials with rats . 30 sprague dawley male rats weighing approximately 250 g . were used in a pharmacokinetic trial . to each animal were applied daily 0 . 3 ml ( 0 . 24 g ) of the gel , containing 0 . 84 mg nicotine , on a shaved area of the back . blood samples were taken and plasma levels of cotininine were determined . cotinine is a stable metabolite of nicotine , easy to detect , and present at a concentration of 10 times the concentration of nicotine . it is used as a standard marker for the drug . in the case of the present test , made over a period of 96 hours , average cotinine levels in the plasma of the animals were around 200 ng / ml , equivalent to approximately 20 ng / ml of nicotine . typically concentrations of nicotine in plasma start being significant shortly after application . they achieve a maxima at around 6 hours after application and gradually decrease after 24 hours , when a new application is due . thus in another trial made with 45 rats , similarly to the one described in example iv , but over a period of 5 days , concentrations of cotinine in the plasma on the fourth day of the trial were as shown are in the table below : to 49 g . of a gel base prepared as per example iv were added 1 . 75 g . of nicotine to obtain a composition containing 35 mg / g ( 28 mg / ml ) of the drug . this was used in a pilot clinical test using three healthy volunteers . one a heavy smoker , one a a light smoker and one a non - smoker . the smokers were requested to abstain from smoking for at least 4 days before the trial . on each volunteer 0 . 5 ml of the gel , containing 14 mg . nicotine , was applied at 8 a . m . urine samples were taken before application and subsequently at four and 24 hours : it can be seen that the heavy smoker did not comply and had smoked during the wash off period , but the test proves that the transdermal composition has a long acting effect . the light smoker and non - smoker show moderate levels of nicotine in the urine .
a composition containing nicotine and an uncrosslinked , water - insoluble vinylpyrrolidone copolymer is applied on the skin of patients in the form of a gel , ointment , solution , suspension or film which slowly releases nicotine and creates levels of the drug in the blood to reduce nicotine - craving in smokers , thereby assisting in smoking - cessation programs .