as described above , a number of taste masking coating compositions are known . none of these compositions , however , are fully satisfactory as complete taste masking combined with rapid release cannot be achieved using these compositions . therefore , the inventors believed there to be a need for a taste masking composition that can provide a dosage form that is both palatable and bioavailable . the inventors have satisfied the above needs by using coating compositions that includes a combination of ( i ) copolymers of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and ( ii ) polyvinyl alcohol - polyethylene glycol copolymer . surprisingly , the inventors have found that when combinations of these two polymers are used as taste masking coating compositions , the release rate of the medicament is increased and optimal results are observed with respect to taste masking and release of active components . moreover , the amount of acrylate and methacrylate copolymers with a quaternary ammonium group in combination with sodium carboxymethylcellulose required for coating can also be reduced , thereby , ensuring the safety and acceptability of the dosage form . copolymers of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose is available under the trade name eudragit rd 100 supplied by rohm gmbh , darmstadt . this copolymer provides ph independent , fast disintegrating films and coatings that are especially suitable for taste masking purposes . a disintegrant , sodium carboxymethylcellulose , is inherently present in the eudragit rd 100 and thereby facilitates the fast release of the medicament . polyvinyl alcohol - polyethylene glycol copolymers are commercially available under the trade name kollicoat ir and are marketed by basf corporation . this copolymer is highly soluble in water and is used as a covering or coating for instantaneous release in tablets . the inventors have found that the combination of these copolymers can be used to formulate an immediate release taste - masked pharmaceutical composition for oral administration . in such formulations , a core containing the bitter or unpleasant tasting drug is coated with a combination of ( i ) copolymers of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and ( ii ) polyvinyl alcohol - polyethylene glycol copolymer . the term “ immediate release ” as used herein means release of the medicament in the gastrointestinal tract within approximately one hour . as described in further detail below , the combination of the copolymers can be prepared as a general taste masking coating that can be applied to almost any medicament to mask the bitter or undesirable taste of the medicament without also delaying the availability of the medicament when consumed orally . further , a pharmaceutical composition using the combination of copolymers can be used in a method of treating , preventing or diagnosing a disease condition that includes orally administering a taste - masked pharmaceutical composition . as described in further detail herein , the pharmaceutical composition includes a core containing the bitter or otherwise unpleasant tasting drug . this drug containing or drug loaded core is coated with a combination of ( i ) copolymers of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and ( ii ) polyvinyl alcohol - polyethylene glycol copolymer . because of the taste masking , the pharmaceutical composition can be orally administered without the concern that the composition will be unpalatable . the drug - containing core may be selected from one or more of pharmaceutically inert insoluble materials , soluble material , and swellable materials . the insoluble inert cores may be , for example , sand ( i . e ., silicon dioxide ), glass , microcrystalline cellulose ( e . g ., celpheres ) or a plastic material ( e . g ., polystyrene ). the soluble inert cores may be a sugar selected from one or more of glucose , mannitol , lactose , xylitol , dextrose , sucrose and the like . the swellable inert cores may be , for example , hydroxypropyl methylcellulose or any other suitable swellable inert material . as described below , the drug is loaded on the core by coating or spraying of the taste masking coating composition . in addition to the above two copolymers , the coating composition also may contain lubricants that function as anti - sticking agents . these lubricants may be selected from talc , glyceryl monostearate , magnesium stearate , colloidal silica , other suitable lubricants , and mixtures thereof . the concentration of lubricant in the composition may be up to 10 % of the dry weight of the taste masking coating composition . the taste masking coating composition can be prepared in numerous ways . for example , the polyvinyl alcohol - polyethylene glycol copolymer may be dispersed in purified water under stirring to form a solution . eudragit then is dispersed in the solution under constant stirring . talc next is added and the stirring is continued for approximately twenty minutes . following this stirring , the coating suspension is filtered through a 250 micron nylon cloth . this coating composition then can be applied to taste mask bitter medicaments by using any suitable procedure , such as spray coating , pan coating , fluidized bed coating , etc . in the coating procedure , the bitter , unpleasant tasting active ingredient can be directly coated with the coating composition . alternatively , a drug loaded core can be coated with the taste masking coating suspension in a fluid bed processor to obtain the desired taste masked product . as described above , the taste masking coating may be a combination of ( i ) copolymers of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and ( ii ) polyvinyl alcohol - polyethylene glycol copolymer . the copolymer of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and polyvinyl alcohol - polyethylene glycol copolymer may be present in a ratio of about 1 : 2 to about 1 : 3 , although formulations that are either below or above this range also are contemplated . the concentration of methacrylate - acrylate copolymer may be used at about 20 % w / w to about 30 % w / w and polyvinyl alcohol - polyethylene glycol copolymer at about 65 % w / w to about 75 % w / w of the total taste masking coating composition . the coating composition may be used to mask the taste of any category of bitter drugs . for example , the drug can be selected from alkaloids , antacids , analgesics , anabolic agents , anti - anginal drugs , anti - allergy agents , anti - arrhythmia agents , antiasthmatics , antibiotics , anticholesterolemics , anticonvulsants , anticoagulants , antidepressants , antidiarrheal preparations , anti - emetics , antihistamines , antihypertensives , anti - infectives , anti - inflammatories , antilipid agents , antimanics , anti - migraine agents , antinauseants , antipsychotics , antistroke agents , antithyroid preparations , anabolic drugs , antiobesity agents , antiparasitics , antipsychotics , antipyretics , antispasmodics , antithrombotics , antitumor agents , antitussives , antiulcer agents , anti - uricemic agents , anxiolytic agents , appetite stimulants , appetite suppressants , beta - blocking agents , bronchodilators , cardiovascular agents , cerebral dilators , chelating agents , cholecystekinin antagonists , chemotherapeutic agents , cholesterol reducing agents , cognition activators , contraceptives , coronary dilators , cough suppressants , cns drugs , decongestants , diabetes agents , diuretics , emollients , enzymes , erythropoietic drugs , expectorants , fertility agents , fungicides , gastrointestinal agents , growth regulators , hormone replacement agents , hyperglycemic agents , hypoglycemic agents , ion - exchange resins , laxatives , migraine treatments , mineral supplements , mucolytics , narcotics , neuroleptics , neuromuscular drugs , non - steroidal anti - inflammatories ( nsaids ), nutritional additives , peripheral vasodilators , polypeptides , prostaglandins , psychotropics , renin inhibitors , respiratory stimulants , sedatives , steroids , stimulants , sympatholytics , thyroid preparations , tranquilizers , uterine relaxants , vaginal preparations , vasoconstrictors , vasodilators , vertigo agents , vitamins , wound healing agents , and others . the analgesics may be such specific drugs as acetaminophen , aspirin , ibuprofen , naproxen , and ketoprofen . the antibiotics may be such specific drugs as cefuroxime axetil , cefpodoxime proxetil , ciprofloxacin , erythromycin , and clarithromycin . the gastrointestinal drugs may be such drugs as loperamide , famotidine , ranitidine , cimetidine and salts thereof . the cardiovascular agents may be such drugs as irbesartan , captopril , lisinopril and salts thereof . the cns drugs may be such drugs as nefazodone , buspirone and salts thereof . the antihistamines may be such drugs as chlorpheniramine and astemizole . the cholesterol reducing agents may be such drugs as statins , e . g ., atorvastatin , simvastatin , pravastatin , and lovastatin . all of these general classes of drugs and the specific drugs are expected to be capable of taste masking using the coating composition described herein . the coated core can be formulated as sprinkles , dry powder , suspension , emulsion , or as whole a chewable or dispersible tablet , or any other suitable oral dosage forms , including conventional tables and capsules . coating additives may be selected from one or more of plasticizers , coloring agents and gloss producers . the plasticizer may be selected from one or more of diethyl phthalate , dibutyl phthalate , triethyl citrate and polyethylene glycol . the coating composition also can be applied to a whole dosage form and thereby conceal the bitter taste of the medicament contained within . the following examples are provided merely to illustrate embodiments of the invention and are not intended to limit the scope of the invention . 1 . microcrystalline cellulose beads 190 . 0 mg 2 . cefpodoxime proxetil ( equivalent to 100 mg 142 . 4 mg cefpodoxime ) 3 . hydroxypropyl methylcellulose 40 . 0 mg 4 . hydroxy propyl cellulose 20 . 0 mg 5 . croscarmellose sodium 15 . 6 mg 6 . purified water qs 7 . isopropyl alcohol qs 1 . drug loaded beads 410 . 0 mg 2 . eudragit rd 100 25 . 0 mg 3 . kollicoat ir 68 . 5 mg 4 . talc 6 . 5 mg 5 . water qs 1 . drug coated , taste mask coated beads 510 . 0 mg 2 . fruit gum flavor 15 . 0 mg 3 . frescofort flavor 15 . 0 mg 4 . colloidal silicon dioxide 17 . 5 mg 5 . carrageenan 30 . 0 mg 6 . microcrystalline cellulose 10 . 0 mg 7 . sodium citrate 5 . 0 mg 8 . citric acid ( anhydrous ) 3 . 0 mg 9 . ferric oxide ( yellow ) 0 . 05 mg 10 . sucrose 2994 . 45 mg a liquid suspension of cefpodoxime proxetil and the combination of binders in water was prepared . frothing was minimized using a small volume of isopropyl alcohol . the liquid suspension was sprayed onto the microcrystalline cellulose beads ( mcc beads ) and dried to provide core beads using a fluid bed processor . the core beads then were screened to remove fines and agglomerates . the core beads were coated again with a taste masking coating ( eudragit rd 100 , kollicoat ir , talc , and water ) and dried in a fluid bed processor . the coated beads were sifted to remove fines and agglomerates . the coated beads were mixed with the various remaining ingredients to form the composition of the dry suspension . the final composition was optionally encapsulated . the in - vitro dissolution release profile of the cefpodoxime proxetil from the dry suspension of example 1 was determined in accordance with the procedure described in pharmacopoeial forum , vol . 23 , number 4 , july - august 1997 , pages 4388 - 4392 . in the procedure a weight equivalent to 5 ml suspension was added to 900 ml of glycine buffer ( ph 3 . 0 ) to form a solution . in this procedure , apparatus 2 with stirring at 75 rpm is used . aliquots of 5 ml of the solution were taken at 15 , 30 and 45 minutes and analyzed spectrophotometrically at a wavelength of 259 nm . the results of the dissolution testing are provided below in table 1 . as can be seen in table 1 , greater than 60 % of the drug is released in 15 minutes , greater than 80 % of the drug is released in 30 minutes , and greater than 90 % of the drug is released in 45 minutes . hydroxypropyl methylcellulose , hydroxypropyl cellulose and croscarmellose sodium were dispersed in purified water under stirring . cefpodoxime proxetil then was dispersed in the above mixture under constant stirring . isopropyl alcohol was added and stirring was continued for thirty minutes . next , microcrystalline cellulose beads were coated with this cefpodoxime proxetil dispersion in a fluid bed processor to form granules . the granules were dried until a limit of detection ( lod ) of nmt 4 . 0 % at 105 ° c . ( on ir balance ). the dried pellets were coated with the taste masking coating suspension in a fluid bed processor to achieve pellets of the desired product . the in - vitro dissolution release of drug from the pellets of example 2 was determined in accordance with the procedure described in pharmacopoeial forum , vol . 23 , number 4 , july - august 1997 , pages 4388 - 4392 . a 0 . 510 gm sample of the coated pellets was added to 900 ml of glycine buffer ( ph 3 . 0 ) to form a solution . in this procedure , apparatus 2 with stirring at 75 rpm is used . aliquots of 5 ml of the solution were taken at 15 , 30 and 45 minutes and analyzed spectrophotometrically at a wavelength of 259 nm . the results of the dissolution testing are provided below in table 2 . as can be seen in table 2 , greater than 70 % of the drug is released in 15 minutes , greater than 85 % of the drug is released in 30 minutes , and greater than 95 % of the drug is released in 45 minutes . while several particular forms of the inventions have been described , it will be apparent that various modifications and combinations of the inventions detailed in the text can be made without departing from the spirit and scope of the inventions . further , it is contemplated that any single feature or any combination of optional features of the inventive variations described herein may be specifically excluded from the claimed inventions and be so described as a negative limitation . accordingly , it is not intended that the inventions be limited , except as by the appended claims .
the present invention relates to coating compositions for taste masking and methods for applying the coating compositions to dosage forms to mask the taste of a medicinal substance . the taste masking coating compositions generally include a copolymer of acrylate and methacrylate with a quaternary ammonium group in combination with sodium carboxymethylcellulose and a polyvinyl alcohol - polyethylene glycol copolymer .