Patent Abstract:
a multiple pulsed dose drug delivery system for pharmaceutically active amphetamine salts , comprising an immediate - release component and an enteric delayed - release component wherein the enteric release coating has a defined minimum thickness and / or there is a protective layer between the pharmaceutically active amphetamine salt and the enteric release coating and / or there is a protective layer over the enteric release coating . the product can be composed of either one or a number of beads in a dosage form , including either capsule , tablet , or sachet method for administering the beads .

Detailed Description:
the present invention comprises a core or starting seed , either prepared or commercially available product . the cores or starting seeds can be sugar spheres ; spheres made from microcrystalline cellulose and any suitable drug crystals . the materials that can be employed in making drug - containing pellets are any of those commonly used in pharmaceutics and should be selected on the basis of compatibility with the active drug and the physicochemical properties of the pellets . the additives except active drugs are chosen below as examples : binders such as cellulose derivatives such as methylcellulose , hydroxyethyl cellulose , hydroxypropyl cellulose , hydroxypropyl methylcellulose , polyvinylpyrrolidone , polyvinylpyrrolidone / vinyl acetate copolymer and the like . disintegration agents such as corn starch , pregelatinized starch , cross - linked carboxymethylcellulose ( ac - di - sol ®), sodium starch glycolate ( explotab ®), cross - linked polyvinylpyrrolidone ( plasdone xl ®), and any disintegration agents used in tablet preparations . filling agents such as lactose , calcium carbonate , calcium phosphate , calcium sulfate , microcrystalline cellulose , dextran , starches , sucrose , xylitol , lactitol , mannitol , sorbitol , sodium chloride , polyethylene glycol , and the like . surfactants such as sodium lauryl sulfate , sorbitan monooleate , polyoxyethylene sorbitan monooleate , bile salts , glyceryl monostearate , pluronic ® line ( basf ), and the like . solubilizers such as citric acid , succinic acid , fumaric acid , malic acid , tartaric acid , maleic acid , glutaric acid sodium bicarbonate and sodium carbonate and the like . stabilizers such as any antioxidation agents , buffers , acids , and the like , can also be utilized . a . extrusion - spheronization — drug ( s ) and other additives are granulated by addition of a binder solution . the wet mass is passed through an extruder equipped with a certain size screen . the extrudates are spheronized in a marumerizer . the resulting pellets are dried and sieved for further applications . b . high - shear granulation — drug ( s ) and other additives are dry - mixed and then the mixture is wetted by addition of a binder solution in a high shear - granulator / mixer . the granules are kneaded after wetting by the combined actions of mixing and milling . the resulting granules or pellets are dried and sieved for further applications . c . solution or suspension layering — a drug solution or dispersion with or without a binder is sprayed onto starting seeds with a certain particle size in a fluid bed processor or other suitable equipment . the drug thus is coated on the surface of the starting seeds . the drug - loaded pellets are dried for further applications . for purposes of the present invention , the core particles have a diameter in the range of about 50 - 1500 microns ; preferably 100 - 800 microns . these particles can then be coated in a fluidized bed apparatus with an alternating sequence of coating layers . the core may be coated directly with a layer or layers of at least one pharmaceutically active amphetamine salts and / or the pharmaceutically active amphetamine salt may be incorporated into the core material . pharmaceutical active amphetamine salts contemplated to be within the scope of the present invention include amphetamine base , all chemical and chiral derivatives and salts thereof ; methylphenidate , all chemical and chiral derivatives and salts thereof ; phenylpropanolamine and its salts ; and all other compounds indicated for the treatment of attention deficit hyperactivity disorder ( adhd ). a protective layer may be added on top of the pharmaceutical active containing layer and also may be provided between active layers . a separation or protective layer may be added onto the surface of the active - loaded core , and then the enteric layer is coated thereupon . another active layer may also be added to the enteric layer to deliver an initial dose . a protective coating layer may be applied immediately outside the core , either a drug - containing core or a drug - layered core , by conventional coating techniques such as pan coating or fluid bed coating using solutions of polymers in water or suitable organic solvents or by using aqueous polymer dispersions . suitable materials for the protective layer include cellulose derivatives such as hydroxyethyl cellulose , hydroxypropyl cellulose , hydroxypropyl methylcellulose , polyvinylpyrrolidone , polyvinylpyrrolidone / vinyl acetate copolymer , ethyl cellulose aqueous dispersions ( aquacoat ®, surelease ®), eudragit ® rl 30d , opadry ® and the like . the suggested coating levels are from 1 to 6 %, preferably 2 - 4 % ( w / w ). the enteric coating layer is applied onto the cores with or without seal coating by conventional coating techniques , such as pan coating or fluid bed coating using solutions of polymers in water or suitable organic solvents or by using aqueous polymer dispersions . all commercially available ph - sensitive polymers are included . the pharmaceutical active is not released in the acidic stomach environment of approximately below ph 4 . 5 , but not limited to this value . the pharmaceutical active should become available when the ph - sensitive layer dissolves at the greater ph ; after a certain delayed time ; or after the unit passes through the stomach . the preferred delay time is in the range of two to six hours . enteric polymers include cellulose acetate phthalate , cellulose acetate trimellitate , hydroxypropyl methylcellulose phthalate , polyvinyl acetate phthalate , carboxymethylethylcellulose , co - polymerized methacrylic acid / methacrylic acid methyl esters such as , for instance , materials known under the trade name eudragit ® l12 . 5 , l100 , or eudragit ® s12 . 5 , s100 or similar compounds used to obtain enteric coatings . aqueous colloidal polymer dispersions or re - dispersions can be also applied , e . g . eudragit ( t l 30d - 55 , eudragit ® l100 - 55 , eudragit ® s100 , eudragit ® preparation 4110d ( rohm pharma ); aquateric ®, aquacoat ® cpd 30 ( fmc ); kollicoat mae ® 30d and 30dp ( basf ); eastacryl ® 30d ( eastman chemical ). the enteric polymers used in this invention can be modified by mixing with other known coating products that are not ph sensitive . examples of such coating products include the neutral methacrylic acid esters with a small portion of trimethylammonioethyl methacrylate chloride , sold currently under the trade names eudragit ® rs and eudragit ® rl ; a neutral ester dispersion without any functional groups , sold under the trade names eudragit ® ne30d ; and other ph independent coating products . the modifying component of the protective layer used over the enteric coating can include a water penetration barrier layer ( semipermeable polymer ) which can be successively coated after the enteric coating to reduce the water penetration rate through the enteric coating layer and thus increase the lag time of the drug release . sustained - release coatings commonly known to one skilled in the art can be used for this purpose by conventional coating techniques such as pan coating or fluid bed coating using solutions of polymers in water or suitable organic solvents or by using aqueous polymer dispersions . for example , the following materials can be used , but not limited to : cellulose acetate , cellulose acetate butyrate , cellulose acetate propionate , ethyl cellulose , fatty acids and their esters , waxes , zein , and aqueous polymer dispersions such as eudragit ® rs and rl 30d , eudragit ® ne 30d , aquacoat ®, surelease ®, cellulose acetate latex . the combination of above polymers and hydrophilic polymers such as hydroxyethyl cellulose , hydroxypropyl cellulose ( klucel ®, hercules corp . ), hydroxypropyl methylcellulose ( methocel ®, dow chemical corp . ), polyvinylpyrrolidone can also be used . an overcoating layer can further optionally be applied to the composition of the present invention . opadry ®, opadry ii ® ( colorcon ) and corresponding color and colorless grades from colorcon can be used to protect the pellets from being tacky and provide colors to the product . the suggested levels of protective or color coating are from 1 to 6 %, preferably 2 - 3 % ( w / w ). many ingredients can be incorporated into the overcoating formula , for example to provide a quicker immediate release , such as plasticizers : acetyltriethyl citrate , triethyl citrate , acetyltributyl citrate , dibutylsebacate , triacetin , polyethylene glycols , propylene glycol and the others ; lubricants : talc , colloidal silica dioxide , magnesium stearate , calcium stearate , titanium dioxide , magnesium silicate , and the like . the composition , preferably in beadlet form , can be incorporated into hard gelatin capsules , either with additional excipients , or alone . typical excipients to be added to a capsule formulation include , but are not limited to : fillers such as microcrystalline cellulose , soy polysaccharides , calcium phosphate dihydrate , calcium sulfate , lactose , sucrose , sorbitol , or any other inert filler . in addition , there can be flow aids such as fumed silicon dioxide , silica gel , magnesium stearate , calcium stearate or any other material imparting flow to powders . a lubricant can further be added if necessary by using polyethylene glycol , leucine , glyceryl behenate , magnesium stearate or calcium stearate . the composition may also be incorporated into a tablet , in particular by incorporation into a tablet matrix , which rapidly disperses the particles after ingestion . in order to incorporate these particles into such a tablet , a filler / binder must be added to a table that can accept the particles , but will not allow their destruction during the tableting process . materials that are suitable for this purpose include , but are not limited to , microcrystalline cellulose ( avicel ®), soy polysaccharide ( emcosoy ®), pre - gelatinized starches ( starch ®) 1500 , national ® 1551 ), and polyethylene glycols ( carbowax ®). the materials should be present in the range of 5 - 75 % ( w / w ), with a preferred range of 25 - 50 % ( w / w ). in addition , disintegrants are added in order to disperse the beads once the tablet is ingested . suitable disintegrants include , but are not limited to : cross - linked sodium carboxymethyl cellulose ( ac - di - sol ®), sodium starch glycolate ( explotab ®, primojel ®), and cross - linked polyvinylpolypyrrolidone ( plasone - xl ). these materials should be present in the rate of 3 - 15 % ( w / w ), with a preferred range of 5 - 10 % ( w / w ). lubricants are also added to assure proper tableting , and these can include , but are not limited to : magnesium stearate , calcium stearate , stearic acid , polyethylene glycol , leucine , glyceryl behanate , and hydrogenated vegetable oil . these lubricants should be present in amounts from 0 . 1 - 10 % ( w / w ), with a preferred range of 0 . 3 - 3 . 0 % ( w / w ). tablets are formed , for example , as follows . the particles are introduced into a blender along with avicel ®, disintegrants and lubricant , mixed for a set number of minutes to provide a homogeneous blend which is then put in the hopper of a tablet press with which tablets are compressed . the compression force used is adequate to form a tablet ; however , not sufficient to fracture the beads or coatings . it will be appreciated that the multiple dosage form of the present invention can deliver rapid and complete dosages of pharmaceutically active amphetamine salts to achieve the desired levels of the drug in a recipient over the course of about 8 hours with a single oral administration . in so doing , the levels of drug in blood plasma of the pharmaceutically active amphetamine salts will reach a peak fairly rapidly after about 2 hours , and after about 4 hours a second pulse dose is released , wherein a second fairly rapid additive increase of plasma drug levels occurs which slowly decreases over the course of the next 12 hours . the following examples are presented to illustrate and do not limit the invention . the following formulation was used to layer the drug onto sugar spheres . nonpareil seeds ( 30 / 35 mesh , paulaur corp ., nj ), 6 . 8 kg were put into a flm - 15 fluid bed processor with a 9 ″ wurster column and fluidized at 60 ° c . the suspension of mixed amphetamine salts ( mas ) with 1 % hpmc e5 premium ( dow chemical ) as a binder was sprayed onto the seed under suitable conditions . almost no agglomeration and no fines were observed with a yield of at least 98 %. the drug - loaded cores were used to test enteric coatings and sustained release coatings . the following formulation was used to coat the mixed amphetamine salts loaded ( masl ) pellets from example 1 with the eudragit ® l 30d - 55 ( rohm pharma , germany ) coating dispersion . 2 kg of masl pellets were loaded into a fluid bed processor with a reduced wurster column equipped with a precision coater ( mp 2 / 3 , niro inc .). the coating dispersion was prepared by dispersing triethyl citrate , talc and eudragit ® l 30d - 55 into water and mixing for at least 30 minutes . under suitable fluidization conditions , the coating dispersion was sprayed onto the fluidized masl pellets . the spraying was continued until the targeted coating level was achieved ( 20μ ). the coated pellets were dried at 30 - 35 ° c . for 5 minutes before stopping the process . the enteric coated ppa pellets were tested at different ph buffers by a usp paddle method . the drug content was analyzed using hplc . the results showed that the enteric coating delayed the drug release from the coated pellets until after exposure to ph 6 or higher ( see table 2 below ). ( reference # ar98125 - 4 ) the following formulation was used to coat the masl pellets from example 1 with the eudragit ® 4110d ( rohm pharma , germany ) coating dispersion . masl pellets ( 2 kg ) were loaded in a fluid bed processor with a reduced wurster column ( gpgc - 15 , glatt ). the coating dispersion was prepared by dispersing triethyl citrate , talc and eudragit ® 4110d into water and mixing for at least 30 minutes . under suitable fluidization conditions , the coating dispersion was sprayed onto the fluidized masl pellets . the spraying was continued until the targeted coating level was achieved . the coated pellets were dried at 30 - 35 ° c . for 5 minutes before stopping the process . the enteric coated masl pellets were tested using a usp paddle method at different ph buffers . the drug content was analyzed using hplc . the enteric coating delayed the drug release for several hours from the coated pellets until the ph value reached 6 . 8 or higher , as shown below in table 3 . ( reference # ar98125 - 3 ) the following formulation was selected to coat the enteric coated masl pellets . coated masl pellets from example 2 or coated masl pellets from example 3 ( 2 kg of either ) were loaded into a fluid bed processor with a reduced wurster column ( gpgc - 15 , glatt ). the coating dispersion was prepared by mixing surelease ® ( colorcon ) and water for at least 15 minutes prior to spraying . under suitable fluidization conditions , the coating dispersion was sprayed onto the fluidized pellets . the spraying was continued until the targeted coating level was achieved . the coated pellets were coated with a thin layer of opadry ® white ( colorcon ) ( 2 %) to prevent the tackiness of the coated pellets during storage . the coated pellets were then dried at 35 - 40 ° c . for 10 minutes before discharging from the bed . the drug dissolution from both coated pellets was performed using a usp paddle method at different ph buffers . the drug content was analyzed using hplc . the 8 % surelease ® coating slightly sustained the drug release from eudragit ® l 30d - 55 coated pellets at ph 7 . 5 buffer , while the surelease ® coating delayed the drug release up to 2 hours after the buffer switched from ph 1 to ph 7 . 5 . ( reference ## ar98125 - 1 ) a pulsatile delivery system can be achieved by combining the immediate release pellets ( example 1 ) with delayed release pellets ( example 2 or example 3 ). the immediate - release pellets equivalent to half the dose and the delayed - release pellets equivalent to half the dose are filled into a hard gelatin capsule to produce the oral pulsed dose delivery system . the delayed - release portion releases the amphetamine salts rapidly and completely , after a specified lag time . the capsule products containing immediate - release pellets and delayed - release pellets ( example 1 plus example 2 and example 1 plus example 3 ) were tested in a crossover human study . fig7 and 8 show the typical profiles of plasma amphetamine concentration after administration of a composite capsule containing the immediate - release pellets and delayed - release pellets from examples 1 and 2 ( 10 mg dose each pellet type ) and a capsule containing the pellets from immediate - release pellets and delayed - release pellets from examples 1 and 3 ( 10 mg dose each pellet type ), respectively . the general plasma profiles are similar to the desired target plasma level profile shown in fig1 . it is to be understood , however , that the scope of the present invention is not to be limited to the specific embodiments described above . the invention may be practiced other than as particularly described and still be within the scope of the accompanying claims . 1 . b . lemmer , “ circadian rhythms and drug delivery ”, j . controlled release , 16 , 63 - 74 ( 1991 ) 2 . b . lemmer , “ why are so many biological systems periodic ?” in pulsatile drug delivery : current applications and future trends , r gurny , h e junginger and n a peppas , eds . 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