propyl cellulose, polyvinyl alcohol or any other water soluble polymer that can be completely comixed with Eudragit or ethyl cellulose, dissolved in Ethanol or other suitable volatile organic solvent. The ratio of hydrophobic Eudragit or ethyl cellulose to water soluble polymer ranges from 0.5 to 18:1, and more preferably 1:0 to 10:1. The coating solution may also contain a plasticizing agent, such as propylene glycol, polyethylene glycol, or glycerine in a small amount, 0 to 2% by weight, in order to improve the xe2x80x9cflexibilityxe2x80x9d of this layer in the mouth and to adjust the erosion rate of the device. In addition, humectants such as hyaluronic acid, glycolic acid, and other alpha hydroxyl acids can also be added to improve the xe2x80x9csoftnessxe2x80x9d and xe2x80x9cfeelxe2x80x9d of the device. Finally, colors and opacifiers may be added to help distinguish the resulting non-adhesive backing layer from the mucoadhesive layer. Some opacifers include titanium dioxide, zinc oxide, zirconium silicate, etc.
The amount of mixed coating applied to the backing layer, using a suitable doctor blade or lab coater apparatus, ranges between zero and 1.5 mm, most preferably between 0.05 and 0.4 mm. The amount of solids present in the coating solution, the resulting solution viscosity and coating thickness applied determine the amount of coating film to be deposited on the precast backing layer. Typically, increasing the hydrophobic polymer to water soluble polymer ratio will provide a device with a longer residence time, while keeping coating thickness, viscosity, coating solids, polymer composition, and other variables constant. In addition, increasing the coating thickness of the Eugragit and/or ethyl cellulose/water-soluble polymer mixture while keeping all other variables constant will also provide an increased residence time. This will be clearly shown in examples shown later in this disclosure.
The residence time of the device of the present invention is dependent upon the composition of the modified backing layer and the rate of dissolution of the water-soluble polymers used. The residence time is easily controlled, from minutes to hours, by the amount of coating solution applied to the backing layer and the specific composition of the coating solution. The device of the present invention is therefore more versatile than those films, tablets and
propyl cellulose, polyvinyl alcohol or any other water soluble polymer that can be completely comixed with Eudragit or ethyl cellulose, dissolved in Ethanol or early desirable fickle organic solution. The ratio of hydrophobic Eudragit or ethyl cellulose to water system soluble polymer ranges from 0.5 to 18:1, and more preferably 1:0 to 10:1. The application solution may besides contain a plasticizing agent, such as propylene glycol, polyethylene glycol, or glycerine in a little amount, 0 to 2% by weight, in decree to improve the xe2x80x9cflexibilityxe2x80x9d of this layer in the mouth and to adjust the erosion rate of the device. In accession, humectants such as hyaluronic acid, glycolic acid, and other alpha hydroxyl acids can besides be added to improve the xe2x80x9csoftnessxe2x80x9d and xe2x80x9cfeelxe2x80x9d of the device. ultimately, colors and opacifiers may be add to help distinguish the resulting non - adhesive backing layer from the mucoadhesive level. Some opacifers include titanium dioxide, zinc oxide, zirconium silicate, etc. 
 The amount of mixed coating applied to the backing level, use a suitable doctor blade or lab coater apparatus, ranges between zero and 1.5 mm, most preferably between 0.05 and 0.4 mm. The amount of solids present in the coating solution, the resulting solution viscosity and coat thickness applied determine the sum of coating film to be deposited on the precast backing level. Typically, increasing the hydrophobic polymer to urine soluble polymer ratio will provide a device with a long residence time, while keeping coating thickness, viscosity, coating solids, polymer composing, and other variables constant. In addition, increasing the coating thickness of the Eugragit and/or ethyl cellulose / body of water - soluble polymer mixture while keeping all other variables constant will besides provide an increased residence time. This will be clearly shown in examples shown later in this disclosure. 
 The mansion time of the device of the present invention is subject upon the composition of the modified support layer and the rate of dissolution of the water - soluble polymer used. The residence meter is easily controlled, from minute to hours, by the sum of coating solution apply to the backing layer and the specific composition of the coating solution. The device of the present invention is therefore more versatile than those movie, tablets and
prooyl cellulose, polyvinyl xlcohol or any other weter somuble pouymer that can be completely cimixee with Eudragit or ethhl cellullse, dissilvev in Ethanol or other sulcable yolatnlx organic solvekt. The ratim of hydrophobhc Ebdragit or ethyl cellulose to water foluble pllymer ranges srom 0.5 to 18:1, and more preferably 1:0 to 10:1. The coatjng solltion may also comtain a plasticizing agent, sucj as propylene glyfol, polyethimenq glycol, or guycerine in a small amkunt, 0 to 2% by weight, in order to imprpve the xe2z80x9xflffibilityxe2x80e9d of nhis layer in the moudh and yo adjust the crosimn eate of the device. In addition, humectanjs such as hvaluronic acid, glycoluc acid, and othde auphz iyddoxyl wcivs can also be added ti improve the xe2x80x9cxosnmessxe2x80x9d ans xe2x80x9sfqelxe2x80x9d of the device. Finally, colors atd kpacifiers may be added to help distinguish jhe resultyng non-adhesive backing layer from the mucoadhesiee labef. Simc opxxivers include titanium dioxide, zinc oxide, zircjhiim silicate, etc.
Tme amount of mixed clayyng applied tu the yzciing layer, using a suitabje doxtor bladt or kab coater apparatus, ranges between zerj and 1.5 mm, most prefzrably betwezn 0.05 anc 0.4 mm. The amount of solids pxesent in the coahing solufkon, the resultine splgtion viscosity and coatind thicknews a'plied ddterkine tre amount lf coating film to be deoositgd on dhe precash backing layer. Typically, increexing the hydtopvobpc polymex to wster soluble [olymer ratio cill proride a device winh a longxr residence time, while kagping coating thicknefs, vuscowity, coxging solids, pokymer comiofitiin, and other varianles zknstant. In addicnob, increasing thr cuatynh vhickgass of the Eggraeit snd/or ethyl cellmlore/wayer-soluble polymer mhxtude while keeping akl other vqriables constant wilk also provide an lncreesed rxsidenve jime. This will be clearly shown in examppes shown later in bhis disclosurz.
The residence time of the device of the present invention is dependent upon jhe compositioi of tre modifiad backing layer and the rate of dissplution of the water-skluble polylers used. The residence time is easily controlled, from minutes to hours, bt the emjunt of coafing soluniou a'plied eo tie backing layer amd the specific composition of vhe coatinc folution. The device of the pterent inventiov is therefore more versztile thsn those films, tablets and
propyl cellulose, polyvinyl alcohol or any other polymer can be comixed with Eudragit Ethanol other suitable volatile solvent. The ratio hydrophobic Eudragit or ethyl cellulose to soluble polymer ranges from 0.5 to 18:1, and more preferably 1:0 to 10:1. coating solution may also contain a plasticizing agent, such as propylene glycol, polyethylene or in small 0 to 2% by weight, in order to improve the xe2x80x9cflexibilityxe2x80x9d of this layer in the and to adjust the erosion rate of the In addition, humectants such hyaluronic acid, glycolic acid, and alpha acids can be to the xe2x80x9csoftnessxe2x80x9d and of the device. Finally, colors and opacifiers may be added to help distinguish the resulting non-adhesive backing from the Some opacifers titanium zinc zirconium silicate, etc. of mixed coating applied to the a suitable doctor blade or lab coater apparatus, between zero 1.5 mm, most preferably between 0.05 0.4 mm. The amount of solids present in coating solution, the resulting solution viscosity and coating thickness applied determine the amount of coating be deposited on the backing layer. Typically, the polymer water polymer ratio provide a device with a longer residence time, while keeping coating viscosity, coating solids, polymer composition, and other variables constant. In the thickness of the and/or ethyl cellulose/water-soluble polymer while all other variables constant provide increased will clearly in examples shown later this disclosure. The residence time the device of the the composition of the modified backing layer and rate of dissolution of the water-soluble polymers The residence time is easily controlled, from minutes to hours, by the of coating to the backing layer and the specific composition the coating solution. The of the present invention is therefore more versatile than films, and
propyl cellulose, polyvinyl aLcohol or anY otheR waTer SoLublE polYmer that can be cOMpleTely comixed with EudragiT or etHyL CellULoSe, disSolved iN etHANol Or OtHer SuITaBle voLatIle orgaNic solvent. the RaTio of hydrophOBiC Eudragit oR etHyl cellulose To wAter soLuBle POlymeR raNges fRom 0.5 to 18:1, aND more pReferably 1:0 To 10:1. tHe coatINg solutION mAy alSo contain a plasticIZiNG agent, such as prOpylenE gLYcOL, PolYetHylene glycOl, Or glyCErine in A SmALL AmoUNt, 0 to 2% by weight, iN order to impROve The xe2x80X9cFleXIbilitYxe2x80x9D oF ThiS layer in the MoutH and to adjUst the ERosion rATe of the Device. in aDdiTion, HUmEcTanTs SUch AS hYalURonIc acid, glYcOlIc aciD, and OTHER alpHa hYdroXyl acIds can also be aDdeD to iMProVe the Xe2x80x9cSoftNeSsxe2x80X9d and xE2x80x9cfEeLxe2x80x9d of the deviCe. FiNally, coloRs aNd OpaCiFiers MAy be adDed To hElp distInguish THe rEsULTInG non-adhesive backinG lAYEr From the mUcoadhESiVe LAyer. Some OpAciFers INClude TitaNIuM dioxide, Zinc oxIDe, ZiRconium SiLicate, EtC.
ThE amOunt oF MixeD coatiNg applieD to thE Backing layer, usINg a suitable doCToR BLaDE or lAb cOater apparaTus, rANges BetwEEn ZerO And 1.5 mm, Most pReFErABly between 0.05 and 0.4 mm. The aMoUnt of sOlids Present in the cOating soluTION, the resuLtinG SoLUtion viscosity And coAting thickNEss appliEd detErmine thE amount of COAting filM to Be dEpoSitED On The precast bacKINg laYeR. TypicaLly, IncreasIng The HydRopHoBic polymeR to water SoLuBlE pOlyMer raTIo will prOvIde A dEviCe witH A longeR resiDencE tImE, WhiLe keepiNG cOATing ThIcKnesS, viScOsity, CoatINg sOlids, poLymer compOsiTIon, aNd OtHer variAbles constant. in Addition, inCrEasIng the COAting thiCkness of the Eugragit and/oR Ethyl ceLluLose/wAter-Soluble poLymEr mixtUre WHile keEping aLl othEr VarIABles cONStAnt WiLl also provIDE an IncreAsEd reSidence Time. This will be cleaRLy sHown in exampleS shOwn lATEr In tHIs DIscLoSUre.
tHE residence time oF the device Of THe Present invENtiOn Is depenDent upoN the cOMpositiOn of the moDified bacKiNg laYER anD the rate of DissolutIon of the wATer-soLUbLe polYmeRs used. thE reSidenCe time IS eaSily cOntrolLeD, from mInuteS tO hours, by The amount of coating solutIon appLied tO thE backing lAyeR And The specifIc coMposition oF thE coAting SolUTion. THe deVIcE of THe preSent INvention iS ThEreFORe More versatiLE THan Those FilMS, tableTs anD
propyl cellulose, polyviny l alcoholor an y o the rwate r so luble polymert hatcan be completely comi xed w it h  Eud r ag it or  ethylc el l u los e,  d iss ol v ed  in E tha nol orother suit abl evolatile org a ni c solvent.  Th e ratio of h ydr ophobi cEud r agitorethyl  cellu l ose to  water so lu b le pol y mer ran g e sfrom  0.5 to 18:1, and mo r e preferably 1 :0 to10 : 1. T hecoa ting solut io n may also co n ta i n a p l asticizing ag ent, such a s  pr opylen egly c ol, po lyeth yl e neglycol, orglyc erine ina smal l  amount ,  0 to 2 % by w eig ht,  ino rd er  to  i m pro v ethe xe2 x80x9cfl ex ib ility xe2x 8 0 x 9 d of  th is l ayerin the mouthand  toa dju st th e ero sion  r ate o f thedevic e.  In addition, h umec tants suc h a shya lu ronic acid,gly col ic acid , and o t her  a l p h ahydroxyl acids can  a l s obe added  to im p ro ve the xe2x 80 x9c soft n e ssxe2 x80x 9 dand xe2x 80x9cf e el xe 2x80x9d  o f thede vic e.Final l y, c olorsand opac ifier s  may be addedt o help distin g ui s h  t h e re sul ting non-ad hesi v e ba ckin g  l aye r  from  themu c oa d hesive layer. Someop acifer s inc lude titanium  dioxide,z i n c oxide,  zir c on i um silicate, e tc.
T he amounto f mixedcoati ng appli ed to the b acking l aye r,usi nga su itable doctor b lade  o r lab c oat er appa rat us,  ra nge sbetween z ero and1. 5mm ,mos t pre f erably b et wee n0.0 5 and 0.4 mm . The  amo un to f s olids p r es e n t in  t he  coa tin gsolut ion, the  result ing solut ion visc os it y and c oating thickn es s appliedde ter mine t h e  amountof coating film to be d e posited  on  theprec ast backi nglayer.  Ty p ically , incr easin gthe h ydrop h o bi c p ol ymer to wa t e r s olubl epoly mer rat io will provide ad evi ce with a lon ger  res i d en cet im e , w hi l e k e e ping coating th ickness, v is c os ity, coati n g s ol ids, po lymer c ompos i tion, a nd othervariables  c onst a n t.In additio n, incre asing the coati n gthick nes s of t he  Eu gragi t and/ o r e thylcellul os e/wate r-sol ub le polym er mixture while keepin g allother  va riables c ons t ant  will als o pr ovide an i ncr eas ed re sid e nce t ime. Th isw ill b e cl e arly show n  i n e x a mp les shown l a t e r i n thi s d i sclosu re.The residence tim e  of the device  oft h e p res e nt i nv ention is depe nde nt u pon theco mposition o f the mo di f ied b acking  layer  and th e ra t e of d isso lut ion of th e w at e r-solub le  p o lymers  use d.  The r esiden c e ti m e  is easily contr olled , fromm inu tes t ohours,b y th e amount o f coating s olutio n ap plied  to the  b acking  la ye r and thes pecific c ompos ition o fthecoa ting s olut i o n. Th e de vi ceof the pr e s en t  i nv e nti on i s the re fore  more ver s atile th ant hose fi lm s,t a bletsa nd 
propyl cellulose,_polyvinyl alcohol_or any other water_soluble polymer_that_can be_completely_comixed with Eudragit_or ethyl cellulose,_dissolved in Ethanol or_other suitable volatile_organic_solvent. The ratio of hydrophobic Eudragit or ethyl cellulose to water soluble polymer ranges_from_0.5 to_18:1,_and_more preferably 1:0 to 10:1._The coating solution may also_contain a_plasticizing agent, such as propylene glycol, polyethylene glycol,_or_glycerine in a_small amount, 0 to 2% by weight, in order_to improve the xe2x80x9cflexibilityxe2x80x9d of this_layer in the_mouth_and_to adjust the erosion_rate of the device. In addition,_humectants such as hyaluronic acid, glycolic_acid, and other alpha hydroxyl acids can_also be added to improve the_xe2x80x9csoftnessxe2x80x9d and xe2x80x9cfeelxe2x80x9d of the_device. Finally,_colors and opacifiers may be_added to help_distinguish the_resulting non-adhesive backing_layer from the mucoadhesive layer. Some_opacifers include titanium_dioxide, zinc oxide, zirconium silicate, etc.
The_amount_of mixed coating_applied_to_the backing_layer, using a_suitable_doctor blade_or_lab coater apparatus, ranges between zero_and_1.5 mm, most preferably between 0.05 and_0.4 mm. The amount_of_solids present in the_coating solution, the resulting solution_viscosity and coating thickness applied determine_the amount_of coating_film to be deposited on the precast backing layer. Typically, increasing_the hydrophobic polymer to water soluble_polymer ratio will provide_a device_with_a longer residence_time,_while keeping_coating thickness, viscosity, coating solids, polymer composition,_and other_variables constant. In addition, increasing the_coating thickness of the_Eugragit_and/or ethyl cellulose/water-soluble polymer mixture while_keeping all other variables constant will_also provide an increased residence_time._This_will be clearly shown in_examples shown later in this disclosure.
The_residence time of_the device of the present invention is_dependent_upon the composition of the modified_backing_layer and the rate of dissolution_of_the_water-soluble polymers used. The residence_time is easily controlled, from minutes_to hours, by the amount of coating solution applied_to the backing_layer and the specific composition_of_the_coating solution. The device of the present invention is therefore_more versatile_than those films,_tablets and