the core tablet formulation of the invention is prepared by blending the following materials : table i matrix core preferred more preferred decongestant 10 - 50 % 20 - 40 % hydrogel forming polymer 50 - 90 % 55 - 75 % filler 0 - 20 % 5 - 15 % antiadherent 0 - 5 % 0 . 01 - 2 % lubricant ( s ) 0 - 10 % 0 . 01 - 5 % the above percentages are based on the total weight of the matrix core . once the ingredients are blended they can be pressed or extruded into a core using conventional tabletting techniques as described in remington &# 39 ; s pharmaceutical sciences 18 th ed . which is incorporated by reference . the preferred decongestant is pseudoephedrine . other possible decongestants include but are not limited to phenylepherine and phenylpropanolamine and other sympathomimetic drugs as well as pharmacologically acceptable salts thereof . the term “ pharmacologically acceptable salts ” encompasses both organic and inorganic salts including , for example sodium , hydrochloric , hydrofluoric , sulfuric , sulfonic , tartic , fumaric , hydrobromic , glycolic , citric , maleic , sulfate , phosphoric , succinic , acetic , nitric , benzoic , ascorbic , p - toluene sulfonic , benzenesulfonic , naphthalenesulfonic , propionic , and the like . the hydrogel forming polymer is preferably a single pharmaceutically acceptable polymeric substance such as hydroxypropyl methylcellulose . the hydroxypropyl methylcellulose of the present invention is the u . s . p . substitution type 2208 and should have an average molecular weight above 100 , 000 , preferably above 200 , 000 . the methyoxy content of the hydroxypropyl methylcellulose should be approximately 19 - 24 weight percent and the hydroxypropyl content of the hydroxypropyl methylcellulose should be approximately 7 . 5 to 8 . 5 weight percent . a suitable grade of hydroxypropyl is available from dow chemical co . of midland , mich . under the trade name methocel k100m which exhibits a viscosity in a 2 % aqueous solution of approximately 100 , 000 cps . other hydrogel forming polymers that can be used include carboxymethylcellulose calcium , carboxymethylcellulose sodium , guar gum , hydroxyethyl cellulose , hydroxypropyl cellulose , methyl cellulose , acrylic acid crosslinked with polyalkenyl ethers or divinyl glycol , sodium alginate and poly ( ethylene oxide ) ( polyox ™). the preferred filler is lactose monohydrate ( spray dried ). other fillers such as starch , dextrose , sucrose , hydroxypropyl cellulose , microcrystalline cellulose and the like may be added . a fumed colloidal silicon dioxide such as cab - o - sil ®, m5 may be used as the glidant . a tablet lubricant may be added to the compressed core matrix . examples of suitable tablet lubricants include magnesium stearate or glyceryl mono - stearate . eastman ® 600p is a commercially available material that may also be used as a lubricant . in a preferred embodiment the lubricants are passed separately through a mesh screen and then blended with a mixture of decongestant , hydrogel forming polymer , filler and glidant which has been passed through a comil . it was found that cores compressed using a pre - compression force yielded better tablets . the precompression force should be between 1 to 7 kp preferably 2 to 5 kp . when observed under the microscope , tablets without pre - compression force showed signs of premature capping around the edge area while these defects on tablet edges were not found on tablets compressed using pre - compression force . surprisingly , tablets without pre - compression had good friability . when subsequently coated , tablets manufactured using a pre - compression force displayed negligible defective edges . in order to prevent the compressed tablet cores from sticking to the tooling , the hardness of the cores should be greater than 18 kp , preferably 20 - 24 kp . the immediate release coating containing an antihistamine , preferably a non - sedating antihistamine is coated directly onto the matrix core or applied over a sealed coated matrix core . the immediate release coating comprises a non - sedating antihistamine and a film forming material or binder and optionally other conventional additives such as lubricants , fillers and antiadherents . the immediate release coating may be applied by any conventional technique such as pan coating or spray coating . in the preferred embodiment the immediate release coating is applied by spraying an aqueous solution or suspension over a pan containing the matrix core tablets . after the immediate release coating is applied to the matrix core the once a day matrix tablet will comprise : drug layering preferred more preferred compressed matrix core 40 - 100 % 75 - 95 % non - sedating antihistamine 0 . 01 - 10 % 0 . 1 - 5 % binder 0 - 20 % 0 . 5 - 10 % glidant 0 - 10 % 0 . 1 - 5 % lubricant 0 - 10 % 0 . 1 - 5 % the above percentages are based upon the total weight of the once daily drug formulation or matrix tablet . the film forming material or binder employ in the immediate release coating preferably comprises opadry clear ®, ys - 1 - 7006 which contains 91 wt % hydroxypropyl methylcellulose ( e - 6 ), 9 wt % polyethylene glycol and is applied in a 8 - 15 % w / w solution in purified water . an antiadherent material such as sodium lauryl sulfate may be used as well . a lubricant such as talc can optionally be used . a polishing agent such as candellila wax may optionally be applied to the immediate release coating by any of the conventional coating techniques described in remington &# 39 ; s pharmaceutical sciences 18 th ed which is incorporated by reference . the once a day formulation prepared in accordance with the present invention will preferably exhibit the following antihistamine release rate in 900 ml of sgf buffer , ph 1 . 2 using a usp apparatus i at 100 rpm , at 37 ° c . amount dissolved amount dissolved time ( preferred ) ( most preferred ) 0 . 25 hours 40 - 80 % nlt 50 % 0 . 50 hours 65 %- 95 % % nlt 75 % 1 . 0 hours nlt - 85 % nlt 90 % the once a day formulation prepared in accordance with the present invention will preferably exhibit the following decongestant release rate in 900 ml of sgf buffer , ph 1 . 2 using a usp apparatus i at 100 rpm , 37 ° c . amount dissolved amount dissolved time ( preferred ) ( most preferred ) 1 . 0 hours 0 - 50 % 10 - 40 % 2 . 0 hours 10 - 60 % % 15 - 45 % 4 . 0 hours 20 - 70 % 25 - 60 % 8 . 0 hours 30 - 85 % 35 - 80 % 12 . 0 hours nlt 45 % nlt 50 % 20 . 0 hours nlt 60 % nlt 70 % an antihistamine / decongestant tablet containing loratadine as an antihistamine and pseudoephedrine as a decongestant is prepared according to the following procedure : 30 kg pseudoephedrine sulfate , 60 kg hydroxypropyl methylcellulose ( methocel ® k100m ), 7 . 25 kg lactose monohydrate nf ( spray dried ) and 0 . 50 kg cab - o - sil ( m5 ) are blended in a 10 cubic foot slant cone mixer with a speed of 17 rpm for 10 minutes . the mixture is passed through a comil equipped with a # 1143 screen and 0 . 175 ″ spacer . the mixture is then further blended in a 10 cubic foot slant cone with a speed of 17 rpm for 30 minutes . 0 . 75 kg of mg stearate and 1 . 5 kg of glyceryl monostearate ( eastman ® 600p ) are passed through a 30 mesh screen and then blended with the mixture from stage i in a 10 cubic foot slant cone with a speed of 17 rpm for 30 minutes to form a tabletting blend . the tabletting blend from stage ii is compressed into standard concave oval 0 . 3640 ″× 0 . 7280 shaped tablets each with a target weight of 800 mg , and containing 240 mg of pseudoephedrine sulfate . the tablets are formed using pre - compression and a manesty tablet press with a press speed of 30 rpm and a final target hardness value of 23 kp . the precompression force is 3 to 4 kp . the compressed matrix core tablets from stage iii are coated with an immediate release dose of loratadine by coating the compressed matrix tablet with an aqueous suspension comprising : 1 . loratadine , micronized 1 . 16 kg 2 . opadry ® clear ys - 1 - 7006 4 . 32 kg 3 . talc , usp 1 . 16 kg 4 . sodium lauryl sulfate , nf 2 . 32 kg 5 . purified water , usp 89 . 63 kg an excess of 3 % of loratadine , opadry clear ®, talc , and sodium lauryl sulfate may be added to compensate for loss in manufacturing . the immediate release layer is prepared by placing the opadry clear ® and purified water into a 25 gallon container then adding the sodium lauryl sulfate and talc and loratadine . stirring of the talc suspension is continued . the suspension is then sprayed onto the matrix core tablets to form an external immediate release layer of loratadine under the following conditions : exhaust temperature : 43 +/− 5 ° c . atomization pressure : 35 +/− 10 psi fan air pressure : 35 +/− 10 psi piston air pressure : 40 +/− 10 psi air volume : 1500 +/− 300 cfm pan speed : 4 - 8 rpm spray rate : 250 +/− 100 g / min nozzle distance : 11 +/− 1 ″ the immediate release coated tablets prepared in stage iv are then coated with a composition comprising a colorant and wax : opadry white ® ys - 1 - 7003 4 . 64 kg purified water 46 . 40 kg candellila wax powder , fcc 0 . 03 kg this color coating is applied by placing the immediate release coated compressed matrix tablets from stage v into a perforated pan coater . the suspension is sprayed onto the tablets to form a color layer under the following conditions : exhaust temperature : 43 +/− 5 ° c . atomization pressure : 35 +/− 10 psi fan pressure : 35 +/− 10 psi piston air pressure : 40 +/− 10 psi air volume : 1500 +/− 300 cfm pan speed : 4 - 8 rpm spray rate : 250 +/− 100 / min nozzle distance : 11 +/− 1 ″ the once daily antihistamine / decongestant formulation prepared in this example was tested using a usp app . 1 @ 100 rpm , 37 ° c . and 900 ml of simulated gastric fluid ( sgf ) buffer . the results of the dissolution testing are shown in fig1 and 2 . the formulation of the preferred embodiment was used to conduct in vivo tests for blood levels of loratadine , pseudoephedrine and descarboethoxyloratadine as compared to claritin ® d24 and the results are shown in fig3 and 5 respectively . the results show the bioequivalence of the preferred embodiment to claritin ® d24 . while certain preferred and alternative embodiments of the invention have been set forth for purposes of disclosing the invention , modifications to the disclosed embodiments may occur to those who are skilled in the art . accordingly , the appended claims are intended to cover all embodiments of the invention and modifications thereof which do not depart from the spirit and scope of the invention .
a controlled release pharmaceutical formulation for the administration of an antihistamine and decongestant to a patient wherein the formulation employs a compressed matrix core for the controlled release of a decongestant and an immediate release coating for the immediate release of the antihistamine .