Claims for Patent: 5,626,874

Summary for Patent: 5,626,874

Title:	Controlled release pharmaceutical tablet having lenticular form
Abstract:	Controlled release pharmaceutical tablet having a lenticular form consisting of three layers of which the central one or core (a) contains the active principle and the two outer layers or barriers (b) and (c) comprise gellable and/or erodible polymeric material, said barrier layers being equal or different among themselves for composition and/or thickness, while the central layer has a limited external annular surface exposed to the dissolution medium, through which the active principle is released.
Inventor(s):	Conte; Ubaldo (Busto-Arsizio, IT), La Manna; Aldo (Pavia, IT), Maggi; Lauretta (Pavia, IT)
Assignee:	Ekita Investments N.V. (Curacao, AN)
Application Number:	08/352,072
Patent Claims:	1. A controlled release pharmaceutical tablet, having a lenticular form consisting of the 3 following over-imposed layers: a central layer or core (a) comprising an active principle, 2external barrier layers (b) and (c) respectively upon and under said core (a) limiting the active principle release, each barrier (b) and (c) comprising a gellable and/or erodible polymeric material, wherein said barrier layers (b) and (c) have the same or different composition and leave exposed only the lateral surface of the core (a), said exposed lateral surface ranging from 5 to 35% of the total tablet surface. 2. The controlled release pharmaceutical tablet according to claim 1, wherein the core (a) additionally contains: from 1 to 90%, based on the total core weight, of polymeric substances capable of modulating the active principle release, said polymeric substances selected from the group consisting of: crosslinked polivinylpyrrolidone, hydroxypropylmethylcellulose, hydroxypropyl-cellulose, crosslinked sodium carboxymethylcellulose, carboxymethyl starch, acrylic and methacrylic acid polymers and copolymers, polyesters, polyanhydrides copolymers, polymethylvinylether/anhydride, potassium methacrylate-divinylbenzene copolymer, polivinylalcohols, glucan, scleroglucan, mannan, betacyclodextrans, and mixtures thereof; hydrophilic substances selected from the group consisting of: sorbitol, mannitol, lactose and xilitol, surface active agents and wetting substances; and hydrophobic substances selected from the group consisting of: gliceryl monostearate, hydrogenated castor oil, waxes, mono-, bi- and tri-substituted glycerides. 3. The controlled release therapeutical tablet according to claim 2, wherein the core (a) contains: from 10 to 45% by weight based on the total core weight of a polymeric substance selected from the group consisting of: hydroxypropylmethylcellulose, crosslinked polyvinylpyrrolidone, sodiumcarboxymethylcellulose and mixtures thereof, a hydrophilic substance consisting of mannitol, and a hydrophobic substance consisting of hydrogenated castor oil. 4. The controlled release pharmaceutical tablet according to claim 1, wherein each of said barrier layers (b) and (c) comprises from 5 to 90% based on the total barrier layer weight of a gellable and/or erodible polymer selected from the group consisting of hydroxypropylmethylcellulose with molecular weight comprised between 1000 and 4,000,000, hydroxypropylcellulose with molecular weight comprised between 2000 and 2,000,000, carboxyvinylpolymers, polyvinylylalcohols, glucans, scleroglucans, mannans, xanthans, alginic acid, polyanhydrides, polyaminoacids, methylvinylethers/maleic anhydride copolymers, carboxymethylcellulose, ethylcellulose, methylcellulose and mixtures thereof; and adjuvants selected from the group consisting of glyceryl monostearate, semisynthetic triglycerides derivatives, semi-synthetic glycerides, hydrogenated castor oil, glycerylpalmitostearate, cetyl alcohol, polyvinylpyrrolidone, glycerol, ethylcellulose, methylcellulose, sodium carboxymethylcellulose, magnesium stearate, stearic acid, talc sodium benzoate, boric acid, polyoxyethyleneglycols, colloidal silica and mixtures thereof. 5. The controlled release pharmaceutical tablet according to claim 4, wherein each of said barrier layers (b) and (c) contains: from 50 to 90% based on the total barrier layer weight of a gellable and/or erodible polymer consisting of hydroxypropylmethylcellulose having an apparent viscosity comprised between 5 and 100,000 cps, an adjuvant selected from the group consisting of mixtures of hydrogenated castor oil, polivinylpyrrolidone, magnesium stearate, colloidal silica. 6. The controlled release pharmaceutical tablet according to claim 1 further comprising a gastroresistant and enterosoluble film wholly coating said finished three layers tablet, said polymeric film being selected from the group consisting of cellulose acetophtalate, cellulose trimellitate, acrylic and methacrylic polymers and copolymers with different molecular weight and with solubility dependant on different pH values.