Claims for Patent: 5,698,226

Summary for Patent: 5,698,226

Title:	Water-dispersible tablets
Abstract:	A water-dispersible tablet comprises an active compound such as acyclovir or lamotrigine and a dispersing agent. The dispersing agent is a swellable clay such as a smectite, e.g. Veegum F or bentonite, and is generally present within the granules of the tablet to provide a tablet which is capable of dispersing in water within 3 minutes to provide a dispersion which will pass through a 710 .mu.m sieve. The tablet can be optionally film-coated in which case the dispersion time is less than 5 minutes.
Inventor(s):	Fielden; Krystyna Elzbieta (Dartford, GB)
Assignee:	Glaxo Wellcome Inc. (Research Triangle Park, NC)
Application Number:	08/659,316
Patent Claims:	1. A water-dispersible tablet having 2.5 to 500 mg lamotrigine and comprising the following components: 3% to 90% w/w lamotrigine, 0.25 to 40% of a pharmaceutically acceptable swellable clay and an additional pharmaceutically acceptable disintegrating agent, said components being present within the granules of the tablet to provide a tablet which is capable: a) of dispersing in water to provide a dispersion which passes through a sieve screen with a mesh aperture of 710 .mu.m; b) of disintegrating within three minutes when examined by the following apparatus and method in accordance with the test for dispersible tablets of the British Pharmacopoeia, 1988, volume II, page 895; said apparatus consisting of: (i) a rigid basket-rack assembly supporting six cylindrical glass tubes 75.0 to 80.0 mm long, 21.5 mm in internal diameter and with a wall thickness of about 2 mm; (ii) a cylindrical disc for each tube, each 20.55 to 20.85 mm in diameter and 9.35 to 9.65 mm thick, made of transparent plastic with a relative density of 1.18 to 1.20, pierced with five holes, each 2 mm in diameter, one in the center and the other four spaced equally on a circle of radius 6 mm from the center of the disc, there being four equally spaced grooves cut in the lateral surface of the disc in such a way that at the upper surface of the disc they are 9.5 mm wide and 2.55 mm deep and at the lower surface 1.6 mm square; (iii) two superimposed transparent plastic plates 90 mm in diameter and 6 mm thick, perforated by six holes having the same diameter as the tubes and holding the tubes vertically, the holes being equidistant from the center of the plate and equally spaced from one another, and a piece of woven gauze made from stainless steel wire 0.635 mm in diameter and having nominal mesh apertures of 2.00 mm attached to the underside of the lower plate; (iv) said plastic plates being held rigidly in position and 77.5 mm apart by vertical metal rods at the periphery and a metal rod fixed to the center of the upper plate to enable the assembly to be attached to a mechanical device capable of raising and lowering it smoothly through a distance of 50 to 60 mm at a constant frequency of between 28 and 32 cycles per minute; (v) said assembly being suspended in water at 19.degree. to 21.degree. C. held in a 1000 ml beaker, the volume of water being such that when the assembly is in the highest position the wire mesh is at least 15 mm below the surface of the water and when the assembly is in the lowest position the wire mesh is at least 25 mm above the bottom of the beaker and the upper open ends of the tubes remain above the surface of the water; said method consisting of introducing one tablet into each of the six tubes, suspending said assembly in the beaker containing the water and operating the apparatus for a maximum period of three minutes so that all six of the tablets disperse. 2. A tablet as claimed in claim 1 which further comprises a filler. 3. A tablet as claimed in claim 2 wherein the filler is microcrystalline cellulose. 4. A tablet as claimed in claim 1 which further comprises a binder to assist in forming the granules. 5. A tablet as claimed in claim 4 wherein the binder is povidone. 6. A tablet as claimed in claim 1 wherein the additional pharmaceutically acceptable disintegrating agent is sodium starch glycolate. 7. A tablet as claimed in claim 1 wherein the swellable clay is selected from the group consisting of smectite and attapulgite. 8. A tablet as claimed in claim 7 wherein the smectite is a montmorillonite clay. 9. A tablet as claimed in claim 8 wherein the montmorillonite is magnesium aluminium silicate or bentonite. 10. A tablet as claimed in claim 1 which is further film coated. 11. A tablet as claimed in claim 1 wherein the dispersion contains particles having a particle size distribution of 100% less than 710 .mu.m and more than 50% less than 300 .mu.m. 12. A water-dispersible tablet having 25 mg to 200 mg lamotrigine and comprising a formulation comprising: 30% w/w to 50% w/w lamotrigine, 26% w/w to 46% w/w calcium carbonate, 5 to 30 % w/w lowhydroxypropylcellulose or microcrystalline cellulose, 0.25% w/w to 30% w/w magnesium aluminium silicate or bentonite, 0.25 to 5% w/w povidone or 1 to 8% w/w pregelled starch, 0 to 8% w/w sodium starch glycolate, 0.25% w/w to 2% w/w magnesium stearate, and optional film coating composites comprising 0.1% w/w to 2% w/w opadry and 0.1% w/w to 0.5% w/w polyethylene glycol. 13. A tablet as claimed in claim 12 wherein the formulation comprises: 35% w/w to 45% w/w lamotrigine, 31% w/w to 41% w/w calcium carbonate, 5 to 15% w/w lowhydroxypropylcellulose or microcrystalline cellulose, 0.25% w/w to 10% w/w magnesium aluminium silicate or bentonite, 0.5 to 2% w/w povidone or 2 to 5% w/w pregelled starch, 0 to 5% w/w sodium starch glycolate, 0.25% w/w to 1% w/w magnesium stearate, and optional film coating composites comprising 0.25% w/w to 1% w/w opadry and 0.1% w/w to 0.2% w/w polyethylene glycol. 14. A tablet as claimed in claim 12 which contains substantially 25 mg or 100 mg lamotrigine. 15. A water-dispersible tablet having 5 mg to 50 mg lamotrigine and having a formulation comprising: 3% w/w to 13% w/w lamotrigine, 50% w/w to 60% w/w lactose or calcium carbonate, 20% w/w to 35% w/w lowhydroxypropylcellulose or microcrystalline cellulose, 0 to 8% w/w sodium starch glycolate, 0.25% w/w to 30% w/w magnesium aluminium silicate or bentonite, 0.25% w/w to 5% w/w povidone or 1% w/w/to 8% w/w/pregelled starch, 0 to 5% w/w sodium docusate, 0 to 3% sodium saccharine, 0.25% w/w to 2% w/w magnesium stearate, and optional film coating composites comprising 0.1% w/w to 2% w/w opadry and 0.1% w/w to 0.5% w/w polyethylene glycol. 16. A tablet as claimed in claim 15 wherein the formulation comprises: 5% w/w to 11% w/w lamotrigine, 53% w/w to 59% w/w lactose or calcium carbonate, 24% w/w to 30% w/w lowhydroxypropylcellulose or microcrystalline cellulose, 0 to 5% w/w sodium starch glycolate, 0.25% w/w to 10% w/w magnesium aluminium silicate or bentonite, 0.5% w/w to 2% w/w povidone or 2% w/w to 5% w/w pregelled starch, 0.15% w/w to 0.5% w/w sodium docusate, 0.5% w/w to 2% sodium saccharine, 0.25% w/w to 1% w/w magnesium stearate, and optional film coating composites comprising 0.25% w/w to 1% w/w opadry and 0.1% w/w to 0.2% w/w polyethylene glycol. 17. A tablet as claimed in claim 15 which contains substantially 5 mg lamotrigine.