Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
2000-02-14
2002-04-16
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C424S464000, C514S772300, C514S778000, C514S781000, C514S784000
Reexamination Certificate
active
06372253
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an improved process for preparing compressed methylcellulose containing tablets which meet USP disintegration standards.
BACKGROUND OF THE INVENTION
The history of cellulose ethers, such as methylcellulose and carboxymethyl-cellulose, supports that these agents have effectiveness as bulk laxatives. Their mechanism of action involves increasing both the water content of, and the bulk content of the stool, as well as lubricating the stool; thereby relieving constipation.
Cellulose ethers have been administered as bulk laxatives in dosage forms comprising of tablets, suspensions, and bulk powders; the latter as sugar-free or in compositions containing high amounts of sugar.
Cellulose ethers administered as suspensions in water may contain high concentrations of sucrose or other sugars and flavors. In such formulations, the sugar competes with the cellulose ether for available water, thereby preventing the cellulose ether from hydrating sufficiently to form a gel. The advantages of using a suspension formulation is that the cellulose either is dispersed sufficiently to avoid any significant lumping in the digestive tract. However, the suspensions are viscous, semi-gelatinous, and visually unappealing to the consumer. Another disadvantage is the unpalatability of the suspensions due to the slimy mouth feel and extreme sweetness of such suspensions. Hence, these dosage forms have not gained significant customer acceptance.
Bulk powders of cellulose ethers often exhibit lumping of individual particles and gelatin and thus, remain undissolved as they pass through the digestive tract. That the products are undissolved means that this will prevent hydration and gelling of the powder and does not provide efficacy. Additionally, administration of bulk powders has caused cramping, nausea, and vomiting in some patients. Therefore, bulk powders are not the preferred dosage form for cellulose ethers.
Palatable and visually appealing bulk powders have, however, been accomplished by addition of water or another aqueous liquid to a dry powder mix of a water-soluble cellulose ether and a dispersing agent/sweetening component, typically sugar. This technology is disclosed in South African patent No. 84,1044, published Sep. 26, 1984. The pitfall with these compositions is that they contain about 400 calories of nutritive value per dose, primarily due to the high sugar content. This high caloric value is not acceptable to the average consumers or to users suffering from blood sugar disorders, including diabetics. Elderly people are normally, the common strata of the population that suffers from constipation and the more frequent users of laxatives, and are also commonly suffering with blood sugar disorders. The consumption of large quantities of sugar could aggravate blood sugar disorders.
Sugar encrusted cellulose ethers have been proposed as alternatives to the bulk powders containing high amounts of sugar. Such formulations have 1) less sugar such as natural sugar or combination of sugars such as sucrose, glucose, fructose or corn syrup solids; 2) lower caloric value; and 3) are readily dispersed in cold aqueous liquids.
Citrucel® Orange Flavor, a bulk forming laxative containing methylcellulose as its active ingredient, was first introduced into the market in 1986. This product contains 15 g of sucrose in a 19 g adult dose, which corresponds to a 2 g dose of methylcellulose. To decrease the sugar content of this product, a natural flavored formula lower in caloric value, and containing only 1 g sucrose, was developed and introduced in 1988. Additional patent protection for this product has focused on producing a sugar-free and virtually calorie-free powder. The product has a sugar-free sweetener, a dispersing agent, other excipients, and flavoring and was marketed in 1991 as Sugar Free Citrucel® Orange Flavor.
There still remains a need in the art to develop a rapidly disintegrating solid dosage form of a bulk agent, preferably methylcellulose, which is convenient to take and transport, sugar free, and easily administered to the consumer having blood sugar disorders or diabetics, for instance.
SUMMARY OF THE INVENTION
The present invention relates to an improved process for preparing methylcellulose tablets which are readily dispersible and meet United States Pharmacopoeia standards for disintegration. The methylcellulose is compressed into tablets which contain a suitable diluent, in preferred w/w ratios. Preferably the tablets rapidly disintegrate, in-vitro in 0.1N hydrochloric acid and water at 37
±
0.5° C.
DETAILED DESCRIPTION OF THE INVENTION
There is a common belief that tableted cellulose ethers do not readily dissolve in the digestive tract because these cellulose ethers are highly hygroscopic. The outer portion of the tablet is said to form a gel-like hydrate that prevents the tablet from breaking up and greatly retards the hydration of the inner portion of the tablet. The present invention overcomes this art recognized problem and involves preparation of a novel composition, and process of making, by which a rapidly disintegrating tablet of methylcellulose is prepared. Preferably, all excipients employed to prepare the tablets of this invention are sugar-free.
The tablets are prepared by a novel process involving a high-shear wet granulation method, followed by fluidized bed drying, milling, mixing with the other ingredients, and compression.
The present invention is to a methylcellulose tablet which comprises methylcellulose, at least one diluent or filler, and other suitable excipents well known to those skilled in the art. In some instances it is recognized that the diluent/filler and the disintegrating agent may be the same.
The tablet formulations of the present invention are advantageous over other dosage forms of methylcellulose because of their convenience of administration and rapid disintegration. This is in contrast to tablets of methylcellulose, formulated as 100% w/w methylcellulose in a 0.5 gm caplet which have been found not to disintegrate in 0.1N HCl solution, using a conventional disintegration apparatus even after two hours. The present tablets should disintegrate in 0.1N HCl from about 20 to about 30 minutes, preferably from about 10 to about 19 minutes, and more preferably less than 10 minutes; and in water, the tablets should disintegrate from about 25 to about 30 minutes, preferably from about 15 to about 24 minutes, and more preferably less than 15 minutes.
It has been found that low molecular weight (mw) methylcellulose is less effective for use as a laxative, and therefore is less desirable for use in a rapidly disintegrating tablet formation. Higher molecular weight methylcellulose is therefore both desirable and necessary in the present invention. The fibers must have a sufficient viscosity to gel and retain water in the gut to provide the stool bulking and softening for laxation use.
By using the testing methods for methylcellulose under standard conditions, such as those found in the USP XXII, p. 894, Apparent Viscosity method for Methylcellulose, or as discussed in Handbook of Pharmaceutical Excipients, APhA, a preferred methylcellulose for use herein should have a viscosity of >1000 centipoises (cps), preferably >2000 centipoises, more preferably >3000 centipoises, and most preferably >4000 centipoise. Higher molecular weight methylcellulose than those described is also desirable, however, the commerical availability of this grade of methylcellulose being the limiting feature. At present the upper limit of commercially available methylcellulose is about 6000 cps, which is encompassed within the scope of this invention. One presently available methylcellulose product for use herein is Methocel A4M, made by Dow Chemical Company, Midland Mich. as Dow Methocel A4M, having a viscosity of about 3000 to about 5,600 cps, which is within 75 to 140% of the desired target viscosity herein.
Preferred swellable diluents or fillers for use in this formulation include, but are not limited to, v
Daggy Bruce
Mehta Naresh I
Nayak Priyashri
Dinner Dara L.
Kinzig Charles M.
SmithKline Beecham Corporation
Spear James M.
Venetianer Stephen
LandOfFree
Rapidly disintegrating methylcellulose tablets does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rapidly disintegrating methylcellulose tablets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rapidly disintegrating methylcellulose tablets will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2906036