Alginate and gellan gum as tablet coating

Details Alginate and gellan gum as tablet coating Alginate and gellan gum as tablet coating

1998-10-30

2001-12-04

Spear, James M. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Tablets, lozenges, or pills

C424S474000, C424S475000, C424S479000, C514S777000, C514S779000, C514S782000

Reexamination Certificate

active

06326028

ABSTRACT:

BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to tablet coating compositions, tablet coatings and to a method to effectively prepare such composition(s). More particularly this invention relates to a tablet coating which comprises alginates and/or gellan gum for use on or with any tablet. Such tablets include but are not limited to a small pellet(s) of medication to be taken orally. Tablet coatings of this invention are useful for tablets for humans including coating(s) on medicinal tablets.
BACKGROUND OF THE INVENTION
Tablets are used in a variety of uses but of interest here are those tablets which are used to deliver a pharmacologically effective amount of a therapeutic drug to humans and animals. Typically such therapeutic effective drugs are those that possess and produce desirable drug effects after consumption by the human or animal.
In many medicinal uses, illustratively and without limitation, a coating is desired in order to obtain one of more of the following: appearance, identification, mouthfeel, reduce dust, stability, color, swallowability and stability, combinations thereof and the like.
Most tablet coatings today are made of low viscosity Hydroxypropylmethylcellulose (HPMC). Usually a ca. 10% HPMC solution, with appropriate plasticizer, is applied by a spraying system or device to a tablet. However, the industry has recognized the need for an improved tablet coating which would provide increased gloss and better mouthfeel for example.
Even with the foregoing and other tablet coating compositions of the art, the industry continues to desire a product which provides enhanced tablet coating properties. The art of preparing such a product economically and efficiently continues to be of interest to industry.
OBJECTS OF THE INVENTION
It is an object of this invention to provide an aqueous or adherent dry or substantially dry tablet coating composition for a tablet whereby such coating composition includes an alginate and/or a gellan gum or a mixture thereof.
It is another object of this invention to provide an efficient process for the preparing such a composition.
It is yet a further object of this invention to provide a highly useful tablet coating composition which provides enhanced properties to the tablet coated with such a composition.
It is yet another objective of this invention to provide a tablet coating system that provides improved recipient and patient mouthfeel.
These and other objectives are met in this invention which is hereinafter described in more detail.
BRIEF SUMMARY OF THE INVENTION
This invention comprises a method for effectively preparing aqueous and dry or substantially dry tablet coating compositions and a coated tablet, the tablet comprising a therapeutically effective amount of a consumable drug, wherein the adherent coating comprises alginate and/or gellan gum. The invention further comprises a coated tablet composition comprising an alginate and/or gellan gum and a method for preparing such a composition.
DETAILED DESCRIPTION OF THE INVENTION
Compositions which are useful as adherent coatings herein on tablets of any kind include those which contain alginates and/or gellan gum, mixtures thereof and the like.
Tablets useful herein come in all shapes and sizes. The tablet shape and size are not critical although preferred shapes and sizes are those which can be effectively consumed by a human or animal recipient with relative ease. Preferred tablets are medicinal tablets for humans or animals.
Gellan gum is useful herein and typical useful gellan gums are those naturally occurring polysaccharides that are typically produced by inoculating a carefully formulated fermentation medium with the microorganism Sphingamonas elodea (ATTC 31461). Gellan Gum is available in a clarified form (KELCOGEL7) for foods and industrial products and a clarified form of (GELRITE7) for microbiological media, plant tissue culture, and pharmaceutical applications. Gellan gum includes non-clarified, clarified, and partially-clarified native, deacetylated and partially deacetylated forms as well as mixtures thereof and the like.
Various alginates are useful in this invention include but are not limited to those which are described in detail by I. W. Cottrell and P. Kovacs in Alginates @ as Chapter 2 of Davidson, ea., Handbook of Water-Soluble Gums and Resins (1980) which is incorporated herein by reference in its entirety.
A particularly preferred alginate useful herein is a sodium alginate, a high-G, ultra low viscosity which is available from Monsanto Company, 800 North Lindbergh Blvd, St. Louis, Mo., 63167.
Other components of the coating composition of this invention include but are not limited to a plasticizer system and color additives as will be readily apparent to those of skill in the art. A typical plasticizer is glycerine although any equivalent or substantially equivalent plasticizer may be satisfactorily employed herein.
A typical composition of this invention comprises in the range from about 0.1% to about 3% alginate and gellan gum based on the dry weight of the tablet and preferably from about 0.5% to about 1% by weight alginate and gellan gum. When employed in such a combination, the weight ratio of alginate to gellan gum is in the range from about 1 to about 20 and preferably from about 1 to about 5 although greater and lesser ratios may be employed if desired as will be apparent to those of skill in the art after reading this specification.
Alginate and gellan gum may be individually employed as a tablet coating composition in this invention.
In practicing this invention, an aqueous composition comprising alginate and/or gellan gum is admixed in any suitable vessel prior to spraying the composition onto a tablet. Preferably, but not required, the alginate and/or gellan gum is admixed with water, the plasticizer is added thereto, and further mixing is carried out to form an aqueous tablet coating composition. The composition is mixed by any suitable mixing system preferably until complete or substantial mixing has been accomplished. A hot solution may be needed. Those of skill in the art will recognize that some heating will be necessary to achieve this.
As employed herein, the term “adherent” means that the coating adheres to the tablet until consumption whereupon the coating dissolves from the tablet containing a drug in order to enable release of the active ingredient therefrom. For example, the coating is wetted in the human's mouth, the recipient swallows the wetted coated tablet and the tablet coating dissolves in the human's stomach whereupon the tablet composition is made available to the patient or recipient to receive the medicinal value of the drug.
The aforementioned admixing is carried out by any convenient means including but not limited to use of a propeller or stirrer system although generally stirring by a convenient mechanical means is acceptable.
Application of the composition as a coating to the tablet is carried out by placing the tablets to receive a tablet composition of this invention in a spray tower such as fluid bed spray tower and then spraying the composition of this invention onto the tablets.
A typical spray tower includes but is not limited to a Wurster spray tower. Also, acceptable for use to prepare coating tablets of this invention are side vented coating pans and convention coating pans with spray nozzles. Also acceptable as a spray tower system is a conventional fluid bed tower with a suitable spray apparatus is included. Any spray system capable of applying a composition of this invention to a tablet is an acceptable system for coating tablets employing the aqueous coating composition of this invention. Any size spray system is acceptable. Batch and continuous processes, semi-continuous and variations thereof are envisioned without limitation.
Although the composition of this invention will initially be an aqueous composition, the tablet coating will become dry or substantially dry upon its exit from the spray system and on the surface of the coated tablet. In pra

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