Rapidly disintegrable tablet composition and method

Rapidly water-disintegrable tablet is provided comprising an active ingredient such as a foodstuff or medicament, and distributed therewithin a small but effective amount of a tablet disintegrable system comprising an unreacted, intimate mixture of alginic acid and a water soluble metal carbonate in proportions reactive to form metal alginic acid salt and carbonic acid when the tablet is placed in water, the bulk of the salt acting to swell the tablet and the carbonic acid acting to simultaneously release carbon dioxide within the swelling tablet whereby rapid disintegration of the tablet is effected.

TECHNICAL FIELD 
This invention has to do with tablet compositions for the rapid generation 
of liquid products of high organoleptic quality and excellent body for 
enhanced consumer appeal. 
More particularly, the invention is concerned with improvements in tablet 
compositions of the type comprising in addition to the active ingredient 
such as a foodstuff, medicament and the like, binder and excipient, a 
novel disintegrant system, of food grade constitution which simultaneously 
bulks the tablet from within and releases carbon dioxide gas for rapid 
disintegration of the tablet and release of the active ingredients, with 
in situ generation of thickening agent to increase apparent body of the 
liquid produced, for increased consumer acceptance, and without use of 
organoleptically offensive acids such as tartaric and citric or their 
salts. 
BACKGROUND ART 
The art of tablet making involves the making of a composition which is 
readily compressible, sturdy for packaging and handling, and disintegrable 
in a predictable manner. Speed of compression to an integral tablet is 
achieved by the use in the tablet, in addition to use of the active 
ingredient, a binder, and an excipient, of a lubricant which facilitates 
release of the powders from the molds in which the tablets are formed and 
from the dies and punches which ram the powders into the molds. In 
general, present lubricants are insoluble in water and will leave a 
residue after tablet disintegration, at a cost of consumer appeal in a 
transparent product such as coffee, tea and clear soups. For rapid 
disintegration tablets are compounded with disintegrants which as their 
name implies act to disintegrate the tablet under predetermined 
conditions. Disintegrants heretofore used include corn starch, alginic 
acid, celluloses, and polyvinyl pyrrolidone. 
Lubricants heretofore used include talcum powder, magnesium stearate, 
calcium stearate, vegetable stearin, stearic acid, Carbowax (trademark), 
and the like. Leucine has been referred to as a lubricant, (Remington's 
Practice of Pharmacy, 12th Edition, 1961, at page 448) but no use thereof 
is known to applicant in combination with any particular product and/or 
disintegrating system, and particularly not previously known is the use of 
a leucine with the present disintegrating system. Such use is novel and 
provides unexpected benefits in that leucine is an amino acid and thus 
biologically acceptable in foodstuffs, is water soluble and thus leaves no 
residue, and has a highly palatable taste in liquids produced therewith, 
in addition to being a fine lubricant for tablet compositions. Thus, 
leucine, together with the disintegrating system disclosed herein, enables 
an organoleptically and esthetically pleasing, residue-free water 
reconstitution of foodstuffs such as beverages ranging from soft drinks to 
coffee, tea, cocoa, and soups, as well as of medications, e.g. those which 
are taken orally, such as asprin and antacid products. 
DESCRIPTION OF THE INVENTION 
It is therefore an object of the invention to provide a new and superior 
tablet composition having a disintegrant system enabling rapid 
disintegration in water, and such compositions using lubricants as well. 
It is another object to provide tablets comprising an active ingredient 
such as a foodstuff or medicament, and a disintegrant which has dual 
action when the tablet is exposed to water, with the production of a 
by-product which acts to body the solution. It is a highly particular 
object to provide tablets including a food grade disintegrating system 
comprising biologically benign components or organoleptically desirable 
qualities. 
These and other objects of the invention to become apparent hereinafter are 
realized in a rapidly water-disintegrable tablet comprising an active 
ingredient, and distributed therewithin a small but effective amount of a 
tablet disintegrating system comprising an unreacted, intimate mixture of 
alginic acid and a water soluble carbonate radical precursor in 
proportions reactive to form alginic acid salt and carbonic acid when the 
tablet is placed in water, the bulk of the formed salt acting to swell the 
tablet and the carbonic acid acting to simultaneously release carbon 
dioxide within the swelling tablet whereby rapid disintegration of the 
tablet is effected, said alginic acid salt acting to body the resulting 
active ingredient solution. 
In particular embodiments, the active ingredient is a medicament, or a 
foodstuff including beverages. 
Additionally, typically the weight ratio of the carbonate radical precursor 
to the alginic acid is three or more; the alginic acid is present in an 
effective amount between 0.05 and 25% by weight based on the weight of the 
tablet; and the metal carbonate is a carbonate or bicarbonate of an alkali 
or alkaline earth metal, such as the metals sodium, potassium, calcium, 
magensium or managnese. 
In further embodiments the tablet further comprises a tablet-lubricating 
effective amount of a lubricant, e.g. a water soluble tablet lubricant 
comprising leucine in tablet-lubricating effective amount, e.g. L-leucine 
or L-isoleucine. 
In particularly preferred embodiments, the invention provides a rapidly 
water-disintegrable tablet comprising an active ingredient, and 
distributed therewithin an effective amount of a tablet disintegrating 
system comprising an unreacted, intimate mixture of alginic acid and a 
water soluble metal carbonate in proportions reactive to form metal 
alginic acid salt and carbonic acid when the tablet is placed in water, 
said alginic acid comprising from 3 to 15% and the metal carbonate from 1 
to 70% of the tablet by weight, the bulk of the salt formed acting to 
swell the tablet and the carbonic acid acting to simultaneously release 
carbon dioxide within the swelling tablet whereby rapid disintegration of 
the tablet is effected, the alginic acid salt acting to body the resulting 
active ingredient solution. 
In this embodiment typically the metal carbonate is a carbonate or 
bicarbonate of an alkali metal, e.g. sodium or potassium; the active 
ingredient is a foodstuff or medicament; the tablet further comprises a 
lubricating effective amount of a lubricant, e.g. a tablet lubricant 
comprising L-leucine or L-isoleucine in an amount between 0.1 and 5 parts, 
and especially between 0.3 and 1.5 parts per 10 parts by weight of the 
tablet particularly where the active ingredient is coffee; and preferably 
the carbonate is sodium bicarbonate and is present in about stoichiometric 
amount for reaction with the alginic acid. 
The invention further contemplates provision of a method of preparing a 
rapidly water-disintegrable tablet, including combining an active 
ingredient with a small but effective amount of an unreacted mixture of a 
water soluble carbonate radical precursor and alginic acid intimately and 
under pressure, pulverizing, and tabletting with a lubricant such as 
L-leucine or L-isoleucine in lubricating effective amount as necessary to 
form a stable tablet. 
PREFERRED MODES 
The tablets embodying the present invention comprise an active ingredient, 
typically powdered, or made into a powder by combination with a solid or 
removal synthetically of the water therein, which has therapeutic, 
nutritious, or medicinal qualities, for example, which it is desired to 
package in tabletted form. The active ingredient can be combined with 
excipients, binders, bulking agents, lubricants, processing aids, dyes and 
colorants, and other expedients normally used in tablet manufacture. In 
general these additives are used in their conventional amounts for their 
known purposes, and are selected so as to not interfere with the desirable 
organoleptic values, residue-free esthetic advantages and in situ bodying 
properties resultant from use of the present invention in constituting the 
tablet. 
The method of combining the ingredients is conventional, with all parts 
being reduced or increased to a suitably tabletable particle size, and 
intimately mixed as necessary for the desired degree of uniformity in the 
tablet composition. In a final stage, the tablet is formed by a punch or 
die acting with a suitable cavity. 
To conventional composition and processing the present invention brings an 
improved disintegrating system. The system comprises alginic acid, a 
commercially available material widely used in tablet making as a 
disintegrant, without however, the generation of carbon dioxide as well. 
To the tablet composition of active ingredient, excipient if any, and 
alginic acid, a carbonate radical (CO.sub.3.sup.--) precursor is added in 
accordance with the invention. The function of the carbonate radical 
precursor is to generate carbon dioxide responsive to neutralizing 
reaction of the carbonate radical precursor with the alginic acid. 
Suitable sources of carbonate radicals are the alkali and alkaline earth 
metal salts of carbonic acid, e.g. sodium, potassium, calcium, magnesium 
or manganese carbonates and bicarbonates, which are effective precursors 
of the carbonate radical in that they form carbonate radicals when exposed 
to water, as the tablets of the invention are. The proportions of 
carbonate radical precursor and alginic acid are desirably stoichiometric, 
i.e. three parts of carbonate radical per part of alginic acid, but can be 
more or less provided carbon dioxide evolution is realized by the 
combination of the alginic acid and carbonate radicals into carbonic acid, 
together with by-product water and alginic acid salt. The alginic acid 
salt, e.g. sodium alginate, is produced in situ in the solution is a known 
thickening agent, and contributes a bodying quality to the solution. 
In a typical tablet according to the invention, there is used from 0.05 to 
25% by weight of the alginic acid, and the mentioned stoichiometric amount 
or more of the carbonate radical precursor. In a particular product useful 
for foodstuffs, the alginic acid comprises from 3-15% of the tablet by 
weight and a metal carbonate, such as sodium bicarbonate, from 1 to 70% of 
the tablet, the balance being active ingredient and any other formulation 
expedients desired. 
As noted above, L-leucine or isoleucine is advantageously used as a 
lubricant in tablets according to the invention, e.g. in amounts of from 
0.1 to 5, and more particularly from 0.3 to 1.5 parts, especially for 
instant coffee tablets prepared in accordance with the invention, or more 
or less amount that is effective for easing tablet formation and release 
from forming tools. The leucines are noteworthy in being water soluble in 
water sufficient to dissolve the tablets being described, so that upon 
addition to water, there is no solid residue, and a highly esthetic food 
or medicinal product can be obtained. Further, the leucines are 
essentially amino acids, so they are biologically safe.

EXAMPLE 1 
Instant Coffee Tablet 
A tabletted form of instant coffee was prepared by combining previously 
prepared powdered, e.g. instant coffee granules of suitable size for 
tabletting by combining for each tablet 
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12.5 gm. powdered coffee 
1.0 gm. alginic acid 
3.0 gm. sodium bicarbonate 
0.7 gm. L-leucine 
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slugging and grinding to about 40-60 U.S. Mesh. 
This intermediate was blended with 1.0 gm. of a 3:1 weight mixture of 
sodium bicarbonate and alginic acid, and 1.0 gm. of L-leucine. Tablet 
formation was effected in a conventional tabletter with each tablet 
weighing about 17.4 gms., as necessary to prepare approximately 1 cup of 
coffee. 
Coffee preparation involved depositing the tablet in very hot water. A 
fizzy evolution of carbon dioxide gas and ubiquitous fragmentation of the 
tablet occurred with rapid distribution of the coffee through the cup 
water. A sweet tasting beverage with seemingly enhanced body was noted. 
Also, inspection of the cup revealed no residue. In a CONTROL the 
procedures of the Example are varied by omitting the alginic acid and 
substituting a like amount of pre-prepared sodium alginate, Control I; or 
by omitting the sodium bicarbonate, Control II. In each instance tablet 
disintegration is markedly slower, stirring is required to fully break up 
the tablet, and the body of the beverage is thinner and less satisfactory. 
It is thus demonstrated that the carbonate alone is inferior to the 
combination of alginic acid and carbonate, and that pre-prepared sodium 
alginate as a disintegrant is inferior to that generated in situ by 
reaction of alginic acid and carbonate. This synergistic result is 
entirely unexpected. 
EXAMPLE 2 
Example 1 is repeated omitting the leucine. Tablet performance is 
equivalent but the resultant coffee is less sweet tasting. Tea, cocoa, and 
soups can be similarly prepared. 
EXAMPLE 3 
Reconstituted Milk 
A powdered milk tablet is prepared substituting powdered milk for the 
coffee in Example 1, and reducing the L-leucine to 0.5 gm. before slugging 
and 300 mg. after, per tablet. On combination with cold water, the tablet 
disintegrates with a self-stirring evolution of gas. A wholesome tasting 
milk is obtained. Enhanced body over other reconstituted milk is noted, 
apparently by virtue of the presence of sodium alginate. 
EXAMPLE 4 
Asprin 
A composition of 
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325 mg. acetylsalicylic acid 
30 mg. starch 
210 mg. disintegrant (1:3 alginic acid: 
potassium carbonate) 
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was tabletted. Dropping the tablets in water results in immediate 
dissolution with outgassing, fragmentation of the tablets, and no residue. 
EXAMPLE 5 
Vitamin C 
A vitamin preparation is prepared from 
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225 mg. ascorbic acid 
125 mg. disintegrant (1:4 alginic acid: 
magnesium carbonate) 
40 mg. leucine 
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Tablet formation is easy, and disintegration in aqueous medium rapid. 
There is thus provided a novel disintegration system for tablet versions of 
foodstuffs, medicaments, and like active ingredient products available or 
potentially available in less convenient powders. The disintegrant not 
only breaks up the tablet by a combination of gas production and bulking, 
but as well generates an alginate salt useful per se as a bodying agent so 
the liquid product is enhanced in consumer appeal.