Title: Chewable soft capsule
United States Patent: 6,258,380
Inventors: Overholt; Susan M. (McLeansville, NC)Assignee: Banner Pharmacaps, Inc. (High Point, NC)
Appl. No.: 262660Filed: March 5, 1999
The present invention comprises chewable, soft gelatin capsules having a sheath formed of a mixture of a low bloom and a medium bloom gelatins, a plasticizer, water, and preferably a moisture retention agent to enhance the machinability and integrity of the sheath composition; and a fill of an active material in a carrier liquid.
SUMMARY OF THE INVENTION
The present invention is directed to chewable soft gelatin
capsules, or chewable softgels comprised of a chewable gelatin sheath
encapsulating a liquid fill. The sheath composition is specifically
characterized by flexibility and a non-sticky consistency so that it can
be formed into capsules using conventional encapsulation machinery, and
the integrity to enclose a fill for an extended period of time, e.g., up
to about two years, without dissolution or leakage, while still being
readily soluble upon consumption.
Most conventional softgel capsules are produced by a rotary die process in
which a molten mass of a gelatin sheath formulation is fed from a
reservoir onto drums to form two spaced sheets or ribbons of gelatin in a
semi-molten state. These ribbons are fed around rollers and brought
together at a convergent angle into the nip of a pair of roller dies that
include opposed die cavities. A liquid or paste medicament or other
material to be encapsulated is fed into the wedge-shaped joiner of the
ribbons.
The gelatin ribbons are continuously conveyed between the dies, with
portions of the medicament being trapped between the sheets inside the die
cavities. The sheets are then pressed together, and severed around each
die so that opposed edges of the sheets flow together to form a continuous
gelatin sheath around the entrapped medicament. The part of the gelatin
sheet that is severed from the segments forming the capsules is then
collected for recycling. The very soft capsules are then dried to increase
the integrity of the sheath, and packaged for later distribution and
consumption.
Manufacture of uniform soft gelatin capsules by this or similar processes
requires a sheath material that has good "machineability," i.e.,
it is of critical importance that the sheath material be of a non-tacky or
non-sticky nature, so that the sheath material can be brought into contact
with the rollers without sticking. At the same time, the sheath
composition must not degrade or dissolve during storage prior to
consumption, allowing the fill material to leak from the capsule.
The properties of the sheath material is determined in significant part by
the cohesive strength of the constituent gelatin, expressed as
"bloom." Conventional soft gelatin capsules normally have a
bloom in the range of from about 150 to about 275. This bloom value is
determined by measuring the weight in grams required to move a plunger 0.5
inch in diameter, 4 mm into a 6.67% gelatin gel that has been held for 17
hours at 10oC.
Chewable softgel capsule sheaths are designed to at least partially
disperse or dissolve in the user's mouth within a brief period of time
after the fill contents have been released, e.g., within about 60 seconds,
so that it can be swallowed. Therefore, in addition to the above
properties, the sheath of these products must also be soluble after the
fill contents are released. The sheath should also have a good "mouth
feel." As used herein, "mouth feel" describes chewability.
Chewing the sheath should be a pleasant, or at least not an unpleasant
sensation that results in a swallowable composition.
Surprisingly, it has been found that a chewable softgel sheath having all
of these desired characteristics can be produced from a specific mixture
of defined gelatins in combination with defined percentages of a
plasticizer and preferably a moisture retaining agent. This combination of
ingredients, to be described herein in detail, has been found to produce
capsule sheaths that have the necessary low stickiness for machineability,
and sufficient integrity for stable fill encapsulation, while having a
desirable mouth-feel and solubility.
More specifically, the present capsule sheaths are formed of a mixture of
a first gelatin having a bloom substantially lower than the bloom of
gelatins conventionally used to form capsule sheaths, in combination with
a minor percentage of a second gelatin having a bloom within the range of
conventional sheath-forming gelatin blooms. The first gelatin has
insufficient integrity for use alone in sheath formation.
Plasticizers are essential in sheath formulations in order to impart the
necessary softness and flexibility to the sheath material, so it can be
formed into capsules. The presence of a significant percentage of
plasticizer, however, may result in a sheath that is difficult to process
because the sheath will stick to the rollers during machining, as
described herein above. Also, the plasticizers tend to dry out the sheath
over any extended shelf-life of the finished product capsule, resulting in
a capsule with a "leathery" mouth feel.
In accordance with an additional embodiment of the present invention, the
tackiness or stickiness of the sheath can be maintained at a desired
machinable level, even in the presence of high percentages of plasticizers,
by adding a small percentage of a moisture retention agent, as hereafter
defined, to the sheath composition. The moisture retention agent also
maintains the desired mouth feel over an extended shelf-life.
While the function of the moisture retention agent is not entirely clear,
it appears that the additive disrupts the gelatin structure to reduce the
gelatin strength and immobilizes or retains water.
More specifically, the present sheath composition is comprised of a first
gelatin, hereinafter referred to as "low bloom" gelatin, having
a bloom of up to about 100, and preferably from about 80 to about 100. The
low bloom gelatin is combined with a second gelatin, hereinafter referred
to as "medium bloom" gelatin, having a bloom in the range of
from about 150 to about 275, and preferably from about 150 to about 175.
The first and second gelatins preferably are present in a ratio of from
about 1:1 to about 10:1, and even more preferably a ratio of from about
3:1 to about 5:1. Type A or B gelatins or a mixture thereof, may be used
for the first and/or the second gelatin. Limed bone, acid bone, fish
and/or pig skin gelatins may be used in the present invention.
The sheath plasticizer preferably is glycerin, sorbitol, maltitol, or a
mixture thereof. Other plasticizing agents known in the art to improve
softness and flexibility are also within the scope of the present
invention. The sheath will normally include at least about 10 percent by
weight plasticizer in order to impart the desired softness and
flexibility. Preferably, from about 20 to about 30 percent by weight of
plasticizer will be employed.
As noted earlier, when the required percentages of plasticizer are
combined with the above-described gelatin mixture, the capsule may not
have desired machinability or extended chewability characteristics.
However, it has been found these characteristics are improved by adding at
least about 0.5% by weight, and preferably from about 1 to about 5% by
weight of a moisture retention agent to the composition.
Materials used in the present invention as moisture retention agents have
been previously added to sheaths used to encapsulate water miscible,
volatile fills, see, e.g., U.S. Pat. No. 4,804,542. In these prior art
compositions, the materials are used to prevent dissolution of the sheath
by the particular fills used. In the present invention, however, the
moisture retention agent serves a different purpose, namely, to improve
machinability and prevent the sheath of the finished capsule from drying
out. In addition, the moisture retention material finds use in both water
miscible, volatile fills, and with carriers of the type described below,
where such materials have not previously been used or required.
Although not meant to limit the scope of the present invention, examples
of moisture retaining agents include celluloses, cellulose derivatives,
starches, starch derivatives, vegetable gums, non-hygroscopic, mono-, di-
and oligosaccharides, and silicon dioxide. Specific stabilizers are:
starches such as LO-TEMP.RTM., SOFT-SET.RTM., OR MIRA-GEL.RTM.
manufactured by A.E. Staley Manufacturing Company of Decatur, Ill.;
microcrystalline cellulose such as AVICEL.RTM. manufactured by FMC
corporation of Philadelphia, Pa.; silicon dioxide such as AEROSIL.RTM.
manufactured by Degussa Aktiengesellschaft of Frankfurt, Germany; and
cellulose such as SOLKA FLOC.RTM. manufactured by Fiber Sales &
Development Corporation of Urbana, Ohio.
Other sheath ingredients may include taste modifiers. For example,
non-reducing sugars, such as xylitol, maltitol, or LYCASIN.RTM.
manufactured by Roquette America, Inc. of Keokuk, Iowa, are commonly added
to the composition. These non-reducing sugars are usually added in amounts
up to about 10% of the sheath composition.
Thus, the preferred sheath compositions of the present invention are
comprised of the following ingredients in the specified percentages:
INGREDIENT % BY WEIGHT
Low Bloom Gelatin 15-30
Medium Bloom Gelatin 5-15
Plasticizer 20-40
Water 10-30
Moisture Retaining Agent 0.5-5
Other Ingredients 0-10
It will be understood that different percentages may be selected within the above ranges so that the sum of the percentages of the sheath ingredients is equal to 100%. If additional ingredients are used, the percentages will be adjusted within the ranges listed to accommodate the additional ingredients.
Based upon the preferred composition described immediately hereinabove, upon casting the sheath into gelatin capsules it is known in the art that the drying process will reduce the water content of the sheath to less than about 10%, with a preferred industry standard of about 6% to about 8%. Accordingly, the capsule sheath formed from the above mixture, after being dried for storage and subsequent use, preferably is comprised of the following ingredients in the specified parts by weight:
INGREDIENT PARTS BY WEIGHT
Low Bloom Gelatin 20-38
Medium Bloom Gelatin 6-20
Plasticizer 26-52
Water 6-8
Moisture Retaining Agent 0.60-6.50
Other Ingredients 0-13
The capsule fill is generally comprised of a liquid carrier, and an active ingredient dissolved or suspended therein. The liquid carrier preferably is a water-immiscible liquid such as a vegetable and aromatic oils, aromatic and aliphatic and aliphatic hydrocarbons, chlorinated hydrocarbons, ethers, esters, high molecular weight organic acids and alcohols, or lower molecular weight polyalkylene glycols, such as polyalkylene glycol 600. Other embodiments may contain water-miscible liquid carriers as well.
As used in the present description, the term "active ingredient" is intended to include medicaments, vitamins, minerals, fruits, herbals and other encapsulatable materials or combinations thereof understood by those skilled in the art to support the desired effect. For example, if the effect desired is mineral supplementation, exemplary active ingredients may be calcium, magnesium and Vitamin D. Additionally, if the desired effect is targeted toward urinary tract health, an exemplary active ingredient of cranberry is included.
The fill may also include other ingredients, such as sweeteners and other flavorants, or flavor modifiers. Suitable flavor modifiers include any natural or artificial flavor or a combination thereof. Also, as is known in the industry, WONF (with other natural flavors) flavorants may be included.
Generally, the active ingredient will be present in an amount of from up to about 50% by weight, with variations allowed for the variable fill employed. Mixtures of active ingredients may also be incorporated into the fill.
Claim 1 of 22 Claims
What is claimed is:
1. A gelatin capsule sheath comprised of:
a) from about 20 to about 38% by weight of a first gelatin having a bloom
of from about 80 to about 100;
to b) from about 6 to about 20% by weight of a second gelatin having a
bloom of from about 150 to about 275;
c) up to about 10% water;
c) a plasticizer in an amount sufficient to render said sheath flexible;
and
d) a moisture retention agent in an amount sufficient to provide sheath
integrity.
____________________________________________
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