Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PCT/EP 93/ 02218 24th August 1994
BOEHRINGER MANNHEIM GMBH 3709/00/PCT
(amended version)
Elongated, divisible tablet
The invention concerns an elongated, divisible tablet
especially for pharmaceutical applications in which each
of the two ends of the tablet underside and upper side
have a zone which protrudes in such a way that, when one
of the said sides is laid on a flat support, the
protruding zones but not the intervening zone touch the
support. The underside of the tablet and the upper side
of the tablet are defined as stated in W.A. Ritschel
"Die Tablette", Editio Cantor KG, page 58, 1966.
In the development of solid pharmaceutical agents a
search is made for forms of administration which can be
manufactured particularly economically such as e.g.
small round tablets. However, in practical use round
tablets are found to have several disadvantages. The
main problem, particularly for older persons, is the
divisibility of such tablets. In many cases half the
dosage is required in the initial phase of treatment
(low initial dose). The division is difficult because
the breaking crevice is very fine and is easily
overlooked or the patients do not know exactly how to
divide the tablet. The result is two fragments of
different sizes or even many small fragments. In
addition one needs both hands for the division. In the
case of older persons especially they additionally have
particular difficulties in picking up small and light
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tablets from a support. It may therefore be the case
that the patient asks the doctor for a form of
administration which is easier to handle. These
disadvantages are only negligibly when the tablet has an
oblong shape instead of a round shape.
There have been no lack of attempts at solving the
problem of divisibility for example by using small
apparatuses such as mini-guillotines. Such apparatuses
are commercially available. However, the operation is
complicated and the device must in each case be matched
to the diameter of the tablet. A so-called kinked tablet
was also developed. It has an angle shape - i.e. it is
asymmetric - and therefore does not remain in the
desired position on a support. Two hands are necessary
to divide the kinked tablet. An additional disadvantage
of this tablet is that it cannot be blister-packed on
packaging machines. A small mechanical load leads to
breakage of the tablet. A further embodiment of a
divisible tablet is the Tiltab~ sold by the SKB Company
which can be easily picked up from a support. This is
the case because when this tablet is placed on a support
it always stands up on one side due to its geometry. Due
to its length (14 mm) and its oval shape, the tablet is
relatively easy to divide. However, the oval shape
especially is a great disadvantage on a packaging
machine because an oval tablet can get wedged on the
feeding rails. Moreover, the manufacture of the
compression tools is complicated and expensive.
In addition tablets are known which are shaped so that
their middle zone is thinner than two opposite end zones
positioned on a straight line running through the middle
zone and preferably have a breaking crevice through
their middle zone which is perpendicular to the said
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straight line. When the tablet is halved the said end
zones of the tablet lie on the support while the middle
zone is spaced from the support. The tablet is divided
into two halves by lever action by pressing a finger on
its middle zone towards the support.
Such a tablet which preferably has a round shape is
described in EP Application 0 207 888 Al. The round
shape is in fact advantageous with regard to processing
in particular during pressing and when providing a
coating. However, round tablets are inferior to
elongated tablets with regard to their divisibility
since much force has to be used for bisecting because
the lever arm is relatively short and the fracture
surface is relatively large. An elongated tablet of this
type in which the tablets rest on the support during
division with a line vertical to the line connecting the
ends or with a narrow surface, is described in the US
patent 5,061,494. Due to the shape of the zones on which
the tablet rests on the support, the tablet has an
almost rectangular shape. The lines or narrow surfaces
perpendicular to the connecting line which are present
on one side of the tablet are in this case positioned on
protruding zones at the ends of the tablet which are
separated from one another by a depression which dips
concavely towards the middle of the tablet. Another
elongated tablet of this type is described in the US
patent 4,735,805. This tablet is composed of an
elliptical plate on both sides of which frustoconical-
like elevations are provided in which a groove with a
round profile is provided extending perpendicular to the
longitudinal axis in such a way that in each case the
deepest point of the groove is approximately in the
geometric middle of the plate and at both ends a ridge
runs across an apex i.e. the frustoconical elevations
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have concave sides. Although the tablets described in
both US patents have advantages over the tablet
described in the EP application with regard to
divisibility, but they have disadvantages in the
manufacture in particular with regard to coating which
is apparently related to the fact that they deviate
relatively strongly from a round convex form not only in
their oblong form but also in the concave sides of their
protruding areas (see below). The tablet known from the
US Patent 4,735,805 also tends to wedge on the feeding
rail of the packaging machines due to its elliptical
shape.
The ability to package a tablet efficiently and to
provide it with a coating are important cost criteria in
tablet manufacture because coating with a film in
particular has to be carried out very often in order to
for example cover up a bad taste or a rough surface of
the tablet or to apply a retarding film. A prerequisite
for the problem-free manufacture of the coating is that
these rotate (roll) perfectly in the coating tank in
addition to the coating composition and the quality of
the tablets to be coated. In practice only round convex
tablets rotate without difficulty. In contrast tablets
whose shape differs strongly from a round convex shape
such as for example conventional oblong tablets do not
roll satisfactorily. These oblong tablets which have the
shape of a flat plate with two large surfaces with
straight 7ongitudinal sides running parallel to one
another and perpendicular to the large surfaces and with
round ends, are not provided with a uniform coating
during coating. In addition they get caught together on
the wall of the coating tank and form structures which
are similar to a net. As a result they are pulled up the
tank wall and break up far above the core bed then to
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fall back into the core bed. In larger coating tanks the
drop height is so large that the tablets can break in
this process. Also the movement within the core bed is
more a sliding than a rolling. Indeed it is often the
case that the tablets do not rotate at all but rather
"slide through". It is therefore not inevitable that the
tablets are coated inhomogeneously which can be seen
with the naked eye particularly in the case of coloured
film tablets. If, in contrast, the tablets have the
property of rolling, the coating is uniform. The object
of the invention is therefore to provide a tablet which
does not have the aforementioned disadvantages. In
particular it should roll well in a coating tank, be
simple to manufacture and coat and if desired, be
divisible so that it can be handled and bisected without
difficulty by older or visually handicapped people.
This object is achieved with a tablet of the type
described in the introduction in which the protruding
zones are in the shape of bulges.
The tablet according to the invention has important
advantages with regard to divisibility and grippability
over the tablets described in the three aforementioned
documents. In particular the tablet according to the
invention can be handled and bisected with ease and is
in addition simple to manufacture and coat. Thus it was
found that - obviously due to the bulges - the new
tablet form rolls perfectly in the bed of a coating tank
i.e. it behaves like a round convex tablet and can thus
be provided with a uniform coating without difficulty.
That was not predictable. A further advantage is that
the tablet according to the invention has a relatively
large volume in relation to its surface so that it has
smaller dimensions than other tablets with the same
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volume. When this embodiment of the tablet according to
the invention is halved, the bulges that are shaped
convex have the advantage over the concave design
described in US patent 4,735,805 that the pressing
finger slides automatically to the lowest point i.e. to
the middle of the tablet where it is intended to divide
it which is very helpful particularly in the case of
older patients whose vision is limited or just allows
handling by them. This advantage in the handling is even
more pronounced compared to the tablets described in the
US patent 5,061,494 in which the side of the tablet
which is pressed during the division is flat apart from
a breaking crevice.
A divisible tablet which also has protruding zones which
are in the shape of bulges is known from the US patent
4,824,677. However, in this known tablet the bulges do
not protrude from the underside of the tablet and/or
from the upper side of the tablet. They rather protrude
from the stem of the tablet i.e. they protrude in a
direction that is about 90 different from that of the
tablet according to the invention. Thus in contrast to
the tablet according to the invention pressure is not
applied to protruding bulges when the known tablet is
divided.
It is advantageous when the tablet has a dumb-bell shape
i.e. has a shape which is axially symmetric to the
longitudinal axis of the tablet because it can then be
divided by finger pressure into two halves in any
position relative to the support. A tablet shaped thus
can also be easily picked up by its middle zone which is
always spaced from the support independent of its
position relative to the support.
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A advantageous embodiment of the tablet according to the
invention has a flat plate wherein the bulges protrude
from the two plate surfaces that are opposite from one
another.
It is advantageous for the fabrication of the tablet
when the plate has the shape of an oblong with
approximately semi-circular end zones and lateral edges
parallel to the longitudinal axis in the middle zone of
the tablet (1), the distance between the edges parallel
to the longitudinal axis preferably being the same as,
but if desired also smaller or larger, than the diameter
of the semicircles at the ends of the oblong whereby if
the distance is smaller the circular sectors are larger
than a semicircle. The compression tools required to
produce such a tablet are simple to manufacture like
those for conventional oblong tablets and a good
guidance on packaging machines is ensured by the lateral
edges parallel to the longitudinal axis in the middle
zone of the tablet. In addition - in contrast to
conventional oblong tablets - the tablets according to
the invention shaped in this manner do not have a
tendency to hook together and to form net-like
structures with the aforementioned disadvantages during
coating in the coating tank despite the oblong-shaped
plate. The tablet according to the invention designed in
this way is thus very advantageous not only in the
tablet manufacture but also in the further processing
i.e. in coating and/or packaging. Moreover the tablet
according to the invention with an oblong-shaped plate
has smaller plate dimensions than a conventional oblong
tablet of the same volume that does not have convex
bulges. In addition the tablet looks subjectively to be
smaller and thus less "threatening" than a conventional
oblong tablet with a plate of the same size.
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It is favourable in the case of the tablet with an
oblong-shaped plate that the bulges form spherical
segments at least in the area of the apexes. The tablet
is particularly easy to handle when the sphere diameter
of the spherical segments is larger than the height
(dimension perpendicular to the large surfaces of the
plate) of the tablet because, when its two spherical
segments have contact with a flat support, it positions
itself automatically on the support in such a way that
the large surfaces of the plate are positioned
approximately parallel to the support i.e. they are in
an advantageous position for division. Contact of the
spherical segments with the support is almost automatic
when the largest dimension (width) of the large surfaces
perpendicular to the longitudinal axis of the tablet is
larger than the height of the tablet. In order to
further facilitate the divisibility it is advantageous
when the tablet has at least one breaking crevice in its
middle zone which is approximately perpendicular to the
line connecting the end zones of the tablet with which
the tablet rests on a support during division.
In a preferred embodiment of the tablet according to the
invention the semicircular end zones of the tablet
halves usually rest on the support after the division
whereas the fracture edge points obliquely upwards. As a
result the halves can be very easily grasped and lifted
from the support. This advantageous position is not
assumed by the tablet halves in all cases i~ - which is
easy to avoid - the centre of gravity of the tablet
halves lies on the connecting line between the apexes of
each tablet half.
In a further advantageous design of the tablet a groove
runs over the apex of at least one of the bulges the
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projection of which on one of the large surfaces of the
plate forms either no or at most an acute angle with the
longitudinal axis of the tablet. The depth of the groove
may also be zero. It is possible to accomodate a name,
e.g. the logo - or a part thereof - of the tablet
manufacturer in such a groove. The edges which the
groove forms with the surface of the bulge preferably
run approximately mirror-symmetrically to a plane
standing approximately perpendicularly to the plate.
When a tablet with groove edges that run in this manner
touches a flat support it has an even more stable hold
on the support than when only its intact spherical
surface touches it. This also additionally simplifies
its divisibility. A similar stable standing position of
the tablet on the support is achieved when the apex of
at least one of the bulges forms a small surface
parallel to the large surfaces of the plate.
The tablet according to the invention is particularly
suitable as a pharmaceutical form of administration for
any active substances. Any desired pharmaceutical active
substance can be used as the active substances, for
example chemotherapeutic agents, phytopharmaceutical
agents, vitamins, enzymes, hormones etc..Bezafibrate,
clodronic acid, Carvedilol or Glibenclamide are
mentioned as examples of active substances. The active
substances can be present in any desired dosage, for
example of 0.1 - 100 ~ by weight of the tablet core. If
the active substances can be pressed directly into
tablets without further pharmaceutical auxiliary or
carrier substances, the tablet according to the
invention can also be composed of the pure active
substance. However, further auxiliary or carrier
substances are usually used for the manufacture such as
for example filling agents, tablet disintegrants,
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lubricants or mould release agents, binding agents,
adsorbents, dissolution retarders, agents which increase
the hydrophilicity, flow-regulating agents, absorption
accelerators, taste corrigents or colourings.
The tablets are preferably manufactured from a granulate
which has been produced by dry, wet or spray granulation
of the tablet components or by compaction.
Further advantageous embodiments of the tablet according
to the invention are disclosed in the subclaims.
The invention is described on the basis of examples of
design illustrated by drawings. Fig. 1 shows an enlarged
diagram in a top view of an embodiment of the tablet
according to the invention which rests on a horizontal
support in a suitable position for the bisection. Fig. 2
shows a longitudinal section through the tablet shown in
Fig. 1 along the lines A - - A drawn in Fig. 1. Fig. 3
gives a view towards the longitudinal axis of the tablet
shown in Fig. 1 and 2.
The tablet 1 illustrated in Fig. 1 to 3 has all
essential and advantageous features of the invention. It
should, however, be made clear that although the tablet
illustrated by the Figures represents the most preferred
embodiment, other embodiments of the tablet according to
the invention encompassed by the scope of the claims can
be used advantageously due to their economical
fabrication and/or good handling.
Fig. 1 shows an oblong, i.e. a structure, which is
composed of a circle cut into two halves and a rectangle
which is inserted between the edges of cut and whose
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sides facing the semicircles are of the same length as
the diameter of the circle. The oblong forms the surface
area of a plate 2. Plate 2 has three planes of symmetry
C, D and E. The planes of symmetry C and D are
perpendicular to the parallel-spaced large surfaces of
plate 2 and the plane of symmetry E is parallel to the
large surfaces. The longitudinal axis of tablet 1
extends along the line of intersection of the planes of
symmetry C and E. The longitudinal section shown in Fig.
2 coincides with the plane of symmetry C and the cross
section shown in Fig. 3 is parallel to the plane of
symmetry D. Each of the two large surfaces of plate 2
have two bulges 3. Perpendicular projections of the
apexes of the bulges 3 onto the plate 2 coincide with
the circle centres of the semicircles. In the apex
region the bulges 3 are in the form of spherical
segments 4. The transition between the spherical
segments 4 and the plate 2 is formed by two plates 5
whose surfaces adjoining the large areas of the plate 2
are congruent with the oblong and taper towards the
spherical segments 4 so that the plates 5 continuously
merge into the spherical segments 4 in the area of the
semicircular ends. It should be made clear that the
division of the tablet into plates 2 and 5 and spherical
segments 4 only serves to unequivocally describe the
tablet. In reality these shaped elements form a unit
which is produced in one pressing process.
The sphere diameter o~ the spherical segments 4 i.e. the
diameter of the spheres of which the spherical segments
form a part is larger than the height of the tablet.
This makes the tablet particularly easy to handle
because when its two spherical segments make contact
with a flat support it positions itself automatically on
the support in such a way that the large areas of the
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plate are aligned approximately parallel to the support.
The contact of the spherical segments with the support
is almost automatic when, in a preferred embodiment of
the tablet, the largest dimension (width) of the large
areas perpendicular to the longitudinal axis of the
tablet is larger than the height of the tablet. The
plates 5 are each divided into two equal halves by the
wedge-shaped breaking crevice 6 which runs symmetrically
to the plane of symmetry D.
A groove 7 of rectangular cross section is provided in
one of the spherical segments 4 on each of the two sides
of plate 2 mirror-symmetrically to the plane of symmetry
C. The bottom of the groove 7 can carry the logo - or a
part thereof - of the company who manufactures or sells
the tablet.
The length of the oblong is typically about 17 and its
width about 8 mm and the bulges 3 each have a height of
about 1.5 mm with a total height (distance between two
apexes of the bulges that are mirror-symmetrical to the
plate 2) of about 5.5 mm. The length of the tablet
should be such that the finger pressure during division
does not act on the apexes of the bulges but rather on
the region between.
The described tablet 1 has advantageous properties. If
the tablet rests on a flat support such that the large
areas of the plate 2 are aligned parallel to the support
and the spherical segments 4 on one side of the plate
touch the support - a position which the tablet will
automatically assume as described above - then the
middle zone of the tablet has no contact with the
support. The tablet can therefore easily be gripped
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there and lifted. The described position of the tablet
is additionally stabilized by the groove 7 because the
edges which the groove 7 forms with the surface of the
sphere run approximately mirror-symmetrically to a plane
which is approximately perpendicular to the plate 2. Due
to the lack of contact of the middle zone with the
support, the tablet can be divided without effort in the
described position even without aids. For this one only
has to exert pressure from above on the middle zone with
a finger. The middle is the place with the maximum
bending moment i.e. that site at which the tablet can be
divided with the least exertion.
In contrast to conventional round or oblong-shaped
tablets, the tablet does not have to be held in the hand
when it is broken. The two spherical segments 4 on the
side of the plate facing away from the support
automatically lead the finger with which the pressure is
exerted to the middle of the tablet. Therefore people
with limited vision can also divide the tablet without
any aids. After the division the fracture edges of the
tablet halves rest on the support while the semicircular
end zones point diagonally upwards. As a result the
halves can be easily gripped and lifted from the
support. In addition the tablets can be easily provided
with a uniform coating by rolling in a coating tank.
Thus despite the straight side walls in the middle
tablet zone which run parallel to one another, it
behaves like a round convex tablet. Due to these
straight side walls it is also possible to guide the
tablet in packaging machines without getting wedged. In
addition the tablet has a relatively large ratio of
volume to outer surface and is thus smaller with regard
to its outer dimensions than for example conventional
oblong tablets of the same volume. Moreover the tablet
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also looks subjectively smaller than a conventional
oblong tablet which has the same dimensions as the
plate 2.
Embodiments of the tablet according to the invention are
also usable which have shapes that are different to that
of the tablets described in the Figures even when they
may not have all of the described advantages. For
example the tablet can have other dimensions or another
length : width : height ratio. It is also possible that
the quadrangle between the semicircular ends is narrower
than the diameter of the circle i.e. the tablet assumes
a dog-biscuit form. The tablet can also be shaped like a
dumb-bell. On the other hand shapes can also be used in
which either the plates 5 which taper towards the
spherical segments 4 are not present or the bulges 3 are
completely absent on one side of the plate 2. If the
bulges 3 of a tablet of the latter shape are laid on a
support, the good divisibility is indeed given as before
but the advantage that the finger is automatically led
to the middle is absent.
