Note: Descriptions are shown in the official language in which they were submitted.
CA 02346670 2001-04-05
WO 00/21505 - 1 - PCT/EP99/07300
Composition for the parenteral administration of active
compounds
Description
The present invention relates to a composition for the
parenteral administration of active compounds, which
composition comprises a particulate, polysaccharide-
based carrier material and a stable suspension thereof.
Active compound carriers which are optimally matched to
the requirements of the respective administration form,
which can be administered in an innocuous manner and
which can specifically influence the biodistribution,
bioavailability or absorption of an active compound are
of particular importance for pharmaceutical or medical
applications.
Furthermore, in the body, the active compound carriers
should decompose in a controlled manner in order, on
the one hand, to enable the active compound to be
released in a contralled manner, if required over a
relatively long period as well, and, on the other hand,
to ensure that th<~ carrier is broken down in a
biocompatible manner.
For parenteral administration, e.g. by means of
injection, it is necE~ssary to select an active compound
carrier which can form a stable suspension and which
possesses outstanding needle traversability, in
particular in the care of a very small needle diameter.
From the point of view of biocompatibility, the
stability of the suspension should be guaranteed even
without adding dispersion aids.
US patent No. 4,451,452 describes a composition for
parenteral administration, with a hydroxyl group-
containing polymer, which is by nature water-soluble
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and which has been made water-insoluble by being
partially esterifie~d, being used as the biodegradable
carrier material. F'or this, various compounds, such as
polyvinyl alcohol or amylose, are mentioned as examples
of the water-sol.u:ble polymer. For injection as a
suspension, it is proposed that the carrier material be
used in the form of particles together with an
emulsification aid such as low molecular weight
polyvinyl alcohol.
WO 96/39464 describes injection-suitable suspensions of
particles composed of a crosslinked, water-soluble
polymer which is still able to pass through needles
having a comparatively small diameter of 20 gauge
(corresponding to a diameter of 0.9 mm and a length of
40 mm) .
Natural polysaccharides, such as amylose, are
mentioned, inter alia, as examples of the water-soluble
polymers.
However, in this connection, a disadvantage is the
necessary employment of crosslinking agents and
emulsification aids, which can exert a negative effect
on biocompatibil:Lt.~~ and degradability and can
furthermore make the preparation process more
elaborate.
US patent No. 1,:143,219 describes a process for
preparing a stable suspension composed of an amylose
material which is isolated from an amylose-rich starch.
In this process, the amylose-rich starch is first of
all degraded by aced hydrolysis and the resulting,
water-insoluble degradation products are then
comminuted mechanically until the material is so finely
divided that it is able to form a stable suspension.
However, the parti~~les which are obtained in this
connection are very _inhomogeneous in size and form and
have therefore too undergo additional grading
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procedures. Furthermore, the patent does not give any
indication of any potential suitability for parenteral
use.
The object of the present invention was to make
available a composition for parenteral administration,
which composition comprises a carrier material which is
able to form a stable suspension, even without the
addition of appropriate adjuvants, which exhibits a
high degree of :needle traversability and which
possesses outstanding biocompatibility.
Furthermore, the carrier material should possess a
retardant effect anal be suitable for the controlled
release of active compound.
This object is achieved by means of a composition for
the parenteral administration of active compounds,
which composition comprises a carrier material and at
least one active compound, with the carrier material
comprising spherical microparticles which have a mean
diameter of from 1 nm to 100 Eun and which are composed
entirely or partially, of at least one water-insoluble,
linear polysaccharid<=_ .
The use, according to the invention, of spherical
microparticles which are composed entirely or partially
of water--insoluble, linear polysaccharides is of
fundamental importance for achieving this object.
These microparticles are distinguished by a high degree
of uniformity in s.i-r.e and shape and therefore possess
outstanding needle traversability even when the needle
diameter is very small. Furthermore, they readily form
stable suspensions even without the addition of
dispersion aids.
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The microparticles employed in accordance with the
invention are also distinguished by a high degree of
biocompatibility.
Furthermore, they can be completely biodegraded and are
not concentrated in an animal, in particular human,
body. In this context, biodegradation is understood as
being any process which takes place in vivo and which
leads to degradation or destruction of the compounds,
in particular the polysaccharides. These processes
include, for example, hydrolytic or enzymic processes.
The fact that. the water-insoluble, linear
polysaccharides which are used for the preparation, and
their degradation products, are identical to the
equivalent natural products is, in particular, of great
importance for the biocompatibility of the
microparticles employed in accordance with the
invention.
The spherical microparticles which are employed as
carrier material have a mean diameter do (number
average value) of from 1 nm to 100 Vim, preferably of
from 100 nm to 10 E~m, and particularly preferably of
f r om 1 ~,un t o 5 ~.lm .
Spherical microparticles are to be understood as being
microparticles which have an approximately spherical
shape. When describing a sphere by means of axes of
equal length which proceed from a common origin, which
are directed into space and which define the radius of
the sphere in all spatial directions, it is possible,
in the case of the spherical particles, for the lengths
of the axes to deviate from the ideal state of the
sphere by from 1o to 400. Preference is given to the
deviation being 25~ o:r less, with 150 or less being
particularly preferrE=_d.
The surface of the :spherical particles can be compared
macroscopically to a~ raspberry, with the depth of the
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irregularities on the particle surface, such as
indentations or clefts being at most 200, preferably
lOg, of the mean diameter of the spherical
microparticles.
The specific surface of the microparticles is generally
from 1 ni'/g to 100 mZ/g, preferably from 1.5 mZ/g to
20 m2/g, and particularly preferably from 3 mz/g to
m2/g.
10 In addition, the particles according to the invention
preferably exhibit a dispersity D - weight average
value of the diameter (dw)/number average value of the
diameter (dn) of from 1.0 to 10.0, in particular of from
1.5 to 5.0, and particularly preferably of from 2.0 to
3Ø
The average values which are used here are defined as
follows:
d" - sum of n~ x d~/sum of n~ = number average value
dw = sum of n~ x d~z~'sum of n~ x d. = weight average value
n~ = number of particles having a diameter d~,
d~ - a given diameter,
j - continuous parameter.
In this connection, the term weight notes a weighted
average, as a result: of which the larger diameters are
given a greater relative importance.
The spherical microparticles are prepared by dissolving
the water-insoluble linear polysaccharide or a mixture
of several thereof and also, where appropriate, other
biocompatible polymers in a solvent, e.g. DMSO,
introducing the solution into a precipitating agent,
e.g. water, preferably at a temperature of from 20°C to
60°C, if required, cooling the solution down to a
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temperature of from -10°C to +10°C, and separating off
the particles which are formed in this context.
In this connection, the process of dissolving the
polysaccharide used as starting material can take place
at room temperature or at higher temperatures.
By using suitable <~dditives at the same time, it is
possible to influence the properties of the
microparticles, such as size, surface structure,
porosity, etc., and also to influence process control.
Examples of suitable additives are surface-active
substances, such as sodium dodecyl sulfate,
N-methylgluconamide, polysorbates (e. g. Tween
(registered trademark)), alkyl polyglycol ether,
ethylene oxide-propylene oxide block polymers (e. g.
Pluronic (registered trademark)), alkyl polyglycol
ether sulfates, generally alkyl sulfates and fatty acid
glycol esters, and sugars, such as fructose, sucrose,
glucose, water-soluble cellulose or hot-water-soluble
poly-alpha-D-glucan, such as native or chemically
modified starches, or poly-alpha-D-glucans which are
obtained from the starches, and also starch-like
compounds.
Usually, these additives are added to the precipitating
agent. The quantity employed depends on the particular
individual case and on the desired particle properties,
with the skilled person knowing how to determine the
advantageous quantity in each case.
However, in contrast to WO 96/39464, for example, which
was cited at the outset, there is no need to use
crosslinking agents when preparing the particles.
Within the meaning of the present invention, linear,
water-insoluble polysaccharides are polysaccharides
which are composed of monosaccharides, disaccharides or
other monomeric building blocks such that the
CA 02346670 2001-04-05
_ 7 _
individual building blocks are always linked together
in the same way. Each basic unit or building block
which is thus defined has precisely two linkages, with
each of these being to another monomer. The only
exceptions to this are the two basic units which form
the beginning and end, respectively, of the
polysaccharide. The~:e basic units only have one linkage
to another monomer and form the end groups of the
linear polysaccharide.
If the basic units possess three or more linkages, this
is then referred to as branching. In this connection,
the degree of branching follows from the number of
hydroxyl groups pe:r 100 basic units which are not
involved in the construction of the linear polymer
backbone and form the branchings.
According to the invention, the linear, water-insoluble
polysaccharides exhibit a degree of branching of at
most 8~, i.e. they have at most 8 branches per 100
basic units. Preference is given to the degree of
branching being less than 4~ and, in particular, at
most 2.5~.
If the water-insoluble linear polysaccharide is a
polyglucan, e.g. po:iy-(1,4-alpha-D-glucan), the degree
of branching in the 6 position is less than 40,
preferably at most 2o and, in particular, at most 0.50,
and the degree of branching in the other positions, for
example in the 2 or 3 position, is preferably in each
case at most 2~, and in particular 10.
Particular preference is given to polysaccharides, in
particular' polyglucans, such as poly-alpha-D-glucans,
which do not exhibit any branchings, or whose degree of
branching is so slight that it can no longer be
detected using conventional methods.
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Examples of preferred water-insoluble, linear
polysaccharides are' linear poly-D-glucans, with the
nature of the linkage being of no importance as long as
there is linearity within the meaning of the invention.
Examples are poly(1,4-alpha-D-glucan) and
poly(1,3-beta-D-glucan), with poly(1,4-alpha-D-glucan)
being particularly preferred.
According to the invention, the prefixes "alpha",
"beta" or "D" refer solely to the linkages which form
the polymer backbone and not to the branchings.
For the present invention, the term "water-insoluble
polysaccharides" i~; understood as meaning compounds
which, corresponding to classes 4 to 7, come within the
categories "not particularly soluble", "difficultly
soluble", "very diff.icultly soluble" and "virtually
insoluble", respectively, in accordance with the
definition in the German Pharmacopeia (DAB - Deutsches
Arzneimittelbuch, W:issenschaftliche Verlagsgesellschaft
mbH, Stuttgart, Govi-Verlag, Frankfurt, 1987 edition).
In the case of the polysaccharides used in accordance
with the invention, this means that at least 980 of the
quantity employed, :in particular at least 99.50, is
insoluble in water (corresponding to classes 4 and 5,
respectively) under normal conditions (T - 25°C +/-
200, p = :101325 Pascals +/- 200).
For the present invention, preference is given to
compounds which are difficultly soluble to virtually
insoluble, in particular compounds which are very
difficult:Ly soluble to virtually insoluble.
"Very difficultly soluble", corresponding to class 6,
can be illustrated by the following experimental
description:
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One gram of the polyglucan/saccharide to be
investigated is heated in 1 1 of deionized water at
130°C and under a pressure of 1 bar. The resulting
solution remains st=able for only a brief period of a
few minutes. On cooling under normal conditions, the
substance precipitates out once again. After cooling
down to room temperature, and separating off by means
of centrifugation, at least 66~ of the quantity
employed is recovered, taking into consideration
experimental losses.
The polysaccharides. employed in accordance with the
invention can be of any origin as long as the
abovementioned conditions regarding the terms "linear"
and "water-insoluble°' are fulfilled.
They can be obtained naturally or by means of
biotechnology.
For example, they can be obtained from natural plant or
animal sources by :isolation and/or purification.
It is also possible to use sources which have been
recombinantly manipulated such that they contain a
higher proportion of unbranched polysaccharides, or of
polysaccharides which are only branched to a
comparatively minor_ extent, compared with the
unmanipulated source.
They can have been prepared from nonlinear
polysaccharides by means of enzymic or chemical
debranching.
Biotechnological nnethods comprise biocatalytical,
including biotransformational, or fermentative
processes.
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An advantageous method for obtaining them
biotechnologically is described, for example, in WO
95/31553.
It is also possible to use modified water-insoluble,
linear polysaccharides, with it being possible, for
example, for the polysaccharides to have been
chemically modified, for example, by esterification
and/or etherification in one or more positions which
are not involved in the linear linkage. In the case of
the preferred 1,4--linked polyglucans, the modification
can take place in the 2, 3 and/or 6 position(s).
The skilled person is sufficiently familiar with
measures for carrying out such modifications.
Thus, linear polysaccharides, such as pullulans,
pectins, mannans or polyfructans, which are water-
soluble per se, can be made water-insoluble by being
modified.
In addition, use can be made of so-called alpha-
amylase-resistant polysaccharides, as are described,
for example, in German patent application No. 198 30
618Ø
For the present invention, preference is given to using
water-insoluble, linear polysaccharides which have been
prepared in a biotechnological process, in particular
in a biocatalytical process or a fermentative process.
In contrast to polysaccharides which are isolated from
natural sources, such as plants, the polysaccharides
which are obtained in such a process exhibit a
particularly homogeneous profile of properties, e.g.
with regard to tree molecular weight distribution;
furthermore, they do not contain any undesirable
incidental products, which have to be separated off in
an elaborate manner, or at most only contain such
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products in very small quantities, and can be
reproduced in a precisely specified manner.
In particular, it is possible to use biotechnological
methods to obtain water-insoluble, linear
polysaccharides, such as poly-1,4-alpha-D-glucans,
which do not contain any branchings or whose degree of
branching is below the detection limit of conventional
analytical methods.
The molecular weights Mw (weight average, determined by
means of gel permeai=ion chromatography as compared with
standardizing with a pullulan standard) of the linear
polysaccharides which are used in accordance with the
invention can vary i.n a wide range from 0.75 x 102 g/mol
to 10' g/mol. The molecular weight Mw is preferably in a
range from 10' g/mo_L to 106 g/mal, and is particularly
preferably from 10' g/mol to 105 g/mol. Another
advantageous range is from 2 x 10' to 8 x 10'.
Corresponding ranger apply for the poly(1,4-D-glucan)
which is preferably employed.
The molecular weight distribution or polydispersity
Mw/M~ may also vary in wide ranges depending on the
method used for preparing the polysaccharide. Preferred
values are from 1.01 to 50, in particular from 1.5 to
15. In this connection, the polydispersity increases
with a bimodal distribution of the molecular weights.
It is possible to use a single linear polysaccharide
substance, in particular linear poly(1,4-D-glucan), or
mixtures which a:re composed of two or more
representatives.
In another embodiment, it is possible to add a water-
insoluble, branched polysaccharide, preferably a
polyglucan, in particular a poly(1,4-alpha-D-glucan) or
a poly(1,3-beta-D-glucan).
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It is also possible to add mixtures composed of two or
more branched polysaccharides.
The branched polysaccharides may be of any arbitrary
origin. In this connection, the reader is referred to
the comments in thi:~ regard which were made in the case
of the linear polysaccharides. Preferred sources are
starch and starch analogs, such as glycogen. If
necessary, the proportion of linear structures in the
branched polysaccharides can be increased using
suitable enrichment methods.
The same specifications as for the linear
polysaccharide apply as regards the water-insolubility;
in the case of the branched polysaccharides, the
molecular weight ca:n also be higher and, for example,
have values of up to preferably 109 g/mol and more.
It is also possible for other biocompatible or
biodegradable polymers to be admixed. In this
connection, the quantity of the other polymers) which
is/are admixed, without the spherical shape and/or
other properties of the microparticles to be prepared
being altered, always depends on the polymer added.
In order to ensure that the microparticles have the
desired properties>, the proportion of linear
polysaccharide should be at least 70o by weight, in
particular 80o by weight, and preferably 90o by weight,
based on the total content of polysaccharide and, where
appropriate, other polymers.
According to a particularly preferred embodiment, 100
by weight of the microparticles consist of linear
polysaccharide.
A detailed description of the microparticles which are
used in the present instance, and of their preparation
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and of the water-insoluble, linear polysaccharides
which can be used for this preparation, can be found in
the applicant's Gerrnan patent applications which are of
earlier priority but not prepublished and which have
the references 197 37 481.6, 198 03 415.6, 198 16
070.4, 198 30 618.0 and 198 27 978.7, which
applications are hereby incorporated into the present
description by reference.
The microparticles which are employed, as carrier
material, for parenteral use can furthermore comprise
other adjuvants which are customary for this purpose in
the usual quantities.
The active compounds. or the active substance for the
composition according to the invention can be any
solid, liquid or gaseous substance which is to be
administered parentally, in particular by means of
injection, to a living organism or else to an
inanimnate object.
In particular when being administered to living
organisms, the active compound or active substance is
also understood to meaning biologically active
substances or substance combinations in the widest
possible sense.
An example of the broad application range for
parenteral administration which may be mentioned is
pharmacy or medicine in the human and veterinary areas,
for example in therapy, diagnosis or prophylaxis.
Examples of active compounds which can be administered
using the microparticles employed in accordance with
the invention are so-called LHRH analogs, such as
Buserelin (a Hoechst Marrion Roussel registered
trademark) for use against prostate cancer,
endometriosis and ot=her tumorous diseases of the sex
organs; erythropoiet:in (EPO) for stimulating the growth
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of red blood cells, pain-alleviating active compounds,
antiallergic agents, growth hormones, steroids for
hormone treatment .and birth control, biphosphonates,
calcitonin (e.g. Cibacalcin from Ciba-Geigy) for
treating osteoporosis, psychatropic drugs and, quite
generally, active compounds, e.g. proteins or peptides,
which are decomposed in the gastrointestinal tract and
cannot therefore be administered orally, or active
compounds which require to be administered parentally,
etc.
The active compounds or active compound combinations
which can be employed can be selected at will for the
desired area of application and are not subject, as
long as they can be administered parenterally, to any
restrictions with regard to the nature of the active
compound, to the wa,yy in which the active compound is
prepared or to the area of application. So-called
macromolecules, in particular peptides, proteins or
nucleotides which c~~n be prepared or synthesized, for
example, by means of biotechnological methods or
methods which depend on modern biotechnology are
particularly suitable.
It goes without saying that the quantity of active
compound to be employed varies depending on the
application field a.nd the purpose, and is to be
determined for each individual case. Thus, quantities
in the microgram range are generally sufficient for
Buserelin, EPO and many other active compounds.
In order to prepare the composition according to the
invention, the active compound or the active compound
combination is brought into contact, in the requisite
quantity, with the carrier material.
For this, the active compound can be added to the
starting compound: used for preparing the
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microparticles, such as the water-insoluble, linear
polysaccharide, such that the microparticles comprise a
mixture consisting of starting compound and active
compound.
The active compound can be encapsulated in the
microparticles, with it being possible to employ
customary encapsulation techniques. Suitable examples
are emulsion proce:~ses or spray drying processes. In
this connection, ~s;praying processes, in which the
particles are sprayed with a solution of the active
compound in a flui.d:ized bed or analogous processes, are
also included in the latter term.
Furthermore, the active compound can be absorbed and/or
adsorbed on the microparticle surface by the active
compound and the microparticles being, for example,
suspended in a suitable medium and left to stand until
equilibrium has been reached, after which the active
compound-loaded particles are separated off.
The composition according to the invention is
particularly suitable for the controlled release of
active compound, without, however, being restricted
thereto.
Controlled release of active compound is understood as
meaning that the active compound is not released
immediately and at once; instead, the release takes
place over a given period of time and/or after a given
period of time has wlapsed. The rate of release can be
changed at will depending on the desired purpose. It
can be constant over- the given period of time or it can
be high at the beginning, with this being followed by a
slower rate of release.
It goes without saying that the rate of release, and
the rate of degradation of the microparticles, in an
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organism is highly dependent on the nature of the
starting materials, on the nature of the active
compound employed, on the size of the particles and on
the preparation method employed. The skilled person
can, as required, produce a system which is tailor-made
for his special purpose by varying these parameters in
a simple manner, with which he is per se familiar.
Parenteral administration is understood as meaning the
administration of any arbitrary active compound by
means of injection or infusion, for which it i:s
particularly advantageous if the composition to be
administered is readily dispersible and exhibits good
needle traversabilit=y.
Because of the outstanding needle traversability of the
microparticles used in accordance with the invention,
the composition according to the invention is
particular (.~-:i~.~~ fir-w-~ae~nti~rri-s~t~ra~i~°"""~~'; "'"ineans,.~
of
injections.
The injection can take place in any arbitrary manner;
it can be administered intravenously, ~,ntramuscularly,
intraarterially, subc:utaneously or intralumbarlly.
A high degree of needle traversability means that the
composition according to t°he invention is also able to
readily pass through injection needles such as
hypodermic needlesF~:aving small needle diameters.
For the admir~z~'strati.on, the composition is suspended in
a suitabl~.~iinedium. ~:t: has been found that, even without
the adc,'tion of further adjuvants, such as dispersing
agerl'~s, the composition according to the invention
fe~rms a stable suspension which remains unaltered even
35"~~A'f ow""~x...~~ve~y~~long"' ~5"~.caf time.
.:
CA 02346670 2001-04-05
- 16~- 17 Oct. 2000
suitable for administration by means of
injections.
The injection can take place in any arbitrary manner;
it can be administered intravenously, intramuscularly,
intraarterially, subc:utaneously or intralumbally.
A high degree of needle traversability means that the
composition according to the invention is also able to
readily pass through injection needles such as
hypodermic needles having small needle diameters.
For the administration, the composition is suspended in
a sequel medium. It has been found that, even without
the addition of further adjuvants, such as dispersing
agents, the composition according to the invention
forms a stable suspension which remains unaltered even
over a relatively long period of time.
According to a prE_ferred embodiment of the present
invention, the composition according to the invention
forms a stable suspension to which a dispersing agent
is added. Particu:l.ar preference is given to this
dispersing agent being a sterile salt solution.
The ability to do without foreign substances such as
dispersing agents is particularly advantageous as far
as biocompatibility is concerned.
Insofar as the microparticles settle when the
suspension is left. to stand, for example during
storage, a stable suspension can be produced once again
simply by shaking briefly, with several seconds
normally sufficing.
The choice of a suitable medium is in turn determined
by the specific purpose which is intended.
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Sterile salt solutions, such as a physiological NaCl
solution, are, forwexample, suitable for medical use.
The good to very good suspendibility is substantiated
by the large concentration ranges. Thus, up to about
25~ solids content can be present in the suspension.
This corresponds to a proportion of 250 mg of particles
to 1 ml of solvent, e.g. physiological sodium chloride
solution. Preferred concentration ranges are from to to
180. A range of :From 5~ to 10o solids content is
particularly preferred. This corresponds to quantities
of from 50 mg to 100 mg of active compound-loaded
microparticles, a value which, in the case of
alternative formulations, even when using a suspension
aid, is only achieved at the cost of high experimental
input.
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.:r~~..:u.~b.llity .to do.. w~.~.~Q~~t ~Q~'~..~-9z'~ . .~1~~,s...-.fir'
dispersing agents is particularly advantageous as .far
as biocompatibility is concerned.
Insofar as the microparticles settle ~ihen the
suspension is left to stand, for example during
storage, a stable suspension can be produced once again
_:
simply by shaking briefly, with veral seconds
normally sufficing. k,
r.
3,..".
The choice of a su_i.table medium ,,~s in turn determined
by the specific purpose which isf<'intended.
Sterile salt solutions, such-as a physiological NaCl
s"
solution, are, for example,.~uitable for medical use.
a ~a
The good to very good ,,fiuspendibility is substantiated
by the large concent~"ation ranges. Thus, up to about
25~ solids content ~r.an be present in the suspension.
t,
This corresponds ~i a proportion of 250 mg of particles
to 1 ml of sol,.v~~n'°t, e.g. physiological sodium chloride
solution. Pr~rred concentration ranges are from 1o to
18 0 . A rae of from 5 o to 10 o solids content is
particul~,~''1~'y preferred. This corresponds to quantities
of fr50 mg to 100 mg of active compound-loaded
r
micr articles, a value which, in the case of
al ernative formulat=:ions, even when using a suspension
p-fid, is only achieved at the cost of high experimental
The very good suspendibility and needle traversability
can be supported, i.n particular, by the observation
that 500 mg of particulate carriers are suspended in
only 3 ml of water and can be administered without
difficulty through a needle having a diameter of
0.6 mm.
If a higher concentration of microparticles is desired
or required in the suspension, it is, of course, also
possible to use auxiliary agents such as Pluronic (a
BASF AG trademark), Haemaccel (a Behringwerke
CA 02346670 2001-04-05
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trademark), sodium dodecyl sulfate, etc., that is
auxiliary agents which are generally recognized and
used for such pharmaceutical administration forms.
In certain cases, the microparticles can themselves act
as the active compound. Thus, the microparticles used
in accordance with the invention can be employed as
contrast agents, for example for ultrasonic diagnosis.
In this case, the composition according to the
invention can be administered with or without an
additional active compound.
Gases are an example of possible additional active
compounds, with it being possible for the nature of the
gas to vary widely (e. g. nitrogen, air, argon, helium,
fluorochlorinated hydrocarbons and fluorinated
hydrocarbons). It is also possible to use aspirin or
NO-releasing compounds, which are of particular
importance in diseases of the coronary circulation.
As explained above, the microparticles which are
employed in acco~_-dance with the invention are
particularly suitab~l.e for parenteral administration
because of their outstanding dispersibility and high
degree of needle traversability.
In that which follows, the present invention is
explained with the aid of some selected examples.
Example 1
Preparing microparticles from poly(1,4-a-D-glucan)
500 mg of poly(1,4-2-D-glucan) are dissolved in 2.5 ml
of dimethyl sulfoxi_de (DMSO, analytical grade, from
Riedel-de-Haen) at approx. 70°C. The DMSO solution is
added dropwise, while stirring, to 100 ml of double
distilled water and this solution is stored overnight
at 5°C. The fine, rn:ilky suspension is centrifuged at
CA 02346670 2001-04-05
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3 500 rpm for 15 minutes and the supernatant is
decanted off. The sediment is suspended using double
distilled water dIld centrifuged once again. The
procedure is repeated a further two times. The
suspension is then freeze-dried. 311 mg of white
poly(1,4-oc-D-glucan) particles are obtained. This
corresponds to a. yield of 620 of colorless
microparticles.
Example 2
Experiments on the needle traversability of suspensions
containing micropart:icles composed of poly(1,4-alpha-D-
glucan)
A method which is accepted for testing and preparing
microparticulate drug delivery systems is used for
assessing the quality of the microparticle suspension.
100 mg of micropart.icles, which have been obtained as
described in example 1, are suspended in 1 ml of double
distilled water. 7:'he individual particles can be
separated from each other simply by shaking the sealed
vessel by hand. The suspension is drawn up through a
septum using a syringe and a needle having a diameter
of 0.5 mm (or greater). The particles are then
expressed through the needle to be tested. The
assessment of the individual needles is summarized in
the following tables. A cross symbolizes the needle
traversability of th.e suspension. The needles used are
obtained from Braun l?etzold GmbH (Melsungen).
In contrast to commercially available preparations, the
addition of a suspension aid had no effect on the
results in the ca=~e of microparticles composed of
poly(1,4-alpha-D-glucan). In commercial systems and
those which are basE:d on a similar technology but use
other materials, a stepwise improvement in
resuspension, up to a limiting value, is observed as
the quantity of the suspension aid (additive)
increases.
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Table 1: Characteri:~tics of needles employed
Size Gauge Diameter in Length in mm
mm
18 G :~c11/2 1 . 2 0 4 0
1 20 G :~11/z 0.90 40
2 21 G ;~11/z 0 . 8 0 4 0
12 22 G ;<11/z 0.70 30
14 23 G ;<11/ 0.60 30
17 24 G o 1 0.55 25
18 26 G ><1 0.45 25
20 27 G ><4/5 0.40 20
30 G >c 1 0.30 25
Table 2: Needle traversability of microparticles
composed of poly(1,4-alpha-D-glucan)
Material Needle diameter (mm)
1.2 0.9 0.8 0.7 0.6 0.5 0.4 0.4 0.3
0 0 0 0 0 5 5 0 0
Poly(1,4- x x x x x x x x x
alpha-D-
glucan)
Example 3
Experiments on the needle traversability of suspensions
containing micropa:rticles composed of comparison
materials (compariso:n examples)
The experiments using comparison substances, as are
used either commercially or in research for preparing
sustained release :systems, were carried out as in
example 1. The systems used are known biodegradable
polymers composed of: lactic acid and glycolic acid or
of tartaric acid or of aspartic acid (cf. table 3).
CA 02346670 2001-04-05
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Example 4
Loading the particles with active compound using a
suspension process
The microparticles or agglomerates, composed of
poly(1,4-a-D-glucan), are loaded with active compound
using a suspension process. 250 mg of Buserelin* are
dissolved in 10 m7. of distilled water. 100 mg of
particles are added. The suspension is stirred for 3 h.
The suspension is centrifuged. The centrifugate is
washed with water. ~'he particulate solid is separated
off by centrifugation (3 000 rpm) and the centrifugate
is freeze-dried. By dissolving an exact quantity of the
particles in a mixture of water and dimethylsulfoxide,
and measuring spectroscopically in a W-Vis
spectrometer, the loading with Buserelin can be
calculated, using <~ calibration curve, to be 3.28
based on the total mass of the particles. The
solubility, and consequently the loading of the
particles with active compounds, can be influenced by
modifying the solvent, e.g. alcohol.
(*5-Oxoprolyl-L-hystidyl-L-tryptophanyl-L-tyrosyl-O-
tert-butyl-D-seryl--L-leucyl-L-arginyl-N-ethyl-L-
prolineamide)
Example 5
Loading the particles with active compound by means of
spray drying
The microparticles are suspended in distilled water or
a mixture composed of water and a readily volatile
component such as acetone or ethanol. For this, 10 g of
the solid are added to 1 000 ml of the solvent. 0.5 g
of theophylline had been dissolved in the solvent
beforehand. The spray dryer (Minispray dryer 191 from
Biichil) is operated as follows:
CA 02346670 2001-04-05
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Atomization air flow 700 liters per hour, inlet
temperature 200°C, activated nozzle cooling, nozzle
diameter 0 . 5 mm, aspirator 70 0, pump 10 0 . Checking the
loading by spect=roscopy (for description, see
example 4) gives a degree of loading of 4.80. This
value is in agreement with the theoretically achievable
value of 5.0~ within the limits of experimental error.
CA 02346670 2001-04-05
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CA 02346670 2001-04-05
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CA 02346670 2001-04-05
- 25 -
In accordance with EP 535 387
In accordance with EP 514 790
~' In accordance with EP 514 790
Manufacturer, F'luka
~5 Manufacturer, F3ehringwerke
The results in parentheses are only achieved when
special filters are additionally used for
separating the :individual particles or the process
is repeated several times using needles of
relatively largre diameter.
' Manufacturer, Medisorb (PLGA - polylactic-co-
glycolic acid 65:35, dl)
