SALT OF NAPHTHYRIDINE CARBOXYLIC ACID DERIVATIVE
TECHNICAL FIELD
The present invention relates to a salt and associated hydrates of
racemic 7-(3-aminomethy 1-4-methoxyiminopyrrolidin-1 -y 1)-1 -cyclopropyl-6-
fluoro-4-oxo-l,4-dihydro-l,8-naphthyridine-3-carboxylic acid, processes for
their preparation, pharmaceutical and veterinary compositions comprising
them, and their use in antibacterial therapy.
BACKGROUND ART
EP 688772 (corresponding to Korean Patent Laid-open Publication
No 96-874) discloses novel quinoline(naphthyridine)carboxylic acid
derivatives, including anhydrous 7-(3-aminomethyl-4-methoxyiminopyrrolidin-
1 -y1)-1 -cyclopropy l-6-fluoro-4-oxe-1,4-dihy dro-1,8-naphthyridine-3-carb
oxylic acid of formula I, having antibacterial activity.
DISCLOSURE OF INVENTION
According to the invention there is provided 7-(3-aminomethyl-
4-methoxy iminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-l ,8
-naphthyridine-3-carboxylic acid methanesulfonate.
9
7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-I-cyciopropy[-6-flu
oro-4-oxo-1.4-dihydro-1,8-naphthyridine-3-carboxylic acid mcthanesulfonatc
(hereinafter referred to as 'the methanesulfonate') may be obtained as an
anhydrate or a hydrate i.e. methanesulfonate . nH:0.
Hydrates of the methanesulfonate wherein n is in the range 1 to
4 are preferred. Particular hydrates of the methanesulfonate which may
be mentioned are those in which n is 1, 1.5, 2, 2.5, 3. 3.5 and 4.
Particularly preferred compounds are those in which n is 1.5 or 3, with
n=1.5 being most preferred.
The moisture content of the methanesulfonate hydrates varies with
the hydration number (n) of the hydrated molecule. The
methanesulfonate has a molecular weight of 485.5 thus the calculated
moisture content of hydrates where n is 1, 1.5, 2, 2.5, 3, 3.5 and 4 is
3.6%, 5%, 6.9%, 85%, 10.0%, 11.5% and 12.9% respectively. However,
the actual moisture content of the methanesulfonate hydrates may differ
from the calculated value depending on various factors including
recrystallization conditions and drying conditions. The observed
moisture content for the methanesulfonate hydrates where n is 1. 1.5. 2.
2.5, 3, 3.5 and 4 is shown in Table 1:
Tabic 1.
It is possible to mix methanesulfonate hydrates having different
moisture contents together to give materials having intermediate moisture
contents, for example, a mixture of 1 hydrate and 1.5 hydrate having a
moisture content of 2 to 6%; a mixture of 1.5 hydrate and 2 hydrate
having a moisture content of 4 to 8%; a mixture of 2 hydrate and 2.5
hydrate having a moisture content of 6 to 9%; a mixture of 1.5 hydrate
and 3 hydrate having a moisture content of 4 to 11%; a mixture of 2.5
hydrate and 3 hydrate having a moisture content of 8 to 11%; a mixture
of 3 hydrate and 3.5 hydrate having a moisture content of 9 to 12%; or
a mixture of 3.5 hydrate and 4 hydrate having a moisture content of 11
to 13%, can be obtained.
Preferred methanesulfonate hydrates have a moisture content of
from 4 to 6% or from 9 to 11%, especially a moisture content of from
4 to 6%.
/ The methanesulfonate has been observed to exist as a stable
hydrate ..over a range of hydration numbers (n). Stability of the hydrate
refers to its resistance to loss or gain of water molecules contained in
the compound. The methanesulfonaie lndrates maintain a constant
moisture content over an extended relative humidity range. The n^3
hydrate has a constant moisture content at a relative humidity of from at
least 23 to 75%, and the n=1.5 hydrate has a constant moisture content
at a relative humidity of from 23 to 64% (see Figure 3 and 4). In
contrast, moisture absorption by the anhydrate varies greatly with relative
humidity.
Both anhydrate and n=3 hydrate undergo transition to n=1.5
hydrate in aqueous suspension indicating that the latter is
thermodynamically more stable. The n=1.5 hydrate is a sesquihydrate at
11 to 64% of relative humidity. Above 75% relative humidity, it takes
up water over 10% and its XRD pattern changes. The new hydrate
(another form of n=3; it has different physiochemical properties from the
ordinary n-5 hydrate of example 2) obtained from n=1.5 hydrate at 93% relative
humidity is not stable at lower relative humidity. It converts back to
n=1.5 hydrate below 75% relative humidity.
Since the moisture content of the anhydrate changes readily
depending on the environment e.g. relative humidity, formulation
additives etc, it may require careful handling during storage or
formulation, with operations such as quantifying precedures being
performed in a dry room. The hydrates do not change in moisture
content as easily and hence products which are stable to prolonged
storage and formulation may be obtained. .
The hydrate can be tabletted without the addition of a binder
since the water contained in the compound itself acts a binder, whereas
it may not be possible to tablet the anhydrate at a similar pressure.
The present invention also provided a process for the preparation
of 7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-l-cyclopropyl-6-nuoro-
4-oxo-l,4-dihydro-l,8-naphthyridine-3-carboxyIic acid methanesulfonate and
hydrates thereof which comprises reacting 7-(3-aminomethyl-4-
methoxy iminopyrrolidin-1 -y 1)- 1-cyclopropy l-6-fiuoro-4-oxo-1,4-dihydro-1.8-
naphthyridine-3-carboxylic acid with methanesulfonic acid and crystallizing
the resulting methanesulfonate from solution, and where desired or
necessary adjusting the hydration of the compound.
The methanesulfonate and its hydrates may be prepared by the
addition of methanesulfonic acid to the free base which may be prepared
as described in EP688772 Preferably, 0.95 to 1.5 molar equivalents
of methanesulfonic acid is added to the free base, or 1 molar equivalent
of methanesulfonic acid dissolved in a suitable solvent is added to the
free base. Suitable solvents for the preparation of the methanesulfonate
and its hydrates include any solvent in which the methanesulfonate is
substantially insoluble, suitable solvents include C1-C4 haloalkanes, C1-C8
alcohols and water, or mixtures thereof. Dichloromethane, chloroform,
1,2-dichloroethane, methanol, ethanol, propanol and water, or mixtures
thereof, are preferred solvents. If necessary, the free base may be
heated in the solvent to facilitate solution before methanesulfonic acid is
added, alternatively the methanesulfonic acid may be added to a
suspension, or partial suspension, of the free base in the solvent.
Following addition of the methanesulfonic acid the reaction mixture is
preferably allowed to stand or is stirred for 1 to 24 hours at a
temperature oi~ from about -10 to 40°C The resulting methanesulfonate
is obtained as a solid which can he isolated by filtration or by remo\al
of the solvent under reduced pressure.
Different hydrates may be obtained by altering the recrystahzation conditions
used in the preparation of the methanesulfonate, such conditions may be
ascertained by conventional methods known to those skilled in the art.
The present invention also provides a process for the preparation of a hydrate of
7-(3-aminomethyl-4-methoxyiminopyrrolidin-1-yl)-1-cyclopropyi-6-fluoro-4-oxo-
1:4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate comprising
exposing the methanesulfonate anhydrate or a solvate thereof to a high relative
humidity.
The methanesulfonate anhydrate or a solvate thereof is preferably exposed to a
relative humidity of at least 75%.
The methanesulfonate anhydrate or solvate thereof may be exposed to high
relative humidity by passing humidified nitrogen gas through the
methanesulfonate anhydrate or solvate thereof or by standing the
methanesulfonate anhydrate or solvates thereof under a high relative humidity.
The humidified nitrogen gas used in this process, for example nitrogen gas
having a humidity of at least 75% may be made by conventional methods. In
this process it is desirable to maintain the temperature in the range above which
moisture condensation could occur. Also, particularly in the large scale
-7~
production, it is preferable to stir the sample thoroughly while the humidified
nitrogen gas is passed through When the hydrate is prepared by standing the
methanesulfonate anhydrate or solvate thereof under a high relative humidity,
for example a relative humidity or at least 75%, it is preferable to spread the
sample as thinly as possible in order to raise the conversion efficiency.
The solvates of methanesulfonate anhydrate which may be used in the process
according to this aspect of the present invention include solvates with one or
more organic solvents. Preferred solvents include C1-C4haloalkanes and C1-
C8 alcohols, for example those selected from the group consisting of ethanol,
dichloromethane, isopropanol and 2-methyl-2-propanol.
Solvates of the methanesulfonate anhydrate are novel. Thus according to a
further aspect of the invention there is provided a solvate of 7-(3-aminomethyl-4-
methoxyiminopyrrolidin-1 -yl)-1 -cycolpropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-
naphthyridine-3-carboxylic acid methanesulfonate with one or more organic
solvents.
The solvates of the methanesulfonate are prepared by recrystallization and
controlled by the condition of recrystallizing system.
8
The methanesuifonaie and its hydrates exhibit the same potent
antibacterial activity as the corresponding free base disclosed in EP
688772. The methanesulfonate and its hydrates also exhibit desirable
physicochemical properties including improved solubility and constant
moisture content regardless of the ambient relative humidity when
compared to the free base and other salts thereof. The
methanesulfonate and its hydrates thus exhibit greater ease of handling,
quality control and formulation than the free base and other salts thereof.
As mentioned above the methanesulfonate and its hydrates exhibit
antibacterial activity. The methanesulfonate and its hydrates may be
formulated for adminstration in any convenient way for use in human or
veterinary medicine, according to techniques and procedures per se
known in the art with reference to other antibiotics, and the invention
therefore includes within its scope a pharmaceutical composition
comprising 7-(3-aminomethy 1-4-methoxyiminopyrrolidin-1 -yl)-1 -cyclopropyl-
6-fluoro-4-oxo-l,4-dihydro-l,8-naph-thyridine-3-carboxylic acid methanesulfonate
and hydrates thereof together with a pharmaceutically acceptable
carrier or excipient. The compositions may be formulated for
administration by any suitable route, such as oral, parenteral or topical
application. The compositions may be in the form of tablets, capsules,
powders, granules, lozenges, creams or liquid preparations, such as oral
or sterile parenteral solutions or suspensions. Tablets and capsules for
oral administration may be in unit dose presentation form and may
contain conventional excipients such as binding agents, for example.
hydroxypropyl methyl cellulose, hydroxy propyl cellulose, syrup acacia,
gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers, for example
microcrystalline cellulose, lactose, sugar, maize-starch, calcium phosphate.
-V
sorbitol or glycine; tabletting lubricants, for example magnesium stearate.
talc, polyethylene glycol or silica; disintegrants, for example sodium
starch glycolate, cross linked polyvinyl pyrrolidone or potato starch; or
acceptable wetting agents such as sodium lauryl sulfate. The tablets
may be coated according to methods well known in normal
pharmaceutical practice. Oral liquid preparations may be in the form
of, for example, aqueous or oily suspensions, solutions, emulsions, syrups
or elixirs, or may be presented as a dry product for reconstitution with
water or other suitable vehicle before use. Such liquid preparations
may contain conventional additives such as suspending agents, for
example sorbitol, methyl cellulose, glucose syrup, gelatin, hydroxyethyl
cellulose, caboxymethyl cellulose, aluminum stearate gel or hydrogenated
edible fats; emulsifying agents, for example lecithin, sorbitan monooleate,
or acacia; non-aqueous vehicles (which may include edible oils), for
example almond oil, oily esters, glycerine, propylene glycol, or ethyl
alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate
or sorbfc acid; and, if desired conventional flavouring or coloring agents.
Suppositories will contain conventional suppository base, e.g.
cocoa-butter or other glyceride.
For parenteral administration, fluid unit dosage forms are prepared
utilizing the compound and a sterile vehicle, water being preferred.
The methanesulfonate or hydrate thereof, can be either suspended or
dissolved in the vehicle, depending on the vehicle and concentration
used. In preparing solutions the methanesulfonate or hydrate thereof
can be dissolved in water for injection and filter sterilized before filling
into a suitable vial or ampoule and sealing. Advantageously, agents
such as local anaesthetic, preservative and buffering agents can be
dissolved in the vehicle. To enhance the stability, the composition can
be lyophilised and the dry lyophilised powder sealed in a vial, an
10
accompanying via! of water for injection may be supplied to reconstitute
the powder prior to use. Parenteral suspensions are prepared in
substantially the same manner except that the methanesulfonate or hydrate
thereof is suspended in the vehicle instead of being dissolved and
sterilization cannot be accomplished by filtration. The methansulfonate
or hydrate thereof can be sterilized by exposure to ethylene oxide before
suspending in the sterile vehicle. Advantageously, a surfactant or
wetting agent is included in the composition to facilitate uniform
distribution of the methanesulfonate or hydrate thereof.The methane solphonate
or hydrate therof may also formulated as a intramammary composition
for veterinary use .
The composition may contain from 0.1% to 100% by weight,
preferably from 10 to 99.5% by weight, more preferably from 50 to
99.5% by weight of the.active ingredient measured as the free base depending on
the method of administration. Where the compositions comprise dosage
units, each unit will preferably contain from 50-1500 mg of the
methansulfonate or hydrate thereof as active ingredient. The dosage as
employed for adult human treatment will preferably range from 100 mg
to 12 g per day for an average adult patient (body weight 70 kg), for
instance 1500 mg per day, depending on the route and frequency of
administration. Such dosages correspond to approximately 1.5 to 170
mg/kg per day. Suitably the dosage is from 1 to 6 g per day.
The daily dosage is suitably given by administering the
methansulfonate or hydrate thereof once or several times in a 24-hour
period, e.g. up to 400 mg maybe administered once a day, in practice,
the dosage and frequency of administration which will be most suitable
for an individual patient will vary with the age. weight and response of
the patients, and there will be occasions when the physician will choose
a higher or lower dosage and a different frequency of administration.
Such dosage regimens are within the scope of this invention.
The present invention also includes a method of treating bacterial
infections in humans and animals which method comprises administering
a therapeutically effective amount of 7-(3-aminomethyl-4-methoxyiminopyrrolidin-
1 -y 1)-1 -cyclopropy l-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3
-carboxylic acid methanesulfonate or a hydrate thereof.
In a further aspect, the present invention also provides the use of
7-(3-aminomethy 1-4-methoxy imino-pyrrolidin-1 -y 1)-1 -cyclopropy l-6-fluoro-4-
oxo-l,4-dihydro-l,8-naphthyridine-3-carboxylic acid methanesulfonate or a
hydrate thereof for the manufacture of a medicament for treating bacterial
infection.
The methanesulfonate and its hydrates are active against a broad
range of Gram-positive and Gram-negative bacteria, and may be used to
treat a wide range of bacterial infections including those in
immunocompromised patients.
Amongst many other uses, the methanesulfonate and its hydrates
are of value in the treatment of skin, soft tissue, respiratory tract and
urinary tract infections and sexyakkt taransmitted diseases
IN HUMANS , The methanesulphone te and its hydrates may also be used
in the treatment of bacterial infections in animals such as mastitisin
cattle. BRIEF DESCRIPTION OF DRAWINGS
The following examples and figures illustrate the invention but are
not intended to limit the scope in any way.
Figure 1 shows the moisture sorption profile of methanesulfonate
anhydrate of Example 1 at 25 "C at several relative humidities.
Figure 2 shows the isothermal moisture sorption profile of
methanesulfonate anhydrate of" Example 1 at 25 "C.
Figure 3 shows the equilibrium moisture content of the
methanesulfonate n=3 hydrate of Example 2 at a relative humidity of 23
to 75%.
Figure 4 shows the equilibrium moisture content of the
methanesulfonate n=1.5 hydrate of Example 3 at a relative humidity of
23 to 75%.
Figure 5 shows the powder X-ray diffraction pattern of the
methanesulfonate anhydrate of Example 1.
Figure 6 shows the powder X-ray diffraction pattern of the
methanesulfonate n=3 hydrate of Example 2. The characteristic peaks
are 2 0 - 1.7, 11.8 *. The exact poshiangof peaks can vary slightly
on the experimental conditions.
Figure 7 shows the powder X-ray diffraction pattern of the
methanesulfonate n=1.5 hydrate of Example 3. The characteristic
peaks are 2 6 - 8.0, 12.2, 14.7 ° . The exact position of peaks can
vary slightly on the experimental conditions.
Figure 8 shows the variation in moisture content with elapsed
time of the methanesulfonate anhydrate of Example 1 taken after 0, 5,
10, 20, 30, and 60 minutes, respectively, from the initial point of
passing humidified nitrogen gas through;
Figure 9 shows the Differential Scanning Calorimetry on the
methanesulfonate anhydrate of Example I and the methanesutfonate n=3
hydrate of Exampie 2.
Figure 10 shows the results of thermogravimetric analysis on the
methanesulfonate n=3 hydrate of Example 2.
Figure 11 shows the change in X-ray diffraction pattern with
elapsed time of the methanesulfonate solvate (ethanol content 0.11%) of
Example 4, from the initial point of passing the humidified nitrogen gas
having a relative humidity of 93% through.
Figure 12 shows the change in X-ray diffraction pattern with
elapsed time of the methanesulfonate solvate (ethanol content 1.9%) of
Example 5, from the initial point of standing the sample under relative
humidity of 93%.
Figure 13 shows the change in X-ray diffraction pattern of the
methanesulfonate solvate (ethanol content 0.12%) of Example 5 under
various relative humidities, that is, relative humidity of 93%(1), relative
humidity of 52%(2) and relative humidity of 11%(3), respectively.
BEST MODE FOR CARRYING OUT THE INVENTION
The solvate has a different crystal structure from the anhydrate or
from the compound in which organic solvent molecules are remained
without any influence on the crystal structure, and thus should be
distinguished from them. The different crystal structure may result
different physicochemical properties such as crystallinity, hygroscopicity,
melting point, solubility, solubilizing rate, etc. Usually the residual
solvent is removed by drying under reduced pressure in the final step.
'to-
However, when the pharmaceutically active compound is present as a
solvate with a specific solvent, that is the solvent molecule is located in
the crystalline structure of the compound, the solvent molecules may
hardly be removed by drying under reduced pressure. In some cases,
the solvents are not removed until the temperature reaches the melting
point of the solvate, and therefore such an elimination process cannot be
applied to industrial process. Since only the medicinal materials
containing the solvent in an amount of less than the. permitted limit
specifically defined for the solvent are valuable, appropriate methods for
removing solvent from each solvates should be established through the
study about characteristics of each solvates.
The present inventors have made several experiments in order to
identify the moisture content and physicochemical property of the
methanesulfonate anhydrate and each hydrate, and the results are
described in connection with the drawings in the following.
Figure 1 / shows the moisture sorption velocity profile of 7-(3-
aminomethyl-4-methoxy iminopyrrolidin-1 -y 1)-1 -cy clopropyl-6-fluoro-4-oxo-1,
4-dihydro-l,8-naphthyridine-3-carboxylic acid methanesulfonate anhydrate
at several relative humidities. Over the whole range of relative
humidity tested, the initial moisture sorption proceeds very speedily at
each relative humidity. In most cases the equilibrium is achieved
within 2 hours. Figure 2 shows the isothermal moisture sorption profile
of the methanesulfonate anhydrate according to the change in relative
humidity at 25 "C. The weight increment (%) of Y-axis represents the
equilibrium moisture content, from which it can be recognized that the
equilibrium moisture content depends on the relative humidity. Figure
3 shows the equilibrium moisture content of the n=3 hydrate (which is
obtained by recrystallization from a solvent mixture of ethanol and water)
-ISafter
it is allowed to stand for 2 weeks under relative humidities in the
range of 23 to 75%. The result shows that the n=3 hydrate is still
more stable than the anhydrate because the hydrate maintains a moisture
content of around 10% under the relative humidities tested. Figure 4
shows the isothermal moisture sorption profile of the n=1.5 hydrate.
Here, it maintains a moisture content of around 5% under the relative
humidity in the range of 23 to 64%. Thus, it is also identified as a
stable hydrate.
On the other hand, it has been identified that the physical
property of the hydrate is very different from that of the anhydrate.
For example, by comparing the powder X-ray diffraction pattern
of the anhydrate in Figure 5, that of the 3 hydrate in Figure 6, and that
of the 1.5 hydrate in Figure 7, it can be seen that their crystal forms
are different from each other. In addition, the thermal analysis using
Differential Scanning Calorimetry shows that the endothermic peak
produced by the vaporization of the water molecules contained in the 3
hydrate begins at around 50 TJ and the exothermic peak by thermal
decomposition is observed at around 185 to 220 TJ, whereas the
anhydrate shows only an exothermic peak at around 185 to 220°C due to
the thermal decomposition without any endothermic peak(see, Figure 9).
At the same time, the thermogravimetric analysis shows a weight
decrement at the temperature range of endothermic peak, the extent of
which corresponds to the moisture content quantified by Karl-Fisher
method(Mettler Toledo DL37KF Coulometer)(see, Figure 10). Therefore,
it is verified that the endothermic peak shown in the DSC analysis is
due to the evaporation of a water molecule.
The present inventors aiso compared the chemical stability under
heating of the hydrate with that of the anhydrate in order to identify
whether or not the hydration exerts any influence on the chemical
stability of the anhydrate. In this test, the anhydrate and hydrate each
are kept at 70°C for 4 weeks, and the extent of decomposition is
analyzed by liquid chromatography. There resulted no difference in
decomposition between the hydrate and the anhydrate, and thus it is
identified that thef hydrate has the same extent of chemical stability with
the anhydrate.
The methanesulfonate thus obtained or its solvate may be
converted into a hydrate under appropriate conditions. This process
can be monitored by the change of X-ray diffraction pattern and the
decrement of the amount of organic solvent in the compound. Such
changes have been caused by the water molecules newly intercalated into
the crystal structure..
As can be seen from Figure 11, the X-ray diffraction peaks based
on the solvate disappear with the passing of humidified nitrogen gas to
leave the peaks based on the hydrate. This means all the solvates are
converted into hydrates. The residual solvent is decreased to the
amount of less than the quantitative limit simultaneously with the change
of X-ray diffraction. Figure 12 shows that the X-ray diffraction peaks
based on the solvate disappear when the solvate is allowed to stand
under 93% relative humidity. However, there is no change in the
X-ray diffraction pattern when the solvate is allowed to stand under
, relative humidity of 11% or 52%(see Figure 13). Therefore, it is
recognized that the change as Figure 12 occurs not by the spontaneous
evaporation of the residual solvent but by the substitution of the organic
solvents in the crystal by water molecules.
preparing the hydrate according to the processes as explained
above, the respective hydrates having a different hydration number can
be obtained by changing conditions such as humidity, time, temperature.
etc. or changing the recrystallization condition. Such conditions should
be controlled differently upon considering whether the starting material is
anhydrate or solvate, and what is the kind of the solvate.
The present invention will be more specifically explained by the
following examples and experimental examples. However, it should be
understood that the examples are intended to illustrate but not to in any
manner limit the scope of the present invention.
Example 1: Synthesis of 7-(3-aminomethyl-4-methoxyiminopvrrolidin-
1 -y 1)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbo
xylic acid methanesulfonate anhydrate
7-(3-AminomethyI-4-methy loxyiminopyrrolidin-1 -y 1)-1 -cyclopropy 1-6-
fluoro-4-oxo-l,4-dihydro-l,8-naphthyridine-3-carboxylic acid (3.89g, 10
mmol) was suspended in a mixture of dichloromethane and ethanol (110
m , 8:2 v/v). Methanesulfonic acid (0.94g, 9.8mmol) was added
dropwise and the resulting solution was stirred for 1 hour at 0°CThe
resulting solid was filtered, washed with ethanol then dried to give
the title compound (4.55g).
m.p. : 195°C (dec.)
1H NMR(DMSO-d6) δ (ppm) 8.57(1 H,s), 8.02(1 H,d).
7.98(3N,br), 4.58(2H.br), 4.39(1 H,m). 3.91(3H,s), 3.85(1 H,m), 3.71(Ml.m).
3.42(1 H,m), 3.20~-3.l0(2H,m), 1.20-1.10(4H,m)
Example 2: Synthesis of 7-(3-aminomethyl-4-methoxyiminopyrrolidin-
1 -vl)-1 -cyclopropyl-6-fluoro-4-oxo-1.4-dihydro-1,8-naphthyridine-3-carbo
xylic acid methanesulfonate n=3 hydrate
A sonicator filled with water was adjusted to 40°C, sealed with a
lid and a nitrogen inlet and outlet connected. When the pressure of
the dried nitrogen introduced through the inlet was 20psi the relative
humidity of the nitrogen exiting through the outlet was more than 93%.
The anhydrate of Example 1 having a moisture content of 2.5% (l.Og)
was introduced into a fritted filter and the humidified nitrogen produced
as described above passed through the filter. Samples were taken after
0, 5, 10, 20, 30, and 60 minutes and the moisture content measured.
From the results shown in Figure 8 it can be seen that a moisture
content of about 10% is maintained when the humidifying procedure is
carried out over about 30 minutes. The X-ray diffraction pattern of the
humidified sample was identical to that of the n=3 hydrate obtained by
recrystallization.
Example 3: Synthesis of 7-(3-aminomethyl-4-methoxyiminopyrrolidin-
1 -y 1)-1 -cyclopropy l-6-fluoro-4-oxo-1,4-dihy dro-1,8-naphthy ridine-3-carbo
xylic acid methanesulfonate n=1.5 hydrate
The title compound can be prepared by two routes:
Route A
The anhydrate of Example 1 (l.0g) was dissolved in a mixture of
water and acetone (17m , 10:7 v/v). The solvent was slowly evaporated
in darkness leaving the title compound as a solid (0.8g).
Route B
The anhydrate of Example 1 (5.0g) was added to water (10m )
and the mixture was heated to 451 to aid dissolution. Ethanol(20m )
was added and the resulting solution stirred then allowed to stand.
The resulting solid was filtered and dried under a flow of nitrogen to
give the title compound (2.6g).
Example 4: Synthesis of the hydrate from the 7-(3-aminomethyl-4-
methy loxy iminopyrrolidin-1 -yl)-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihy dro-1,8
-naphthyridine-3-carboxylic acid methanesulfonate solvate(using a
humidified nitrogen gas)
A sonicator filled with water was adjusted to 40°C, sealed with a
lid and a nitrogen inlet and outlet connected. When the pressure of
the dried nitrogen introduced through the inlet was 20psi the relative
humidity of the nitrogen exiting through the outlet was more than 93%.
The so!vate(lg,' ethanol 0.11%) of the anhydrate of Example 1 was
introduced into a fritted filter and the humidified nitrogen gas prepared
as Example 2 was passed through. Samples were taken after 40
minutes, 3.5 and 6 hours, respectively. Then, the change in the amount
of the residual organic solvent and X-ray diffraction pattern with the
lapse of time were examined. After 3.5 hours, it was identified that
the product contains the organic solvent in an amount of less than
50ppm and that the peaks based on the solvate disappear, while the
peaks based on the mixture of 3 hydrate and 1.5 hydrate are newly
come out.
-a©-
Example 5: Synthesis of the hydrate from the 7-(3-aminomethyl-4-y
methyloxylminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1.4-dihydro-1.8
-naphthyridine-3-carboxylic acid methanesulfonate solvate(using a high
relative humidity)
Saturated aqueous potassium nitrate solution was placed in a
desiccator, and accordingly the relative humidity inside the desiccator was
controlled to 93%. For tests under relative humidity of 11% or 52%,
desiccators containing saturated aqueous solutions of lithium chloride and
magnesium nitrate, respectively, were prepared. Into the desiccator
having a relative humidity of 93% was introduced a solvate containing
1.9% of ethanol, and into each of the desiccators having a relative
humidity of 93%, 52% or 11% was introduced a solvate containing
0.12% of ethanol. The solvates therein were stored not to contact the
salt solutions aforementioned. After a certain period of time has
passed, samples were taken and subjected to gas chromatography in order
to analyze the residual solvent As a result, it was identified that both
solvates which have been stored for 4 weeks under 93% relative
humidity contain the organic solvent in an amount of less than 50ppm.
Also, it was identified by X-ray diffraction pattern that peaks based on
the solvates disappear after 4 weeks. To the contrary, in case the
samples are stored under relative humidity of 52% or 11 %, the amount
of residual organic solvent and X-ray diffraction pattern after 4 weeks
are identical with those at the beginning.
Example 6: Synthesis of n=3 hydrates from the various
7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-l-cyclopripyl-6-l]uoro-4-
oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate
solvates
Dried nitrogen gas and humidified nitrogen gas having a relative
humidity of 78 to 84% were passed over 24 hours, respectively, through
l0g of four different solvates each of which has a different kind and
amount of organic solvent from the others. Then, the amount of the
residual organic solvent among the sample was measured and the change
in X-ray diffraction pattern was analyzed, the results of which are shown
in the following Table 2. The X-ray diffraction analysis shows that the
samples through which dried nitrogen gas has been passed remains as
the original solvates, while the samples through which humidified
nitrogen gas has been passed have the same X-ray diffraction pattern and
crystallinity to those of the n=3 hydrate obtained by recrystallization.
The different results from both experiments suggest that water
molecules contained in the humidified nitrogen gas replace the organic
solvents in the solvate. And this suggestion can also be supported by
the change in X-ray diffraction pattern influenced by a relative humidity.
Table 2.
-Zl-
Example7: Synthesis of the ethanolate containing ethanol 0.11 %.
The anhydrate of Example 1(5.0g) was added to a solvent mixture of ethanol
(25ml)and water (25ml) and the mixture was heated to 50°C to facilitate
dissolution. Then the solution was cooled slowly to -3°C and allowed to stand at
that temperature for about 3 hours. The resulting solid was filtered and washed
with a solvent mixture of ethanol and water (16.5ml, ethanol: water=20:8,v/v) to
give the title compound quantitatively.
-03--
Test Example 1: Moisture sorption of the anhydrate of Example 1
The moisture sorption velocity and the equilibrium moisture
content of the anhydrate of Example 1 was determined by means of an
automatic moisture sorption analyzer (MB 300G Gravimetric Sorption
Analyzer). This instrument produces a specific relative humidity at a
specific temperature and continuously records the weight change of a
sample due to sorption or desorption of moisture as measured by a
micro balance inside the instrument. The anhydrate of Example 1 (16
mg) was loaded onto the micro balance and the moisture contained in the
sample removed under a stream of dried nitrogen at 50°C. A weight
change of less than 5μg per 5 minutes was the criterion for complete
dryness. Thereafter, the inner temperature was adjusted to 25°C and
the sample tested at 5% intervals whilst varying the humidity from 0 to
95%. The sample was considered to have reached equilibrium when
the weight change was less than 5μg per 5 minutes. Figure 1 shows
the moisture sorption velocity, that is the time required for the sample to
reach equilibrium at each relative humidity. As can be seen initial
moisture sorption proceeded rapidly at each relative humidity tested, in
most cases equilibrium was reached within 2 hours. Figure 2 shows
the weight increment at each relative humidity, i.e. the equilibrium
moisture content. It is clear from Figure 2 that the equilibrium
moisture content of the anhydrate is dependent on the relative humidity.
Test Example 2: Thermal analysis of the anhydrate of Example 1
and n=3 hydrate prepared in Example 2
For the Differential Scanning Calorimetry. METTLER TOLEDO
DSC821e and METTLER TOLEDO STARe System were used. The
sample (3,7mg) was weighed into the aluminum pan which was then
press sealed with an aluminum lid. Three tiny needle holes were made
on the lid and the sample was tested by heating from normal
temperature to 250 °C at a rate of 10°C/min. As can be seen from
Figure 9, the endothermic peak due to the vaporization of the water
molecules contained in the n=3 hydrate begins at around 50°C and the
exothermic peak due to the thermal decomposition is observed at around
180 to 220°C. In contrast, the anhydrate showed only an exothermic
peak due to the thermal decomposition at around 185 to 220°C without
any endothermic peak.
In the thermogravimetric analysis, SEIKO TG/DTA220 was used.
The sample (3.8mg) was weighed into an aluminum pan and was heated
from normal temperature to 250°C at a rate of 10°C/min according to
the temperature raising program. As can be seen from Figure 10,
weight decrement was observed at the temperature range of endothermic
peak, the extent of which corresponds to the moisture content determined
by Karl-Fisher method (Mettler Toledo Coulometer).
Test Example 3: Equilibrium moisture content determination of
hydrates
Six saturated aqueous salt solutions were introduced into each
desiccator to control the inner relative humidity to a specific value as
shown in Table 3. Then, equilibrium moisture contents of n=--3 hydrate
and n=1.5 hydrate of Examples 2 and 3, respectively, were determined at
several relative humidities.
-is-
Table 3. Saturated salt solutions inside the desiccator
The sample (l00mg) was spread on a pre-weighed Petri dish and
the total weight was accurately measured, then three of the sample were
placed in each desiccator of Table 3. The desiccators were allowed to
stand at normal temperature for 7 days and then the sample was taken
to be weighed. After 13 days one of the three samples inside each
desiccator was taken and the moisture content of each was measured by
the thermogravimetric analysis described in Test Example 2. Equilibrium
moisture content at each relative humidity is represented in Figure 3
(n=3 hydrate) and Figure 4 (n=1.5 hydrate). Figure 3 shows that
moisture content of the n=3 hydrate is maintained around 10% for the
whole relative humidity range tested; Figure 4 shows that the moisture
content of the n=1.5 hydrate is maintained around 5% at the relative
humidity of 23 to 64%. Both hydrates are stable since they keep a
constant equilibrium moisture content regardless of the relative humidity
change.
Text Example 4: X-ray Diffraction analysis
The anhydrate of Example 1,n=3 hydrate of Example 2 and n=1.5 hydrate of
Example (50mg of each ) were thinly spread on the sample holder, X-ray
diffraction analysis (35kV x 20mA Rigaku Gergeflex D/max-lll C )were
performed under the conditions listed below.
-scan speed (20) 5°/min
-sampling time: 00.3 sec
-scan mode: continuous
-20/9- reflection
-Cu-target (Ni filter)
Results of X-ray diffraction analyses on the anhydrate, n=3 hydrate, and the
n=1.5 hydrate are shown in Figure 5,6 and 7. The diffraction patterns illustrate
the difference in crystal form of these 3 compounds.
According to a further aspect of the invention we provide 7-(3-aminomethyl-4
-methoxyiminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-
naphthyridine-3-carboxylic acid methanesulfonate having an X-ray diffraction
pattern substantially as shown in Figure 5,6 or 7.
We also provide 7-(3-aminomethyl-4-methoxyiminopyrrolidin-1-yl)-1-cyciopropyl-
6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate
hydrate having peaks at 20 =8.0 ° ,12.2 ° and 14.7 ° in its X-ray diffraction
- 2 . - 7 -
pattern 7-(3-aminomethyl-4-methoxyiminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-
4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid methanesulfonate hydrate
having peaks at 20 =7.7 ° and 11.8 ° in its X-ray diffraction pattern.
The change of crystallinity during the conversion from the solvate to the hydrate
in Examples 4 and 5 was identified by X-ray diffraction analysis under the same
conditions as mentioned above (see, Figure 11 to 13). Figure 11 shows the Xray
Diffraction pattern of the solvate is changed into that of the 3 hydrate (see,
Example 4); Figure 12 represents the change in X-ray diffraction pattern of the
solvate containing 1.9% of _
-28-
ethanol before and after storage of one week, two weeks, three weeks
and four weeks at 93% of relative humidity; and Figure 13 represents
the change in X-ray diffraction pattern of the solvate containing 0.12%
of ethanol after storage of four weeks at 93%, 52% and 11% of relative
humidity, respectively(see, Example 5).
Test Example 5: Chemical stability
Hie chemical stability of the n=3 hydrate of Example 2 and the
n=1.5 hydrate of Example 3 and the anhydrate of Example 1 was
compared at elevated temperature in order to determine the effect on
chemical stability of the extent of hydration.
The anhydrate and each of the hydrates were introduced into a
glass vial and maintained at 70°C. The extent of decomposition with
elapsed time was analyzed by liquid chromatography. The results
obtained and shown in Table 4.
Table 4. Thermal stability with elapsed time (at 70°C, Unit: %)
As can be seen from Table 4, the n=3 hydrate and the n=1.5
hydrate both show _. the same degree of chemical stability as the
anhydrate.
Test Example 6: In vitro antibacterial activity
In order to determine whether 7-(3-aminomethyl-4-methyloxyiminopyrrolidin-
1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3
-carboxylic acid methanesulfonate has the same antibacterial activity as
the free base, in vitro antibacterial activity of the methanesulfonate was
measured using agar medium dilution method. The results are shown
in Tables 5. The minimum inhibitory concentration (MIC, μg/m .) was
simply calculated simply in the ratio of weight without considering the
molecular weight, and ciprofloxacin was chosen as the control.
Table 5. In vitro Antibacterial activity(Minimum Inhibitory Concentration:
MIC, μg/m )
t
Test Example 7: Water solubility of the anhydrate of Example !
The water solubility of the free base and various salts of
7-(3-aminomethyl-4-methoxyiminopyrrolidin-1 -y 1)-1 -cyclopropyl-6-fluoro-4-
oxo-1,4-dihydro-l,8-naphthyridine-3-carboxylic acid, including the
methanesulfonate of Example 1, was measured. The results are shown
in Table 6.
Table 6. Water Solubility (at 251)
As can be seen, the methanesulfonate shows increased water
solubility compared to that of the tartarate, the sulfurate, and the
p-toluenesulfonate and the free base.

WE CLAIM:
1. 7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-l-cyclopropyl-6-fluoro-4-
oxo-1, 4-dihydro-l, 8-naphthyridine-3-carboxylic acid
methanesulfonate.nH2O, wherein n is 1.5 having peaks at 2 0 =8.0,12.2 and
14.7 in its X-ray diffraction pattern ,or n is 3 having peaks at 2 0 = 7.7 and
11.8 in its X- ray diffraction pattern.
2. A compound as claimed in claim 1 is 7-(3-aminomethyl-4-
methoxyiminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1, 8-
naphthyridine-3-carboxylic acid methanesulfonate.nH2O, wherein n is 1.5
having peaks at 2 0 =8.0.12.2 and 14.7 in its X-ray diffraction pattern ,
3. A compound as claimed in claim 2 having an X-ray diffraction pattern
substantially as shown in Figure 7.
4. A compound as claimed in claim 1 is 7-(3-aminomethyl-4-
methoxyiminopyrrolidin-l-yl)-l-cyclopropyl-6-fluoro-4-oxo-l,4-dihydro-l, 8-
naphthyridine-3-carboxylic acid methanesulfonate.nH2O, wherein n is 3
having peaks at 2 0 = 7.7 and 11.8 in its X- ray diffraction pattern.
5. A compound as claimed in claim 4 having an X-ray diffraction pattern
substantially as shown in Figure 6.
6. A compound as claimed in claim 2, which has a moisture content of from 4 to
6%.
7, A compound as claimed in claim 4, which has a moisture content of from 9 to
11%.
8. A pharmaceutical composition comprising from 0.1% to 99.5% by weight of 7-
(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-l-cyclopropyl-6-fluoro-4-oxo-
L 4-dihydro-l, 8-naphthyridine-3-carboxylic acid methanesulfonate.nH2O as
defined in any one of claims 1 to 7, together with a pharmaceutical acceptable
carrier or excipient such as herein described .
9. A compound as claimed in any of the claims 1 to 10, for use as a pharmaceutical.
10. A process for the preparation of a compound as claimed in any one of claims 1
to 7 comprising exposing 7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-leyclopropyl-
6-fluoro-4-oxo-l ,4-dihydro-1,8-naphthyridine-3-carboxylic acid
methanesulfonate anhydrate or a solvate thereof to a relative humidity of at least
75%.
I I . A process as claimed in claim 10 wherein the solvate is a solvate with one or
more organic solvents selected from C1-C4 haloalkanes and C1-C8 alcohols.
12. A process for the preparation of 7-(3-aminomethyl-4-methoxyiminopyrrolidin-
I -yl)-1 -cyclopropyl-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic
acid methanesulfonate. nH2O substantially as herein described with reference to
the foregoing description and the accompanying examples and figures.
13. 7-(3-aminomethyl-4-methoxyiminopyrrolidin-l-yl)-l-cyclopropyl-6-fluoro-4-
oxp-1,4-dihydro-l ,8-naphthyridine-3-carboxylic acid methanesulfonate.nH2O
substantially as herein described with reference to the foregoing description and
the accompanying examples and figures.
14. A pharmaceutical composition containing 0.1% to 99.5% by weight of 7-(3-
Am inomethy 1-4-methoxyiminopyrrolidin-1 -yl)-1 -cyclopropyl-6-fluoro-4-oxo-
1,4-dihydro-l,8- naphthyridine-3-carboxylic acid methanesulfonate.nH2O
substantially as herein described with reference to the foregoing description and
the accompanying examples and figures.