Note: Descriptions are shown in the official language in which they were submitted.
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Docket No.: 648510J959-CAO
NOVEL CRUDE AND CRYSTALLINE FORMS OF LERCANIDIPINE
HYDROCHLORIDE
FIELD OF THE INVENTION
The invention is directed to novel crude forms and crystalline forms of
lercanidipine
hydrochloride, and to processes for the preparation of these forms.
Pharmaceutical
compositions comprising the novel crystalline forms also are contemplated.
BACKGROUND OF THE INVENTION
Lercanidipine (methyl l,l;N-trimethyl-N-(3,3-diphenylpropyl)-2-aminoethyl 1,4-
dihydro-2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5-dicarboxylate) is a highly
lipophilic
dihydropyridine calcium antagonist with long duration of action and high
vascular selectivity.
Its mechanism of antihypertensive activity is attributed to a direct relaxant
effect on vascular
smooth muscle; which lowers total peripheral resistance. The recommended
starting dose of
lercanidipine as monotherapy is 10 mg daily by oral route, with a drug
titration as necessary to
20 mg daily. Lercanidipine is rapidly absorbed following oral administration
with peak plasma
levels occurring 2-3 ;hours following dosing. Elimination is essentially via
the hepatic route.
By virtue of its high lipophilicity and high membrane coefficient,
lercanidipine
combines a short;plasma half life with a long duration of action. In fact, the
preferential
distribution of the drug into membranes of smooth muscle cells results in
membrane-controlled
pharmacokinetics which is characterized by a prolonged pharmacological effect.
In comparison
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-v
to other calcium antagonists, lercanidipine is characterized by gradual onset
and long-lasting
duration of action despite decreasing plasma levels. In vitro studies show
that isolated rat aorta
response to high K+' may be attenuated by lercanidipine, even after the drug
has been removed
from the environment of the aortic tissue for 6 hours.
Lercanidipine is commercially available from Recordati S.p.A. (Milan; Italy)
and has
been described along with methods for making it and resolving it into
individual enantiomers in
U.S. Patent Nos. 4,705,797; 5,767,136; 4,968,832; 5,912,31; and 5,696,139.
The process for preparing lercanidipine described in U.S. Patent No. 4,705,797
involves
the following scheme:
Ph
Ph CH3 (1 ) pH
H3C~ ~~ + G -~ HsC
N Ph ~ N Ph
H OH CH3
H3C
Hs
N02
O O CH3 Ph
i~~ H
CH3 O ~N -
~ (s)
CH3
O H2N
N02 CH3 Ph
~ \ p- N~~.~Ph +
I Hs
~3 ~3
O CHs
(4)
Lercanidipine
(1 ): xylene at reflux; (2): toluene, 85°C; (3) HCI +CHCI3; 0°C;
(4) HO-CH(CH3)2 at reflux
The crude lercanidipine is an oily residue that must be purified by flash
chromatography
using chloroform; containing increasing amounts of acetone, as the eluent. The
solvent is then
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evaporated to dryness and remaining residue is dissolved in methanol adding a
small excess of
hydrochloric acid in ethanol. After evaporation of the solvent; the hemi-
hydrated hydrochloride
salt is prepared by treatment with diluted hydrochloric acid in the presence
of sodium chloride.
A major disadvantage of the process of preparing lercanidipine, as it is
described in U.S.
Patent No. 4,705,797, is that the disclosed cyclization reaction generates
several by-products,
which results in a lower yield for the desired product. Moreover, the
purification and isolation
of lercanidipine from the reaction mixture is quite complex, since it requires
numerous
treatments with different solvents. Finally, the purification and isolation
steps are difficult to
perform on an industrial scale because of the necessity of purifying the
product by column
chromatography:
U.S. Patent 5;912,351 describes a simpler process for the preparation of
lercanidipine
hydrochloride. It involves reaction of 1,4-dihydro-2,6-dimethyl-5-
methoxycarbonyl-4- (3-
nitrophenyl) pyridine-3-carboxylic acid with thionyl chloride in
dichloromethane and
dimethylformamide at a temperature between -4 and +1°C and subsequent
esterification of the
obtained acid chloride with 2, N-dimethyl-N-(3,3-diphenylpropyl)-1-amino-2-
propyl alcohol at
a temperature between -10 and 0°C. The process yields lercanidipine
hydrochloride in an
anhydrous non-hygroscopic crystalline form, and avoids the formation of
unwanted by-products
and the subsequent purification on chromatography columns.
However; the isolation of lercanidipine hydrochloride in crystalline form is
again quite
complex. After evaporating the solvent from the reaction mixture and
dissolving the residue
thus obtained in ethyl aceate, the solution is washed first with brine, then
washed further five
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times with a 10% solution of sodium carbonate, five times with 1N hydrochloric
acid, and
eventually once again with brine.
Therefore, there is a need in the art for a process for the preparation of
lercanidipine
hydrochloride in crystalline form which avoids one more of the disadvantages
of the currently
S used processes.
In addition, it was observed that lercanidipine, as produced by the second-
described
process above, displayed batch-to-batch variability despite careful process
control and even
observation of the melting point believed to be characteristic of the solid
product obtained by
the process of Example 3 of USP 5;767,136 of 186-188EC. This variability was
manifest in
seemingly unpredictably appearing (and disappearing} differences in one or
more of product
appearance (e.g., color), melting point and solubility. This raised issues as
to whether
assurances of purity and/or reproducibility can be made (e.g., to regulatory
authorities) that the
product is always the same.
Further research by the present inventors revealed bitch-to-batch differences
in
bioavailability in; animals, and differences in crystal size. In the course of
researching the
causes of the variability problem, the inventors surprisingly discovered novel
lercanidipine
polymorphs. They also discovered more suitable processes for the preparation
and isolation of
crystalline lercanidipine hydrochloride products from the reaction mixture. It
was surprisingly
determined that lercanidipine hydrochloride shows polymorphic features and
crystallizes into
different crystalline forms depending on the process followed and on the
solvents used.
Furthermore, the isolation of each of these crystalline forms has become
possible, thus
decreasing the possibility of batch to batch variability of lercanidipine,
which the present
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inventors determined was due to mixtures of different solid forms being
present by the same
batch and to such mixtures of different composition having the same melting
point. As a result,
more reproducible batches of lercanidipine more suitable for large scale
manufacture and
quality control became available by the present inventors.
SUMMARY OF THE INVENTION
The present invention provides novel crude forms and crystalline forms of
lercanidipine
hydrochloride and processes for making them.
In one embodiment, the invention provides novel crude lercanidipine
hydrochloride
Form (A), which has a melting point of about 150-152EC (DSC peak) and
comprises about 3-
4% (w/w) ethyl acetate.
In another embodiment, the invention provides novel crude lercanidipine
hydrochloride
Form (B) which has a melting point of about 131-135EC (I~SC peak) and
comprises about 0.3-
0.7% (w/w) ethyl acetate.
Methods are provided for the independent syntheses of crude lercanidipine
hydrochloride Form (A) and crude lercanidipine hydrochloride Form (B), making
possible to
obtain each crude form in isolated form.
In a further embodiment, isolated lercanidipine hydrochloride crystalline Form
(I) is
provided which has the following X-ray diffraction pattern, at wavelength Ka
wherein distances
between peaks (D in X), relative intensity ratios (IIIo) ratios, and angles of
significant peaks
(2B) are:
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D (X) Relative intensity 2 B angle
(I/Io)
16.3 83 5.4
6.2 47 14.2
4.78 29 18:6
4.10 63 21.7
4.06 36 21.9
3.90 100 22.8
The lercanidipine hydrochloride crystalline Form (I) has a melting point of
about 197-
201EC, when said melting point is determined as DSC peak.
In an alternative embodiment, isolated lercanidipine hydrochloride crystalline
Form (II)
is provided, which has the following X-ray diffraction pattern, at wavelength
Ka, as shown
wherein distances, (I/Io) ratios, and 2 8 angles of significant peaks are:
D (X) Relative intensit 2 B an 1e
I/Io)
9.3 35 9.5
6.0 45 14.7
5.49 65 16.1
4.65 52 19.1
4.27 74 20.8
3.81 41 23.4
3.77 100 23.6
3.58 44 24.8
3.54 29 25.2
The lercanidipine hydrochloride crystalline Form (II) has a melting point of
about 207-
21 lEC, when said melting point is determined as DSC peak.
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The present invention thus permits obtaining mixtures of Form I and Form II
having a
predetermined and reproducible content of each form, and optionally, also
other forms of
lercanidipine, such as amorphous.
Also provided are methods of syntheses in which each of isolated lercanidipine
hydrochloride crystalline Form (I) and Form (II) may be obi;ained;
independently, from the
starting material of lercanidipine hydrochloride crude Form (A) or crude Form
(B).
Also provided are pharmaceutical compositions comprising (1) lercanidipine
hydrochloride, wherein the lercanidipine hydrochloride is selected from the
group consisting of
lercanidipine hydrochloride crystalline Form (I), lercanidipine hydrochloride
crystalline Form
(II), and combinations thereof comprising a predetermined content of each
form, and (2) at least
one component selected from the group consisting of a pharmaceutically
acceptable earner or
diluent, a flavorant, a sweetener; a preservative, a dye, a binder, a
suspending agent, a
dispersing agent, a colorant, a disintegrant, an excipient, a lubricant, a
plasticizer, and an edible
oil.
In certain embodiments the aforementioned pharmaceutical compositions are
provided
as a dosage form comprising lercanidipine hydrochloride crystalline Form (I)
and/or Form (II).
In further embodiments; the invention also provides for methods of treating a
subject
with arterial hypertension, the method comprising administering a
therapeutically effective
amount of lercanidipine hydrochloride crystalline Form (I), lercanidipine
hydrochloride
crystalline Form (II), or combinations thereof comprising a predetermined
content of each form
to a subject in need of such treatment.
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In other embodiments, a method of treating or preventing atherosclerotic
lesions in
arteries of a subject is provided, the method comprising administering a
therapeutically
effective amount of lercanidipine hydrochloride crystalline Form (I),
lercanidipine
hydrochloride crystalline Form (II), or combinations hereof comprising a
predetermined
amount of each form, to a subject in need of such treatment.
These and other aspects of the present invention will be apparent to those of
ordinary
skill in the art in light of the present description, claims and figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a graph of DSC analysis carried out on crystalline Form (I),
according to the
working conditions described in Example 12. The ordinate indicates heat flow
in mW and the
abscissa temperature in °C.
Figure 2 is a graph of DSC analysis carned out on crystalline Form (II),
according to
the working conditions described in Example 12. The ordinate indicates heat
flow in mW and
the abscissa temperature in °C.
Figure 3 is a graph of the results of the thermogravimetric tests carried out
on Form (I)
and Form (II), respectively, as described in Example 13. The abscissa
indicates temperature in
°C and the ordinate indicates percent mass variation.
Figure 4 is a graph of solubility at 25°C of Forms (I) and (II) in
ethanol at increasing
water concentrations. The experiments are described in Example 15. The
ordinate indicates
solubility expressed as w/w and the abscissa % by weight of water in ethanol.
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Figure 5 is a graph of solubility at 40°C of Forms (I) and (II) in
ethanol at increasing
water concentrations: The tests axe described in Example 15. The ordinate
indicates
solubility expressed as w/w and the abscissa % by weight of water in ethanol.
Figure 6 shows i3C NMR spectra in solid phase of crystalline Form (I). The
signals and
attributes of the corresponding carbon atoms can be found in Table 4.
Figure 7 shows 13C NMR spectra in solid phase of crystalline Form (II). The
signals
and attributes of the corresponding carbon atoms can be found in Table 5.
Figure 8 shows IR spectra of Form (I): The signal and corresponding attributes
can be
found in Table 6.
Figure 9 shows IR spectra of Form (II). The signal and corresponding
attributes can be
found in Table 7.
Figure 10 represents percent average concentration of lercanidipine
hydrochloride in
dog plasma after administration of crystalline Form (I) and of crystalline
Form (II) in an amount
of 3 mg/kg, in the form of a hard gelatin capsule. The ordinate indicates the
mean value of
concentration in plasma and the abscissa indicates time (in minutes).
Figures 11 and 12 show X-ray diffraction spectra at wavelength Ka of
crystalline Forms
(I) and (II), respectively. The distances (d) in X, the (I/Io) ratios and
values of 28 angles of the
most significant peaks can be found in Tables 1 and 2 below. The ordinate
indicates the number
of counts/sec and the abscissa shows the values of 2B angles.
Figures 13 and l4 are plots of percent mass change as a function of tinge in
hygroscopicity tests carried out on Forms (I) and (II) of lercanidipine
hydrochloride,
respectively. The ordinate on the Left indicates percent mass changes and the
ordinate on the
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right percent relative humidity; the abscissa indicates time in minutes. The
protocol for the
hygroscopicity tests are described in Example 14.
Figures 15 and 16 show X-ray diffraction spectra at wavelength Ka of crude
lercanidipine hydrochloride Form (A) and of crude lercanidipine hydrochloride
Form (B),
respectively.
Figures 17 and 18 show Raman spectra of crude lercanidipine hydrochloride Form
{A)
and of crude lercanidipine hydrochloride Form (B), respectively, where the
ordinate represents
Raman units and the abscissa represents wave number (cm 1).
Figures 19 and 20 show the results of the thermogravimetric analysis carried
out on
crude lercanidipine hydrochloride Form (A) and on crude lercanidipine
hydrochloride Form (B),
respectively. In these figures, the abscissa indicates temperature (in
°C) and the ordinate
indicates percent mass variation.
DETAILED DESCRIPTION OF THE INVENTION
The present invention discloses novel crude forms and crystalline forms of
lercanidipine
hydrochloride and processes for making them. Applicants have determined that
lercanidipine
hydrochloride exhibits polymorphism and crystallizes in different forms
depending on the
process followed and on the solvents used, especially for crystallization.
Additionally, the
various novel forms have distinct chemical and physical properties and
bioavailability profiles
in animals, though not in man, as discussed herein.
The novel methods for preparation of crude of lercarudipine hydrochloride are
suitable
for highly reproducible commercial scale production of reproducible solid
compositions of
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lercanidipine hydrochloride. The methods advantageously produce novel crude
Forms (A) and
(B) of lercanidipine hydrochloride which also exhibit characteristics
desirable for industrial
applications. Crude Forms (A) and (B), e:g., exhibit higher solubility and
faster drying rates
compared to other crude forms of lercanidipine hydrochloride that have
previously been
reported. Crude Forms (A) and (B) further allow simplified crystallization
procedures to be
used for production of novel isolated crystalline forms of lereanidipine
hydrochloride.
The novel isolated crystalline forms of Iercanidipine hydrochloride of the
present
invention can be obtained from lercanidipine hydrochloride crude Forms (A) and
(B) and are
termed lercanidipine hydrochloride crystalline Form (I) and Form (I17. Either
of isolated Form
(I) or isolated Form (II) may be reproducibly obtained from the (A) and (B)
intermediates by
varying the crystallization conditions as described below. Both lercanidipine
hydrochloride
crystalline Forms (I) and (II) exhibit good stability. Form (I) is
characterized by a paler yellow
color, smaller crystal size, higher solubility in aqueous meda.a (all compared
to Form (In), and a
melting point (DSC peak) within the rage of about 197EC to about 201EC, more
specifically,
1 S about 198.7EC, and the X-ray diffraction pattern set forth, supra.
Form (In is characterized by a more pronounced yellow color, larger crystal
size,
slightly lower solubility in aqueous media (all compared to Form (I)), and a
melting point (DSC
peak) within the range of about 207-2l lEC, more specifically about 209.3EC.
Both Form (1~ and Form (II) are stable. Form II exhibited higher
bioavailability in the
dog, but in man there is no difference in bioavailability between Form (I) and
Form (II).
The novel crystalline Forms (1) and (II) represent crystalline forms of
lercanidipine
hydrochloride of a purity and uniformity that has not been obtained with
previously achieved
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solid forms of lercanidipine hydrochloride. The purity and uniformity of Forms
(I) and (II)
allow for increased ease in production of lercanidipine dosage forms, due to,
e.g., more
precisely defined physico-chemical characteristics, such as, for example,
increased uniformity
of particle size following micronization and more reproducible solubility.
Forms (I) and (II)
also provide dosage forms with more precisely defined characteristics, e.g.;
bioavailability,
compared to previously achieved dosage formswhich the present inventors have
found
comprised undefined and variable mixtures of lercanidipine hydrochloride solid
forms that vaxy
in their physico-chemical characteristics. Finally, the availability of pure
Forms (I) and (II)
provides for the ability to blend the two polymorphs into dosage forms with
novel controlled
characteristics, e.g., a dosage form with both a rapid onset and sustained
biological action.
As used herein, the term "crude form" refers to precipitated solid forms
comprising
crystals of a compound that have not been washed and/or recrystallized to
remove impurities
(including but not limited to solvent) hat may be present. In the present
specification, the crude
forms are referred to as Forms (A) and (B) of lercanidipine hydrochloride.
As used herein, the term "crystalline form" refers to crystals of a compound
that have
been washed and recrystallized to remove impurities: In the present invention;
the term
crystalline forms refers to Forms (I) and (i1) of lercanidipine hydrochloride.
These crystalline
forms have an HPLC purity ~ 99.5 % and residual solvents content of < 3000
ppm.
As used herein, the term "polymorphism" refers to a property of a compound to
crystallize in two or more forms with distinct structures. The different
crystalline forms can be
detected directly by crystallographic techniques or indirectly by assessment
of differences in
physical and/or chemical properties associated with each particular polymorph.
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The present invention contemplates any method that may be used to produce the
novel
crude forms of lercanidipine hydrochloride described herein. These forms have
different
physico-chemical properties, e:g., melting points (which can be determined
byDSC analysis);
than the crude form,of lercanidipine hydrochloride produced by other known
methods, e.g., by
the method described in U.S. Patent No. 5,912,351; termed Form (C). Form (A)
has a melting
point of about 150EC to about 152EC (DSC peak), Form (13) has a melting point
of about
131EC to about 135EC (DSC peak), and Form (C) has a melting point of about
186EC to about
192EC (DSC peak). Additionally, thermogravimetric studies show that Form (A)
comprises 3 -
4 % residual ethyl acetate and Form (B) comprises 0.3-0.7 % residual ethyl
acetate, byweight.
Comparatively, the residual liquid present in Form (C) has been determined to
be 0-0.1%.
The invention is directed to processes for the preparation of lercanidipine
hydrochloride,
each resulting in a different crude form of the product. The first two steps
in producing either
crude form are identical and are:
(a) reacting 2, 6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1;4-
dihydropyridine-3-
carboxylic acid with thionyl chloride or oxalyl chloride in a mixture of an
aprotic Bipolar
solvent and of an aprotic polar solvent to yield a chloride compound, and
(b) in-situ reacting the chloride obtained from the above step with 2, N-
dimethyl-N-(3,3-
diphenylpropyl)-1-amino-2-propyl alcohol, at a temperature preferably between -
5 and +5°C, in
a mixture of an aprotic Bipolar solvent and of an aprotic polar solvent.
In a preferred embodiment, the mixture of an aprotic Bipolar solvent and of an
aprotic
polar solvent is ethyl acetate and dirnethylformamide used at a ratio of 4:1.
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After the in-situ reaction, the lercanidipine hydrochloride is isolated and
recovered from
the mixture. The method of isolation used determines the crude form of
lercanidipine
hydrochloride obtained. Following the protocol below (a protocol) yields Form
(A):
i) washing the mixture of step (b) preferably with water,
ii) removing water from the reaction mixture of step i), preferably by
azeotropic distillation
under vacuum at 200-300 mmHg at a temperature below about 60°C
(preferably at 40-50°C);
iii) concentrating the mixture of step ii) preferably to about 1/3 of the
initial volume at the
same temperature and pressure as in step (ii), adding fresh solvent (ethyl
acetate) preferably to
obtain the initial volume, thus obtaining a suspension with a water content,
as determined
according to Karl Fischer (U.S. Pharmacopoeia 25, Method 921) preferably
between 0.10 and
0.15%;
iv) cooling the suspension of step iii) preferably to 0-5°C to produce
a solid;
v) filtering the solid of step iv);
vi) re-suspending the solid of step v) preferably irr ethyl acetate and
stirring preferably at
60-65°C for about 1 hour; and
vii) cooling to 5-10°C, filtering and drying the solid of sl;ep vi)
(e.g., in an oven at about
70°C).
The second process ((3 protocol; used to prepare Forrn (B)) is performed using
the
following steps:
i') washing the mixture of step (b)'preferably with water,
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ii') removing he water from step i') preferably by azeotropically refluxing
the product of
step i') with a Dean Stark apparatus until a water content of about 2%,
measured according to
Karl Fischer, is obtained;
iii') concentrating the mixture of step ii') o preferably 3/4 of the initial
volume and adding
fresh solvent (ethyl acetate) to the mixture preferably until (1) the initial
volume is achieved and
(2) a water content, measured according to Karl Fischer, between 0.9 and 1.1 %
is obtained;
iv') cooling the solution of step iii') preferably to 0-5°C to obtain a
solid;
v') filtering the solid of step iv');
vi') re-suspending the solid of step v') preferably in ethyl acetate and
stirnng at preferably
60-65°C for about 1 hour; and
vii') cooling the suspension of step vi') preferably to 5-10°C to
produce a solid, filtering and
drying the solid of step vi') preferably in an oven at about 70°C.
It is understood that these protocols are examples of methods that may be
used. Any
other method and obvious variations of these methods that produces Forms (A)
and (B) is
within the scope of the present invention.
The temperature of step vii') should be carefully controlled. The preferred
range of 5-
10°C is very important.
These novel crude forms of lercanidipine hydrochloride present the advantage
of higher
solubility and faster drying rate with regard to Form (C) and make a
simplified further
crystallization process possible (which can advantageously be used to prepare
Form (I) or Form
(II)). Compared to the crude form produced by U.S. Patent No. 5,912,351, these
forms permit
use of less solvent to recrystallize the compound. This increases yield by
reducing loss of
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compound. Additionally, the methods used to produce these crude forms are more
adaptable to
use in a large scale setting and commercial setting.
It has been surprisingly found that crude lercanidipine hydrochloride Form (A)
and
Form (B), when undergoing different purification treatments, result in two
novel and different
crystalline forms of lercanidipine hydrochloride. Studies indicate that these
novel crystalline
forms have different physical and chemical properties. DSC analysis of
crystalline Form (I)
indicates that it has a melting peak of about I97EC to about 201EC,
specifically about 198.7EC.
DSC analysis of crystalline Form (II) indicates that it has a melting
temperature of about 207EC
to about 211EC, specifically about 209.3EC.
One purification process ('y process), that leads to formation of one of the
novel
crystalline forms ;(Form (I)) comprises the following steps:
Process for Making Form (I)
d) adding isopropanol to crude lercanidipine hydrochloride (Form (A) or Form
(B))
and heating under reflux with stirring to produce a solution (if the solution
is not clear, it must
1 S be filtered hot);
e) cooling the solution of step d) preferably to a temperature between 30 and
40°C
and stirnng for a period of time preferably between 12 and 48 hours to produce
a solid; and
f) filtering the solid obtained from step e), washing the solid with
isopropanol, re-
filtering the solid; and drying the solid (e.g., in an oven) at preferably
70°C for a period of time
preferably between 12-48 hours.
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In step e), crystallization is considered complete when the content of the
solution
is #2% lercanidipine HCI. Other alcohols may also be used as the solvent in
step d). An
alternatively preferred solvent is a Cl-Cs alcohol containing a maximum of 5%
water; e.g.,
anhydrous ethanol. Crystalline Form (I) may be added in step (e) as seeds to
further promote
crystal formation;
Alternative Process for MakinE Form (I)
The present application also contemplates an alternative method of producing
lercanidipine hydrochloride having crystalline Form (I) which comprises the
steps of
d') adding ethanol to crude lercanidipine hydrochloride preferably at a
weight/volume ratio of lercanidipine hydrochloride solvent of l :4 to 1:6,
most preferably 1:4,
refluxing under stirring in order to obtain a solution (if the solution is not
clear it should
preferably be filtered hot), cooling under stirring preferably to 20°C
and adding crystalline seeds
of Form (I);
e') cooling the seeded mixture of step d') preferably to a temperature between
10
and 15°C and stirring at this temperature for a period of time
preferably between 24 and 96
hours to form a solid; and
f ) filtering the solid of step e') and drying it preferably in an oven at
preferably
70°C to obtain lercanidipine hydrochloride Form (I).
In step e'), crystallization is considered complete when the content of the
solution is #
2% lercanidipine HCI. Crystalline seeds of Form (I) (preferably authentic) may
also be added
to steps e') to further promote crystal formation or to induce such formation.
Process for Making Form (II)
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The second purification process (8 process), which yields crystalline Form
(II),
comprises the steps of:
d") adding acetonitrile to crude lercanidipine hydrochloride (Form (A) or Form
(B))
and heating the mixture under reflux and-stirring,
a") cooling of the mixture of step d") to room temperature and stirring
preferably for
24 hours to form a solid,
f ') filtering the solid obtained from step a") and drying it preferably in an
oven.
In step a"), crystallization is considered complete when the content of the
solution is #
2% lercanidipine HCl
The present application also contemplates two additional methods for producing
Form
(II).
First Alternative Process for Making Form (II)
The first alternative method comprises the steps of:
d"') adding isopropanol or ethanol, preferably ethanol, with a water content
preferably between 5 to 10% by weight to lercanidipine hydrochloride,
refluxing with stirring to
produce a solution;
a"') cooling the mixture to a temperature preferably between 20 and
40°C and stirring
for a period preferably between 24 and 96 hours to form a solid;
") filtering the solid and drying (e.g:, in an oven) at preferably 70°C
for 12-l8 hours
to produce lercanidipine hydrochloride Form (II).
In step a"'), crystallization is considered complete when the content of the
solution is #
2% lercanidipine HCI.
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Second Alternative Method for Mal~in~ Form II
The second alternative method of obtaining the Form (II) polymorph comprises
the steps
of
d"") dissolving crude lercanidipine hydrochloride or its crystalline Form (I)
in protic
polar or aprotic Bipolar solvents preferably containing up to 50% by weight of
water at a
temperature preferably between 20 and 70°C to produce a solution;
a"") stirnng the solution of step d"") at a temperature preferably between 20
and 25°C
to produce a solid;
f"') filtering the solid of step a"") and drying (e.g., in an oven) at
preferably 70°C for
preferably 12-18 hours.
The second alternative method may optionally comprise the step of adding up to
60%
water to the solution of step d"") prior to step a""). The second alternative
method may further
comprise irradiating with ultrasound and/or adding preferably authentic
crystalline seeds of
Form (II) to step a""). In step a""), crystallization is considered complete
when the content of
the solution is #2% lercanidipine HCI. In a preferred embodiment, the erotic
polar solvent is an
alcohol solvent such as, but not limited to, methanol, ethanol n-propanol,
isopropanol. In
another preferred embodiment, the aprotic Bipolar solvent is N-methyl-
pyrrolidone.
The preferred process for preparing Form (I) is the 'y processes and the
preferred process
for preparing Form (II) is the 8 process: Applicants have determined that Form
(I) can be
quantitatively obtained by use of C1-CS anhydrous alcohol (preferably
anhydrous ethanol or
isopropanol) or Ci-C5 alcohol containing up to 5% water under controlled
conditions d' -f). In
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CA 02380202 2002-04-03
fact, the ~ and 8 processes can be used to produce the desired polymorph
reproducibly and
consistently.
In addition to differences in melting point, the two crystalline forms exhibit
differences
in x-ray structure; solubility, and bioavailability. Solubility studies show
that Form (I) is more
soluble than Form (II) in water, ethanol, and mixtures thereof (See Tables 2 &
3).
Bioavailability studies in dogs indicate that Form (II) is more bioavailable
than Form (I)
(though this difference has not been observed in man). Finally, x-ray
diffraction studies show
that these two forms have different diffraction patterns (see :Figures 11 and
12 and Example 20).
Form I has a smaller crystal and hence particle size before micronization and
so is easier and
faster to process than Form II, which presents with larger crystals.
The present application further discloses pharmaceutical formulations and unit
dosage
forms that comprise one of the isolated polymorphs of the present invention or
a mixture thereof
of predetermined,polymorph content.
The present invention is also directed to a method of treating a subject with
arterial
hypertension; the method comprising administering a therapeutically effective
amount of
isolated lercanidipine hydrochloride crystalline Form (I), lercanidipine
hydrochloride crystalline
Form (II), or combinations thereof of predetermined polymorph content
(optionally with other
form of lercanidipine, such as amorphous form) to a subject in need of such
treatment.
The invention also contemplates a method of treating and preventing
atherosclerotic
lesions in arteries of a subject, the method comprising administering a
therapeutically effective
amount of isolated lercanidipine hydrochloride crystalline Form (I), isolated
lercanidipine
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CA 02380202 2002-04-03
hydrochloride crystalline Form (II), or combinations thereof to a subject in
need of such
treatment.
Pharmaceutical Cornpositiohs
The compounds and polymorphs of the present invention may be formulated into a
pharmaceutical composition. The pharmaceutical composition also may include
optional
additives; such as a pharmaceutically acceptable earner or diluent, a
flavorant; a sweetener, a
preservative; a dye, a binder, a suspending agent; a dispersing agent, a
colorant, a disintegrant,
an excipient, a film forming agent, a lubricant, a plasticizer, an edible oil
or any combination of
two or more of the foregoing.
Both crystalline forms can undergo micronization, using any method known in
the art.
The average size of particle produced by this method are preferably D(50%)2-8
~.m,
D(90%)<15 /am.
Suitable pharmaceutically acceptable earners or diluents include, but are not
limited to,
ethanol; water; glycerol; propylene glycol, aloe vera gel; allantoin;
glycerin; vitamin A and E
oils; mineral oil; PPG2 myristyl propionate; magnesium carbonate; potassium
phosphate;
vegetable oil; animal oil; and solketal.
Suitable binders include, but are not limited to, starch; gelatin; natural
sugars, such as
glucose, sucrose and lactose; corn sweeteners; natural and synthetic gums,
such as acacia,
tragacanth, vegetable gum, and sodium alginate; carboxymethylcellulose;
hydroxypropylmethylcellulose; polyethylene glycol; povidorle; waxes; and the'
like.
Suitable disintegrators include; but are not limited to, starch; e.g., corn
starch, methyl
cellulose, agar, bentonite, xanthan gum, sodium starch glycolate,
crosspovidone and the like.
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Suitable lubricants include, but are not limited to, sodium oleate, sodium
stearate,
sodium stearyl fumarate, magnesium stearate, sodium benzoate; sodium acetate,
sodium
chloride and the like.
A suitable suspending agent is, but is not limited to, bentonite, ethoxylated
isostearyl
alcohols, polyoxyethylene sorbitol and sorbitan esters, micracrystalline
cellulose, aluminum
metahydroxide, agar-agar and tragacanth, or mixtures of two or more of these
substances, and
the like.
Suitable dispersing and suspending agents include; but are not limited to,
synthetic and
natural gums, such as vegetable gum; tragacanth, acacia, alginate, dextran,
sodium
carboxymethylcellulose, methylcellulose, polyvinyl-pyrrolidone and gelatin.
Suitable film forming agents include, but are not limited to,
hydroxypropylmethylcellulose, ethylcellulose and polymethacrylates.
Suitable plasticizers include, but are not limited to, polyethylene glycols of
different
molecular weights (e:g., 200-8000 Da) and propylene glycol.
Suitable colorants include, but are not limited to, ferric oxide(s), titanium
dioxide and
natural and synthetic lakes.
Suitable edible oils include, but are not limited to, cottonseed oil, sesame
oil, coconut oil
and peanut oil.
Examples of additional additives include; but are not limited to, sorbitol,
talc, stearic
acid, dicalcium phosphate and polydextrose.
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Uhit Dosage Forms
The pharmaceutical composition maybe formulated as unit dosage forms, such as
tablets, pills, capsules, caplets; boluses; powders, granules, sterile
parenteral solutions, sterile
parenteral suspensions, sterile parenteral emulsions, elixirs, 'tinctures,
metered aerosol or liquid
sprays, drops, ampoules; autoinjector devices or suppositories. Unit dosage
forms may be used
for oral, parenteral, intranasal; sublingual or rectal administration; or for
administration by
inhalation or insufflation, transdermal patches, and a lyophilized
composition. In general, any
delivery of active ingredients that results in systemic availability of them
can be used.
Preferably the unit dosage form is an oral dosage form, most; preferably a
solid oral dosage
form, therefore the preferred dosage forms are tablets, pills, caplets and
capsules. However;
parenteral preparations also are preferred.
Solid unit dosage forms may be prepared by mixing the active agents ofahe
present
invention with a pharmaceutically acceptable carrier and any other desired
additives as
described above. The mixture is typically mixed until a homogeneous mixture of
the active
agents of the present invention and the carrier and any other desired
additives is formed, i.e.,
until the active agents are dispersed evenly throughout the composition. In
this case, the
compositions can be formed as dry or moist granules.
Tablets or pills can be coated or otherwise compounded to form a unit dosage
form
which has delayed and/or prolonged action, such as time release and sustained
release unit
dosage forms. For example, the tablet or pill can comprise an inner dosage and
an outer dosage
component, the latter being in the form of a layer or envelope over the
former. The two
components can be separated by an enteric layer which serves to resist
disintegration in the
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CA 02380202 2002-04-03
stomach and permits the inner component to pass intact into the duodenum or to
be delayed in
release.
Biodegradable polymers for controlling the release of the active agents;
include, but are
not limited to, polylactic acid, polyepsilon caprolactone; polyhydroxy butyric
acid,
polyorthoesters, polyacetals, polydihydro-pyrans, polycyanoacrylates and cross-
linked or
amphipathic block copolymers of hydrogels.
For liquid dosage forms, the active substances or their physiologically
acceptable salts
are brought into solution, suspension or emulsion, optionally with the usually
employed
substances such as solubilizers, emulsifiers or other auxiliaries. Solvents
for the active
combinations and the corresponding physiologically acceptable salts, can
include water,
physiological salt solutions or alcohols, e.g: ethanol, propane-diol or
glycerol. ', Additionally,
sugar solutions such as glucose or mannitol solutions may be used. A mixture
of the various
solvents mentioned may further be used in the present invention:
A transdermal dosage form also is contemplated by the present invention.
Transdermal
forms maybe a diffusion-driven transdermal system (transdermal patch) using
either a fluid
reservoir or a drug-in-adhesive matrix system. Other transdermal dosage forms
include, but are
not limited to, topical gels, lotions, ointments, transmucosal systems and
devices, and
iontohoretic (electrical diffusion) delivery system. Transdermal dosage forms
may be used for
timed release and sustained release of the active agents of the present
invention.
Pharmaceutical compositions and unit dosage forms ~f the present invention for
administration parenterally; and in particular by injection; typically include
a pharmaceutically
acceptable carrier, as described above. A preferred liquid carrier is
vegetable oil. Injection may
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CA 02380202 2002-04-03
be, for example, intravenous, intrathecal, intramuscular, intraruminal,
intratracheal, or
subcutaneous.
The active agent also can be administered in the form of liposome delivery
systems,
such as small unilamellar vesicles, large unilamellar vesicles and
multilamellar vesicles.
Liposomes can be formed from a variety of phospholipids, such as cholesterol;
stearylamine or
phosphatidylcholines.
The polymorphs of the present invention also may be coupled with soluble
polymers as
targetable drug Garners. Such polymers include, but are not limited to,
polyvinyl-pyrrolidone,
pyran copolymer, polyhydroxypropylmethacryl-amidephenol, polyhydroxy-
ethylaspartamidephenol, and polyethyl-eneoxideopolylysine substituted with
palmitoyl residues.
Administration
The pharmaceutical composition or unit dosage forms of the present invention
maybe
administered by a variety of routes such as intravenous, intratracheal,
subcutaneous, oral,
mucosal parenteral, buccal, sublingual, opthalmic, pulmonary, transmucosal,
transdermal, and
intramuscular. Unit dosage forms also can be administered i.n intranasal form
via topical use of
suitable intranasal vehicles, or via transdermal routes, using those forms of
transdermal skin
patches known to those of ordinary skill in the art. Oral adrninistration is
preferred.
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CA 02380202 2002-04-03
The pharmaceutical composition or unit dosage forms of the present invention
may be
administered to an animal; preferably a human being, in need of
antihypertensive treatment.
The pharmaceutical composition or unit dosage form of the present invention
may be
administered according to a dosage and administration regimen defined by
routine testing in
light of the guidelines given above in order to obtain optimal
antihypertensive activity and a
decreased in blood pressure while minimizing toxicity or side-effects for a
particular patient.
However, such fine turning of the therapeutic regimen is routine in light of
the guidelines given
herein.
The dosage of the composition containing polymorphs or mixtures of the present
invention may vary according to a variety of factors such as underlying
disease state, the
individual's condition, weight; sex and age and the mode of administration.
For oral
administration, the pharmaceutical compositions can be provided in the form of
scored or
unscored solid unit dosage forms.
A pharmaceutical composition comprising (1) lercanidipine hydrochloride, where
the
lercanidipine hydrochloride is selected from the group consisting of isolated
lercanidipine
hydrochloride crystalline Form (I), isolated lercanidipine hydrochloride
crystalline Form (II), or
combinations thereof of predetermined-polymorph composition; and (2) at least
one component
selected from the;group consisting of a pharmaceutically acceptable carrier or
diluent, a
flavorant, a sweetener, a preservative, a dye, a binder, a suspending agent, a
dispersing agent, a
colorant, a disintegrant, an excipient; a diluent, a lubricant, a plasticizer,
and an edible oil. In a
preferred embodiment, the pharmaceutical composition or dosage form 0.1 to 400
mg
lercanidipine hydrochloride. Preferably, the composition or dosage form
comprises 1 to 200 mg
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CA 02380202 2002-04-03
lercanidipine hydrochloride. More preferably, the composition or dosage form
comprises S to
40 mg lercanidipine hydrochloride:
The pharmaceutical composition or unit dosage form may be administered in a
single
daily dose, or the total daily dosage maybe administered in divided doses. In
addition, co-
administration or equential administration of other active agents may be
desirable. The
polymorphs and mixtures thereof of the invention may be combined with any
known drug
therapy, preferably for treatment of hypertension. For example, bimodal
therapy involving in
addition a diuretic, a ~-receptor blocker, an ACE inhibitor or an angiotensin
II receptor
antagonist is contemplated by the present invention (see, e.g., U.S.
Provisional Application No.
60/344,601; filed October 23, 2001; Italian Application No. MI 2001 A 002136
filed October
16, 2001 ).
For combination therapy the compounds may initially be provided as separate
dosage
forms until an optimum dosage combination and administration regimen is
achieved.
Therefore, the patient may be titrated to the appropriate dosages for his/her
particular
hypertensive condition. After the appropriate dosage of each of the compounds
is determined to
achieve a decrease of the blood pressure without untoward side effects, the
patient then may be
switched to a single dosage form containing the appropriate dosages of each of
the active
agents, or may continue with a dual dosage form.
The exact'dosage and administration regimen utilizing the combination therapy
of the
present invention is selected in accordance with a variety of factors
including type, species, age,
weight, sex and medical condition of the patient; the severity and etiology of
the hypertension to
be treated; the route of administration; the renal and hepatic function of the
patient; the
CA 02380202 2002-04-03
treatment history of the patient; and the responsiveness of the patient.
Optimal precision in
achieving concentrations of compounds within the range that yields efficacy
without toxicity
requires a regimen based on the kinetics of the drug's availability to target
sites. This involves a
consideration of the absorption, distribution, metabolism, excretion of a
drug, and
responsiveness of the patient to the dosage regimen. However, such fine tuning
of the
therapeutic regimen is routine in light of the guidelines given herein.
A pharmaceutical composition for parenteral administration contains not below
0.1 %,
preferably from about 0.5% to about 30%, by weight of a polymorph or mixture
of the present
invention, based upon the total weight of the pharmaceutical composition.
Individual isolated
polyrnorphs are preferred for parenteral administration.
Generally; transdermal dosage forms contain from about 0.01 % to about 100% by
weight of the active agents, based upon 100% total weight of the dosage.
In a preferred embodiment of the present invention, the composition is
administered
daily to the patient. In a further preferred embodiment, the pharmaceutical
composition or
1 S dosage form 0.1 to 400 mg lercanidipine hydrochloride. Preferably, the
composition or dosage
form comprises l to 200 mg lercanidipine hydrochloride. More preferably, the
composition or
dosage form comprises 5 to 40 mg lercanidipine hydrochloride.
EXAMPLES
The following examples of preparation of lercanidipine hydrochloride crude
Forms (A)
and (B) and crystalline Forms (I) and (II) are now disclosed for illustrative
non-limiting
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CA 02380202 2002-04-03
purposes; together with the results of DSC analysis and solubility, stability
and hygroscopicity
tests; the bioavailability tests for the new crystalline forms are also
disclosed.
EXAMPLE 1: Initial preparation
Thionyl chloride (36 g) diluted in ethyl acetate (25 g) was slowly added to a
solution of
2,6-dimethyl-5-methoxycarbonyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-
carboxylic acid (90
g) in dimethylformamide (11 S g) and ethyl acetate (396 g), keeping
temperature between -1 and
+1°C. A solution of 2, N-dimethyl-N-(3,3-diphenylpropyl)-1-amino-2-
propanol (84 g) in ethyl
acetate (72 g) was slowly added to the mixture thus obtained. The whole was
kept under
stirring at the same temperature for 3 hours. The mixture was then heated to
2U-25°C and kept
under stirring for 12 hours. Water (340 ml) was then added, the whole was
stirred for 30 ruin
and after settling the aqueous phase was discarded. The organic phase was
washed again with
water (340 ml).
EXAMPLE 2- Crude lercanidipine hydrochloride Form (A)
The organic phase obtained from Example 1 was than subjected to azeotropic
distillation
under vacuum at about 250 mmHg; without going above a temperature of
60°C. After removing
about 50 ml of water, the solution was concentrated to about 1/3 of the
initial volume in the
same conditions of temperature and pressure and then brought to its initial
volume with fresh
ethyl acetate until the K.F. value (Karl Fisher value) was about 0:10-0.15%.
The final
suspension was cooled to 0-5°C. The solid was filtered, suspended in
ethyl acetate (350 g) and
stirred at 60-65°C for 1 hour. The whole was cooled to 5-10°C
and then filtered. The solid was
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CA 02380202 2002-04-03
dried in an oven at 70°C. 133 g of dry raw lercanidipine hydrochloride
Form (A) was obtained
(75% yield), DSC peak 150-152°C:
EXAMPLE 3 - Crude lercanidipine hydrochloride Form (B)
The organic phase obtained at the end of Example 1 was heated under reflex (70-
75°C)
and the water contained in the solution was removed with a Dean Stark
apparatus (Spaziani
Rolando, Nettuno, Rome, Italy) until a K.F. value of about 2% was obtained.
The whole was
then distilled at atmospheric pressure to reach 3/4 of initial volume. The
solution was brought to
its initial volume by adding fresh ethyl acetate. The K.F. value at the end of
this operation was
0.9-1.1 %. The final solution was cooled to 0-5°C. A solid slowly
precipitates which was
filtered. The solid thus obtained was suspended in ethyl acetate (350 g) and
stirred at 60-65°C
for 1 hour. The whole was cooled to 5-10°C, then filtered and dried in
an oven at 70°C, thus
obtaining 133 g of crude lercanidipine hydrochloride Form (B), DSC peak 13 T-
135°C; 75%
yield.
EXAMPLE 3A - Crude lercanidipine hydrochloride Form (B)
The organic phase obtained at the end of Example 1 was heated under reflex (70-
75°C)
and the water contained in the solution was removed with a :Dean Stark
apparatus until a K.F.
value of about 2% was obtained. The whole was then distilled at atmospheric
pressure to reach
3/4 of initial volume. The solution was brought to its initial volume by
adding fresh ethyl
acetate. The K.F. value at the end of this operation was 0.9-1.1 %, The final
solution was cooled
to 20°C, seeded with 0.1 % of crude lercanidipine hydrochloride Form
(B) and cooled to 0-5°C.
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CA 02380202 2002-04-03
A solid slowly precipitated and was then filtered. The solid thus obtained was
suspended in
ethyl acetate (350: g);and stirred at 60-65°C for 1 hour: The whole was
cooled at S-10°C, then
filtered and dried in an oven at 70°C for 24 hours, thus obtaining 133
g of crude lercanidipine
hydrochloride Form (B); DSC peak 131-135°C; 75% yield.
EXAMPLE 4 - Preparation of lercanidipine hydrochloride crystalline Form (I)
In separate representative experiments, 100 g of crude Iercanidipine
hydrochloride Form
(A), (B), or (C) was loaded into a reactor, followed by 400 ml of 2-propanol.
The mixture was
heated under strong reflux and under stirnng, thus obtaining an almost
complete dissolution of
the crude substanbe. The mixture was hot filtered to eliminate a slight
opalescence and the clear
solution kept under stirring was cooled to 40°C: Temperature was then
set at 35°C. The whole
was kept for 24 hours under stirring at 35°C, then temperature was set
at 30°C, and stirring was
continued at said temperature for another 24 hours. The solid was filtered at
30°C and washed
with 50 rnl of 2-propanol; then dried in an oven at 70°C under vacuum
for 24 hours. Weight of
dry product in each case was (lercanidipine HCI (I)) 90 g (HPLC purity of the
product in Form
(I) > 99.5%).
EXAMPLE 4A - Preparation of lercanidipine hydrochloride crystalline Form (I)
In separate representative experiments, 1U0 g of crude lercanidipine
hydrochloride Form
(A), (B), or (C) was loaded into a reactor, followed by 400 ml of 2-pxopanol.
The mixture was
heated under strong reflux and under stirring, thus obtaining an almost
complete dissolution of
the crude substance. The mixture was hot filtered to eliminate a slight
opalescence and the clear
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CA 02380202 2002-04-03
solution kept under stirnng is slowly cooled to 40°C. Precipitation was
then triggered with 100
mg of lercanidipine hydrochloride Form (I) and temperature was set at
35°C, keeping the
mixture under stirring. The whole was kept for 24 hours under stirnng at
35°C, then
temperature was set at 30°C, keeping under stirring at said temperature
for another 24 hours.
The solid was filtered at 30°C and washed with 50 ml of Z-propanol,
then dried in an oven at
70°C under vacuum: for 24 hours. Weight of dry product (lercanidipine
HCl (I)) was 90 g
(HPLC purity of the product in Form (I) > 99.5%).
EXAMPLE 5- Preparation of lercanidipine hydrochloride crystalline Form (I)
In independent preparations; 25 kg of crude lercanidipine hydrochloride, Form
(A) or
(B), and then 100 mL of 95% ethanol were loaded and brought to strong reflux
under stirring.
The solution was cooled under stirring at 20°C and then seeded with
crystalline Form (I). The
whole was then cooled to a temperature between 10 and 15°C, keeping the
reaction mixture
under stirring for 4 days. The solid thus obtained was filtered and washed
with 95% ethanol,
the precipitate was filtered and dried in an oven under vacuum at 70°C
for 24 hours. 20.2 kg of
product was obtained, corresponding to a yield of 81%; HPLC purity in Form (I)
> 99.5%.
Comparable results are obtained with Form (C) as starting material.
EXAMPLE 6 - Preparation of lercanidipine hydrochloride crystalline Form (II)
100 g of crude lercanidipine hydrochloride Form (C) and then 200 ml of
acetonitrile was
loaded into a reactor. The mixture was heated under strong reflux and under
stirring, thus
obtaining a complete dissolution. The mixture was brought to 20-30°C
under slight stirring and
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CA 02380202 2002-04-03
kept at said temperature for 24 hours. The precipitate was filtered and dried
in an oven at 70°C
for 24 hours. 95 g of dry product was obtained, corresponding to a 95% yield;
HPLC purity >
99.5% in lercanidipine hydrochloride Form (II). Comparable results are
obtained when
lercanidipine hydrochloride Form (A) or (B) is used as starting material.
EXAMPLE 7 - Preparation of lercanidipine hydrochloride crystalline Form (I17
In separate representative experiments, 100 g of crude lercanidipine
hydrochloride Form
(A), (B), or (C) in 200 ml of 95% ethanol was loaded into a reactor, the
mixture thus obtained
was heated under stirring and under strong reflux and hen cooled at
25°C always under stirring.
The solution was kept at said temperature for 24 hours under stirring. The
precipitate thus
obtained was then filtered and dried in an oven at 70°C for 24 hours.
90 g of Form (II), HPLC
purity > 99.5% was obtained.
EXAMPLE 7A - Preparation of lercanidipine hydrochloride crystalline Form (II)
25 g of lercanidipine HCl crude substance or Form (C) was dissolved at
60°C in 100 ml
of a mixture ethanol-H20 (8:2). The whole was filtered by ~,~ravity to
eliminate the possible
insoluble portion and diluted with 100 ml of H20. The solution thus obtained
was stirred at
25°C as such, or it was added with 0.1 g of lercanidipine hydrochloride
Form (II) or it was
sonicated for 6 seconds at 20 kHz and 100 Watts, always at 25°C.
Whatever the choice, after 48
hours under stirring the precipitate thus formed was collected and dried in an
oven at 70°C for
24 hours; obtaining a 80-85% yield of Form (I>7: Comparable results are
obtained using crude
Forms (A) or (B) or lercanidipine hydrochloride crystalline Form (I) as
starting material.
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CA 02380202 2002-04-03
As an alternative, the initial clear solution is diluted with 100 ml of
ethanol and seeded
with lercanidipine hydrochloride Form {II) (0.1 g). After 48 hours with
stirring at 25°C, 80%
yield with respect to stoichiometric lercanidipine hydrochloride Form (II) is
obtained.
EXAMPLE 8 - Preparation of lercanidipine hydrochloride crystalline Form (II)
in
aqueous methanol
In representative independent examples, 40 g of lercanidipine hydrochloride
crude Form
(C) or crystalline Form (I) was dissolved in 100 ml of methanol at
30°C. The whole was filtered
by gravity to eliminate the possible insoluble portion and 25 ml of water was
added. The
solution thus obtained was stirred at 25°C as such, or was mixed with
0.1 g of lercanidipine
hydrochloride Form (II), or was sonicated for 6 seconds at 20 kHz and 100
Watts, always at
25°C. Whichever the choice, after 48 hours under stirnng the
precipitate thus formed was
collected and dried, with yields of 80-85% with respect to stoichiometric
lercanidipine
hydrochloride Form (II). Comparable results are obtained using crude Form (A)
or (B).
EXAMPLE 9 - Preparation of lercanidipine hydrochloride crystalline Form (II)
in
aqueous 1-propanol
60 g of lercanidipine HCl crude Form (C) was dissolved at 60°C in 100
ml of 1-
propanol-H20 (8:2). After filtering by gravity the possible insoluble portion
the solution was
cooled in two hours to 25°C and stirred for 120 hours at said.
temperature, with or without
sonication for 6 seconds at 20 kHz and 100 Watts: The precipitate thus formed
was collected,
obtaining 90% yield with respect to stoichiometric lercanidipine hydrochloride
Form (II) after a
drying step. Comparable results are obtained using crude Forms (A) or (B) or
lercanidipine
hydrochloride crystalline Form (I) as starting material.
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CA 02380202 2002-04-03
EXAMPLE 10 - Preparation of lercanidipine hydrochloride crystalline Form (II)
in
aqueous 2-propanol
30 g of lercanidipine hydrochloride crude Form (C) wvas dissolved at
60°C in 100 ml of
2-propanol-H20 (8:2). After filtering by gravity the possible insoluble
portion the solution was
cooled in two hours to 25°C and stirred for 72 hours at said
temperature, with or without
sonication for 6 seconds at 20 kHz and 100 Watts. The precipitate thus formed
was collected,
obtaining 85% yield with respect to stoichiometric lercanidipinehydrochloride
Form (II) after a
drying step. The same result is obtained by stirring for 168 hours at
10°C. Comparable results
are obtained using crude Forms (A) or (B) or lercanidipine hydrochloride
crystalline Form (I) as
starting material.
EXAMPLE 11- Preparation of lercanidipine hydrochloride crystalline Form (II)
in
aqueous N-methylpyrrolidone
A suspension of 50 g of lercanidipine hydrochloride crude Form (C) in 30 ml of
N-
methylpyrrolidone/water (1:l) was stirred at 20-25°C for 12 days. The
solid thus formed was
collected by filtration and dried, yielding 40 g of lercanidipine
hydrochloride Form (II).
Comparable results are obtained using crude Forms (A) or (B) or lercanidipine
hydrochloride
crystalline Form (I) as starting material.
EXAMPLE 12 - DSC analysis of lercanidipine hydrochloride crystalline Forms (I)
and
(II)
DSC analysis measures changes that occur in a given sample with heating,
wherein the
changes identify transition phases. Enthalpy variations taking place in a
transition phase are
calculated on the basis of the area under the curve. The most common
transition phases are
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CA 02380202 2002-04-03
melting and sublimation. The temperature at which transition starts, onset T,
is given by the
point in which the curve starts to deviate from the base line (flex point).
DSC of Form (I): 3.8 mg of Form (I) was placed in a golden pan of the
apparatus Perkin
Elmer DSC7. The heating speed during,the test was 10°C/min.
DSC Form (II): 4.6 mg of Form (II) was placed in a golden pan of the apparatus
Perkin
Elmer DSC7. The heating speed during the test was 10°C/min.
The data are shown in Figures 1 and 2 and the characteristic points of the
figures are
briefly summarized in the following Table 1:
Table 1.
Compound Melting T (Tpeak) Onset T [C]
[C]
Form (I) 198.7 179.8
Form (II) 209.3 169.0
Immediately after melting of Form (I) or (II) an exothermic event due to salt
decomposition can be observed.
EXAMPLE 13 - Thermogravimetry
A gravimetric analysis associated with an IR analysis was carned out on both
crystalline
Forms (I) and (II); and also on crude lercanidipine hydrochloride Form (A) and
on crude
lercanidipine hydrochloride Form (B), using a Netsch Thermomicrobalance 209 in
combination
with a spectrometer FTIR Broker Vector 22.
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CA 02380202 2002-04-03
The tests were carried out according to the following working conditions: 2-5
mg of
sample was heated in a steel crucible in nitrogen atmosphere; with a heating
speed of 10°C/min.
The results obtained with crystalline Forms (I) and (II) are shown in Figure
3, from
which it can be inferred that in both crystalline forms no weight loss can be
observed up to their
melting point (i.e., until about 190-200°C).
During degradation, which takes places as indicated above after melting, a C02
loss can
be observed.
The results obtained with crude lercanidipine hydrochloride Form (A) are shown
in
Figure 19; where a weight loss of 3.4% can be observed in the temperature
range 25-153°C.
The volatile compound has been identified by its corresponding IR spectrum and
is ethyl
acetate. During degradation (T > 170°C) a small amount of ethyl acetate
in gas phase could be
observed.
The results obtained with crude lercanidipine hydrochloride Form (B) are shown
in
Figure 20, where a weight loss of 0.5% in temperature range 25-153°C
can be observed. The
volatile compound identified with its corresponding IR spectrum is ethyl
acetate (0.4%) and
water (0.1 %). During degradation (T > 170°C) a small amount of ethyl
acetate in gas phase can
be observed.
EXAMPLE 14 - Hygroscopicity of crystalline Forms (I) and (II)
The hygroscopicity of both crystalline Forms (I) and (II) was measured with
DVS
analysis by means of a water absorption analyzer (SURFACE MEASUREMENT SYSTEM,
Marion, Buckinghamshire, UK) according to the following working conditions:
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CA 02380202 2002-04-03
10-15 mg of Form (I) and (II) respectively were placed in a quartz sample-
holder, placed
in its turn on a microbalance, and the sample underwent humidity cycles
between 0 and 95%,
starting from 50% of relative humidity (25°C, relative humidity (RH):
50-95-0-95-0-50% at
RH/h:5%).
The results of the tests are shown in the diagrams of Figures 13 and 14.
14-1 Results obtained with crystalline Form (1)
The exposure of Form (I) to humidity in the DVS analyzer results in a mass
change of
+0.15% at 95% RH, and of -0.3% at 0% RH, with almost no hysteresis during mass
increase
and loss. These slight variations are probably due to a reversible surface
absorption of water.
14-2 Results obtained with crystalline Form (II)
The exposure of Form (II) to humidity in DVS causes a negligible mass
variation (<
0.05%) in the whole RH range tested.
EXAMPLE 15- Solubility of crystalline Forms (I) and (II)
15.1 Solubility in water and in ethanol at room temperature
The solubility at 23°C of both crystalline Forms (I) and (II) was
evaluated by UV-
Visible spectroscopy in bi-distilled water (at the pH value spontaneously
reached by the system)
and in absolute ethanol. The molar absorptivity had been previously determined
in acetonitrile.
The same molar absorptivity was considered for he determination in water and
in ethanol.
Solubility in water certainly depends on pH. The residual solid obtained by
filtration of the
suspension was immediately analyzed with Raman spectroscopy. The results are
shown in the
following Tables'2 and 3.
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CA 02380202 2002-04-03
TABLE 2. Solubility in water (about 40 mg/ml as initial condition).
Starting materialTime [min] Solubility[mg/ml]Residual material
~~I
i
Form (I) 5/25/451990 0.4/0:5/0.5/0.5Form (I)
Form (II) 5/25/45/990 0.2/0.2/0.3/0.3Form (II)
TABLE 3. Solubility in ethanol (100 mg/ml as initial condition)
Starting materialTime [min] Solubility Residual material
{mg/ml]
Form (I) 15/45/120 28/27/27 Form (I)
Form (II) 15/45/120 11/12/12 Form (II)
Form (II) is less soluble than Form (I) in both solvents.
15.2 Solubility in-mixtures of water-ethanol at 25°C and at
40°C, with increasing water
concentrations
Figures 4 and 5 show solubility in water-ethanol at 25°C and at
40°C of Form (I) and of
Form (II). The maximum solubility is reached for both forms, at both
temperatures, when water
concentration is of 20%. Also in this case the solubility of crystalline Form
(I) is higher than
that of crystalline Farm (II).
EXAMPLE 16: Solid phase 13C-NMR studies
The high resolution 13C-NMR solid phase spectra were carried out with the
Bruker,
ASX300 Instrument equipped with a 7 mm Rotor accessory, using several combined
techniques:
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CA 02380202 2002-04-03
Magic angle spi~(MAS). About 300 mg of the sample was placed in the rotor
spinning at 4.3 kHz around an axis oriented at the magic angle (54°
70') to the magnetic field to
overcome the Bipolar bradening caused by CSA (Chemical shift Anisotropy). The
experiments
were conducted at room temerature.
bipolar Coupling. Since much of line broadening in 13C spectra of organic
solids is due
to coupling to protons, it was removed by heteronuclear decoupling (decoupling
power level
was almost 1 Kilowatt).
Cross polarization (CP). Cross polarization allowed carbon magnetization from
larger
proton magnetization via the Bipolar coupling to increase signal intensity.
Total suppression ofsidebands TOSS). TOSS was performed using spin-echoes
synchronized with the rotation of the sample to cause phase alteration of the
spinning sidebands,
resulting-in cancellation when successive spectra were added together.
Crystalline Forms (I) and (II) show different 13C-NMR spectra in solid phase.
The
signals (chemical shift ) and attribution of the corresponding carbon atoms
(as numbered in the
formula of lercanidipine hydrochloride shown below) are represented in the
following Tables 4
and 5, respectively.
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CA 02380202 2002-04-03
2 23
36 3534 N O 2
~~ \ / 31 O 13 16 2
32
15 ~ / 17\ 19 25
~9~ ~4~ ~11~ 12 N 18
f"~3Cr~ 5 3 + 2
~~ ~ ~ /~
31' 27
g~6'H/2~ O
C
29
Table 4. Lercanidipine hydrochloride crystalline Form (I)
Chemical shift ( ; ppm) Attribution of carbon atoms
168.7; 167.7 9; l l or 1l; 9
150.1 to 120.4 2; 6 and 20 to 37
104.3;100.9 3;5o5;3
79.7 12
63.0; 60.1 (weak) 15; 17 o r 17;15
48.6 10
47.7 16
45.4 19
41.1 4
31.6 18
27.7; 26.4 13; 14 or 14; 13
19.6; 18.0 7; 8 or 8; 7
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CA 02380202 2002-04-03
Table 5. Lercanidipine hydrochloride crystalline Form (II)
Chemical shift ( ; ppm) Attribution of carbon atoms
168.1; 166.6 9; 11 or l l; 9
151.9 to 121.9 2; 6 and from 20 to 37
104.0; 102.8 3; S or 5; 3
79.0 12
66.0; 58:0 (weak) 1 S; 17 or 17;15
49.7 10
48.8 16
44.3 19
140.5 4
I 29.8 18
~, 27.6; 23.5 13; 14 or 14; 13
19.6; 18.3 7; 8 or 8; 7
EXAMPLE 17: IR Studies
The IR (infrared) spectra were recorded in KBr powder by Diffuse Reflectance
Technique using a Perkin Elmer Spectrum-one instrument. IR spectra, whose wave
lengths and
corresponding attribution are shown in the following Tables 6 and 7, are
clearly different for the
new Forms (I) and (II).
Table 6. IR spectrum in KBr powder of lercanidipine hydrochloride Form (I)
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CA 02380202 2002-04-03
Wavelength (cm -1) Attribution
3186 NH stretching
3100-2800 Alkyl and phenyl stretching
2565 N'-H stretching
', 1673 C=O tretching
1525; 1348 Asymmetric and symmetric
stretching
of N02 group
I 1405; 1386 Bending of geminal methyl
groups
', 785-685 Out-of plane bending of 5
and 3
adjacent hydrogens on aromatic
rings
Table 7. IR spectrum in KBr powder of lercanidipine hydrochloride Form (II)
Wavelength (cm'-1) Attribution
3183 NH stretching
3100-2800 Alkyl,and phenyl stretching
2684 N'~H stretching
1705;1675 C=O stretching
1526; 1350 Asymmetric and symmetric
stretching
of N02 group
1402; 1380 Bending of geminal methyl
groups
800-680 Out-of-plane bending of 5
and 3
adjacent hydrogens on aromatic
rings
EXAMPLE 18: Roman Spectra
A Bruker FT-Roman RFS 100 Spectrophotometer was utilized under the following
typical conditions: about 10 mg sample (without anyprevious treatment), 64
scans 2 cm 1
resolution, 100 mW laser power; Ge-detector
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CA 02380202 2002-04-03
The following Tables 8 and 9 show the most significant peaks of Kaman spectra
of Form
(I) and Form (II), respectively.
Table 8. Kaman' pectrum of crystalline Form (I)
Wave number (cm 1) Peak intensity
3054 M
3040 M
2981 M
2941 M
1675 S
1'646 M
1583 M
1489 M
1349 Vs
1236 M
1005 S
821 M
174 M
98 S
73 Vs
* M= moderate; S= strong, Vs =very strong
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CA 02380202 2002-04-03
Table 9. Raman pectrum of crystalline Form (II)
Wave number (cW 1) Peak intensity
3074 M
3064 M
3055 M
3048 M
3030 M
2973 M
2940 M
1675 S
1647 s
1630 M
1584 M
1489 M
1351 Vs
1005 M
!, 995 M
103 Vs
85 S
* M= moderate; S= strong, Vs =very strong
EXAMPLE 19 - Bioavailability of crystalline Forms (I) and (II)
A study was carnied out on six Beagle dogs to evaluate the bioavailability of
crystalline
Forms (I) and (II).
The products; in micronized form, were administered orally by hard gelatin
capsules
filled up with the active agent, Form (I) and (II), at a dosage of 3 mg/kg,
administered once in
the morning of the day of the experiment.
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CA 02380202 2002-04-03
Blood samples were taken at given times and plasma concentrations of
lercanidipine
were determined with a stereoselective analytical method HPLC-MS/MS, according
to the
following working conditions;
Lercanidipine was extracted from dog plasma by means of a liquid-liquid
extraction
with a mixture of n-hexane and ethyl ether. The dry residue of the organic
phase was taken up
with a mixture of methanol and water and a liquid-phase chromatographic
separation (LC) was
carried out; the two enantiomers of lercanidipine were separated on a
CHIROBIOTIC V column
(Vancomycin) (particle size 5 m, column size 150 x 4.6 mm (ASTEC, NJ, USA))
and were
detected with a mass spectrometer (MS/MS) by using an electrospray technique.
The analytical method was validated in a concentration range between 0.1 and
20 ng/ml
of plasma for both enantiomers. The method has shown to be specific with an
accuracy of
15%. The average concentrations of lercanidipine in the tables represent the
sum of both
enantiomers.
The profiles referring to the average concentrations of lercanidipine for both
forms are
shown in Figure 10. The following Tables l0 and 11 show single values
referring to AUC,
Tmax, Cmax and to plasma concentrations.
TABLE 10. Mean values (n=5) of AUCO-t, Cmax and Tmax of lercanidipine
hydrochloride
(S+R) crystalline Form (I) and crystalline Form (II), in dogs; after oral
administration at a
dosage of 3 mg/kg.
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~ 02380202 2002-04-03
Form (I)
ParameterDog Dog Dog Dog Dog Dog Mean SD
2* 3- 4 5 6
AUCO-t 15:41263.8327.54446.57 70.39 28.72 37.73 19.12
ng/h/ml
Tmax (h) 2:00 4:00 6.00 3.00 3:00 6.00 4.00 1.67
Cmax 8:29 128.8711.62 27:17 22.58 17:83 17.50 6.91
(ng/ml)
Form (II)
ParameterDog Dog 2* Dog Dog Dog Dog Mean SD
3 4 5 6
AUCO-t 54:59119.77 75.62173:82142.34 61.91 104:6843.99
nglh/ml
Tmax (h) 3:00 1.50 1.50 4.00 2:00 6.00 3.00 1.61
Cmax 18:4652.19 19.78 52.64 55.38 18.56 36.17 17:27
(n~ml)
* not included W the calculation of mean value
Table 11: Average concentration in plasma of lercanidipine hydrochloride (S+R)
crystalline
Form (1) and crystalline Form (II), in dogs, after oral administration at a
dosage of 3 mg/kg.
Form (I)
Time Dog Dog Dog Dog Dog Dog Mean SD
(h) 1 2* 3 4 5 6
0 0.00 0.00 0.00 0.00 0.00 0.00 0:00 0:00
0.5 0.1 0.20 0.00 0:00 0.00 0.00 0.00 0.02
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CA 02380202 2002-04-03
1 0.59 0.29 0.00 0.00 0.00 0.00 0.12 0.22
1.5 1.83 1.06 0.32 0.00 1.33 0.00 0.70 0.73
2 8.29 8.94 0:94 0.35 17.11 0.28 5.39 6.34
3 4.44 36.39 0.92 27.17 22.58 1.29 11.28 11.11
4 1:81 128:879.42 11.07 16.39 6.26 8:99 5.56
6 0.80 26.65 11.62 2.53 9.73 17.83 8.50 6.50
Form (II)
Time (h) Dog 1 Dog Dog Dog Dog Dog Mean SD
2* 3 4 5 6
0 0.00 0.00 0.00 0:00 0.00 0.00 0.00 0.00
0.5 0.00 22.67 6.99 0.00 0.00 0.00 1.40 2.61
1 0:00 '52.13 16:61 5.50 3.28 0.00 5.08 5.91
1.5 0.23 52.19 19.78 35.43 32.69 3.49 18.32 14.88
2 7.63 35.45 17.81 38.10 55.38 10.19 25.82 19.23
3 18.46 17.43 15.80 28.36 40.57 14.10 23.46 12.56
4 14.83 5.17 14.10 52.64 23.66 13.24 23.69 16.26
6 8.05 4.50 3:62 17.46 6.76 18.56 10.89 6.82
* not included in the calculation of mean value
The formulation containing Form (II) is more bioavailable than the one
containing
crystalline Form (I) in 5 animals out of 6.
To simplify the comparison, dog 2 was, excluded from the evaluation, since
after the
administration of Form (I) dog 2 shows a plasma AUC of 264 ng/h/ml versus a
mean value of
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CA 02380202 2002-04-03
38 19 (SD) of the other 5 dogs. On the other hand, its AUC after
administration of Form (I) is
similar to that of the' other animals; the value being 120 versus 105 44
ng/h/ml.
The bioavailability of lercanidipine hydrochloride (Form (II)), expressed as
increase in
the AUC of lercanidipine (R+S) obtained after administration of Form (II), is
about 3 times
S higher than that obtained with Form (I). The average profile of plasma
concentrations for both
crystalline forms is shown in Figure 10
The analysis of these results shows that the amount of lercanidipine (S+R)
absorbed
after administration of crystalline Form (II) is 3 times higher that of Form
(I), whereas the
absorption speed; expressed as Tmax, is practically unchanged.
Plasma concentrations 6 hours after administration (last sampling time) are
similar, the
concentrations being of 8:5 6.5 after administration of Form (I) and of 10.9
6.8 ng/ml after
administration of'Form (II).
EXAMPLE 20 X-ray diffraction studies
Philips PW 1710 and Philips X pert PW 3040 powder diffractometer (Copper Koc
radiation) were used; under the following typical conditions: about 5-70 mg
sample (without
any previous treatment) with application of a slight pressure to obtain a flat
surface. Ambient
air atmosphere. 0:02° 2B stepsize; 2 sec step-1, 2-50 28.
The obtained spectra are given in Figures 11 and 12 and the corresponding main
peaks
are described in Tables 12 and 13. The data are clearly different for new
isolated Forms (I) and
(II).
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CA 02380202 2002-04-03
Table 12. X RD spectrum of lercanidipine hydrochloride Form (I).
D, (O) Relative intensity2 B angle
(I/Io)
16.3 83 5:4
6.2 47 14.2
4.78 29 18.6
4.10 63 21.7
4.06 36 21.9
3.90 100 22.8
Table 13. X RD; spectrum of lercanidipine hydrochloride Form (II).
D (0) Relative intensity2 8 angle
(I/Io)
9.3 35 9.5
6.0 45 14.7
5.49 65 16:1
4.65 52 19.1
4.27 74 20.8
3.81 41 23.4
3'.77 100 23.6
3.58 44 24.8
3.54 29 25.2
EXAMPLE 21. Melting point determination of various mixtures of lercanidipine
hydrochloride crystalline Forms (I) and (II)
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CA 02380202 2002-04-03
The melting points of compositions consisting of known ratios of lercanidipine
hydrochloride
crystalline Forms (I) and (II) were determined manually. Conditions consisted
of using a set
point of 177°C and introducing the capillary into the instrument
(Melting Point Apparatus
model 535; Biichi Labortechnik AG, Flawil; Switzerland) at approximately
5°C below the
melting point. Results are shown in Table 14.
Table 14. Melting points of compositions consisting of known ratios of
lercanidipine
hydrochloride crystalline Forms (I) and (II) . Samples in Series A and Series
B were heated at
a gradient of 1 °C/min and 0.5°C/min, respectively. Results are
given in °C.
Ratio
lercanidipine
hydrochloride
crystalline
Sample Pure Form Pure
(n:
Form
(I>)
Form 9;1 7:3 1:1 3:7 1:9 Form
(I)
(II)
Series 186.8 188.0 189.5 190.0 192.2 194.2 194.3
A
Series 185.9- 184:4- 184.5- 186.7- 186:5- 188.7- 190.6-
B
186.8 186.1 187.0 187.4 189.4 190.5 192.9
U.S: Patent No. 5,767,136 discloses crystalline lercanidipine hydrochloride as
having a melting point of 186-188°C. Table 14 shows that this melting
point is exhibited by
mixtures of Form (I) and Form(II) in which the ratio of Form (I):Form (II)
varies between 9:1 to
3:7. Bianchi et al: (Drugs of the Future, 1987, 12:1113-1110 report a melting
point of 186-
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CA 02380202 2002-04-03
188EC (non DSC) for a lercanidipine product they characterize as "crystals".
Hence, the
melting point of a preparation of lercanidipine hydrochloride is not
sufficient by itself to
distinguish the particular form or forms present therein; and many mixtures of
different
compositions have the same melting point range.
EXAMPLE 22. Micronization of lercanidipine hydrochloride.
Micronization is carried out by a jet-mill process using a MICRONETTE H300
from the
firm NUEVA GUSEO (Villanova sull'Arda -PC- Italy). Parameters are as follows:
Injection
pressure, 5 Kg/cmq; micronization pressure, 9 Kg/cmq; and cyclone pressure,
2:5 Kg/cmq.
Capacity of micronization is 16 Kg/h. Particle size is determined by laser
light scattering using
a GALAI CIS 1 laser instrument (GALAI; Haifa, Israel). Micronization is
performed to obtain
an average particle size of D (S0%) 2-8 ~.m and' D (90%) < 15 ~;m.
*
The present invention is not to be limited in scope by the specific
embodiments
described herein. Indeed, various modifications of the invention in addition
to those described
herein will become apparent to those skilled in the art from the foregoing
description and the
accompanying figures. Such modifications are intended to fall within the scope
of the appended
claims.
Patents, patent applications, publications; procedures, and the like are cited
throughout
this application, the disclosures of which are incorporated herein by
reference in their entireties.
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