Title of Invention

A PROCESS FOR THE PREPARATION OF A PIROXICAM : BETACYCLODEXTRIN INCLUSION COMPOUND

Abstract There is disclosed a process for the preparation of a 1:2.5 piroxicam:β-cyclodextrin inclusion compound involving the following steps: i. dissolving piroxicam and β-cyclodextrin in 1 to 2.5 molar ratio in water brought to a temperature higher than 60°C in the presence of ammonium hydroxide; ii. feeding the resulting aqueous solution into the drying chamber of a spray-drier through an atomizing device to form droplets; iii. introducing a stream of drying gas into the drying chamber to form powder particles; iv. further drying and separating the powder particles from the moist gas; characterized in that in step iii) the temperature of the inlet drying gas (inlet temperature) is comprised between 165°C and 200°C and the feed flow rate of the solution in step ii) and the flow rate of the drying gas are suitably adjusted in such a way as that the temperature of the outlet drying gas (outlet temperature) is comprised between 105°C and 130°C.
Full Text A PROCESS FOR THE PREPARATION OF A PIROXICAM: BETA-
CYCLODEXTRIN INCLUSION COMPOUND
The present invention relates to a process for the preparation of an
inclusion compound of piroxicam with β-cyclodextrin by spray-drying,
applicable on a pilot or industrial scale.
More particularly, the present invention is directed to a process for the
preparation of 1:2.5 piroxicam:β-cyclodextrin inclusion compound provided
with optimal physico-chemical characteristics as well as technological and
biopharmaceutical properties for preparing solid pharmaceutical compositions
for the oral administration.
BACKGROUND OF THE INVENTION
Piroxicam is a compound belonging to the class of the Non Steroidal
Anti-Inflammatory Drugs (NSAIDs) widely applied in rheumatoid arthritis,
osteoarthritis, acute pain in musculoskeletal disorders, post-operative and
post-traumatic pain and dysmenorrhoea.
Piroxicam is poorly soluble in water (0.003% at pH 5, 37°C) and
exhibits a low surface wettability (water contact angle 76°) and a high crystal
lattice energy as demonstrated by its melting point (198-200°C).
Since piroxicam molecule exhibits good membrane permeation
characteristics, its low solubility is responsible for the slow dissolution rate in
the gastro-intestinal fluids, which in turn results in slow absorption and delay
in the onset of action.
Slow dissolution can also exacerbate local side effects associated to the
drug (e.g. gastric irritation).
The handling of piroxicam is complicated due to its possible tautomeric
switches and polymorphism. Said molecule can indeed exist in two
polymorphic forms α and β, which have the same intramolecular structure

EZE (I) but different intra- and intermolecular hydrogen bond interactions and
in the pseudopolymorph which is the hydrate of the zwitter-ionic form ZZZ,
one of the possible resonance forms of which is represented by formula (II)

An efficient method for overcoming the problems related to the low
solubility of piroxicam relies on the preparation of inclusion complexes with
cyclodextrins as claimed in EP 153998. Hereinafter, the terms complexes,
inclusion complexes and inclusion compounds are used as synonyms.
Cyclodextrins (CDs) are natural cyclic oligosaccharides having a torus-
like macro-ring shape obtained by enzymatic degradation of starch. The three
major cyclodextrins consist of 6(α), 7(β) or 8(γ) (1→4) D-glucopyranosidic
units. Among them, PCD turned out to be the most useful for complexing
piroxicam.
The solubilisation kinetic in water of piroxicam, released from the
inclusion complex with β-cyclodextrin in the preferred molar ratio of 1 to 2.5,
is the fastest of any other piroxicam obtained through any technological
modification of the crystalline form known so far.
For solubilisation kinetic we mean the time to reach the highest
concentration of dissolved piroxicam after dispersion in water of the inclusion
complex in the form of a powder.
The 1:2.5 piroxicam:β-cyclodextrin inclusion complex (in the following
1:2.5 PβCD), having the molecular formula C15H13N3O4S*2.5 C42H70O35 and a

molecular weight of 3168.912, has been also referred to as CHF 1194.
The 1:2.5 PβCD inclusion compound, like piroxicam, exhibits anti-
inflammatory, analgesic and antipyretic properties. As analgesic drug, it is
indicated for the treatment of diseases such as dental pain, post-traumatic
pain, headache and dysmenorrhoea. It is administered by oral route in the form
of tablets or granules, preferably tablets.
Pre-clinical and clinical studies have demonstrated that the oral
absorption of piroxicam, from 1:2.5 PβCD tablets and granules is faster and
more efficient than that from piroxicam capsules.
In particular, the bioavailability of the active ingredient in terms of rate
as well as of extent of absorption in the first two hours is significantly
enhanced.
As a consequence of the faster absorption the onset of action of
piroxicam from'the 1:2.5 βCD complex is more rapid making the product
particularly effective as analgesic. It has been observed that to ensure the best
performances in terms of dissolution rate and hence rapid absorption of
piroxicam following the administration of 1:2.5 PβCD tablets, the powdery
raw material should be able to produce after dispersion in water a
concentration of dissolved piroxicam equal to or higher than 0.4 g per 100 ml
(0.4% w/v) within the first 15 minutes.
The successful results achieved with the use of cyclodextrins rely on the
fact that, through complexation, it is possible to obtain a stable amorphous
structure; since the amorphous form has a larger surface area and its lattice
energy is much less than in crystals, both wettability and aqueous solubility of
piroxicam are increased. Amorphous piroxicam as such is, indeed, a
metastable form which crystallises within few hours. Moreover, it has also
been demonstrated by Raman studies that piroxicam, in the β-cyclodextrin
inclusion compound, assumes a zwitter-ionic structure with positive and

negative charges delocalized similar to that of the hydrate pseudopolymorph
(II). This structure is stabilized due to the chemical interaction with
β-cyclodextrin via electrostatic and hydrogen bonds. The dipolar character of
the zwitter-ionic structure improves the solubilisation kinetics and instant
solubility of piroxicam.
Since the solubilisation kinetic in water of piroxicam also depends on
the intramolecular structure assumed by piroxicam in the 1:2.5 PβCD
inclusion compound, the relevant manufacturing process should be able to
achieve the complete conversion of piroxicam in the zwitter-ionic form.
Moreover, the manufacturing process should be able to achieve the
completeness of the inclusion reaction as well as the complete amorphization
of the whole product.
On the other hand, an amorphous active substance may incur the risk of
crystallisation during storage due to the presence of residual water. Once the
amorphous substance is formulated under the form of solid pharmaceutical
preparations such as tablets, said crystallization can be responsible for
phenomena such as swelling or loss of hardness of the tablets. Therefore it is
also very important that the manufacturing process yields an amorphous
substance wherein the amount of residual water is the lowest as possible and
in the case of 1:2.5 PβCD equal to or lower than 5% w/w, preferably equal to
or lower than 4% w/w.
In summary, a manufacturing process suitable for the preparation of the
1:2.5 PβCD inclusion compound in the form of powder should be able to give
rise to:
i) no significant degradation of the two ingredient, i.e. piroxicam and
β-cyclodextrin;
ii) completeness of the inclusion reaction;
iii) complete amorphization;

iv) complete conversion of piroxicam into the zwitter-ionic form;
v) an amount of residual water equal to or lower than 5% w/w,
preferably equal to or lower than 4% w/w.
Moreover said process should provide a 1:2.5 PβCD able to produce,
after dispersion of the powder in water, a concentration of dissolved
piroxicam equal to or higher than 0.4 g per 100 ml (0.4% w/v) within the first
15 minutes.
As reported above, the latter characteristic, when 1:2.5 PβCD is utilised
for the preparation of solid pharmaceutical formulations for oral
administration, and in particular tablets, is of paramount importance for
ensuring optimal performances in term of piroxicam dissolution rate.
PRIOR ART
Cyclodextrin inclusion complexes can be prepared by reaction between
the components in the solid state or semi-solid state or liquid state.
In the solid state method, the two components may be optionally
screened to uniform particle size and thoroughly mixed whereafter they are
ground in a high-energy mill with optional heating, screened and
homogenized.
In the semi-solid state, the two components are kneaded in the presence
of small amounts of a suitable solvent, and the resulting complex is oven
dried, screened and homogenized.
The complex formation in the liquid state is accomplished, in general
terms, by dissolving the cyclodextrin and the drug in a suitable solvent and
subsequently isolating the solid state complex by crystallization, evaporation,
spray-drying or freeze-drying (lyophilization).
In particular freeze-drying and spray-drying are methods applicable on
industrial scale.
Freeze-drying is the process of removing water from a product by

sublimation, i.e. at a product temperature that is lower than its eutectic
temperature.
In WO 03/105906 the applicant described a process for the preparation
of 1:2.5 PβCD by freeze-drying on an industrial scale wherein a diluted
aqueous solution of two components, piroxicam and β-cyclodextrin is
subjected, before drying, to a freezing process at a very high rate.
Although it is very convenient for potentially thermolabile molecules
such as piroxicam and β-cyclodextrin since it does not envision heating,
freeze-drying involves a rather length step of removing a large amount of
water by sublimation.
Spray-drying can constitute an alternative process of removing water
from a product. It can be faster than freeze-drying but it requires heating so it
could present some drawbacks when applied to potentially thermolabile
molecules such as piroxicam and β-cyclodextrin.
Basically spray-drying is accomplished by atomizing a pre-heated
solution (preferably an aqueous solution) into the drying chamber of the
spray-drier apparatus where the small droplets are subjected to a stream of
temperature-controlled hot gas and converted to powder particles. As the
powder is discharged for the drying chamber, it is passed through a
powder/gas separator, for example a cyclone, where it is further dried and
collected.
The parameters which can be adjusted for obtaining a powder with well
defined characteristics are: i) the type of atomizing device; ii) the temperature
of the inlet gas used to dry the sprayed material in the drying chamber
(hereinafter referred to as inlet temperature); iii) the gas flow rate and iv) the
flow rate of the feed solution (hereinafter the feed flow rate). Another
important parameter which affect the final moisture content of the powder is
the temperature of the drying gas coming out from the spray-drying chamber

(hereinafter referred to as outlet temperature).
The preparation of inclusion complexes of piroxicam with cyclodextrins
by spray-drying on a lab scale is mentioned in several documents of the prior
art. But the experimental conditions are not disclosed or, when disclosed,
came out not suitable for preparing a 1:2.5 PβCD inclusion compound which
fulfills the requirements previously illustrated.
EP 153998 generically discloses that complexes of piroxicam and
cyclodextrins in a molar ratio comprised between 1:1 and 1:10 can be
prepared in different ways:
a) by crystallization from an aqueous or an organic/aqueous solution
containing the two ingredients;
b) by evaporation of a water/ammonia solution;
c) by freeze-drying or atomization in air stream (spray drying) of a
water/ammonia solution.
All the examples refer to preparations of 1:2.5 PβCD on a lab scale
(from milligram to grams). The conditions for obtaining the product by
spray-drying are not reported.
EP 449167 discloses a process for preparing inclusion complexes of
piroxicam with β-cyclodextrin characterized in that the two ingredients, both
in powder form, are mixed together, then co-ground in a high-energy mill
whose grinding chamber has been saturated with steam. In the example 2 of
EP 449167, the dissolution rate of tablets containing as active ingredient the
1:2.5 PβCD prepared according to the claimed process was compared with
that of analogous pharmaceutical composition containing the same active
ingredient obtained by different methods, including spray drying and with a
piroxicam composition in the form of capsules available on the market. The
conditions for obtaining the product by spray-drying are not reported.
In Acerbi D et al (Drug Invest 1990, 2, Suppl. 4, 29-36), a flow-chart

showing the manufacturing process(es) for 1:2.5 PβCD is sketched. As far as
spray-drying process is concerned, no conditions are reported except for the
temperature of the βCD aqueous solution (65°C-70°C) before it is added to the
apparatus. Moreover, as it can be appreciated from Figure 7 dealing with the
solubilisation curves of piroxicam from complexes prepared with different
methods, 1:2.5 PβCD obtained by spray-drying, after dispersion of the
powder, gives rise to a maximum concentration of dissolved piroxicam of only
about 0.03 g per 100 ml of water within the first five minutes (0.03% w/v).
Pezoa R et al (Proceedings of the 6th International Conference on
Pharmaceutical Technology, June, 2-4, 1992, Paris) reports the
characterization of 1:1 PβCD complex obtained by freeze-drying and spray-
drying methods. Experimental conditions are reported neither for
freeze-drying nor for spray-drying. In the paper, it is generically stated that
the dissolution profile of hard gelatine capsules containing the spray-dried
complex shows a significant increase in the rate of dissolution but less than
those containing the freeze-dried complex.
Pavlova A V et al (Analyt Lab 1995, 4, 87-91) concerns the analytical
characterization of 1:2.5 PβCD inclusion complexes prepared in different
ways. Among other methods, the inclusion complex was prepared by
spray-drying but no conditions are reported.
In Van Hees T et al (Proceeding of the Ninth International Symposium
on Cyclodextrins, Kluwer, 1999, 211-214), a comparative study of the
dissolution properties of inclusion complexes of piroxicam with
β-cyclodextrin prepared by different methods is reported. Complexes were
prepared by supercritical CO2, freeze-drying and spray-drying. The conditions
for obtaining the product by spray-drying are not reported. The dissolution or
solubilisation kinetic was determined on the spray-dried substance in a USP
XXIII N. 2 dissolution apparatus using 500 ml of solutions at pH 1.2 and pH

6.8. Within the first 15 min, very low amounts of piroxicam, of about 30 mg
and about 50 mg per 100 ml, were dissolved corresponding to concentrations
of 0.03% and 0.05% w/v.
In Kata M et al (Proceedings of the 10th International Cyclodextrin
Symposium, Wacker, 2000, 629-634) inclusion compounds of piroxicam:
β-cyclodextrin in four different molar ratios (2:1, 1:1, 1:2 and 1:3) were
prepared by spray-drying using a lab scale apparatus (Niro Minor atomizer).
The powder mixtures were dissolved in dimethylformamide and water and
submitted to spray-drying under the following conditions: feed flow rate:
600 ml/h (i.e. 0.6 1/h), temperature of inlet air: 155°C; temperature of outlet
air: 90°C; pressure: 3 atm (corresponding to about 3 bar).
In Lin S-Y et al (Int J Pharm 1989, 56. 249-259) a 1:1 PβCD was
prepared by spray-drying under the following conditions: inlet temperature:
145 ± 1°C, outlet temperature: 75± 1°C, drying (gas) flow rate: 0.37 mVmin
(i.e. approximately 22 kg/h), atomizing air pressure: 1.0 kg/cm2 (i.e.
approximately 1 bar), sample feeding speed (feed flow rate): 4.5 ml/min (i.e.
0.27 1/h). The product turned out to be amorphous. The dissolution rate of the
tablets prepared with the spray-dried product, carried out using the USP XXI
paddle dissolution method at a rotational speed of 50 r.p.m. and at a
temperature of 37°C, was faster than that of the physical mixture and pure
drug but, as it can be appreciated from Figure 6(A) only about 20% of the
amount of piroxicam was released after 30 minutes.
In Kata M and Lin S-Y processes, the outlet temperature is of 90°C or
less.
As reported on page 4 of the present application, the 1:2.5 PβCD solid
material to be utilised for the preparation of pharmaceutical formulations such
as tablets should have a residual water equal to or lower than 5% w/w.
According to the findings of the applicant, outlet temperatures such as

those reported in the above mentioned papers are too low for obtaining a
product meeting said specification.
Therefore both Kata M and Lin S-Y disclose conditions not suitable for
preparing 1:2.5 PβCD which fulfills the requirements previously mentioned in
terms of residual water and solubilisation kinetic.
Van Hees T et al Pharm Res 1999, 16, 1864-1870 deals with the
application of supercritical carbon dioxide for the preparation of a 1:2.5 PβCD
inclusion compound. For comparison 1:2.5 PβCD was also prepared using the
lab scale apparatus "Niro mobile minor™ spray-dryer", by applying the
following conditions: inlet temperature of 175°C, feed flow rate of 15 ml/min
(i.e. 0.9 1/h) and spray pressure of 0.2-0.3 MPa (corresponding to 2-3 baT).
In Table II, said spray-dried 1:2.5 PβCD turned out to include an
amount of water of 4.4%. However, the paper is silent about the gas flow rate
and the outlet temperature, that are parameters of paramount importance in
order to obtain a 1:2.5 PβCD complex capable to ensure the desired
solubilisation kinetic of piroxicam.
In view of the prior art, it would be highly advantageous to provide a
process for preparing 1:2.5 PβCD inclusion compound by spray-drying,
applicable on a pilot or an industrial scale, said process being able to give rise
to:
i) no significant degradation of the two ingredient, i.e. piroxicam and
β-cyclodextrin;
ii) completeness of the inclusion reaction;
iii) complete amorphization;
iv) complete conversion of piroxicam into the zwitter-ionic form;
v) an amount of residual water equal to or lower than 5% w/w
preferably equal to or lower than 4% w/w.
Moreover it would be even more advantageous to provide a

spray-drying process which yields a 1:2.5 PβCD inclusion compound able to
produce, after dispersion of the powder in water, a concentration of dissolved
piroxicam equal to or higher than 0.4 g per 100 ml (0.4% w/v) within the first
15 minutes.
THE OBJECT OF THE INVENTION
The present invention is directed to a process for the preparation of a
1:2.5 piroxicam:β-cyclodextrin (1:2.5 PβCD) inclusion compound hy
spray-drying, said process comprising the following steps:
i. dissolving piroxicam and β-cyclodextrin in the 1 to 2.5 molar ratio
in hot water in the presence of ammonium hydroxide;
ii. feeding the resulting aqueous solution into the drying chamber of a
spray-drier through an atomizing device to form droplets;
iii. introducing a stream of pre-heated drying gas into the drying
chamber to form powder particles;
iv. further drying and separating the powder particles from the moist
gas
characterized in that in step iii) the temperature of the inlet drying gas (inlet
temperature) is comprised between 165°C and 200°C and the temperature of
the outlet drying gas (outlet temperature) is comprised between 105°C and
l30°C.
We have found that in order to obtain a 1:2.5 PβCD inclusion
compound which fulfills the requirements mentioned before, it is necessary to
strictly control both the inlet and the outlet temperatures in the drying
chamber.
In particular, we have found that by applying an inlet temperature
higher than 200°C, it is not possible to achieve after dispersion of the 1:2.5
PβCD powder in water a concentration of dissolved piroxicam equal to or
higher than 0.4 g per 100 ml within the first 15 minutes. On the other hand, we

have also found that if the outlet temperature is lower than 105°C, it would
not be possible to obtain a residual amount of water lower than 5% w/w.
Therefore the inlet temperature should be set to a value of at least 165°C and,
after suitably adjusting other parameters such as the flow rate of the feed
aqueous solution and the gas flow rate, the outlet temperature in the drying
chamber should be equal to or higher than the critical value of 105°C.
By operating in the ranges of temperatures of the invention, piroxicam
remains chemically stable and no significant degradation products of 1:2.5
PβCD were observed.
The present invention is also directed to pharmaceutical compositions
containing as active ingredient, 1:2.5 PβCD inclusion compound obtainable by
the aforementioned process.
DETAILED DESCRIPTION OF THE INVENTION
The characteristics of the process of the invention for preparing 1:2.5
PβCD inclusion compound on a pilot or industrial scale by spray-drying will
be more apparent from the following detailed description.
For pilot or industrial scale, we mean the preparation of batches of at
least 10 kg, preferably from 10 kg to 300 kg.
Spray-drier apparatus in a wide variety of sizes and configurations can
be used as currently supplied by commercially suppliers. The diagram in
Figure 1 shows a schematic representation of a typical spray-drying apparatus.
In a first step, piroxicam and β-cyclodextrin in the 1:2.5 molar ratio and
ammonium hydroxide are added to a tank containing water brought to a
temperature higher than 60°C, preferably higher than 70°C, more preferably
between 70°C and 80°C, then mixed until dissolution. Advantageously the
concentration of piroxicam in water shall be of about 2% w/v and that of
β-cyclodextrin shall be of about 17% w/v. Advantageously concentrated
ammonium hydroxide is added, preferably in a cone, of 28-30% w/w and in a

1:1 ratio w/w with respect to piroxicam.
In a second step the hot solution is loaded with a fluid pump (1 in
Figure 1) through an atomizing device (2) into the drying chamber (7) of the
spray-drier.
In the Example of the present invention, a pressure atomizing device
was used and the process parameters of the spray-dryer were adjusted
accordingly, in order to achieve an outlet temperature comprised between
105°C and 130°C.
The pressure atomizing device can consist of a single or a plurality of
nozzles through which the solution is forced by the pump breaking up into
droplets. When a pressure atomizing device consisting of a single nozzle is
used, advantageously the pressure of the nozzle will be comprised between 10
and 350 bar, preferably between 20 and 200 bar. Typically, the nozzle shall
have an internal diameter of 0.5 to 0.7 mm.
For the spraying process, other kinds of atomizing device such as a
rotary (centrifugal) atomizing device or other suitable devices can be used.
The person skilled in the art will adapt the various process conditions and
parameters accordingly.
The rotary (centrifugal) atomizing device, for example, is a spinning
disk assembly with radial or curved plates which rotates at high velocities,
usually comprised between 15000 and 25000 r.p.m. The solution is delivered
near the center and spreads between the two plates and is accelerated to high
linear velocities before it is thrown off the disk in the form of droplets.
In the drying chamber, the droplets meet a stream of hot gas and they
loose their moisture very rapidly while still suspended in the drying gas.
While no particular restrictions are placed on the gas used to dry the sprayed
solution, it is advantageous to use air, nitrogen gas or an inert gas, preferably
air, more preferably with a residual moisture content equal to or lower than

7000 p.p.m. The gas is electrically heated (5) and can be introduced via a
suitable distributor (6).
The heated gas stream may flow concurrently with the droplets, but it
would also be possible to employ counter-current flow, cross-current flow, or
other flow patterns.
Advantageously the inlet temperature in the drying chamber of the
spray-drier will vary between 165°C and 200°C, more advantageously
between 170°C and 200°C, preferably between 175°C and 195°C, more
preferably between 178°C and 182°C.
The outlet temperature in the drying chamber shall be comprised
between 105°C and 130°C, preferably between 110CC and 120°C, even more
preferably between 112°C and 115°C.
In order to prepare an amount of inclusion complex of about 10 kg, the
spray-drying process of the invention is carried out by applying a feed flow
rate of at least 12 kg/h (approximately 12 1/h). For a higher amount, the feed
flow rate shall be comprised between 12 kg/h and 200 ton/h, preferably
between 12 kg/h and 300 kg/h.
Analogously, the flow rate of the drying gas is of at least 80 Kg/h,
preferably 100 Kg/h, more preferably 300 Kg/h, even more preferably of at
least 600 kg/h.
For higher amounts, the gas flow rate shall be comprised between
600 kg/h and 30 ton/h.
Once defined the inlet and outlet temperature ranges provided by the
present invention, the other process parameters shall be properly and mutually
adjusted by the person skilled in the art on the basis of the size of the batch.
In the example that follows, for a batch of about 10 kg of 1:2.5 PβCD,
an inlet temperature of between 178°C and 182°C, a nozzle of 0.5 mm with a
pressure of 21 bar, a feed flow of 12 kg/h (approximately 12 1/h) and a air

flow rate of 600 kg/h are used in order to achieve the suitable outlet
temperature of 112°C-115°C.
Advantageously the difference between the inlet and the outlet
temperatures is comprised between 45°C and 95°C, preferably between 65°C
and 75°C.
The powder is dried and separated from the moist gas in a cyclone (8)
by centrifugal action. The centrifugal action is caused by the great increase in
gas speed when the mixture of powder particles and gas enters into the
cyclone. The dense powder particles are forced toward the cyclone walls and
the product is collected under the cyclone on a vessel (9) through a
discharging device such as a rotary valve. The lighter particles of moist gas
are aspirated away by an aspirator (10) through the exhaust pipes.
Alternatively, separation may be achieved by using a filter medium
such as a membrane medium (bag filter), a sintered metal fiber filter, or the
like.
In the amorphous 1:2.5 PβCD inclusion compound obtainable by the
process of the present invention piroxicam is completely present in the
zwitter-ionic form and it can be characterized by its Raman spectrum, X-ray
powder diffraction pattern and thermal behavior which are reported in the PCT
application n. WO 03/105906.
The FT-Raman spectrum, obtained by simply packing the powder into a
cup, shows the following main peaks in the 165β-1000 cm-1 range (accuracy
± 1 cm-1):
1613 cm-1 (sh), 1593 (s), 1578 (sh), 1561 (w), 1525 (br), 1519 (br),
1464 (m), 1436 (m), 1394 (s), 1331 (brm)/1306 (sh), 1280 (w), 1260 (w), 1234
(w), 1217 (vw), 1186 (w), 1158 (m), 1119 (m), 1083 (w), 1053 (w), 1036 (w),
992 (w), 947 (brw).
Legend: sh = shoulder; s = strong; m = medium; w = weak; vw = very

weak; br = broad, brm = broad medium, brw - broad weak.
The amount of residual water in the 1:2.5 PβCD obtainable by the
process of the present invention can be determined by Karl-Fisher method and
it should be equal or lower than 5% w/w, preferably equal to or lower than 4%
w/w. Since 1:2.5 PβCD tends to absorb water, the determination should be
carried out as soon as the product is obtained and in any case after protection
from moisture ingress.
The solubilisation kinetic of piroxicam from the 1:2.5 PβCD shall be
determined according to the dispersed powder method reported in the
following Example 2.
Advantageously, the concentration of dissolved piroxicam within the
first 15 minutes shall be equal to or higher than 0.4% w/v, preferably equal to
or higher than 0.5% w/v.
The 1:2.5 PβCD obtainable with the process of the invention can be
advantageously used to prepare pharmaceutical compositions having
analgesic, anti-inflammatory and anti-rheumatic activity, for the oral
administration, preferably in the form of tablets, effervescent tablets or
sachets for oral administration, more preferably in the form of tablets.
Advantageously the tablets for oral administration contain between
50 mg and 200 mg of the 1:2.5 PβCD complex per unit dose, preferably
95.6 mg or 191.2 mg (corresponding to 10 and 20 mg of piroxicam,
respectively) in admixture with suitable excipients such as lactose,
crospovidone, sodium starch glycolate, silica, starch and magnesium stearate.
The following examples better illustrate the invention.
Example 1 - Preparation of 1:2.5 PβCD by spray-drying
About 50 litres of water was poured into a tank and heated up to a
temperature of 73°C-75°C.
8.6 kg (7.57 moles) of β-cyclodextrin, 1 kg (3.02 moles) of piroxicam

and 1 kg of 28% ammonium hydroxide were added in succession, and the
mixture stirred for 30 min. The solution was filtered using a 55 µm filter and
loaded into a spray dryer Niro. The following process parameters were used:
nozzle diameter: 0.5 mm; nozzle pressure: 21 bar; air flow rate: 600 kg/h; feed
flow rate: 12 kg/h (approximately 12 1/h); inlet temperature: 182°C; outlet
temperature: 113°C.
The 1:2.5 PβCD product in the form of free-flowing powder was
collected under the cyclone through a rotary valve.
The resulting product shows the thermal curve and the Raman spectrum
reported respectively in Figures 2 and 3, which arc typical of a 1:2.5 PβCD
wherein a complete inclusion complex reaction has occurred and piroxicam is
present in the zwitter-ionic form. Powder X-ray analysis shows the diffused
diffraction pattern typical of amorphous products, After HPLC analysis, no
significant amount of degradation products of piroxicam was detected.
The residual amount of water was 3.8% w/w as determined by Karl
Fischer method.
Example 2 - Solubilisation kinetic of piroxicam from 1:2.5 PβCD
prepared in the Example 1
The solubilisation kinetic was determined according to the dispersed
powder method.
In a dissolution test apparatus Sotax A76, 250 ml of water were
introduced and the temperature was set at 37°C ± 0.5°C. Then, 20 g of PβCD
as obtained in the Example 1, corresponding to about 2 g of piroxicam, was
added and the resulting dispersion was maintained under stirring at 125 r.p.m.
After 15 minutes, an aliquot of the solution was withdrawn and filtered. The
concentration of dissolved piroxicam, measured by UV spectrophotometry,
turned out to be 0.5 g per 100 ml, i.e. 0.5% w/v.

WE CLAIM: .
1. A process for the preparation of a 1:2.5 piroxicam:β-cyclodextrin inclusion compound, said
process comprising the following steps:
i. dissolving piroxicam and β-cyclodextrin in 1 to 2.5 molar ratio in water brought to a
temperature higher than 60°C in the presence of ammonium hydroxide;
ii. feeding the resulting aqueous solution into the drying chamber of a spray-drier through
an atomizing device to form droplets;
iii. introducing a stream of drying gas into the drying chamber to form powder particles;
iv. further drying and separating the powder particles from the moist gas;
characterized in that in step iii) the temperature of the inlet drying gas (inlet temperature) is
comprised between 165°C and 200°C and the feed flow rate of the solution in step ii) and the
flow rate of the drying gas are suitably adjusted in such a way as that the temperature of the
outlet drying gas (outlet temperature) is comprised between 105°C and 130°C.
2. The process as claimed in claim 1, wherein the feed flow rate of the solution of step ii) is of at
least 12 kg/h.
3. The process as claimed in claim 1 or 2, wherein the flow rate of the drying gas is of at least 600
kg/h.
4. The process as claimed in any one of claims 1 to 3, wherein the inlet temperature is comprised
between 175°C and 195°C.
5. The process as claimed in claim 4, wherein the inlet temperature is comprised between 178°C
and 182°C.
6. The process as claimed in any one of claims 1 to 5, wherein the outlet temperature is comprised
between 110°C and 120°C.
7. The process as claimed in claim 6, wherein the outlet temperature is comprised between 112°C
and 115°C.
8. The process as claimed in any one of the claims 1 to 7, wherein the atomizing device is a rotary
(centrifugal) atomizer.

9. The process as claimed in any one of claims 1 to 7, wherein the atomizing device is a pressure
atomizer.
10. The process as claimed in any one of the preceding claims, wherein the separation of the
powder particles in step iv) is carried out in a cyclone by centrifugal action.
11. The process as claimed in claim 1, wherein the water is brought to a temperature above 70°C.
12. The process as claimed in claim 1, wherein the water is brought to a temperature comprised
between 70°C and 80oC.
13. The process as claimed in claim 1, wherein the ammonium hydroxide in step i) is used in a
concentration ranging from 28 to 30 % and in a 1:1 ratio (w/w) with respect to piroxicam.


There is disclosed a process for the preparation of a 1:2.5 piroxicam:β-cyclodextrin inclusion
compound involving the following steps:
i. dissolving piroxicam and β-cyclodextrin in 1 to 2.5 molar ratio in water brought to a
temperature higher than 60°C in the presence of ammonium hydroxide;
ii. feeding the resulting aqueous solution into the drying chamber of a spray-drier through
an atomizing device to form droplets;
iii. introducing a stream of drying gas into the drying chamber to form powder particles;
iv. further drying and separating the powder particles from the moist gas;
characterized in that in step iii) the temperature of the inlet drying gas (inlet temperature) is
comprised between 165°C and 200°C and the feed flow rate of the solution in step ii) and the
flow rate of the drying gas are suitably adjusted in such a way as that the temperature of the
outlet drying gas (outlet temperature) is comprised between 105°C and 130°C.

Documents:

00360-kolnp-2007-assignment.pdf

00360-kolnp-2007-correspondence-1.1.pdf

00360-kolnp-2007-form-3-1.1.pdf

0360-kolnp-2007 abstract.pdf

0360-kolnp-2007 claims.pdf

0360-kolnp-2007 correspondence others.pdf

0360-kolnp-2007 description(complete).pdf

0360-kolnp-2007 drawings.pdf

0360-kolnp-2007 form-1.pdf

0360-kolnp-2007 form-3.pdf

0360-kolnp-2007 form-5.pdf

0360-kolnp-2007 international publication.pdf

0360-kolnp-2007 pct form.pdf

0360-kolnp-2007 priority document.pdf

360-KOLNP-2007-ABSTRACT 1.1.pdf

360-KOLNP-2007-AMANDED CLAIMS.pdf

360-KOLNP-2007-ASSIGNMENT.pdf

360-KOLNP-2007-CORRESPONDENCE 1.1.pdf

360-KOLNP-2007-CORRESPONDENCE 1.2.pdf

360-KOLNP-2007-CORRESPONDENCE.pdf

360-KOLNP-2007-DESCRIPTION (COMPLETE) 1.1.pdf

360-KOLNP-2007-DRAWINGS 1.1.pdf

360-KOLNP-2007-EXAMINATION REPORT.pdf

360-KOLNP-2007-FORM 1-1.1.pdf

360-KOLNP-2007-FORM 13 1.1.pdf

360-KOLNP-2007-FORM 13.pdf

360-KOLNP-2007-FORM 18 1.1.pdf

360-kolnp-2007-form 18.pdf

360-KOLNP-2007-FORM 2.pdf

360-KOLNP-2007-FORM 3 1.1.pdf

360-KOLNP-2007-FORM 3-1.1.pdf

360-KOLNP-2007-FORM 5 1.1.pdf

360-KOLNP-2007-GPA.pdf

360-KOLNP-2007-GRANTED-ABSTRACT.pdf

360-KOLNP-2007-GRANTED-CLAIMS.pdf

360-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

360-KOLNP-2007-GRANTED-DRAWINGS.pdf

360-KOLNP-2007-GRANTED-FORM 1.pdf

360-KOLNP-2007-GRANTED-FORM 2.pdf

360-KOLNP-2007-GRANTED-SPECIFICATION.pdf

360-KOLNP-2007-OTHERS 1.1.pdf

360-KOLNP-2007-OTHERS.pdf

360-KOLNP-2007-PA.pdf

360-KOLNP-2007-PETITION UNDER RULE 137-1.1.pdf

360-KOLNP-2007-PETITION UNDER RULE 137.pdf

360-KOLNP-2007-REPLY TO EXAMINATION REPORT 1.1.pdf

360-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf


Patent Number 251621
Indian Patent Application Number 360/KOLNP/2007
PG Journal Number 13/2012
Publication Date 30-Mar-2012
Grant Date 27-Mar-2012
Date of Filing 01-Feb-2007
Name of Patentee CHIESI FARMACEUTICI S.P.A.
Applicant Address VIA PALERMO, 26/A, I-43100 PARMA
Inventors:
# Inventor's Name Inventor's Address
1 PIGHI ROBERTO VIA PALERMO, 26/A, I-43100 PARMA
2 FJORDGAARD ANDERSEN SOREN VIA PALERMO, 26/A, I-43100 PARMA
PCT International Classification Number A61K47/48
PCT International Application Number PCT/EP2005/008105
PCT International Filing date 2005-07-26
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 04018261.0 2004-08-02 EUROPEAN UNION