FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
"AN IMPROVED INJECTABLE FORMULATION OF
DICLOFENAC"
We, BA Research India Limited, of BA Research House, Opposite "Pushparaj Towers", Nr. Judges Bunglows, Bodakdev, Ahmedabad-380054, Gujarat, India.
The following specification particularly describes the nature of the invention and the manner in which it is performed:

Field of the Invention
The present invention is directed to an injectable formulation of nanoparticulate diclofenac that produces minimal or no intramuscular pain or burning sensation upon administration, methods of making such a formulation, and methods of using such a formulation. Background of the Invention
Diclofenac is used, most commonly, as the Sodium or Potassium salt for relief from pain and inflammation such as Musculoskeletal and joint disorders including rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis. It is also useful in peri-articular disorders such as renal colic, acute gout, dysmenorrhea following surgical procedures. It has also been used in some countries for the management of fever.
British National Formulary recommends intramuscular injection into the gluteal muscle. Likewise, Martindale, the Extrapharmacopoea recommends intragluteal injections. The other route of administration, recommended is by IV infusion. A typical parenteral administration is prepared by suspending or dissolving Sodium / Potassium salt of diclofenac in a non-toxic aqueous or oleaginous medium liquid vehicle. Diclofenac injections have to be administered deep intramuscularly and are generally administered intragluteally as the injection causes substantial pain at the site of injection and its administration in the deltoid (upper arm) region is generally avoided. Pain at the site of injection is due to relatively large volume of the injection (3ml) and the fact that the injection solution contains relatively high volumes of propylene glycol, which is a known irritant upon parenteral administration. As mentioned in Applied Nursing Research, -Vol. 16, No. 2, August, 2002 empirical data from published research reports, recommendations of established advisory panels and generally accepted scientific principals conclude that only small volumes of medication (2ml or less) should be given in the deltoid site. In fact, according to Nursing, Jan 1997, page 62-63, recommends the use of deltoid muscle only for volumes of 1ml or less.
On the other hand intramuscular injection volumes above 2 ml and up to 5 ml must be administered into the gluteal muscle (Applied Nursing Research, Vol. 16, No. 2, August, 2002). This is because; the gluteal muscle is larger as compared to the deltoid muscle and hence can accommodate the relatively larger injected volume (3-5ml) On the other hand if this relatively larger volume is injected into the deltoid muscle, which has relatively lesser muscle mass, the injected solution will cause excessive stretching of the muscle fiber, thereby damaging the local muscle tissue and hence cause pain and discomfort to the patient.(Svendsen and Blom, Arch, Toxicol, Suppl. 7,1984)

Further, injectable diclofenac preparations contain relatively high amounts (18- 40%) of propylene glycol, which is a known irritant. The Extra Pharmacopoeia 28th edition, Hand book of excipients, further reports that aqueous solution of 2% propylene glycol iso-osmotic with serum causes 100% haemolysis of erythrocytes in 45 min. (Martindale, the Extrapharmacopoea 28th Edition)
Diclofenac is a more potent pain reliever than aspirin, especially for menstrual cramps, toothaches, minor arthritis, and injuries accompanied by inflammation, such as tendinitis. The diclofenac sodium salt is specifically indicated in the treatment of various types of acute and very high intensity pain because it induces a rapid and sustained remission. In addition, it is possible to obtain a good analgesic effect with few administrations, due to diclofenac's particular pharmacokinetics.
Oral administration of diclofenac frequently results in gastrointestinal irritation. All NSAIDs produce gastrointestinal symptoms to some degree upon oral administration. Such symptoms most commonly are constipation, gastric bums, diarrhea, stomatitis, dyspepsia, nausea, vomiting, upper abdominal pain, and heartburn. Oral administration may also lead to an ufcer or bleeding from the stomach or duodenum. Gastrointestinal irritation resulting from oral administration of an NSAID can be significant. Numerous literature articles detail the severity of gastric irritation caused by NSAID compositions. For example, one report states that between 10, 000 and 20, 000 people in Canada each year are hospitalized with major gastro-intestinal bleeding caused by oral ingestion of NSAIDs, with effects resulting in death for at least 1, 000 of these patients. See Marketplace, October 24, 1996. Yet another reference states that gastrointestinal complications of NSAID use may be responsible for over 10, 000 deaths each year. See American Family Physician, March 1997.
Injectable formulations of diclofenac are preferable over oral administration forms for several reasons. First, such formulations can lessen or eliminate side effects of gastrointestinal irritation. Second, intravenous (IV) or intramuscular (IM) administration of a drug results in a significantly shorter response time as compared to oral administration. Moreover, injectable formulations of pain medication are also preferable for post-operative health care, where oral administration may not be feasible. Injectable formulations of diclofenac are particularly preferred, as diclofenac is not addictive, in contrast to other injectable formulations of drugs, such as morphine and ketorolac (Toradol). However, injectable diclofenac formulations are difficult to formulate due to the low solubility of diclofenac. Moreover, current injectable formulations of diclofenac are undesirable because they produce intense pain and/or a burning sensation upon administration.

Formulators have attempted to eliminate propylene glycol from the formulation in order to minimize pain at the site of the injection. It must be however be appreciated that the total volume of the injection solution plays a very significant role in addition to the amount of propylene glycol in the cause of pain at the site of the injection. As mentioned above, the volume of the injected solution causes stretching of the muscle fiber, and the higher the volume, more is the damage to the local muscle tissue and hence pain and discomfort at the site of injection.
US Patent No.3558690 discloses injectable preparations comprising water soluble salts of substituted phenyl acetic acid derivatives (diclofenac being one such compound) in concentrations of 0.5 to 5 %
Conventional diclofenac injections marketed as single dose ampoules, contain 75mg diclofenac sodium in 3 ml aqueous solution (2.5%). Multi dose vials (30 ml) contain 750 mg in 30 ml solution (10 doses) are also being marketed.
WO 9603121 Al describes a antiphlogistic, analgesic, antipyretic parenteral preparation comprising diclofenac, its salt, or both, a surfactant, co-surfactant, water, at pH of 3-10 and optionally comprising an oily component, that can exhibit sustained therapeutic levels of diclofenac in plasma and which does not cause pain at site of injection. US Patent 5,554,650 discloses an antiphlogistic, analgesic, antipyretic parenteral preparation that can exhibit sustained therapeutic levels of diclofenac in plasma comprising diclofenac, its salt, or both, a surfactant, co-surfactant, water, adjusted to pH of 3-10 and optionally comprising an oily component. Some preparations claim not to cause pain at site of injection since they exclude propylene glycol and instead use a surfactant and co-surfactant or oil with surfactant and co surfactant to dissolve the diclofenac.
European Patent Application number 0658347 A3 describes a method of preparing an injectable pharmaceutical or veterinary composition, which comprises either diclofenac or a salt thereof, and 2 hydroxypropyl betacyclodextrin, or an inclusion complex of diclofenac or a salt thereof and 2 hydorxypropyle betacyclodextrin. Propylene glycol is excluded and solubilisation effected with the help of 2 hydroxypropyl betacyclodextrin Such pain is counter-productive, particularly as the patient to be treated is generally already suffering from intense pain. Thus, the pain upon administration interferes with patient treatment, and has led to the use of alternative, but less desirable, injectable pain medications. There is currently a need for a safe and effective injectable formulation of diclofenac that produces minimal or no pain or burning sensation upon administration. In addition, there is a need in the art for methods of making and methods of using such diclofenac formulations. The present invention satisfies these needs.

Summary of the Invention
The present invention is directed to the surprising and unexpected discovery of a new injectable formulation of diclofenac that produces minimal or no pain or burning sensation upon administration. The injectable formulation comprises nanoparticulate diclofenac having a povidone polymer adsorbed on the surface thereof in an amount sufficient to maintain an effective average particle size of less than about 600 nm. Preferably, the effective average particle size of the nanoparticulate diclofenac is less than about 450 nm, more preferably less than about 300 nm, even more preferably less than about 250 nm, and most preferably less than about 100 nm. Nanoparticulate compositions were first described in U. S. Patent No. 5, 145, 684 ("the '684 patent"), which is specifically incorporated herein by reference. The invention provides for compositions comprising high diclofenac concentrations in low injection volumes, with rapid drug dissolution upon administration. In another aspect of the invention there is provided a method of preparing injectable nanoparticulate diclofenac formulations. The method comprises: (1) dispersing diclofenac in a liquid dispersion medium comprising a povidone polymer with a molecular weight of less than about 40, 000 daltons; and (2) mechanically reducing the particle size of the diclofenac to an effective average particle size of less than about 600 nm. Preferably, the pH of the liquid dispersion medium is maintained within the range of from about 3 to about 8 during the size reduction process.
Yet, another aspect of the present invention provides a method of treating a mammal requiring anti-inflammatory, analgesic, or antipyretic treatment comprising administering to the mammal the above-described injectable nanoparticulate diclofenac formulation. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Other objects, advantages, and novel features will be readily apparent to those skilled in the art from the following detailed description of the invention. Detailed Description of the Invention
The present invention is directed to the surprising and unexpected discovery of a new injectable formulation of diclofenac that produces minimal or no pain or burning sensation upon administration. The injectable composition comprises nanoparticulate diclofenac having a povidone polymer with a molecular weight of less than about 40, 000 daltons adsorbed on the surface thereof in an amount sufficient to maintain a.n effective average particle size of less than about 600 nm. Preferably, the effective average particle size of the nanoparticulate diclofenac is less than about 450 nm, more preferably less than about 300 nm, even more preferably less than about 250 nm, and most preferably less than about 100 nm.

Diclofenac has a pKa of 4. 4. Below its pKa of 4. 4, the solubility of diclofenac is about 20 micrograms/ml. However, above pKa of 4. 4, the solubility of diclofenac is about 3 mg/ml. It is preferred that the nanoparticulate diclofenac/povidone polymer pharmaceutical formulation of the invention has a pH of between about 6 to about 7.
In human therapy, it is important to provide a diclofenac dosage form that delivers the required therapeutic amount of the drug in vivo, and that renders the drug bioavailable in a rapid and constant manner. The injectable nanoparticulate diclofenac formulations of the present invention satisfy these needs. Povidone Polvmers
Povidone polymers, also known as polyvidon(e), povidonum, PVP, and polyvinylpyrrolidone, are sold under the trade names Kollidone (BASF Corp. ) and Plasdonee (ISP Technologies, Inc.). They are polydisperse macromolecular molecules, with a chemical name of l-ethenyl-2-pyrrolidinone polymers and 1-vinyl2-pyrrolidinone polymers. Povidone polymers are produced commercially as a series of products having mean molecular weights ranging from about 10, 000 to about 700, 000 daltons. To be useful as a surface modifier for a drug compound to be administered to a mammal, the povidone polymer must have a molecular weight of less than about 40, 000 daltons, as a molecular weight of greater than 40, 000 daltons would have difficulty clearing the body. Povidone polymers are prepared by, for example, Reppe's process, comprising : (I) obtaining 1, 4-butanediol from acetylene and formaldehyde by the Reppe butadiene synthesis;
(2) dehydrogenating the I, 4-butanediol over copper at 200 to form y-butyrolactone ; and
(3) reacting y-butyrolactone with ammonia to yield pyrrolidone. Subsequent treatment
with acetylene gives the vinyl pyrrolidone monomer. Polymerization is carried out by heating
in the presence of H20 and NH3. See TheMeroklndex, 10th Edition, pp. 7581 (Merck &
Co.Rahway, NJ, 1983).
The manufacturing process for povidone polymers produces polymers containing molecules of unequal chain length, and thus different molecular weights.
The molecular weights of the molecules vary about a mean or average for each particular commercially available grade. Because it is difficult to determine the polymer's molecular weight directly, the most widely used method of classifying various molecular weight grades is by K-values, based on viscosity measurements.
The K-values of various grades of povidone polymers represent a function of the average molecular weight, and are derived from viscosity measurements and calculated according to Fikentscher's formula.

The weight-average of the molecular weight, Mw, is determined by methods that measure the weights of the individual molecules, such as by light scattering. Table 1 provides molecular weight data for several commercially available povidone polymers, all of which are soluble.

Povidone K-Value Mv(Daltons) ** MwMn(Dattons)** Mn(Dattons)**
PlasdoneC-15 17±1 7000 10,500 3000
PlasdoneC-30 30.5 ±1.5 38000 62500 16500
KolHdonl2PF 11-14 3900 2000-3000 1300
Kollidonl7PF 16-18 9300 7000-11000 2500
Kollidon 25 24-32 25700 28000-34000 6000
*Because the molecular weight is greater than 40, 000 daltons, this povidone polymer is not useful as a surface stabilizer for a drug compound to be administered parenterally (i. e., injected).
**Mv is the viscosity-average molecular weight, Mn is the number-average molecular weight, and Mw is the weight average molecular weight. Mw and Mn were determined by light scattering and ultra-centrifugation, and Mv was determined by viscosity measurements. Based on the data provided in Table 1, exemplary preferred commercially available povidone polymers include, but are not limited to, Plasdone C-1S, Kollidon 12 PF , Kollidon 17 PF , and Kollidon 25 Injectable Nanoparticulate Diclofenac Formulations
The invention provides injectable nanoparticulate diclofenac formulations that can comprise high drug concentrations in low injection volumes, with rapid drug dissolution upon administration. Preferred compositions comprise, based on %

Diclofenac I 5-50%
Povidone polymer 0.1-50%
Preservatives 0.05-0.25%
PH adjusting agent PH about 6 to about 7
Water for Injection q.s.

Exemplary preservatives include methylparaben (about 0. 18% based on % w/w), propylparaben (about 0. 02% based on % wv), phenol (about 0. 5% based on % w/w), and benzyl alcohol (up to 2% v/v). An exemplary pH adjusting agent is sodium hydroxide, and an

exemplary liquid carrier is sterile water for injection.
Other useful preservatives, pH adjusting agents, and liquid carriers are well-known in the art. Methods of Making Injectable Diclofenac Formulations
In another aspect of the invention there is provided a method of preparing the injectable nanoparticulate diclofenac formulations of the invention. The method comprises : (1) dispersing diclofenac in a liquid dispersion medium comprising a povidone polymer with a molecular weight of less than about 40, 000 daltons ; and (2) mechanically reducing the particle size of the diclofenac to an effective average particle size of less than about 600 nm. Preferably, the effective average particle size of the nanoparticulate diclofenac is less than about 450 nm, more preferably less than about 300 nm, even more preferably less than about 250 nm, and most preferably less than about 100 nm. The pH of the liquid dispersion medium is preferably maintained within the range of from about 5. 0 to about 7. 5 during the size reduction process. Preferably, the dispersion medium used for the size reduction process is aqueous.
Effective methods of providing mechanical force for particle size reduction of diclofenac include ball milling, media milling, and homogenization, for example, with a Microfluidizere (Microfluidics Corp. ). Ball milling is a low energy milling process that uses milling media, drug, stabilizer, and liquid. The materials are placed in a milling vessel that is rotated at optimal speed such that the media cascades and reduces the drug particle size by impaction. The media used must have a high density as the energy for the particle reduction is provided by gravity and the mass of the attrition media. Media milling is a high energy milling process. Drug, stabilizer, and liquid are placed in a reservoir and recirculated in a chamber containing media and a rotating shaft/impeller. The rotating shaft agitates the media which subjects the drug to impaction and sheer forces, thereby reducing the drug particle size.
Homogenization is a technique that does not use milling media. Drug, stabilizer, and liquid (or drug and liquid with the stabilizer added after particle size reduction) constitute a process stream propelled into a process zone, which in the Microfluidizero is called the Interaction Chamber. The product to be treated is inducted into the pump, and then forced out. The priming valve of the Microfluidizero purges air out of the pump. Once the pump is filled with product, the priming valve is closed and the product is forced through the interaction chamber. The geometry of the interaction chamber produces powerful forces of sheer, impact, and cavitation which are responsible for particle size reduction. Specifically, inside the interaction chamber, the pressurized product is split into two streams and accelerated to extremely high velocities. The formed jets are then directed toward each

other and collide in the interaction zone. The resulting product has very fine and uniform particle or droplet size. The Microfluidizer also provides a heat exchanger to allow cooling of the product. U. S, Patent No. 5, 510, 118, which is specifically incorporated by reference, refers to a process using a Microfluidizers resulting in sub 400 nm particles.
Using a particle size reduction method, the particle size of diclofenac is reduced to an effective average particle size of less than about 600 nm. Preferably, the effective average particle size of the nanoparticulate diclofenac is less than about 450 nm, more preferably less than about 300 nm, even more preferably less than about 250 nm, and most preferably less than about 100 nm. The diclofenac particles can be reduced in size in the presence of a povidone polymer, or the povidone polymer can be added to the diclofenac dispersion following particle size reduction.
Diclofenac can be added to a liquid medium in which it is essentially insoluble to form a premix. The concentration of the diclofenac in the liquid medium can vary from about 5 to about 60%, and preferably is from about 15 to about 50% (w/v), and more preferably about 20 to about 40%. The povidone polymer can be present in the premix or it can be added to the drug dispersion following particle size reduction.
The concentration of the povidone polymer can vary from about 0. I to about 50%, and preferably is from about 0. 5 to about 20%, and more preferably from about 1 to about 10%, by weight.
The premix can be used directly by subjecting it to mechanical means to reduce the average diclofenac particle size in the dispersion to less than about 600 nm. It is preferred that the premix be used directly when a ball mill is used for attrition. Alternatively, diclofenac and the povidone polymer can be dispersed in the liquid medium using suitable agitation, e. g., a Cowles type mixer, until a homogeneous dispersion is observed in which there are no large agglomerates visible to the naked eye. It is preferred that the premix be subjected to such a premilling dispersion step when a recirculating media mill is used for attrition.
The mechanical means applied to reduce the diclofenac particle size conveniently can take the form of a dispersion mill. Suitable dispersion mills include a ball mill, an attritor mill, a vibratory mill, and media mills such as a sand mill and a bead mill. A media mill is preferred due to the relatively shorter milling time required to provide the desired reduction in particle size. For media milling, the apparent viscosity of the premix is preferably from about 100 to about 1000 centipoise, and for ball milling the apparent viscosity of the premix is preferably from about 1 up to about 100 centipoise. Such ranges tend to afford an optimal balance between efficient particle size reduction and media erosion.

The attrition time can vary widely and depends primarily upon the particular mechanical means and processing conditions selected. For ball mills, processing times of up to five days or longer may be required. Alternatively, processing times of less than 1 day (residence times of one minute up to several hours) are possible with the use of a high shear media mill.
The diclofenac particles must be reduced in size at a temperature which does not significantly degrade diclofenac. Processing temperatures of less than about 30 to less than about 40 C are ordinarily preferred. If desired, the processing equipment can be cooled with conventional cooling equipment. Control of the temperature, e. g., by jacketing or immersion of the milling chamber in ice water, is contemplated.
Generally, the method of the invention is conveniently carried out under conditions of ambient temperature and at processing pressures which are safe and effective for the milling process. Ambient processing pressures are typical of ball mills, attritor mills, and vibratory mills. Grinding Media
The grinding media can comprise particles that are preferably substantially spherical in shape, e. g., beads, consisting essentially of polymeric resin.
Alternatively, the grinding media can comprise a core having a coating of a polymeric resin adhered thereon.
In general, suitable polymeric resins are chemically and physically inert, substantially free of metals, solvent, and monomers, and of sufficient hardness and friability to enable them to avoid being chipped or crushed during grinding. Suitable polymeric resins include crosslinked polystyrenes, such as polystyrene crosslinked with divinylbenzene ; styrene copolymers ; polycarbonates ; polyacetals, such as Delrine (E.I. du Pont de Nemours and Co.) ; vinyl chloride polymers and copolymers ; polyurethanes; polyamides; poly(tetrafluoroethylenes), e.g, Teflon(E.I. du Pont deNemours and Co. ), and other fluoropolymers ; high density polyethylenes ; polypropylenes ; cellulose ethers and esters such as cellulose acetate ; polyhydroxymethacrylate ; polyhydroxyethyl acrylate ; and silicone-containing polymers such as polysiloxanes and the like. The polymer can be biodegradable.
Exemplary biodegradable polymers include poly (lactides), poly (glycolide) copolymers of lactides and glycolide, polyanhydrides, poly (hydroxyethyl methacylate), poly (imino carbonates), poly(N-acylhydroxyproline)esters, poly(N- palmitoyl hydroxyproline) esters, ethylene-vinyl acetate copolymers, poly (orthoesters), poly (caprolactones), and poly (phosphazenes). For biodegradable polymers, contamination from the media itself

advantageously can metabolize in vivo into biologically acceptable products that can be eliminated from the body.
The grinding media preferably ranges in size from about 0. 01 to about 3 mm For fine grinding, the grinding media is preferably from about 0. 02 to about 2 mm, and more preferably from about 0. 03 to about 1 mm in size.
The polymeric resin can have a density from about 0. 8 to about 3. 0 g/cm. In a preferred grinding process the particles are made continuously. Such a method comprises continuously introducing diclofenac into a milling chamber, contacting the diclofenac with grinding media while in the chamber to reduce the diclofenac particle size, and continuously removing the nanoparticulate diclofenac from the milling chamber. The grinding media is separated from the milled nanoparticulate diclofenac using conventional separation techniques, in a secondary process such as by simple filtration, sieving through a mesh filter or screen, and the like. Other separation techniques such as centrifugation may also be employed. Particle Size
As used herein, particle size is determined on the basis of the weight average particle size as measured by conventional particle size measuring techniques well known to those skilled in the art. Such techniques include, for example, sedimentation field flow fractionation, photon correlation spectroscopy, light scattering, and disk centrifugation. By"an effective average particle size of less than about 600 nm"it is meant that at least 90% of the particles, by weight, have a particle size of less than about 600 nm when measured by the above-noted techniques. In preferred embodiments, the effective average particle size is less than about 450 nm, and more preferably less than about 400 nm. The diclofenac particles can also have an effective average particle size of less than about 300 nm, less than about 250 nm, and less than about 100 nm. With reference to the effective average particle size, it is preferred that at least 90%, more preferably at least 95%, and most preferably at least 99% of the particles have a particle size less than the effective average particle size. In particularly preferred embodiments essentially all of the particles have a size less than about 600 nm.
While applicants do not wish to be bound by theoretical mechanisms, it is believed that the povidone polymer hinders the flocculation and/or agglomeration of the diclofenac particles by functioning as a mechanical or steric barrier between the particles, minimizing the close, interparticle approach necessary for agglomeration and flocculation. Method of Treatment
Yet, another aspect of the present invention provides a method of treating a mammal, including a human, requiring anti-inflammatory, analgesic, or antipyretic treatment

comprising administering to the mammal the injectable nanoparticulate diclofenac formulation of the invention. Particularly advantageous features of the present invention include that the pharmaceutical formulation of the invention exhibits unexpectedly rapid drug absorption upon administration, and produces minimal or no pain or irritation upon administration. In addition, the injectable formulation of the invention can provide a high diclofenac concentration in a small volume to be injecte. A general protocol for administration comprises a bolus injection of diclofenac, with one continuous fast injection, rather than a slow infusion of the drug. Sterile Product Manufacturing
Development of injectable compositions requires the production of a sterile product. The manufacturing process of the present invention is similar to typical known manufacturing processes for sterile suspensions. A typical sterile suspension manufacturing process flowchart is as follows
(MediaConditioning)
↓
Compounding
↓
ParticleSIzeReduction
↓
VialFilling
|
(Lyophilization) and/or (Terminal Sterilization)
As indicated by the optional steps in parentheses, some of the processing is dependent upon the method of particle size reduction and/or method of sterilization.
For example, media conditioning is not required for a milling method that does not use media. If terminal sterilization is not feasible due to chemical and/or physical instability, aseptic processing can be used.
The following examples are given to illustrate the present invention. It should be understood, however, that the invention is not to be limited to the specific conditions or details described in these examples

Example 1
The purpose of this example was to evaluate the use of different types of surface modifiers for the preparation of an injectable nanoparticulate formulation of diclofenac. The study was conducted by screening eleven surface stabilizers to identify the most suitable stabilizer for parenteral administration of diclofenac. The dispersions were formulated at 40% solids to 2. 4% surface stabilizer.

SurfaceStabilizer Manufacturer Results
Plasdone ISP Technologies, Inc size reduction < 400 nm
C15®(polyvinylpyrrolidone)
Kollidon 17PF® (a BASF Corp size reduction < 400 nm
polyvinylpyrrolidone
polymer)
Povidone K30® (a ISP Technologies, Inc size reduction < 400 nm
polyvinylpyrrolidone
polymer)
Tyloxapol Nycomed, Inc size reduction > 400 nm
Pluronic F68® (a high BASF Corp size reduction > 400 nm
molecular weight
polyoxyalkylene ether)
Pluronic F108® (a high BASF Corp size reduction > 400 nm
molecular weight
polyoxyalkylene ether)
Tween 80® (a ICI Americas size reduction > 400 nm
polyoxyethylene sorbitan
fatty acid ester)
dioctylsulfosuccinate (CAS Ashland Chem. Co., size reduction > 400 nm
No. 577-11-7; aka Docusate Columbus, OH
Sodium)
B20-5000® (a triblock Dow Chemical size reduction > 400 nm
copolymer surface modifier)
B20-5000-sulfonated (a Dow Chemical size reduction > 400 nm
triblock copolymer surface

modifier)
lecithin (CAS No. 8002-43-5) Ashland Chem. Co., Columbus, OH size reduction > 400 nm
Povidone K30® and Pluronic F108® [SP Technologies, Inc. and BASF Corp size reduction > 400 nm
Only the use of the povidone polymers Plasdone C 150, Povidone K30 , and Kollidon 17PF49 resulted in a nanoparticulate diclofenac composition having an effective average particle size of less than about 400 nm. Example 2
The purpose of this example was to determine the rates of absorption for intravenously and intramuscularly administered diclofenac.
The plasma concentration of diclofenac (pg/ml) in rabbits after administration of 15 mg/kg by either the IV or IM routes versus time in hours was determined. The method used for quantification of diclofenac in rabbit plasma was modified from a procedure by Shimek et al., Jouzmal of Pharm. Sci., 15:436-439 (1982).
For IM administration, the mean peak plasma level concentration (C,max) of 45 + 9 ,ug/ml was reached at two hours. The absorption after IM injection was rapid with a mean plasma concentration of 23.5 # 5.1 g/ml at 30 minutes after injection. At twelve hours post injection, plasma concentrations were still measurable at 5. 2 3.4, ug/ml. Pharmacokinetic Analysis: The area-under-curve value (AUC) (i. e., plasma - concentration time curve) calculations for the IM and IV routes were 287.1, ug/ml. hr and 212.0 pg/ml. hr, respectively. Mean clearance was calculated to be 3. 4 ml/min after IM administration and 5.1 ml/min following IV administration. The calculated T"2 (te time period in which the maximum plasma concentration drops by half) following IM administration was 6. 9 hours, and 7. 0 hours following IV administration. Example 3
The purpose of this example was to demonstrate the feasibility of using a Microfluidizer for aseptically producing an injectable formulation of a diclofenac colloidal dispersion.
A Microfluidizer, Model No. M110EH (Microfluidics Corp. ), was successfully used to produce a sterile colloidal dispersion of diclofenac suitable for injection. The diclofenac slurry was heat sterilized prior to microfluidizing.

Example 4
The purpose of this example was to determine the potential local irritation of an injectable nanoparticulate diclofenac formulation when administered intramuscularly to rats. This information correlates to the irritation or pain experienced upon administration of the formulation. Test Formulation
Injectable nanoparticulate diclofenac having a concentration of 489 mg/ml was used, comprising 489 mg/ml diclofenac, 40 mg/ml of ISP PlasdoneTM C 15, 1. 9 mg/ml methylparaben (preservative), and 0. 2 mg/ml propylparaben. Dosages of 49 and 134 mg/kg were administered intramuscularly. The intramuscular route was chosen because it is a possible route of administration to human. The test and control articles were stored at room temperature and protected from light. Test animals
Twenty male Albino rats (Sprague-Dawley CrI : CD@) were used for the study, obtained from Charles River. The animals were laboratory bred and were experimentally naive at the outset of the study. Animals selected for use were as uniform in age and weight as possible, they were approximately 7-8 weeks of age, and their body weights ranged from 210. 7 to 247. 0 gm. Each animal was identified by a unique number via an ear tag. All animals were acclimated to laboratory conditions for approximately 12 days prior to study initiation, and the animals were housed individually in stainless-steel cages
PMI Feeds, Inc., Certified Rodent Chow was available ad libitum via food hoppers. No contaminants are known to be present in the certified diet that would interfere with the results of the study. Tap water was available ad libitum via automatic watering device or water bottle. The water was routinely analyzed for contaminants. No contaminants are known to be present in the water that would interfere with the results of the study.
All animals were kept in one room and with no additional studies or other species housed in the same room. The room was well ventilated ( > 10 air changes per hour) with 100% fresh air (no air recirculation). A 12-hour light/12-hour dark photoperiod was maintained. Room temperature and relative humidity were set to be maintained between 223 C and 40 to 70%, respectively. Administration Protocol and Methods
The twenty test animals were assigned to treatment groups as shown in Table 3 below. Each animal received a single intramuscular injection of the test article and the vehicle in distinct previously shaven sites ofcontralateral legs : thigh muscle of the right and left hind legs, respectively. Prior to the day of dosing (designated Day 1 of the study), all

animals were fasted overnight. Following dosing, animals were returned to their cages and
subsequently provided with hoppers containing food. The animals were evaluated for changes
in clinical signs and body weight and the injection sites were examined for any local reaction.
Ten animals each were sacrificed at approximately 48 and 96 hours after the IM injection and
the injection site areas removed and processed for histopathological examination.
Table 3

Treatment Groups
Group Number of males Treatment Dose
(mg/kg) Dose Vol. (mg/kg) Day of Sacrifice
1 5 Control 0 0.1 3

Nanoaproxen 49 0.1

2 5 Control 0 0.1 5

Nanoaproxen 49 0.1

3 5 Control 0 0.275 3

Nanoaproxen 134 0.275

4 5 Control 0 0.275 5

Nanoaproxen 134 0.275

Antemortem Procedures
Animals were observed once daily prior to dosing. During the study, each animal was observed once each morning and afternoon for changes in general appearance and behavior. In addition, the injection sites were examined daily thereafter for local reactions. The severity of any injection site observation was graded and if possible measured (length, width, and height). Body weights were measured prior to dosing and at sacrifice. 1. Clinical Observations and Mortality
Twice daily individual clinical observations are presented in Table 4. No animals died and no treatment-related clinical signs were seen in animals given 49 mg/kg of nanoparticulate diclofenac by intramuscular injection. At a dose of 134 mg/kg/treatment-related signs such as chromorhinorrhea, pallor, rough coat, and some chromodacryorrhea and brown staining were observed.

Clinical observation
Text Article Animal
No. Clinical observation
Nanoparticulate Diclofenac; 49 mg/kg For 3 day test period 311M 1-3: normal

312M 1-3: normal

313M 1-3: normal

314M 1-2: normal
Day 3: abrasion neck right side; stain red neck right side; scab scapula right

315M 1-3: normal

Nanoparticulate Diclofenac; 49 mg/kg For 5 day test period 321M 1-5: normal

322M 1-5: normal

323M Day 1: normal
Day 2: slight bluish color at injection site 2 Days 3-5: normal

324M Days 1-4: normal
Day 5: dehydrated; scab at injection site on right hind limb

325M 1-5: normal
Nanoparticulate 331M Day 1: normal
Diclofenac; 134 mg/kg Days 2-3: infrequent Stool
Day 3: chromorhinorrhea, pallor
For 3 day test period 332M Day 1: normal
Days 2-3: infrequent stool; chromorhinorrhea; pallor;
rough coat
Day 3: chromodacryorrhea-both; brown-stained
scrotum
333M Day 1: normal
Days 2-3: infrequent Stool
Day 3: chromorhinorrhea; pallor; dehydrated; scab at
right injection site
334M Day 1: normal
Days 2-3: infrequent stool; chromorhinorrhea; wet
coat pelvic region
Day 3: pallor; scabs at both injection sites left and
right hind limbs
335M Day 1: normal
Days 2-3: infrequent stool
Day 3: chromodacryorrhea both; chromorhinorrhea;
dehydrated; pallor; diarrhea; dark stool
Nanoparticulate 341M Day 1: normal
Diclofenac; 134 mg/kg Days 2-4: chromorhinorrhea
For 5 day test period Days 2-5: infrequent stool; pallor
Day 3: brown-stained forefeet
Days 3-5: rough coat
Day 4: prostrate
Day 5: dehydrated; scab at injection sites on right


hand limb
342 Day 1: normal
Days 2-: chromorhinorrhea
Days 2-3: infrequent stool; pallor
Days 3-5: rough coat
Day 4-5: scab head
Day 5: scab at injection sites on right hand limb
343M Day 1: normal
Days 2-5: infrequent stool;
Days 3-5: rough coat, dehydrated
344M Day 1: normal
Days 2-: loose stool chromorhinorrhea
Days 2-3: infrequent stool;
Days 2-4: rough coat
Day 5: scab at injection sites
345M Day 1: normal
Days 2-5: infrequent stool; chromorhinorrhea
pallor
Days 3-5: rough coat, chromorhinorrhea
Day 4-5: brown stained forefeet
Day 5: dehydrated; scab at injection sites on hand
limb
2. Body Weight
Individual and group mean body weights are presented in Table 5. The Day 3 low-dose group (49 mg/kg) was inadvertently not fasted for necropsy and, therefore, showed a much larger weight gain than the fasted low-dose group sacrificed on Day 5. However, animals in the high-dose group (134 mg/kg) sacrificed on Days 3 (also, inadvertently not fasted) or 5 showed an overall average weight loss that was considered to be treatment related.
Table 5
Individual and Group Mean Dermal irritation (Erythema or Eschar) scores

Treatment Animal no. Day 2 Day 3 Day 4 Day 5
Control 311M 0 0

312M 0 0

313 M 0 0

314 M 0 0

315 M 0 0

Comp. BA-019

Mean ±SD 0±0 0±0
Nanoparticulate Diclofenac:
49mg/Kg 311 M 0 0

312M 0 0

313M 0 0

314M 0 0

315M 0 0

Mean ±SD 0±0 0±0
Control 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 0±0
Nanoparticulate
Diclofenac:
49mg/Kg 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 0±0
Control 331M 0 0
332M 0 0
333M 0 0
334M 0 0
335M 0 0
336M 0±0 0±0
Injection Site Evaluation
Individual and group mean dermal irritation (erythema/eschar) and (edema) are presented in Tables 6 and 7, respectively. No erythema/eschar or edema responses were noted
in any of the animals (indicated by "0" in Tables 6 and 7).

Individual and Group Mean Dermal irritation (Erythema or Eschar) scores

Treatment Animal no. Day 2 Day 3 Day 4 Day 5
Control 311M 0 0

312M 0 0

313 M 0 0

314M 0 0

315M 0 0

Mean ±SD 0±0 0±0
Nanoparticuiate
Diclofenac:
49mg/Kg 311M 0 0

312M 0 0

313M 0 0

314M 0 0

315M 0 0

Mean ±SD 0±0 0±0
Control 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 0±0
Nanoparticuiate
Diclofenac:
49mg/Kg 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 o±o
Control 331M 0 0

332M 0 0
333M 0 0
334M 0 0
335M 0 0
Nanoparticulate
Diclofenac:
49mg/Kg 331 M 0 0

332 M 0 0

333 M 0 0

334 M 0 0

335 M 0 0

Mean
±SD o±o 0±0
Control 341M 0 0 0 0

342M 0 0 0 0

343M 0 0 0 0

344M 0 0 0 0

345M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 0±0

Nanoparticulate
Diclofenac:
49mg/Kg 341M 0 0 0 0

342M 0 0 0 0

343M 0 0 0 0

344M 0 0 0 0

345M 0 0 0 0

Mean ±SD o±o 0±0 0±0 0±0
Individual and Group Mean Dermal irritation (Edema) scores

Treatment Animal Day 2 Day 3 Day 4 Day 5

No.
Nanoparticulate
Diclofenac:
49mg/Kg 331M 0 0

332M 0 0

333M 0 0

334M 0 0

335M 0 0

Mean ±SD 0±0 0±0
Control 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 o±o 0±0
Nanoparticulate
Diclofenac:
49mg/Kg 321M 0 0 0 0

322M 0 0 0 0

323M 0 0 0 0

324M 0 0 0 0

325M 0 0 0 0

Mean ±SD 0±0 0±0 0±0 0±0
Control 331M 0 0
332M 0 0
333M 0 0
334M 0 0
Mean ±SD 0±0 0±0
335M 0 0
Nanoparticulate
Diclofenac:
134mg/Kg 331M 0 0

332M 0 0

333M 0 0

334M 0 0

335M 0 0

Mean ±SD 0±0 0±0


Postmortem Procedures
All animals were terminated by C02 asphyxiation and exsanguination. Gross necropsy was limited to examination of the injection sites. No treatment-related effects were observed as all injection sites (muscle) were normal. One animal (#333) had a single red subcutaneous focus above the muscle injection site that probably corresponded to hemorrhage. Injection site scabs noted on the twice daily clinical observations generally corresponded to dried blood. Although no internal gross examination was performed, two high-dose animals (#'s 332 and 333) were observed to have severely distended stomachs filled with fluid and gas when they were terminated by exsanguination. These observed findings were considered to be treatment related. Conclusion
No dermal irritation was observed following single-dose intramuscular administration of injectable nanoparticulate diclofenac at doses of 49 mg/kg and 134 mg/kg, in comparison to the control animals. Similarly, no treatment-related clinical signs were observed at doses of 49 mg/kg. At a dose of 134 mg/kg, the following clinical signs were observed: chromorhinorrhea, pallor, rough coat, some chromodacryorrhea, and brown staining At necropsy, no treatment-related gross findings at the injection sites were observed. Similarly, histopathological examination of the injection sites revealed no treatment-related effects.
It will be apparent to those skilled in the art that various modifications and variations can be made in the compositions, methods, and uses of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim,
1. An injectable pharmaceutical composition comprising: (1) diclofenac particles having an effective average particle size of less than 600 nm; (2) a povidone polymer adsorbed on the surface of the diclofenac particles, wherein the povidone polymer has a molecular weight of 40,000 daltons or less; and (3) a pharmaceutically acceptable carrier.
2. The composition as claimed in claim 1, wherein the effective average particle size of the diclofenac particles is less than 450 nm.
3. The composition as claimed in claims 1 or 2, wherein the effective average particle size of the diclofenac particles is selected from the group consisting of less than 400 nm, less than 300 nm, less than 250 nm, and less than 100 nm.
4. The composition as claimed any in preceding claim, wherein the povidone polymer is present in an amount of 0.1 to 50% (w/w) based on the total weight of the diclofenac and povidone polymer.
5. The composition as claimed in any preceding claim, wherein the diclofenac is present in an amount of 5.0 to 50% (w/w), by weight.
6. The composition as claimed in claim 1 to 5 for use as an anti-inflammatory, analgesic or antipyretic treatment.
7. Use of the composition as claimed in claim 1 to 6 for the preparation of an injectable pharmaceutical composition for anti-inflammatory, analgesic or antipyretic treatment.
8. A method of preparing an injectable pharmaceutical composition that produces minimal or no pain or irritation upon administration, wherein the composition comprises: (1) diclofenac particles having an effective average particle size of less than 600 nm; (2) a povidone polymer adsorbed on the surface of the diclofenac particles, wherein the povidone polymer has a molecular weight of 40,000 daltons or less; and (3) a pharmaceutically acceptable carrier, wherein the method comprises:
(a) dispersing the diclofenac particles in a liquid dispersion medium comprising a povidone polymer; and

(b) mechanically reducing the particle size of the diclofenac to an effective average particle size of less than 600 nm.
9. The method as claimed in claim 8, wherein the effective average particle size of the
diclofenac particles is less than 450 nm.
10. The method as claimed in claims 8 or 9, wherein the effective average particle size of the
diclofenac particles is selected from the group consisting of less than 400 nm, less than 300
nm, less than 250 nm, and less than 100 nm.
11. A method of preparing an injectable pharmaceutical composition comprising: (1)
diclofenac particles having an effective average particle size of less than 600 nm; (2) a
povidone polymer adsorbed on the surface of the diclofenac particles, wherein the povidone
polymer has a molecular weight of 40,000 daltons or less; and (3) a pharmaceutically
acceptable carrier, wherein the method comprises:
(a) dispersing the diclofenac particles in a liquid dispersion;
(b) mechanically reducing the particle size of the diclofenac to an effective average particle size of less than 600 nm; and
(c) adding a povidone polymer to the dispersion of diclofenac particles.

12. The method as claimed in claim 11, wherein the effective average particle size of the diclofenac particles is less than 450 nm.
13. The method as claimed in claims 11 or 12, wherein the effective average particle size of the diclofenac particles is selected from the group consisting of less than 400 nm, less than 300 nm, less than 250 nm, and less than 100 nm.
14. The composition as claimed in claims 1 to 5, wherein the pH of the nanoparticulate composition is between 6 to 7.
15. The composition as claimed in claims 1 to 5 for use as in claims 6, wherein the pH of the nanoparticulate composition is between 6 to 7.
16. The use as claimed in claim 7, wherein the pH of the nanoparticulate composition is between 6 to 7.

17. The method as claimed in claims 8 to 13, wherein the pH of the nanoparticulate composition is between 6 to 7.