WO2008135829A2

WO2008135829A2 - Nanoparticles comprising cox-2 inhibitors and a non-ionizable polymer

Info

Publication number: WO2008135829A2
Application number: PCT/IB2008/001061
Authority: WO
Inventors: Corey Jay Bloom; Marshall David Crew; Warren Kenyon Miller; Michael Mark Morgen; Daniel Tod Smithey
Original assignee: Pfizer Products Inc.
Priority date: 2007-05-03
Filing date: 2008-04-21
Publication date: 2008-11-13
Also published as: WO2008135829A3

Abstract

A pharmaceutical composition comprises nanoparticles comprising a COX-2 inhibitor and a poorly aqueous soluble non-ionizable polymer.

Description

NANOPARTICLES COMPRISING COX-2 INHIBITORS AND A NON-IONIZABLE

POLYMER

BACKGROUND OF THE INVENTION The present invention relates to nanoparticles comprising COX-2 inhibitors and a poorly aqueous soluble non-ionizable polymer.

Inhibitors of cyclooxygenase-2 (COX-2 inhibitors) are nonsteroidal antiinflammatory drugs that exhibit anti-inflammatory, analgesic and antipyretic effects. Selective COX-2 inhibitors, meaning drugs that are able to inhibit COX-2 without significant inhibition of cyclooxygenase-1 (COX-1), have therapeutic and prophylactic uses, and have utility in treatment and prevention of specific COX-2 mediated disorders and of such disorders in general.

However, as a class, COX-2 inhibitors tend to have a low solubility in water, which can limit the bioavailability of the drug. For example, celecoxib has a solubility^' in model fasted duodenal (MFD) solution of about 40 μg/mL, valdecoxib has a solubility in water of about 10 μg/mL, rofecoxib has a solubility in water of about 6 μg/mL, and etoricoxib has a solubility in water of about 77 μg/mL.

It is known that poorly water-soluble drugs may be formulated as nanoparticles. Nanoparticles are of interest for a variety of reasons, such as to improve the bioavailability of poorly water-soluble drugs, to provide targeted drug delivery to specific areas of the body, to provide rapid onset of the drug, to reduce side effects, or to reduce variability in vivo.

A variety of approaches have been taken to formulate drugs as nanoparticles. One approach is to decrease the size of crystalline drug by grinding or milling the drug in the presence of a surface modifier. See, e.g., U.S. Patent No.

5,145,684. Another approach to forming nanoparticles is to precipitate the drug in the presence of a film forming material such as a polymer. See, e.g., U.S. Patent No. 5,118,528.

However, there remain problems with formulating COX-2 inhibitors as a nanoparticle. The nanoparticles must be stabilized so that they do not aggregate into larger particles in aqueous suspensions. Often surface modifiers such as surfactants are used to stabilize the nanoparticles, but such materials can have adverse physiological effects when administered in vivo. In addition, without a surface modifier present, the surface of the nanoparticles is unprotected, leading to a decrease in performance and stability because of particle aggregation and/or coalescence. Additionally, if the COX-2 inhibitor in the nanoparticle is non-crystalline, the COX-2 inhibitor must be stabilized in the nanoparticle so that it does not crystallize in the nanoparticle. Furthermore, the composition must be stabilized so that once the noncrystalline COX-2 inhibitor is released in an aqueous use environment, the COX-2 inhibitor does not crystallize in solution. Finally, when formulated as a dry material, the composition should spontaneously form nanoparticles when the composition is added to an aqueous use environment.

Accordingly, there is still a continuing need to formulate COX-2 inhibitors for enhancing bioavailability and to provide rapid dissolution of the drug, particularly in treatment of acute disorders where early relief from pain or other symptoms is desired.

BRIEF SUMMARY OF THE INVENTION

In a first aspect, a pharmaceutical composition comprises nanoparticles, the nanoparticles comprising (a) a COX-2 inhibitor having a solubility in water of less than 1 mg/mL over the pH range of 6.5 to 7.5 at 25°C, at least 90 wt% of the COX-2 inhibitor in the nanoparticles being non-crystalline; and (b) a poorly aqueous soluble non-ionizable polymer; wherein the nanoparticles have an average size of less than 500 nm, the nanoparticles comprising a solid core wherein the COX-2 inhibitor and the non-ionizable polymer collectively constitute at least 70 wt% of the core. In one embodiment, the nanoparticles further comprise a surface stabilizer.

In another embodiment, the non-ionizable polymer is selected from the group consisting of methylcellulose, ethylcellulose, propylcellulose, butylcellulose, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate, methyl cellulose acetate, methyl cellulose propionate, methyl cellulose butyrate, ethyl cellulose acetate, ethyl cellulose propionate, ethyl cellulose butyrate, low-substituted hydroxypropyl cellulose, hydroxypropyl methylcellulose acetate, hydroxypropyl methylcellulose propionate, hydroxypropyl methylcellulose butyrate, poly(lactide), poly(glycolide), poly(ε-caprolactone), . polyOactide-co-glycolide), poly(lactide-co-ε-caprolactone), poly(ethylene oxide-co-ε- caprolactone), poly(ethylene oxide-co-lactide), and poly(ethylene oxide-co-lactide-co- glycolide), poly(isobutyl)cyanoacrylate, and poly(hexyl)cyanoacrylate.

In another embodiment, the non-ionizable polymer is selected from the group consisting of ethylcellulose and poly(ethylene oxide-co-ε-caprolactone). Nanoparticles comprising COX-2 inhibitors and a poorly aqueous soluble non-ionizable polymer improve the bioavailability of the COX-2 inhibitor when administered to an aqueous use environment. This is surprising because both the COX-2 inhibitor and the polymer by themselves have very poor water solubility. In addition, because the non-ionizable polymer is poorly aqueous soluble at physiological pH, the nanoparticles maintain the COX-2 inhibitor in a noncrystalline form within a solid (or at least undissolved) polymer matrix when the nanoparticles are suspended in an aqueous solution. Thus, the rate of crystallization of the COX-2 inhibitor in the nanoparticle is reduced. It is well known that the non- crystalline form of a drug provides a greater aqueous concentration of drug relative to the crystalline form of the drug when administered to an aqueous use environment. However, it is also well known that when the drug is not stabilized in the non-crystalline form, the drug rapidly converts to the crystalline form in the use environment. See, for example, Hancock and Parks (Pharmaceutical Research, Vol. 17, No. 4, 2000). Thus, the polymer is selected to maintain the stability of the non-crystalline drug in the nanoparticle and while suspended in an aqueous solution, resulting in an enhanced concentration of free drug when the nanoparticle is administered to an aqueous use environment.

The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG 1. is the Powder X Ray Diffraction (PXRD) diffraction pattern of the nanoparticles of Example 17.

FIG 2. is the PXRD diffraction pattern of the nanoparticles of

Example 18.

DETAILED DESCRIPTION OF THE INVENTION The nanoparticles of the present invention comprise a COX-2 inhibitor and a poorly aqueous soluble non-ionizable polymer. The nature of the nanoparticles, exemplary COX-2 inhibitors, suitable polymers, and methods for making nanoparticles are described in detail below. Nanoparticles

The nanoparticles are small particles comprising a COX-2 inhibitor and the non-ionizable polymer. By "nanoparticles" is meant a plurality of small particles in which the average size of the particles in suspension is less than about 500 nm. By "average size" is meant the effective cumulant diameter as measured by dynamic light scattering, using for example, Brookhaven Instruments' 90Plus particle sizing instrument. By "size" is meant the diameter for spherical particles, or the maximum diameter for non-spherical particles. Preferably, the average size of the nanoparticles is less than 400 nm, more preferably less than 300 nm, more preferably less than 200 nm, more preferably less than 150 nm, and most preferably less than 100 nm.

The width of the particle size distribution in suspension is given by the "polydispersity" of the particles, which is defined as the relative variance in the correlation decay rate distribution, as is known by one skilled in the art. See B.J. Fisken, "Revisiting the method of cumulants for the analysis of dynamic light-scattering data," Applied Optics, 40(24), 4087-4091 (2001 ) for a discussion of cumulant diameter and polydispersity. Preferably, the polydispersity of the nanoparticles is less than 0.5. More preferably, the polydispersity of the nanoparticles is less than about 0.3. In one embodiment, the average size of the nanoparticles is less than 500 nm with a polydispersity of 0.5 or less. In another embodiment, the average size of the nanoparticles is less than 300 nm with a polydispersity of 0.5 or less. In still another embodiment, the average size of the nanoparticles is less than 200 nm with a polydispersity of 0.5 or less. In yet another embodiment, the average size of the nanoparticles is less than 200 nm with a polydispersity of 0.3 or less.

At least 90 wt% of the COX-2 inhibitor in the nanoparticles is non- crystalline. The term "crystalline," as used herein, means a particular solid form of a compound that exhibits long-range order in three dimensions. "Non-crystalline" refers to material that does not have long-range three-dimensional order, and is intended to include not only material which has essentially no order, but also material which may have some small degree of order, but the order is in less than three dimensions and/or is only over short distances. Another term for a non-crystalline form of a material is the "amorphous" form of the material. As previously discussed, the non-crystalline.form of a COX-2 inhibitor is preferred as it provides a greater aqueous concentration of drug relative to the crystalline form of the drug in an aqueous use environment. Preferably at least about 95 wt% of the COX-2 inhibitor in the nanoparticle is non-crystalline; in other words, the amount of COX-2 inhibitor in crystalline form does not exceed about 5 wt%. Amounts of crystalline COX-2 inhibitor may be measured by Powder X-Ray Diffraction (PXRD), by Differential Scanning Calorimetry (DSC), by solid state nuclear magnetic resonance (NMR), or by any other known quantitative measurement.

The nanoparticles can exist in a number of different configurations. In one embodiment, the nanoparticles comprise a core, the core comprising the noncrystalline COX-2 inhibitor and ethylcellulose. As used herein, the term "core" refers to the interior portion of the nanoparticle. The nanoparticles also have a "surface portion," meaning the outside or exterior portion of the nanoparticle. Thus, the nanoparticles consist of a core (i.e., the interior portion) and a surface portion. In some embodiments, described herein below, materials may be adsorbed to the surface portion of the nanoparticle. Materials adsorbed to the surface portion of the nanoparticle are considered part of the nanoparticle, but are distinguishable from the core of the nanoparticle. Methods to distinguish materials present in the core versus materials adsorbed to the surface portion of the nanoparticle include (1 ) thermal methods, such as differential scanning calorimetry (DSC); (2) spectroscopic methods, such as X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) with energy dispersive X-ray (EDX) analysis, fourier transform infra red (FTIR) analysis, and raman spectroscopy; (3) chromatographic techniques, such as high performance liquid chromatography (HPLC), and gel-permeation chromatography (GPC); and (4) other techniques known in the art.

In one embodiment, the COX-2 inhibitor and the poorly aqueous soluble non-ionizable polymer constitute at least 70 wt% of the core, more preferably at least 80 wt% of the core, and most preferably at least 90 wt% of the core. In another embodiment, the core consists essentially of the COX-2 inhibitor and the poorly aqueous soluble non-ionizable polymer.

The COX-2 inhibitor present in the core can exist in non-crystalline COX-2 inhibitor domains, as a thermodynamically stable solid solution of noncrystalline COX-2 inhibitor homogeneously distributed throughout the non-ionizable polymer, as a supersaturated solid solution of COX-2 inhibitor homogeneously distributed throughout the non-ionizable polymer, or any combination of these states or those states that lie between them. When the glass-transition temperature (T₉) of COX-2 inhibitor is different from the T₉ of the pure polymer by at least about 20⁰C, the core may exhibit a T₉ that is different than the T₉ of pure non-crystalline COX-2 inhibitor or pure polymer. Preferably, less than 20 wt% of the COX-2 inhibitor is present in non- crystalline COX-2 inhibitor domains, with the remaining COX-2 inhibitor homogeneously distributed throughout the non-ionizable polymer.

In yet another embodiment, the core comprises the COX-2 inhibitor, the poorly aqueous soluble non-ionizable polymer, and an optional surface stabilizer. The core may be (1 ) a homogeneous molecular mixture of the COX-2 inhibitor, non- ionizable polymer, and surface stabilizer, (2) domains of pure COX-2 inhibitor, domains of pure non-ionizable polymer, and domains of pure surface stabilizer distributed throughout the core, or (3) any combination of these states or those states that lie between them. In one embodiment, the COX-2 inhibitor, non-ionizable polymer, and surface stabilizer are homogeneously distributed throughout the core as a supersaturated solid solution. In another embodiment, the surface portion of the nanoparticle has a higher concentration of surface stabilizer relative to the nanoparticle as a whole.

In still another embodiment, the core comprises the COX-2 inhibitor and the poorly aqueous soluble non-ionizable polymer, with the surface stabilizer adsorbed to the surface portion of the nanoparticle.

In yet another embodiment, the core comprises the COX-2 inhibitor, the poorly aqueous soluble non-ionizable polymer, and a portion of the surface stabilizer. The remaining portion of the surface stabilizer is adsorbed to the surface portion of the nanoparticle. In this embodiment, a portion of the surface stabilizer is integral to the core, while the remaining portion of surface stabilizer is adsorbed to the surface portion of the nanoparticle.

The COX-2 inhibitor and the poorly aqueous soluble non-ionizable polymer are collectively present in the core in an amount ranging from about 70 wt% to 100 wt%. Preferably, the COX-2 inhibitor and polymer collectively constitute at least 75 wt%, more preferably at least 80 wt%, even more preferably at least 90 wt%, and most preferably at least 95 wt% of the core..

The COX-2 inhibitor, the poorly aqueous soluble non-ionizable polymer, and the optional surface stabilizer are collectively present in the nanoparticle in an amount ranging from 80 wt% to 100 wt%. Preferably, the COX-2 inhibitor, the poorly aqueous soluble non-ionizable polymer, and the optional surface stabilizer collectively constitute at least 90 wt%, more preferably at least 95 wt% of the nanoparticle. In one embodiment, the nanoparticles consist essentially of the COX-2 inhibitor, the non- ionizable polymer, and the optional surface stabilizer. By "consist essentially of is meant that the nanoparticle contains less than 1 wt% of any other excipients and that any such excipients have no affect on the performance or properties of the nanoparticle.

The amount of COX-2 inhibitor in the nanoparticle may range from 0.1 wt% to 90 wt%. Preferably the amount of COX-2 inhibitor in the nanoparticle ranges from about 1 wt% to about 85 wt%, more preferably from about 5 wt% to about 80 wt%, even more preferably from about 10 wt% to about 75 wt%, and most preferably from about 20 wt% to about 50 wt%.

The amount of poorly aqueous soluble non-ionizable polymer may range from 10 wt% to 99.9 wt%. The physical stability of the COX-2 inhibitor in the nanoparticle tends to improve with increasing amounts of the poorly aqueous soluble non-ionizable polymer. Accordingly, it is preferred that the amount of poorly aqueous soluble non-ionizable polymer in the nanoparticle is at least 15 wt%, more preferably at least 20 wt%, and most preferably at least 25 wt%. However, too much non-ionizable polymer will lead to a low loading of COX-2 inhibitor in the nanoparticle. Thus, it is preferred that the amount of poorly aqueous soluble non-ionizable polymer in the nanoparticle is 75% or less, and most preferably 70 wt% or less.

In one embodiment, the nanoparticles further comprise a surface stabilizer. When a surface stabilizer is present, the amount may range from 0.1 wt% to 50 wt% of the nanoparticle. The surface stabilizer acts to reduce or prevent aggregation or flocculation of the nanoparticles in an aqueous suspension, resulting in nanoparticles with improved stability. Generally, lower concentrations of surface stabilizer are preferred. Thus, preferably the surface stabilizer constitutes about 45 wt%.or less, more preferably about 40 wt% or less, and most preferably about 35 wt% or less the total mass of the nanoparticles. Preferred embodiments of nanoparticles have the following amounts of

COX-2 inhibitor, poorly aqueous soluble non-ionizable polymer, and optional surface stabilizer:

10 to 75 wt%, preferably 20 to 50 wt% COX-2 inhibitor;

20 to 75 wt%, preferably 25 to 70 wt% poorly aqueous soluble non- ionizable polymer; and

0 to 50 wt%, preferably 1 to 40 wt% optional surface stabilizer.

In one embodiment, the nanoparticles comprise at least 30 wt% COX-2 . inhibitor and at least 30 wt% of a poorly aqueous soluble non-ionizable polymer.

In another embodiment, the nanoparticles comprise 35 to 40 wt% COX- 2 inhibitor and 35 to 40 wt% of a poorly aqueous soluble non-ionizable polymer. COX-2 Inhibitors

COX-2 inhibitors are nonsteroidal anti-inflammatory drugs that exhibit anti-inflammatory, analgesic and antipyretic effects. Preferably, the COX-2 inhibitor is a selective COX-2 inhibitor, meaning that the drug is able to inhibit COX-2 without significant inhibition of cyclooxygenase-1 (COX-1 ). Preferably, the COX-2 inhibitor has a potency such that the concentration of drug that inhibits 50% of COX-2 enzyme in an in vitro test (i.e., the IC₅₀ value) is less than about 10 μM, preferably less than 5 μM, more preferably less than 2 μM. In addition, it is also preferable that the COX-2 inhibitor be selective relative to COX-1. Thus, preferably, the ratio of the IC₅₀,cox-2 to IC_δo.cox-i ratio for the compound is less than 0.5, more preferably less than 0.3, and most preferably less than 0.2.

The COX-2 inhibitor is "poorly water soluble," meaning that the compound has a solubility in water (over the pH range of 6.5 to 7.5 at 25 ⁰C) of less than 1 mg/mL The utility of the invention increases as the water solubility of the COX- 2 inhibitor decreases. The COX-2 inhibitor may have an even lower solubility in water, such as less than about 0.5 mg/mL, less than about 0.1 mg/mL, and even less than about 0.01 mg/mL.

In general, it may be said that the COX-2 inhibitor has a dose-to- aqueous solubility ratio greater than about 10 mL, and more typically greater than about 100 mL, where the aqueous solubility (mg/mL) is the minimum value observed in any physiologically relevant aqueous solution (i.e., solutions with pH 1- 8), including USP simulated gastric and intestinal buffers, and dose is in mg. Thus, a dose-to- aqueous solubility ratio may be calculated by dividing the dose (in mg) by the aqueous solubility (in mg/mL).

Each named drug should be understood to include the nonionized form of the drug or pharmaceutically acceptable forms of the drug. By "pharmaceutically acceptable forms" is meant any pharmaceutically acceptable derivative or variation, including stereoisomers, stereoisomer mixtures, enantiomers, solvates, hydrates, isomorphs, polymorphs, pseudomorphs, neutral forms, salt forms and prodrugs.

Specific examples of COX-2 inhibitors include 4-(5-(4-methylphenyl)-3- (trifluoromethyl)-i H-pyrazol-1-yl)benzenesulfonamide (celecoxib); 4-(5-methyl-3- phenylisoxazol-4-yl)benzenesulfonamide (valdecoxib); N-(4-(5-methyl-3- phenylisoxazol-4-yl)phenylsulfonyl)propionamide (paracoxb); sodium (S)-6,8-dichloro- 2-(trifluoromethyl)-2H-chromene-3-carboxylate; sodium (S)-7-tert-butyl-6-chloro-2- (trifluoromethyl)-2H-chromene-3-carboxylate; 2-[(2-chloro-6-fluorophenyl)arπino]-5- methyl benzeneacetic acid (lumiracoxib); 4-(3-(difluoromethyl)-5-(3-fluoro-4- methoxyphenyl)-1 H-pyrazol-1-yl)benzenesulfonamide (deracoxib); 4-(4- (methylsulfonyl)phenyl)-3-phenylfuran-2(5H)-one (rofecoxib); 5-chloro-2-(6- methylpyridin-3-yl)-3-(4-(methylsulfonylf phenyl)pyridine (etoricoxib); 2-(3,4- difluorophenyl)-4-(3-hydroxy-3-methylbutoxy)-5-(4-(methylsulfonyl)phenyl)pyridazin- 3(2H)-one; (Z)-3-((3-chlorophenyl)(4-(methylsulfonyl)phenyl)methylene)-dihydrofuran- 2(3H)-one; N-(2-(cyclohexyloxy)-4-nitrophenyl)methanesulfonamide; 4-Methyl-2-(3,4- dimethylphenyl)-1-(4-sulfamoyl-phenyl)-1 H-pyrrole; 6-((5-(4-chlorobenzoyl)-1 ,4- dimethyl-1 H-pyrrol-2-yl)methyl)pyridazin-3(2H)-one; 4-(4-cyclohexyl-2-methyloxazol-5- yl)-2-fluorobenzenesulfonamide (tilmacoxib); 2-(4-Ethoxyphenyl)-4-methyl-1 -(4- sulfamoylphenyl)-1 H-pyrrole; 4-hydroxy-2-methyl-N-(5-methyl-2-thiazolyl)-2H-1 ,2- benzothiazine-3-carboxamide-1 ,1 -dioxide (meloxicam); 4-(4-chloro-5-(3-fluoro-4- methoxyphenyl)-1 H-pyrazol-i-yl)benzenesulfonamide(cimicoxib), and pharmaceutically acceptable forms thereof; and the compounds disclosed in the following patents and published applications, the disclosures of which are incorporated herein by reference: US 5,466,823, US 5,633,272, US 5,932,598, US 6,034,256, US 6,180,651 , US 5,908,858, US 5,521 ,207, US 5,691 ,374, WO 99/11605, WO 98/03484, and WO 00/24719. Preferably the COX-2 inhibitor is selected from the group consisting of celecoxib; valdecoxib; paracoxb; sodium (S)-6,8-dichloro-2-(trifluoromethyl)-2H- chromene-3-carboxylate; sodium (S)-7-tert-butyl-6-chloro-2-(trifluoromethyl)-2H- chromene-3-carboxylate; and pharmaceutically acceptable forms thereof. In one embodiment, the COX-2 inhibitor is celecoxib or pharmaceutically acceptable forms thereof.

Non-ionizable Polymers

The nanoparticles of the present invention comprise a poorly aqueous soluble non-ionizable polymer. The term "polymer" is used conventionally, meaning a compound that is made of monomers connected together to form a larger molecule. A polymer generally consists of at least about 20 monomers connected together. Thus, the molecular weight of the polymer generally will be about 2000 daltons or more. The polymer should be inert, in the sense that it does not chemically react with the COX-2 inhibitor in an adverse manner, and should be pharmaceutically acceptable. The polymer is a poorly aqueous soluble non-ionizable polymer. By "poorly aqueous soluble" is meant that the polymer has a solubility of less than 0.1 mg/mL when administered alone at a concentration of 0.2 mg/mL to a phosphate buffered saline solution (PBS) at pH 6.5. An appropriate PBS solution is an aqueous solution comprising 20 mM sodium phosphate (Na₂HPO₄), 47 mM potassium phosphate (KH₂PO₄), 87 mM NaCI, and 0.2 mM KCI, adjusted to pH 6.5 with NaOH. A test to determine the aqueous solubility of a non-ionizable polymer may be performed as follows. The non-ionizable polymer is initially present in bulk powder form with average particle sizes of greater than about 1 micron. The non-ionizable polymer alone is administered at a concentration of 0.2 mg/ml to the pH 6.5 PBS and stirred for approximately 1 hour at room temperature. Next, a nylon 0.45 μm filter is weighed, and the non-ionizable polymer solution is filtered. The filter is dried overnight at 40⁰C, and weighed the following morning. The amount of non-ionizable polymer dissolved is calculated from the amount of non-ionizable polymer added to the pH 6.5 PBS minus the amount of non-ionizable polymer remaining on the filter (mg). The non-ionizable polymer is considered to be poorly aqueous soluble if it has a solubility of less than 0.1 mg/mL in this test. Preferably, when administered at a concentration of 0.2 mg/mL to the pH 6.5 PBS, a poorly aqueous soluble non-ionizable polymer has a solubility of less than 0.07 mg/mL, more preferably less than 0.05 mg/mL, and most preferably less than 0.01 mg/mL.

To ease processing, it is preferred that the poorly aqueous soluble non- ionizable polymer be soluble in an organic solvent. Preferably the polymer has a solubility in an organic solvent of at least about 0.1 mg/mL, and preferably at least 1 mg/mL. Preferably the polymer is not crosslinked. The polymer is "non-ionizable," meaning that the polymer possesses substantially no ionizable functional groups. By "substantially no ionizable functional groups" is meant that the number of ionizable groups covalently attached to the polymer is less than about 0.05 milliequivalents per gram of polymer. Preferably, the number is less than about 0.02 milliequivalents per gram of polymer. By "ionizable groups" is meant functional groups that are at least about 10% ionized over at least a portion of the physiologically relevant pH range of 1 to 8. Such groups have pKg values of about 0 to 9.

Poorly aqueous soluble non-ionizable polymers for use with the present invention include substituted cellulosics, and non-cellulosics. By "cellulosic" is meant a cellulose polymer that has been modified by reaction of at least a portion of the hydroxyl groups on the cellulose repeating units with a compound to form an ester or an ether substituent.

In order to be poorly aqueous soluble, the polymer preferably has a sufficient number of hydrophobic groups relative to hydrophilic groups. In a preferred embodiment, the poorly aqueous soluble non-ionizable cellulosic polymer has an ether- or ester-linked alkyl substituent. Suitable alkyl substituents include C₁ to C₄ alkyl groups. Exemplary ether-linked substituents include methyl, ethyl, propyl, and butyl groups. Exemplary ester-linked substituents include acetate, propionate, and butyrate groups. In general, the hydrophobic substituent is present at a degree of substitution of at least 0.03.

Exemplary substituted cellulosics include methylcellulose, ethylcellulose, propylcellulose, butylcellulose, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate, methyl cellulose acetate, methyl cellulose propionate, methyl cellulose butyrate, ethyl cellulose acetate, ethyl cellulose propionate, ethyl cellulose butyrate, low-substituted hydroxypropyl cellulose, hydroxypropyl methylcellulose acetate, hydroxypropyl methylcellulose propionate, and hydroxypropyl methylcellulose butyrate. Preferably the poorly aqueous soluble non-ionizable polymer is selected from the group consisting of ethyl cellulose, cellulose acetate, and cellulose acetate butyrate.

Exemplary non-cellulosics include vinyl polymers and copolymers, such as polyvinyl acetate), polyvinyl acetate-co- vinyl alcohol), and poly(ethylene-co-vinyl acetate); polymethacrylate and polyacrylate polymers and copolymers, such as poly(ethyl acrylate-methyl methacrylate) (2:1 monomer ratio), available as EUDRAGIT® NE; polylactones, such as poly(lactide), poly(glycolide), poly(ε- caprolactone), and copolymers of these, including poly(lactide-co-glycolide), poly(lactide-co-ε-caprolactone), poly(ethylene oxide-co-ε-caprolactone), poly(ethylene oxide-co-lactide), and poly(ethylene oxide-co-lactide-co-glycolide); and poly(alkyl)cyanoacrylates, such as poly(isobutyl)cyanoacrylate, and poly(hexyl)cyanoacrylate.

Thus, in one embodiment, the poorly aqueous soluble non-ionizable polymer is selected from the group consisting of methylcellulose, ethylcellulose, propylcellulose, butylcellulose, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate, methyl cellulose acetate, methyl cellulose propionate, methyl cellulose butyrate, ethyl cellulose acetate, ethyl cellulose propionate, ethyl cellulose butyrate, low-substituted hydroxypropyl cellulose, hydroxypropyl methylcellulose acetate, hydroxypropyl methylcellulose propionate, hydroxypropyl methylcellulose butyrate, poly(lactide), poly(glycolide), poly(ε-caprolactone), poly(lactide-co-glycolide), poly(lactide-co-ε-caprolactone), poly(ethylene oxide-co-ε-caprolactone), poly(ethylene oxide-co-lactide), poly(ethylene oxide-co-lactide-co-glycolide), poly(isobutyl)cyanoacrylate, and poly(hexyl)cyanoacrylate. In another embodiment, the non-ionizable polymer is selected from the group consisting of ethylcellulose and poly(ethylene oxide-co-ε- caprolactone.

Optional Surface Stabilizers

The nanoparticles of the present invention may optionally comprise a surface stabilizer in addition to the COX-2 inhibitor and the non-ionizable polymer. The purpose of the surface stabilizer is to reduce or prevent aggregation or flocculation of the nanoparticles in an aqueous suspension, resulting in nanoparticles with improved stability. In one embodiment, the surface stabilizer is used to stabilize the nanoparticles during the formation process. The stabilizer should be inert, in the sense that it does not chemically react with the COX-2 inhibitor in an adverse manner, and should be pharmaceutically acceptable. In one embodiment, the surface stabilizer is an amphiphilic compound, meaning that it has both hydrophobic and hydrophilic regions. In another embodiment, the surface stabilizer is a surfactant, including anionic, cationic, zwitterionic, and non- ionic surfactants. Mixtures of surface stabilizers may also be used.

Exemplary surface stabilizers include casein, caseinates, polyvinyl pyrrolidone (PVP), polyoxyethylene alkyl ethers, polyoxyethylene stearates, polyoxyethylene castor oil derivatives, poly(ethylene oxide-propylene oxide) (also known as poloxamers), tragacanth, gelatin, polyethylene glycol, bile salts (such as salts of dihydroxy cholic acids, including sodium and potassium salts of cholic acid, glycocholic acid, and taurocholic acid), phospholipids (such as phosphatidyl cholines, including 1 ,2-diacylphosphatidylcholine also referred to as PPC or lecithin), sodium dodecylsulfate (also known as sodium lauryl sulfate), benzalkonium chloride, sorbitan esters, polyoxyethylene alkyl ethers, polyoxyethylene castor oil derivatives, polyoxyethylene sorbitan fatty acid esters (polysorbates), polyoxyethylene stearates, triethanolamine, sodium docusate, sodium stearyl fumarate, sodium cyclamate, and mixtures and pharmaceutically acceptable forms thereof. In a preferred embodiment, the surface stabilizer is selected from the group consisting of casein, caseinates, and pharmaceutically acceptable forms and mixtures thereof.

. Process for Making Nanoparticles The nanoparticles may be formed by any process that results in formation of nanoparticles of the COX-2 inhibitor and a non-ionizable polymer. The COX-2 inhibitor used to form the nanoparticles may be in a crystalline or non-crystalline form; however, at least 90 wt% of the COX-2 inhibitor in the resulting nanoparticles is in non-crystalline form. One process for forming nanoparticles is an emulsification process. In this process, the COX-2 inhibitor and polymer are dissolved in an organic solvent that is immiscible with an aqueous solution in which the COX-2 inhibitor and polymer are poorly soluble, forming an organic solution. The COX-2 inhibitor and polymer should have poor solubility in the aqueous solution. Solvents suitable for forming the organic solution of dissolved COX-2 inhibitor and polymer can be any compound or mixture of compounds in which the COX-2 inhibitor and the polymer are mutually soluble and which is immiscible with the aqueous solution. As used herein, the term "immiscible" means that the organic solvent has a solubility in the aqueous solution of less than about 10 wt%, preferably less than about 5 wt%, and most preferably less than about 3 wt%. Preferably, the organic solvent is also volatile with a boiling point of 150⁰C or less. Exemplary solvents include methylene chloride, trichloroethylene, tetrachloroethane, trichloroethane, dichloroethane, dibromoethane, ethyl acetate, phenol, chloroform, toluene, xylene, ethyl-benzene, methyl-ethyl ketone, methyl- isobutyl ketone, and mixtures thereof. Preferred solvents are methylene chloride, ethyl acetate, benzyl alcohol, and mixtures thereof. The aqueous solution is preferably water.

Once the organic solution is formed, it is then mixed with the aqueous solution and homogenized to form an emulsion of fine droplets of the water immiscible solvent distributed throughout the aqueous phase. The volume ratio of organic solution to aqueous solution used in the process will generally range from 1:100 (organic solution:aqueous solution) to 2:3 (organic solution:aqueous solution). Preferably, the organic solution:aqueous solution volume ratio ranges from 1 :9 to 1 :2 (organic solution:aqueous solution). The emulsion is generally formed by a two-step homogenization procedure. The solution of COX-2 inhibitor, polymer and organic solvent is first mixed with the aqueous solution using a rotor/stator or similar mixer to create a "pre-emulsion". This mixture is then further processed with a high-pressure homogenizer that subjects the droplets to very high shear, creating a uniform emulsion of very small droplets. At least a major portion of the organic solvent is then removed forming a suspension of the nanoparticles in the aqueous solution. Exemplary processes for removing the organic solvent include evaporation, extraction, diafiltration, pervaporation, vapor permeation, distillation, and filtration. Preferably, the organic solvent is removed to a level that is acceptable according to The International Committee on Harmonization (ICH) guidelines. Preferably, the concentration of organic solvent in the nanoparticle suspension is less than the solubility of the organic solvent in the aqueous solution. Even lower concentrations of organic solvent are preferred. Thus, the concentration of organic solvent in the nanoparticle suspension may be less than about 5 wt%, less than about 3 wt%, less than 1 wt%, and even less than 0.1 wt%.

Thus, in one embodiment, a process for forming nanoparticles comprises: (a) dissolving a COX-2 inhibitor having a solubility in water of less than 1 mg/mL over the pH range of 6.5 to 7.5 at 25°C, and a poorly aqueous soluble non- ionizable polymer in an organic solvent to form an organic solution; (b) forming an aqueous solution, the COX-2 inhibitor and the poorly aqueous soluble non-ionizable polymer being poorly soluble in the aqueous solution and the solvent being immiscible with aqueous solution; (c) forming an emulsion comprising the organic solution and the aqueous solution; (d) removing the organic solvent to form a suspension of solid nanoparticles having an average size of less than 500 nm, the nanoparticles comprising a solid core, wherein the COX-2 inhibitor and the non-ionizable polymer, collectively constitute at least 75 wt% of the core. In a preferred embodiment, the process for forming the nanoparticles comprises the additional step (e) adding an optional surface stabilizer to the organic solution of step (a) or the aqueous solution of step (b), prior to step (c). The optional surface stabilizer will aid in formation of the emulsion from which the nanoparticles are formed. Generally, the amount of surface stabilizer added to the organic solution of step (a) or the aqueous solution of step (b) will be at least 0.1 mg/mL of solvent used in the process, but will generally be less than about 100 mg/mL of solvent used in the process. Preferably, the amount of surface stabilizer will range from 1 mg/mL to 50 mg/mL of solvent used in the process.

When forming nanoparticles by the above emulsion process, the volume ratio of organic solution to aqueous solution used in the process will generally range from 1 :100 (organic solutioiτaqueous solution) to 2:3 (organic solution:aqueous solution). Preferably, the organic solution:aqueous solution volume ratio ranges from 1 :9 to 1 :2 (organic solution:aqueous solution).

An alternative process to form the nanoparticles is a precipitation process. In this process, the COX-2 inhibitor and polymer are first dissolved in an organic solvent that is miscible with an aqueous solution in which the COX-2 inhibitor and polymer are poorly soluble to form an organic solution. The organic solution is mixed with the aqueous solution causing the nanoparticles to precipitate. Solvents suitable for forming the organic solution of dissolved COX-2 inhibitor and polymer can be any compound or mixture of compounds in which the COX-2 inhibitor and the polymer are mutually soluble and which is miscible in the aqueous solution. Preferably, the organic solvent is also volatile with a boiling point of 150°C or less. Exemplary solvents include acetone, methanol, ethanol, tetrahydrofuran (THF), and dimethylsulfoxide (DMSO). Mixtures of solvents, such as 50% methanol and 50% acetone, can also be used, so long as the polymer and the COX-2 inhibitor are sufficiently soluble to dissolve the COX-2 inhibitor and polymer. Preferred solvents are methanol, acetone, and mixtures thereof.

The aqueous solution may be any compound or mixture of compounds in which the COX-2 inhibitor and polymer are sufficiently insoluble so as to precipitate to form nanoparticles. The aqueous solution is preferably water.

The organic solution and aqueous solution are combined under conditions that cause solids to precipitate as nanoparticles. The mixing can be by addition of a bolus or stream of organic solution to a stirring container of the aqueous solution. Alternately a stream or jet of organic solution can be mixed with a moving stream of aqueous solution. In either case, the precipitation results in the formation of a suspension of nanoparticles in the aqueous solution.

For the precipitation process, the amount of COX-2 inhibitor and polymer in the organic solution depends on the solubility of each in the solvent and the desired ratios of COX-2 inhibitor to polymer in the resulting nanoparticles. The organic solution may comprise from about 0.1 wt% to about 20 wt% dissolved solids. A dissolved solids content of from about 0.5 wt% to 10 wt% is preferred.

The organic solution:aqueous solution volume ratio should be selected such that there is sufficient aqueous solution in the nanoparticle suspension that the nanoparticles solidify and do not rapidly agglomerate. However, too much aqueous solution will result in a very dilute suspension of nanoparticles, which may require further processing for ultimate use. Generally, the organic solution:aqueous solution volume ratio should be at least 1 :100, but generally should be less than 1 :2 (organic solution:aqueous solution). Preferably, the organic solution:aqueous solution volume ratio ranges from about 1 :20 to about 1 :3. Once the nanoparticle suspension is made, a portion of the organic solvent may be removed from the suspension using methods known in the art. Exemplary processes for removing the organic solvent include evaporation, extraction, diafiltration, pervaporation, vapor permeation, distillation, and filtration. Preferably, the solvent is removed to a level that is acceptable according to ICH guidelines. Thus, the concentration of solvent in the nanoparticle suspension may be less than about

10 wt%, less than about 5 wt%, less than about 3 wt%, less than 1 wt%, and even less than 0.1 wt%.

When an optional surface stabilizer is included in the nanoparticle composition, it may be added to either the organic solution or the aqueous solution for either of the processes described above.

Thus, in one embodiment, a process for forming nanoparticles comprises: (a) forming an organic solution comprising a COX-2 inhibitor having a solubility in water of less than 1 mg/mL over the pH range of 6.5 to 7.5 at 25°C, and a poorly aqueous soluble non-ionizable polymer dissolved in a solvent; (b) forming aqueous solution, wherein the COX-2 inhibitor and the non-ionizable polymer are poorly soluble in the aqueous solution; (c) mixing the organic solution with the aqueous solution to form a first mixture; (d) removing the solvent from the first mixture to form a suspension comprising the nanoparticles and the aqueous solution, wherein (i) the nanoparticles have an average size of less than 500 nm, (ii) at least 90 wt% of the COX-2 inhibitor in the nanoparticles being in a non-crystalline form, and (iii) the nanoparticles comprising a solid core, wherein the COX-2 inhibitor and the non- ionizable polymer, collectively constitute at least 75 wt% of the core.

Both the emulsion process and the precipitation process result in the formation of a suspension of the nanoparticles in the aqueous solution. In some instances it is desirable to concentrate the nanoparticles or to isolate the nanoparticles in solid form by removing some or all of the liquid from the suspension. Exemplary processes for removing at least a portion of the liquid include spray drying, spray coating, spray layering, lyophylization, evaporation, vacuum evaporation, filtration, ultrafiltration, reverse osmosis, and other processes known in the art. A preferred process is spray drying. One or more processes may be combined to remove the liquid from the nanoparticle suspension to yield a solid composition. For example, a portion of the liquids may be removed by filtration to concentrate the nanoparticles, followed by spray-drying to remove most of the remaining liquids, followed by a further drying step such as tray-drying. When isolating the nanoparticles in solid form, it is often desirable to include a matrix material in the suspension of nanoparticles prior to removal of the liquids. The matrix material functions to help slow or prevent agglomeration of the nanoparticles as the liquids are being removed, as well as to help re-suspend the nanoparticles when the solid composition is added to an aqueous solution (e.g., an aqueous environment of use). The matrix material is preferably pharmaceutically acceptable and water soluble. Examples of matrix materials include polyvinyl pyrrolidone (PVP), trehalose, hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC), casein, caseinate, albumin, gelatin, acacia, lactose, mannitol, and other matrix materials know in the art, and pharmaceutically acceptable forms and mixtures thereof. Preferably, the matrix material is selected from the group consisting of casein, caseinate, and pharmaceutically acceptable forms or mixtures thereof.

In one embodiment of the invention, a solid composition comprises (a) a plurality of nanoparticles comprising a COX-2 inhibitor and a poorly aqueous soluble non-ionizable polymer, and (b) a matrix material. As used herein, the term "solid pharmaceutical composition" means that the composition is in a solid form and substantially free of liquids. The nanoparticles are entrapped or encapsulated in the matrix material.

In yet another embodiment, a solid composition comprises (a) a plurality of nanoparticles comprising a COX-2 inhibitor, a poorly aqueous soluble non-ionizable polymer, and casein or a pharmaceutically acceptable form thereof, wherein at least 90 wt% of the COX-2 inhibitor is in a non-crystalline form, and wherein the nanoparticles comprise from 30 to 40 wt% COX-2 inhibitor, from 30 to 40 wt% poorly aqueous soluble non-ionizable polymer, and from 20 to 40 wt% casein or a pharmaceutically acceptable form thereof. In another embodiment, the nanoparticles comprise from 35 to 40 wt% COX-2 inhibitor, from 35 to 40 wt% poorly aqueous soluble non-ionizable polymer, and from 20 to 30 wt% casein or a pharmaceutically acceptable form thereof. In a preferred embodiment, the poorly aqueous soluble non- ionizable polymer is ethylcellulose. Dosage Forms

The nanoparticles may be administered using any known dosage form. The nanoparticles may be formulated for administration via oral, topical, subdermal, intranasal, buccal, intrathecal, ocular, intraaural, intraarticular, subcutaneous spaces, vaginal tract, arterial and venous blood vessels, pulmonary tract or intramuscular tissue of an animal, such as a mammal and particularly a human. Oral dosage forms include: powders or granules; tablets; chewable tablets; capsules; unit dose packets, sometimes referred to in the art as "sachets" or "oral powders for constitution" (OPC); syrups; and suspensions. In one embodiment, the compositions of the present invention are capable of improving the concentration of dissolved COX-2 inhibitor in a use environment relative to a control composition consisting essentially of the COX-2 inhibitor alone without any poorly aqueous soluble non-ionizable polymer. In order to determine concentration enhancement in vitro, the amount of "free" COX-2 inhibitor, or solvated COX-2 inhibitor is measured. By "free" COX-2 inhibitor is meant COX-2 inhibitor which is in the form of dissolved COX-2 inhibitor or present in micelles, but which is not in the nanoparticles or any solid particles larger than 500 nm, such as precipitate. A composition of the invention provides concentration enhancement if, when administered to an aqueous use environment, it provides a free COX-2 inhibitor concentration that is at least 1.25-fold the free COX-2 inhibitor concentration provided by the control composition. Preferably, the free COX-2 inhibitor concentration provided by the compositions of the invention are at least about 1.5-fold, more preferably at least about 2-fold, and most preferably at least about 3-fold that provided by the control composition. Alternatively, the compositions of the present invention, when administered to a human or other animal, provide an area under the concentration of COX-2 inhibitor in the blood plasma or serum versus time curve (AUC) that is at least 1.25-fold that observed in comparison to the control composition. Preferably, the blood AUC is at least about 2-fold, more preferably at least about 3-fold, even more preferably at least about 4-fold, still more preferably at least about 6-fold, yet more preferably at least about 10-fold, and most preferably at least about 20-fold that of the control composition. The determination of AUCs is a well-known procedure and is described, for example, in Welling, "Pharmacokinetics Processes and Mathematics," ACS Monograph 185 (1986). Alternatively, the compositions of the present invention, when administered to a human or other animal, provide a maximum COX-2 inhibitor concentration in the blood plasma or serum (C_max) that is at least 1.25-fold that observed in comparison to the control composition. Preferably, the C_max is at least about 2-fold, more preferably at least about 3-fold, even more preferably at least about 4-fold, still more preferably at least about 6-fold, yet more preferably at least about 10- fold, and most preferably at least about 20-fold that of the control composition. Thus, compositions that meet the in vitro or in vivo performance criteria, or both, are considered to be within the scope of the invention. Without further elaboration, it is believed that one of ordinary skill in the art can, using the foregoing description, utilize the present invention to its fullest extent. Therefore, the following specific embodiments are to be construed as merely illustrative and not restrictive of the scope of the invention. Those of ordinary skill in the art will understand that variations of the conditions and processes of the following examples can be used.

EXAMPLES

Drugs Used in Examples

The following drugs were used in the examples described below. Drug 1 was 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1 H-pyrazol-1-yl] benzenesulfonamide, also known as celecoxib, having the structure:

Drug 1 is a selective COX-2 inhibitor, having an IC₅₀,cox-₂ value of about 1 μM, and an

ratio of about 0.1. Drug 1 has a solubility in MFD solution of about 40 μg/mL, and a CLog P value of 3.75. The T_m of Drug 1 is 158°C, and the T_g of amorphous Drug 1 was determined by DSC analysis to be 54°C.

Drug 2 was 4-(5-methyl-3-phenyl-4-isoxazolyl) benzenesulfonamide, also known as valdecoxib, having the structure:

Drug 2 is a selective COX-2 inhibitor, having an IC₅₀,cox-₂ value of about 1 μM, and an IC₅o-cox-₂/IC5o,cox-i ratio of about 0.05. Drug 2 has a solubility in water of about 10 μg/mL, and a CLog P value of about 3.0. The T₉ of non-crystalline Drug 2 was determined by DSC analysis to be 55°C, while the T_m of crystalline Drug 2 was 170⁰C.

Excipients Used in the Examples

The following poorly aqueous soluble non-ionizable polymers were used in the examples: ethylcellulose (ETHOCEL(S) Viscosity 4, Dow Chemical Co., Midland, Ml), and poly(ethylene oxide-co-ε-caprolactone), designated as pCL-PEG (grade

P3128-EOCL available from Polymer Source Inc., Montreal, Quebec, Canada), having a polycaprolactone molecular weight of 10,000 daltons and a poly(ethylene oxide) molecular weight of 5000 daltons.

The non-ionizable polymers were evaluated using the following procedure to determine their aqueous solubility. First, 0.2 mg/mL of the polymer was added to a PBS solution consisting of 20 mM Na₂HPO₄, 47 mM KH₂PO₄, 87 mM NaCI, and 0.2 mM KCI, adjusted to pH 6.5 with NaOH. The polymer was stirred in the PBS solution for approximately 1 hour at room temperature. Next, the polymer solution was filtered through a nylon 0.45 μm filter that was weighed dry prior to filtration. The filter was dried overnight at 40⁰C, and weighed the following morning. The amount of soluble polymer was calculated from amount of polymer added to form the polymer solution minus the amount of polymer remaining on the filter. The results of these tests are shown in Table 1 and show that all of the polymers tested are poorly aqueous soluble.

Table 1

Sodium caseinate was obtained from several sources: (1) Spectrum Chemicals, Gardena, CA, (2) American Casein Company, Burlington, NJ, and (3) Sigma Chemicals, St Louis, MO.

Sodium β-caseinate was formed from β-casein (obtained from Sigma), using the following procedure. First, 400 mg β-casein was added to 80 ml. deionized water. Next, 5 mL 0.001 N NaOH, and 12 ml_ 0.01 N NaOH, were added to reach a pH of 7.02. The solution was lyophilized to obtain solid sodium β-caseinate.

Example 1 Nanoparticles containing Drug 1 were prepared as follows. First,

120 mg Drug 1 and 360 mg ethylcellulose were dissolved in 7.5 mL methylene chloride to form an organic solution. Next, 120 mg sodium caseinate was added to 30 mL deionized water to form an aqueous solution. The organic solution was then poured into the aqueous solution and emulsified for 3 min using a Kinematica Polytron 3100 rotor/stator (Kinematica AG, Lucerne, Switzerland) at 10,000 rpm (high-shear mixing). The pre-emulsion was further emulsified using a Microfluidizer (Microfluidics [Newton, MA] model M-110S F12Y with ice bath and cooling coil), for 6 minutes (high-pressure homogenization). The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles, with a mass ratio of 20:60:20 Drug 1 :ethylcellulose:sodium caseinate.

Light Scattering Analysis

The particle size of the nanoparticles in the aqueous suspension was determined using dynamic light scattering (DLS) as follows. First, the aqueous suspension was filtered using a 1 μm glass membrane filter (Anotop filter, Whatman), and poured into a cuvette. Light-scattering was measured using a Brookhaven Instruments (Holtsville, NY) BI-200SM particle size analyzer with a BI-9000AT correlator. The sums of exponentials from the autocorrelation functions are analyzed to extract size distributions from the samples, and the size is reported as the cumulant value. The average diameter was found to be 79 nm, with a polydispersity of 0.16. The aqueous suspension was allowed to stand unmixed for 2 days

(ambient conditions) to measure stability. DLS analysis showed that the average cumulant diameter of the nanoparticle suspension after 2 days was 75 nm, with a polydispersity of 0.14. These results demonstrate that the nanoparticle suspension of Example 1 was stable for at least 2 days with no significant particle agglomeration. lsolation of Solid Compositions

A solid composition comprising the nanoparticles and sodium caseinate was prepared using the following process. First, 150 mg sodium caseinate (5 mg/mL) was added to the aqueous suspension of Example 1 , resulting in a suspension with a mass ratio of 16:48:36 Drug 1 :ethylcellulose: sodium caseinate.

To form the solid composition of Example 1 , the aqueous nanoparticle suspension was added to a reservoir and pumped to a two fluid nozzle located in a spray-drying chamber, using an HPLC pump (model 515, Waters Corp., Milford, MA) at a flow rate of about 0.15 g/min. The spray-drying chamber consisted of two sections: a straight-side section (top), and a cone section (bottom). The top of the straight-side section was equipped with a spray-solution inlet. The spray solution was sprayed through the spray-solution inlet using the two-fluid nozzle, into the straight-side section of the spray-drying chamber. The straight-side section had a diameter of 10 cm and a length of 19 cm. The atomizing and drying gas (nitrogen) was introduced to the drying chamber through the gas inlet of the two-fluid nozzle at a flow of about 1.0 SCFM and an inlet temperature of about 120⁰C. The flow rate of drying gas and spray solution were selected such that the atomized spray solution was sufficiently dry by the time it reached the walls of the spray-drying chamber that it did not stick to the walls. The diameter of the cone section at the top was 10 cm, and the distance from the top of the cone section to the bottom was 19 cm. At the bottom of the cone section was a 4.7-cm diameter outlet port, fitted with a 0.8 μm nylon filter (Magna, GE Osmonics, Minnetonka, MN) supported by a metal screen. The spray dried composition was collected on the filter, and evaporated solvent and drying gas were removed from the spray-drying chamber through the outlet port.

Nanoparticle Resuspension

The solid composition of Example 1 was resuspended in deionized water as follows. About 40 mg of the solid composition was added to 2 mL of water, vortexed 10 seconds, and sonicated 5 minutes. DLS analysis is summarized in Table 2, and showed that the average cumulant diameter of the nanoparticle suspension was 83 nm, with a polydispersity of 0.14. This demonstrates that the solid composition of Example 1 resulted in the formation of nanoparticles upon resuspension in water. Table 2

Example 2

For Example 2, nanoparticles containing Drug 1 were prepared as described in Example 1 with the following exceptions. The organic solution consisted of 120 mg Drug 1 and 420 mg ethylcellulose dissolved in 6 ml. methylene chloride. The aqueous solution consisted of 120 mg sodium β-caseinate (made as described above) in 15 mL deionized water. This process resulted in an aqueous suspension of nanoparticles, with a mass ratio of 18:64:18 Drug 1 :ethylcellulose:sodium β-caseinate. DLS analysis showed that the average cumulant diameter of the nanoparticles in suspension was 104 nm, with a polydispersity of 0.19.

Isolation of Solid Composition

The nanoparticle suspension of Example 2 was spray-dried as described in Example 1 to form a solid composition of Example 2. Nanoparticle Resuspension

The solid composition of Example 2 was resuspended by adding a 37.7 mg sample to 4 mL deionized water containing 5 wt% dextrose. DLS analysis showed that the average cumulant diameter of the nanoparticle suspension was ^" 145 nm, with a polydispersity of 0.24. This demonstrates that resuspension of the solid composition of Example 2 resulted in the formation of nanoparticles.

Examples 3 and 4

The nanoparticles of Examples 3 and 4 were made containing Drug 1 , ethylcellulose, and two concentrations of sodium caseinate. For the nanoparticles of Example 3, 120 mg Drug 1 and 360 mg ethylcellulose were dissolved in 7.5 mL methylene chloride to form an organic solution, and 120 mg sodium caseinate was added to 30 mL deionized water to form an aqueous solution. For the nanoparticles of Example 4, 120 mg Drug 1 and 330 mg ethylcellulose were dissolved in 7.5 mL methylene chloride to form an organic solution, and 150 mg sodium caseinate was added to 30 mL deionized water to form an aqueous solution. The mixtures were emulsified as described in Example 1. The methylene chloride was removed using a rotary evaporator, to obtain the aqueous suspensions of nanoparticles of Examples 3 and 4. The nanoparticles of Example 3 had a mass ratio of 20:60:20 Drug 1:ethylcellulose: sodium caseinate, and the nanoparticles of Example 4 had a mass ratio of 20:55:25 Drug 1 :ethylcellulose: sodium caseinate. DLS analysis showed that the average cumulant diameter of the nanoparticles of Example 3 was 85 nm, with a polydispersity of 0.10. The average cumulant diameter of the nanoparticles of Example 4 was also 85 nm, with a polydispersity of 0.10.

The aqueous suspensions were allowed to stand unmixed for 24 hours (ambient conditions) to measure stability. DLS analysis showed that the average cumulant diameter of the nanoparticles of Example 3 after 24 hours was 86 nm, with a polydispersity of 0.10. The average cumulant diameter of the nanoparticles of Example 4 after 24 hours was 85 nm, with a polydispersity of 0.10. These results demonstrate that the nanoparticle suspensions of Examples 3 and 4 are stable for at least 24 hours with no measurable particle agglomeration.

Isolation of Solid Compositions The nanoparticles of Examples 3 and 4 were spray-dried as described in

Example 1.

Nanoparticle Resuspension Stability

The solid compositions of Examples 3 and 4 were resuspended by adding a 38 mg sample to 2 mL deionized water. The so-formed suspensions were allowed to stand unmixed for 24 hours (ambient conditions) to measure stability. DLS analysis (see Table 3) showed that the average cumulant diameter of the nanoparticles of Example 3 was 96 nm, with a polydispersity of 0.21. The average cumulant diameter of the nanoparticles of Example 4 was 96 nm, with a polydispersity of 0.11. These results demonstrate that a small particle size can be maintained after isolation of the solid composition, and that the resuspended nanoparticles are stable for at least 24 hours with no measurable particle agglomeration.

Table 3

Example 5

For Example 5, nanoparticles containing Drug 1 were prepared as follows. First, 120 mg Drug 1 and 330 mg ethylcellulose were dissolved in 6 mL methylene chloride to form an organic solution. Next, 150 mg sodium β-caseinate was added to 20 ml. deionized water to form an aqueous solution. The organic solution was then poured into the aqueous solution and emulsified as described in Example 1. The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles, with a mass ratio of 20:55:25 Drug 1 :ethylcellulose:sodium β-caseinate. DLS analysis showed that the average cumulant diameter of the nanoparticles in suspension was 96 nm, with a polydispersity of 0.19.

Isolation of Solid Compositions The nanoparticle suspension of Example 5 was spray-dried as described in Example 1 , resulting in the formation of a solid composition of the invention.

Nanoparticle Resuspension

The solid composition of Example 5 was resuspended by adding a 33.1 mg sample to 3 mL deionized water. DLS analysis showed that the average cumulant diameter of the nanoparticle suspension was 133 nm, with a polydispersity of 0.36.

Filter Potency

A filter potency test was used to characterize the resuspended nanoparticles of Example 5. A 50 μL sample of the aqueous nanoparticle suspension of Example 5 was added to 1 mL 80/20 methanol/acetonitrile, and the concentration of drug in solution was analyzed by HPLC. The suspension was then filtered using a 0.2 μm filter and diluted in 80/20 methanol/acetonitrile for HPLC analysis. The results of this analysis showed that 87% of the nanoparticle suspension potency is maintained following filtration by a 0.2 μm filter. This indicates that most of the nanoparticles in suspension remained small and unagglomerated.

Examples 6 - 10

The nanoparticles of Examples 6 - 10 were made containing Drug 1 , ethylcellulose, and sodium caseinate, in varying ratios. The amounts of each ingredient used to make Examples 6 - 10 are shown in Table 4. The nanoparticles were emulsified, and the methylene chloride was removed, as described in Example 1. Results of DLS analysis of the nanoparticle suspensions are also shown in Table 4. Table 4

The aqueous suspensions of Examples 6 - 10 were allowed to stand unmixed at 5°C to measure stability. The results of DLS analysis are shown in Table 5. These results demonstrate that the nanoparticle suspensions are stable during storage with no significant particle agglomeration.

Table 5

Isolation of Solid Compositions

The nanoparticles of Examples 6 - 10 were spray-dried as described in Example 1 , resulting in the formation of solid compositions of the invention.

Nanoparticle Resuspension

The solid compositions of Examples 6 - 10 were resuspended by adding a sufficient amount of sample to obtain 20 mg/mL solids in deionized water. The results of DLS analysis are shown in Table 6. This demonstrates that the small particle size was maintained after isolation of the nanoparticles in dry powder form, followed by resuspension. Table 6

Filter Potency

A filter potency test was used to characterize the resuspended nanoparticles of Examples 6 - 10. First, a 25 μl_ sample of the aqueous nanoparticle suspension was added to 975 μL 80/20 acetonitrile/methanol, and the concentration of drug in solution was analyzed by HPLC. Next, the suspension was filtered using a 0.45 μm filter and diluted in 80/20 methanql/acetonitrile for HPLC analysis.

Potencies of the nanoparticle suspensions are shown in Table 7. The results in Table 7 show that all of the samples retained high potency, indicating that the nanoparticles in suspension remained small and unagglomerated.

Table 7

Example 11

For Example 11 , nanoparticles containing Drug 1 , ethylcellulose, and sodium taurocholate (NaTC) were prepared as follows. First, 96 mg Drug 1 and 336 mg ethylcellulose were dissolved in 6 mL methylene chloride to form an organic solution. Next, 48 mg sodium taurocholate (NaTC) as a surface stabilizer was added to 24 mL deionized water to form an aqueous solution. The organic solution was then poured into the aqueous solution and emulsified as described above. The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles, with a composition ratio of 20:70:10 Drug 1 :ethylcellulose:NaTC. DLS analysis showed that the average cumulant diameter of the nanoparticles in suspension was 73 nm, with a polydispersity of 0.17. A nanoparticle suspension was formed by adding 120 mg sodium caseinate (5 mg/mL) to the aqueous nanoparticle suspension, resulting in a mass ratio of 16:56:8:20 Drug 1 :ethylcellulose:NaTC:sodium caseinate.

Isolation of Solid Compositions

The nanoparticle suspension of the present invention was spray dried as described in Example 1 , resulting in the formation of a solid composition of the present invention.

Nanoparticle Resuspension

The solid composition of Example 11 was resuspended by adding a 25 mg sample to 1.1 ml. deionized water. DLS analysis showed that the average cumulant diameter of the nanoparticle suspension was 107 nm, with a polydispersity of 0.20. This demonstrates that a small particle size can be obtained after isolation of the solid composition, followed by resuspension.

Filter Potency

A filter potency test was used to characterize the resuspended nanoparticles of Example 11. A 100 μL sample of the aqueous nanoparticle suspension of Example 11 was added to 1 mL 80/20 methanol/acetonitrile, and the concentration of drug in solution was analyzed by HPLC. Next, the suspension was filtered using a 0.2 μm filter and diluted in 80/20 methanol/acetonitrile for HPLC analysis.

Potencies of the nanoparticle suspensions are shown in Table 8. The results in Table 8 show that 94% of the nanoparticle suspension potency is maintained following filtration by a 0.2 μm filter. This indicates that most of the nanoparticles in suspension remain small and unagglomerated.

Table 8

Examples 12 - 14

The nanoparticles of Examples 12, 13, and 14 were made containing Drug 1 , ethylcellulose, and NaTC, and spray-dried with two concentrations of sodium caseinate. For the nanoparticles of Example 12, 240 mg Drug 1 and 300 mg ethylcellulose were dissolved in 7.5 mL methylene chloride to form an organic solution, and 60 mg NaTC was added to 30 ml_ deionized water to form an aqueous solution. For the nanoparticles of Example 13, 8 g Drug 1 and 10 g ethylcellulose were dissolved in 300 mL methylene chloride to form an organic solution, and 2 g NaTC was added to 1 L deionized water to form an aqueous solution. For the nanoparticles of Example 14, 120 mg Drug 1 and 420 mg ethylcellulose were dissolved in 7.5 mL methylene chloride to form an organic solution, and 60 mg NaTC was added to 30 mL deionized water to form an aqueous solution. The solutions were mixed and emulsified as described for Example 1. The methylene chloride was removed using a rotary evaporator, to obtain the aqueous suspensions of nanoparticles of Examples 12, 13, and 14. The nanoparticles of Examples 12 and 13 both had mass ratios of 40:50:10 Drug

1 :ethylcellulose:NaTC, while the nanoparticles of Example 14 had a mass ratio of 20:70:10 Drug 1 :ethylcellulose:NaTC. DLS analysis showed that the average cumulant diameter of the nanoparticles of Example 12 was 69 nm, with a polydispersity of 0.19. The average cumulant diameter of the nanoparticles of Example 13 was 90 nm, with a polydispersity of 0.08. The average cumulant diameter of the nanoparticles of Example 14 was 63 nm, with a polydispersity of 0.08.

Nanoparticle suspensions of the present invention were formed by adding 150 mg sodium caseinate (5 mg/mL) to the aqueous nanoparticle suspension of Example 12, 6.67 mg sodium caseinate to the aqueous nanoparticle suspension of Example 13, and 166.3 mg sodium caseinate to the aqueous suspension of Example 14. The nanoparticle suspension of Example 12 had a mass ratio of 32:40:8:20 Drug 1:ethylcellulose:NaTC: sodium caseinate, the nanoparticle suspension of Example 13 had a mass ratio of 30:37.5:7.5:25 Drug 1 :ethylcellulose:NaTC: sodium caseinate, while the nanoparticle suspension of Example 14 had a mass ratio of 15:52.5:7.5:25 Drug 1 :ethylcellulose:NaTC: sodium caseinate.

Isolation of Solid Compositions

Solid compositions of the invention were prepared by spray drying the nanoparticle suspensions of Examples 12 and 14 using the procedure described in Example 1. The nanoparticle suspension of Example 13 was spray dried as follows. The nanoparticle suspension was pumped to a Niro type XP Portable Spray-Drier with a Liquid-Feed Process Vessel ("PSD-1"), equipped with a pressure nozzle (Schlick 1.0; Dusen Schlick, GmbH of Untersiemau, Germany). The PSD-1 was equipped with 9- inch and 4-inch chamber extensions. The chamber extensions were added to the spray drier to increase the vertical length of the dryer. The added length increased the residence time within the drier, which allowed the product to dry before reaching the angled section of the spray dryer. The nanoparticle suspension was pumped to the spray drier at about 20 g/min at a pressure of 175 psig. Drying gas (nitrogen) was introduced into the chamber at an inlet temperature of 90°C. The evaporated solvent and drying gas exited the spray drier at a temperature of 50⁰C. The resulting solid composition was collected in a cyclone.

Nanoparticle Resuspension

The solid composition of Example 12 was resuspended by adding a 37 mg sample to 2 ml_ deionized water. DLS analysis showed that the average cumulant diameter of the nanoparticles of Example 12 was 88 nm, with a polydispersity of 0.19.

The solid composition of Example 13 was stored in a sealed container at room temperature for 66 days to evaluate storage stability of the nanoparticles in dried form. The effect of storage on nanoparticle agglomeration was determined by resuspending the aged sample and analyzing the particle size in the suspension. The aged solid compositions of Example 13 were resuspended by adding a 25 mg sample to 1 mL deionized water. The average cumulant diameter of the nanoparticles of Example 13 was 110 nm, with a polydispersity of 0.02.

The solid composition of Example 14 was resuspended by adding a 37.7 mg sample to 4 mL deionized water. DLS analysis showed that the average cumulant diameter of the nanoparticle suspension was 107 nm, with a polydispersity of 0.34. These results demonstrate successful resuspension of the nanoparticles, maintaining small particle size, and storage of solid compositions without particle agglomeration.

Control 1

The nanoparticles of Control 1 were made containing Drug 1 and sodium caseinate, without the non-ionizable polymer, using the procedures described in Example 1 with the following exceptions. The organic solution consisted of 150.0 mg Drug 1 dissolved in 6 mL methylene chloride, while the aqueous solution consisted of 454.8 mg sodium caseinate (Spectrum Chemicals) in 20 mL deionized water. The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles. DLS analysis showed that the average cumulant diameter of the nanoparticles in suspension was 97 nm, with a polydispersity of 0.31. However, crystals were visible in the suspension within 10 minutes, and the suspension appeared cloudier over time. Filter Potency

A filter potency test was used to characterize the nanoparticle suspension of Control 1. A 100 μL sample of the aqueous nanoparticle suspension was added to 1 ml. 80/20 acetonitrile/methanol, and the concentration of drug in solution was analyzed by HPLC. Next, the suspension was filtered using a 1 μm glass membrane filter and diluted in 80/20 methanol/acetonitrile for HPLC analysis.

Potencies of the nanoparticle suspensions are shown in Table 9. The results in Table 9 show that 96% of the nanoparticle suspension potency was lost following filtration by a 1 μm filter. This indicates that without the non-ionizable polymer, the nanoparticles are not stable in suspension.

Table 9

Control 2 The nanoparticles of Control 2 were made containing Drug 1 and an aqueous soluble non-ionizable polymer, polyvinyl pyrrolidone ("PVP", Plasdone K - 29/32, available from ISP Technologies, Wayne, NJ), using the procedures described in Example 1 with the following exceptions. The organic solution consisted of 112.1 mg Drug 1 and 113.9 mg PVP dissolved in 5 mL methylene chloride, while the aqueous solution consisted of 20 mL deionized water. The organic solution was poured into the aqueous solution and emulsified as described in Example 1. The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles. DLS analysis showed that the average cumulant ' diameter of the nanoparticles in suspension was 530 nm, with a polydispersity of 0.33. The suspension was analyzed using the light microscope, and the particles appeared to be agglomerating

The aqueous suspension was allowed to stand unmixed for 2 days (ambient conditions) to measure stability. After two days large agglomerates had precipitated to the bottom of the container, showing that the suspension was not stable. This demonstrates that when an aqueous soluble polymer is used to form nanoparticles with Drug 1 , small, suspension-stable nanoparticles are not formed. Example 15

Nanoparticles containing Drug 1 were prepared as follows. First, an organic solution was made containing 8.620 wt% Drug 1 , 8.620 wt% ethylcellulose, and 82.759 wt% ethyl acetate. Next, an aqueous solution was made containing 2.042 wt% sodium caseinate and 97.957 wt% water. The organic solution was then poured into the aqueous solution in a 30-L stainless-steel jacketed tank, and homogenized using a Bematek Systems (Salem, MA) in-line rotor-stator mixer at 3600 rpm for 20 minutes. This mixture was then homogenized to form an emulsion using an Avestin C55 homogenizer (Ottawa, Ontario), with 20 passes at a pressure of 12,500 psi for 280 minutes. Solvent was removed from the emulsion by heating to 40⁰C and drawing a vacuum (with a pressure of 250 mbar) in a mixing tank while stirring for 30 minutes, forming an aqueous suspension of nanoparticles.

Isolation of Solid Compositions

The aqueous suspension was spray-dried using a spray dryer to form a solid composition of the invention. To form the solid powder, the suspension was pumped using a high-pressure pump to a spray drier (a Niro type XP Portable Spray- Dryer with a Liquid-Feed Process Vessel ("PSD-1")), equipped with a Schlick #1.0 pressure nozzle (available from Dusen Schlick GmbH of Untersiemau, Germany). The PSD-1 was equipped with a 9-inch chamber extension to increase the vertical length of the dryer. A high-pressure pump was used to deliver liquid to the nozzle. The suspension was pumped to the spray drier at about 24 g/min at a pressure of 300 psig. Drying gas (e.g., nitrogen) at a flow rate of 1850 g/min was circulated at an inlet temperature of 100⁰C, and the evaporated solvent and drying gas exited the spray drier at a temperature of 50⁰C. The resulting solid composition was collected in a cyclone, with a mass ratio of 37.5:37.5:25 Drug 1 :ethylcellulose: sodium caseinate.

The properties of the solid composition of the invention are shown in Table 10. Table 10

Nanoparticle Resuspension and Filter Potency

The solid composition of Example 15 was resuspended by adding about 20 mg/mL sample to filtered deionized water, and vortexing 30 seconds. DLS analysis showed that the cumulant particle size of the resuspended nanoparticles was 135 nm, with a polydispersity of 0.17.

A filter potency test was used to characterize the resuspended nanoparticles of Example 15. A sample of the resuspension was diluted in methanol, and the concentration of drug in solution was analyzed by HPLC. Next, the resuspension was filtered using 0.45 μm and 0.2 μm filters, and diluted in methanol for HPLC analysis.

Potencies of the nanoparticle resuspensions are shown in Table 11. The results in Table 11 show that 92% passed through a 0.2-μm filter. Additionally, the resuspension was stored at 5°C for 8 hours and filter potency was repeated, and 97% of the particles passed through the filter. Based on these data, most of the nanoparticles in suspension remain small and unagglomerated, indicating that the resuspension has acceptable stability.

Table 11

Example 16

Nanoparticles containing valdecoxib ("Drug 2") were prepared using the procedures outlined in Example 1 with the following exceptions. The organic solution consisted of 30.2 mg Drug 2 and 90.1 mg ethylcellulose dissolved in 9.7 ml_ methylene chloride to form an organic solution. The aqueous solution consisted of 30.3 mg sodium glycocholate ("NaGIy"; available from Sigma, a surface stabilizer) dissolved in 20 mL deionized water. The organic solution was then poured into the aqueous solution and emulsified for 5 min using a Kinematica Polytron 3100 rotor/stator at 10,000 rpm (high-shear mixing). The solution was further emulsified using a Microfluidizer (Microfluidics model M-110L F12Y with Z chamber, ice bath and cooling coil), with an inlet pressure of 65 psi and a final pressure of 12,500 psi, for 5 minutes. The methylene chloride was removed from the emulsion using a rotary evaporator, resulting in an aqueous suspension of nanoparticles. DLS analysis of the aqueous suspension was performed using the procedures described in Example 1 and showed that the cumulant diameter of the nanoparticles was 72 nm, with a polydispersity of 0.16.

Nanoparticle Suspension Stability The nanoparticle suspension of Example 16 was allowed to stand unmixed for 18 days (ambient conditions) to measure stability. DLS analysis showed that the cumulant diameter of the nanoparticles after 18 days was 66 nm, with a polydispersity of 0.18. These results demonstrate that the nanoparticle suspension is stable for at least 18 days with no measurable particle agglomeration.

Example 17

Nanoparticles containing valdecoxib were prepared as described in Example 16 with the following exceptions. The organic solution consisted of 180.1 mg Drug 2 and 540.0 mg ethylcellulose dissolved in 59 mL methylene chloride. The aqueous solution consisted of 11.9 mg NaGIy dissolved in 120 mL deionized water. The organic solution was then poured into the aqueous solution and emulsified as described for Example 1 , except that the high-pressure homogenization time was 2 minutes. Following methylene chloride removal using a rotary evaporator, 2.4 g trehalose and 588.2 mg sodium glycocholate were added to the aqueous nanoparticle suspension, and the suspension was filtered using a 1 μm glass filter.

The nanoparticle suspension was spray-dried using the following procedure. The suspension was pumped to a spray-drier equipped with a pressure nozzle (Schlick 1; Dusen Schlick, GmbH of Untersiemau, Germany), at about 15 g/min. Drying gas (i.e., nitrogen) was delivered into the spray drier at 425 g/min with an inlet temperature of 210⁰C. The water vapor and drying gas exited the spray drier at a temperature of 45°C. The nanoparticles of Example 17 were collected in dried powder form.

Differential Scanning Calorimetry

The dried nanoparticles of Example 17 were analyzed using modulated differential scanning calorimetry (MDSC) initially, and after storage for 8 months at room temperature. The sample pans were crimped and sealed at ambient temperature and humidity, then loaded into a Thermal Analysis Q1000 DSC equipped with an autosampler. The samples were heated by modulating the temperature at ±1.5°C/min, and ramping at 2.5°C/min to about 200⁰C. The glass transition temperature (T₉) of the nanoparticles of Example 17 was found to be 56.3°C initially, and 54.5°C after storage for 8 months. The T₉ of amorphous Drug 2 is 55°C. The DSC results indicate that Drug 2 in the nanoparticles of Example 17 is initially in the amorphous form, and the amorphous form is stable for at least 8 months.

PXRD Evaluation The nanoparticles of Example 17 were examined using powder x-ray diffraction (PXRD) with a Bruker AXS D8 Advance diffractometer to determine the amorphous character of the drug in the nanoparticles. Samples (approximately 100 mg) were packed in Lucite sample cups fitted with Si(511 ) plates as the bottom of the cup to give no background signal. Samples were spun in the φ plane at a rate of 30 rpm to minimize crystal orientation effects. The x-ray source (KCu_α, λ = 1.54 A) was operated at a voltage of 45 kV and a current of 40 mA. Data for each sample were collected over a period of 27 minutes in continuous detector scan mode at a scan speed of 1.8 seconds/step and a step size of 0.04°/step. Diffractograms were collected over the 2Θ range of 4° to 40°. FIG. 1 is the diffraction pattern for the nanoparticles of Example 17, which showed only an amorphous halo, with no sharp peaks characteristic of crystalline drug. These data indicate that the drug in the nanoparticles of Example 17 is in a non crystalline form.

Example 18 Nanoparticles containing Drug 2 were prepared using the procedures of

Example 16 with the following exceptions. The organic solution consisted of 61.3 mg Drug 2 and 182.0 mg ethylcellulose dissolved in 19.6 mL methylene chloride. The aqueous solution consisted of 201.1 mg NaGIy dissolved in 40 mL deionized water. Following methylene chloride removal using a rotary evaporator, the aqueous suspension was analyzed using DLS as described in Example 1. The cumulant diameter was found to be 37 nm, with a polydispersity of 0.16.

Isolation of Solid Composition

A portion of the nanoparticle suspension was spray-dried using the following procedure. First, 0.4 g trehalose was added to a 20 ml. aliquot of the aqueous suspension, and the suspension was filtered using a 1 μm glass filter. The suspension was pumped into a "mini" spray-drying apparatus via a Cole Parmer 74900 series rate-controlling syringe pump at a rate of 0.1 ml/min. The suspension was atomized through a Spraying Systems Co. two-fluid nozzle, Model No. SU 1 A using a heated stream of nitrogen at a flow rate of 1 SCFM. The suspension was sprayed into an 11-cm diameter stainless steel chamber. The heated gas entered the chamber at 'an inlet temperature of 100⁰C and exited at ambient temperature. The resulting material was collected in dried powder form, and stored in a vacuum desiccator.

Measurement of Free Drug The amount of free drug provided by a suspension of the nanoparticles of Example 18 was measured using the following procedure. Following rotary evaporation of the methylene chloride (prior to spray-drying), 200 μl_ of the aqueous nanoparticle suspension of Example 18 was centrifuged using a 100,000-Dalton molecular-weight cutoff centrifuge tube filter, and 50 μl_ of the supernatant was added to 250 μl_ DMSO. The sample was assayed by HPLC. As shown in Table 12, free drug is enhanced 6.6-fold in the suspension containing the Drug 2 nanoparticles of Example 18, relative to crystalline Drug 2.

Table 12

PXRD Evaluation

The spray-dried composition of Example 18 was examined using powder x-ray diffraction (PXRD) as described for Example 17. Figure 2 is a diffraction pattern of the solid composition of Example 18, which shows only an amorphous halo. These data indicate that the drug in the nanoparticles of Example 18 is in a non- crystalline form. Nanoparticle Resuspension

The spray-dried composition of Example 18 was resuspended by adding 44 mg dried composition to 1 mL Hank's balanced buffer (available from HyClone Corp., Logan, Utah), to obtain a resuspension potency of about 2 mgA/mL. The suspension was vortexed 15 seconds, then analyzed using DLS. The average cumulant diameter was found to be 74 nm, with a polydispersity of 0.36. This demonstrates that a small particle size can be maintained after isolation of the nanoparticles in dry powder form, followed by resuspension. ( Nanoparticle Resuspension Stability The resuspended nanoparticles were allowed to stand unmixed for

5 days at ambient conditions. DLS analysis showed that the average cumulant diameter of the resuspended nanoparticles after 5 days was 35 nm, with a polydispersity of 0.19. These results demonstrate that the nanoparticle suspensions are stable for at least 5 days with no measurable particle agglomeration.

Example 19

Nanoparticles containing valdecoxib were prepared using the procedures described in Example 16 with the following exceptions. The organic solution consisted of 180.3 mg Drug 2 and 540.0 mg ethyl cellulose dissolved in 59 mL methylene chloride. The aqueous solution consisted of 600.1 mg NaGIy dissolved in 120 mL deionized water. The organic solution was then poured into the aqueous solution and emulsified as described for Example 16, except that the high-pressure homogenization time was 10 minutes. Following methylene chloride removal using a rotary evaporator, the aqueous suspension analyzed using DLS as described above. The average cumulant diameter was found to be 44 nm, with a polydispersity of 0.14. Next, 2.4 g trehalose was added to the aqueous nanoparticle suspension, and the suspension was filtered using a 1 μm glass filter. The nanoparticle suspension was spray-dried as described in Example 17.

Measurement of Free Drug The amount of free drug provided by a suspension of the nanoparticles of Example 19 was measured as follows. The suspension was formed by adding approximately 30 mg of the spray-dried composition 500 μL dextrose solution in an HPLC vial, and sonicating for 20 minutes. A 250 μL sample of the nanoparticle suspension was centrifuged for 5 minutes at 12,000 rpm using a 100,000-dalton molecular-weight cutoff centrifuge tube filter, and 20 μL of the supernatant was added to 500 μL DMSO. The sample was assayed by HPLC. As shown in Table 13, free drug is enhanced 7.3-fold in the suspension containing the valdecoxib nanoparticles of Example 19 relative to crystalline Drug 2.

Table 13

Nanoparticle Dissolution Test

The dissolution rate of Drug 2 from nanoparticles of Example 19 was measured using the dissolution test as follows. The spray-dried composition of Example 19 was added to Hank's buffer to obtain a valdecoxib concentration of about 1 mgA/mL The suspension was diluted to 10 μg/mL by adding 0.2 mL suspension to 20 mL buffer. The diluted suspension was placed on a shaker table in a 37°C chamber, and aliquots were removed at 2, 5, and 10 minutes. The aliquots were centrifuged for 5 minutes at 12,000 rpm using a 30,000-dalton molecular-weight cutoff centrifuge tube filter, and 100 μL of the supernatant was added to 250 μL acetonitrile. The samples were assayed by HPLC. Crystalline Drug 2 alone was tested for comparison. The dissolution rate (percent of total drug released per minute) is shown in Table 14. The dissolution rate for nanoparticles of the invention was 3.6 times that of crystalline drug alone.

Table 14

The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims

We claim:

1. A pharmaceutical composition comprising nanoparticles, said nanoparticles comprising:

(a) a COX-2 inhibitor having a solubility in water of less than 1 mg/mL over the pH range of 6.5 to 7.5 at 25°C, wherein at least 90 wt% of said COX-

2 inhibitor is non-crystalline; and

(b) a poorly aqueous soluble non-ionizable polymer; wherein said nanoparticles have an average size of less than 500 nm; and said nanoparticles comprise a solid core, wherein said COX-2 inhibitor and said non- ionizable polymer, collectively constitute at least 70 wt% of said core.

2. The composition of claim 1 wherein said COX-2 inhibitor and said non-ionizable polymer collectively constitute at least 90 wt% of said core.

3. The composition of any one of the preceding claims wherein said core consist essentially of said COX-2 inhibitor and said non-ionizable polymer.

4. The composition of any one of the preceding claims wherein said nanoparticles comprise from 5 wt% to 80 wt% said COX-2 inhibitor and from 20 wt% to 95 wt% said non-ionizable polymer.

5. The composition of any one of the preceding claims wherein said average size is less than 300 nm.

6. The composition of claim 5 wherein said average size is less than 100 nm.

7. The composition of any one of the preceding claims wherein said non-ionizable polymer is selected from the group consisting of methylcellulose, ethylcellulose, propylcellulose, butylcellulose, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate, methyl cellulose acetate, methyl cellulose propionate, methyl cellulose butyrate, ethyl cellulose acetate, ethyl cellulose propionate, ethyl cellulose butyrate, low-substituted hydroxypropyl cellulose, hydroxypropyl methylcellulose acetate, hydroxypropyl methylcellulose propionate, hydroxypropyl methylcellulose butyrate, poly(lactide), poly(glycolide), poly(ε-caprolactone), poly(lactide-co-glycolide), poly(lactide-co-ε-caprolactone), poly(ethylene oxide-co-ε-caprolactone), poly(ethylene oxide-co-lactide), poly(ethylene oxide-co-lactide-co-glycolide), poly(isobutyl)cyanoacrylate, and poly(hexyl)cyanoacrylate.

8. The composition of any one of the preceding claims wherein said non-ionizable polymer is selected from the group consisting of ethylcellulose and poly(ethylene oxide- co-ε-caprolactone).

9. The composition of any one of the preceding claims wherein said nanoparticles further comprise a surface stabilizer.

10. The composition of claim 9 wherein said surface stabilizer constitutes from 0.1 to 40 wt% of said nanoparticles.

11. The composition of any one of claims 9-10 wherein said surface stabilizer is selected from the group consisting of casein, caseinates, polyvinyl pyrrolidone, polyoxyethylene alkyl ethers, polyoxyethylene stearates, polyoxyethylene castor oil derivatives, poly(ethylene oxide-propylene oxide), tragacanth, gelatin, polyethylene glycol, sodium and potassium salts of cholic acid, glycocholic acid, and taurocholic acid, phospholipids (such as phosphatidyl cholines, including 1 ,2- diacylphosphatidylcholine also referred to as PPC or lecithin), sodium dodecylsulfate (also known as sodium lauryl sulfate), benzalkonium chloride, sorbitan esters, polyoxyethylene alkyl ethers, polyoxyethylene castor oil derivatives, polyoxyethylene sorbitan fatty acid esters (polysorbates), polyoxyethylene stearates, triethanolamine, sodium docusate, sodium stearyl fumarate, sodium cyclamate, and mixtures and pharmaceutically acceptable forms thereof.

12. The composition of any one of claims 9-11 wherein said surface stabilizer is casein or a pharmaceutically acceptable form thereof.

13. The composition of any one of claims 9-12 wherein said nanoparticles comprise from 10 to 75 wt% said COX-2 inhibitor, from 20 to 75 wt% said poorly aqueous soluble non-ionizable polymer, and from 0.1 to 50 wt% said surface stabilizer.

14. The composition of any one of claims 9-13 wherein said poorly aqueous soluble non-ionizable polymer is ethylcellulose and said surface stabilizer is casein or a pharmaceutically acceptable form thereof.

15. The composition of any one of claims 9-14 wherein said nanoparticles comprise a surface portion and said surface stabilizer is adsorbed to said surface portion of said nanoparticles.

16. The composition of any one of the preceding claims wherein said nanoparticles comprise from 35 to 40 wt% COX-2 inhibitor, from 35 to 40 wt% ethylcellulose, and from 20 to 30 wt% casein or a pharmaceutically acceptable form thereof.

17. The composition of any one of the preceding claims wherein said COX-2 inhibitor is selected from the group consisting of celecoxib; valdecoxib; paracoxb; sodium (SJ-θ.δ-dichloro^-^rifluoromethyO^H-chromene-S-carboxylate; sodium (S)-7- tert-butyl-θ-chloro^-^rifluoromethyO^H-chromene-S-carboxylate; and pharmaceutically acceptable forms thereof.

18. The composition of any one of the preceding claims wherein said COX-2 inhibitor is celecoxib or pharmaceutically acceptable forms thereof.

19. A pharmaceutical composition comprising an aqueous suspension of the nanoparticles of any one of the preceding claims.

20. A pharmaceutical composition comprising the nanoparticles of any one of the preceding claims and a matrix material.

21. A process for forming nanoparticles, comprising:

(a) forming an organic solution comprising a COX-2 inhibitor having a solubility in water of less than 1 mg/mL over the pH range of 6.5 to 7.5 at

25°C, and a poorly aqueous soluble non-ionizable polymer dissolved in a solvent;

(b) forming an aqueous solution, wherein said COX-2 inhibitor and said non-ionizable polymer are poorly soluble in said aqueous solution; (c) mixing said organic solution with said aqueous solution to form a first mixture;

(d) removing said solvent from said first mixture to form a suspension comprising said nanoparticles and aqueous solution, wherein (i) said nanoparticles have an average size of less than 500 nm,

(ii) at least 90 wt% of said COX-2 inhibitor in said nanoparticles is non-crystalline form; and (iii) said nanoparticles comprising a solid core, wherein said COX-2 inhibitor and said non-ionizable polymer, collectively constitute at least 75 wt% of said core.

22. The process of claim 21 comprising the additional step

(e) adding an optional surface stabilizer to said organic solution of step (a) or said aqueous solution of step (b), prior to step (c).

23. The process of any one of claims 21 and 22 comprising the additional step

(f) ' adding a matrix material to said suspension of step (d).

24. The process of claim 23 wherein said matrix material is selected from the group consisting of polyvinylpyrrolidone, trehalose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, casein, caseinate, albumin, gelatin, acacia, lactose, mannitol, and mixtures or pharmaceutically acceptable forms thereof.

25. The process of any one of claims 21-24 comprising the additional step (g) removing liquid from said suspension to form a solid composition.

26. The process of claim 25 wherein said liquid is removed by one or more process selected from the group consisting of spray drying, spray coating, spray layering, lyophylization, evaporation, vacuum evaporation, and filtration.

27. The process of claim 26 wherein said liquid is removed by spray drying.