Insoluble drug delivery

The present invention provides a novel method for producing sub-micron sized particles of water-insoluble compounds (particularly water-insoluble drugs) having biological uses.<u style="single">Background and summary of the invention</u>Almost one-third of US Pharmacopeia drugs are water-insoluble or sparingly soluble in water. Many of the currently available injectable formulations of such drugs are labeled with serious adverse warnings caused by detergents and other drugs used to solubilize the drug. Have been described. Oral formulations of water-insoluble drugs or compounds with biological uses are often of low bioavailability and instability. Moreover, the problem of poor solubility in water delays the development of many new drugs and other biologically useful compounds, or eliminates the potential for development altogether. Two possible approaches to the delivery of insoluble drugs are microparticles-based approaches, including the formation of phospholipid-stabilized aqueous suspensions of submicron-sized particles of the drug (US Pat. No. 5,091,187; No. 5,091,188; And 5,246,707), as well as a mictodroplets approach, which involves forming a phospholipid-stabilized oil-in-water emulsion by dissolving the drug in a suitable biocompatible hydrophobic carrier (US). See patents 4,622,219 and 4,725,442). The pharmacokinetic properties of oral microparticle formulations and injectable microparticle formulations depend on particle size and phospholipid surface modifiers. However, when using certain water-insoluble compounds, there are problems with the particle size reduction methods currently in use. Therefore, the overall object of the present invention is to produce surface modified stabilized suspensions of water-insoluble drugs having an average particle size of 100 nm to about 300 nm and a narrow particle size distribution. The purpose is to develop new methods based on the use of compressed fluids, including supercritical fluid technology. The methods of the invention are stable operating, can be weighed, and are applicable to a wide range of water-insoluble compounds with biological applications.<u style="single">[Simple explanation of drawings]</u>The attached drawings will be described below. FIG. 1 is a schematic view of an apparatus for carrying out the present invention by precipitating a bioactive substance by rapid expansion from a supercritical solution. FIG. 2A is a more detailed view of the preheater assembly of FIG. FIG. 2B is an enlarged perspective view of the expansion nozzle of FIG. FIG. 3 outlines an apparatus for producing submicron-sized particles of the present invention by precipitating a bioactive substance (properly solubilized) in a compressed gas, liquid, or supercritical fluid. It is a figure. FIG. 4 is a graph showing the particle size distribution of the cyclosporin particles obtained in Example 1 by volume weighting when expanded into a phospholipid containing 1% by weight of a stabilizer. FIG. 5 is a graph showing the particle size distribution of the cyclosporin particles obtained in Example 1 by volume weighting when expanded into a phospholipid containing 2% by weight of a stabilizer. FIG. 6 is a graph showing the particle size distribution of the indomethacin particles obtained in Example 3 by volume weighting when directly sprayed into carbon dioxide. FIG. 7 is a graph showing a Gaussian distribution of particle size due to volume weighting of the indomethacin particles obtained in Example 3 when sprayed into a phospholipid containing 2% by weight of a stabilizer. FIG. 8 is a graph showing the particle size distribution of the tetracaine hydrochloride particles obtained in Example 4 by volume weighting when sprayed into a mixture of carbon dioxide and water. FIG. 9 shows the volume-weighted particle size distribution of the tetracaine hydrochloride particles obtained in Example 4 when sprayed into a mixture containing carbon dioxide, water, and an additional 1% by weight of stabilizer. It is a graph. FIG. 10 shows the Gaussian distribution of the particle size of the tetracaine hydrochloride particles obtained in Example 4 by volume weighting when sprayed into a mixture containing carbon dioxide, water, and 2% by weight of a stabilizer. It is a graph.<u style="single">Description of the invention</u>In the present invention, (1) a solution in which a compound is dissolved is prepared by precipitating the compound by rapid expansion (rapid expansion from a supercritical solution); or (2) a solution in which the compound is dissolved is prepared. By precipitating the compound by spraying into a compressed gas, liquid, or supercritical fluid that is compatible with the solution but is antisolvent to the compound; using a compressed fluid. This is a method for producing submicron-sized particles of industrially useful low-solubility or insoluble compounds having biological uses. In this way, precipitation using a non-solvent called a compressed fluid (compressed fluid non-solvent) is achieved. The methods of the invention may optionally incorporate phospholipids dissolved in water or other suitable surface modifiers (eg, surfactants) into the process. The surfactant is selected to be active at the compound-water interface, but when carbon dioxide is used as a supercritical solution, at the carbon dioxide-organic solvent interface or the carbon dioxide-compound interface. Is not selected to be active. A unique feature of the present invention is the combination of rapid expansion or compressed fluid non-solvents from supercritical solutions and the recovery of surface-modified stable submicron particles into the aqueous phase. The industrially useful insoluble or poorly soluble compounds as we describe are biologically useful compounds, imaging agents, pharmaceutically useful compounds, and especially drugs for human and veterinary medicine. including. Water-insoluble compounds are compounds that are less soluble in water (ie, less than 5 mg / ml at a physiological pH of 6.5-7.4), but even if the water solubility is less than 1 mg / ml, and even 0.1 mg. It may be less than / ml. Examples of some preferred water-insoluble drugs are immunosuppressants and immunoactive drugs, antiviral and antifungal drugs, antitumor drugs, analgesics and anti-inflammatory drugs, antibiotics, antiepileptic drugs, anesthetics, hypnosis. Drugs, analgesics, antipsychotics, nerve relaxants, antidepressants, anxiety relievers, anticonvulsants, antagonists, neuroleptics, anticholinergic agents, cholinergic agents, antimuscarinic agents and muscarinic agents , Antiadrenaline agonists, antiarrhythmic drugs, antihypertensive drugs, antitumor drugs, hormones, and nutrients. A detailed description of these and other suitable drugs can be found in "Remington's Pharmaceutical Science, 18th Edition, 1990 (Mack Publishing Co., Philadelphia, PA)". To illustrate the present invention, cyclosporine (a water-insoluble immunosuppressive drug) will be used as a model. This drug was selected because it was not possible to achieve the particle size and particle distribution considered necessary to reach the desired pharmacokinetic performance by using conventional particle size reduction methods. Cyclosporine is a water-insoluble, lipophilic 11-amino acid polypeptide with unique immunosuppressive properties. Its main use is as an immunosuppressive drug in solid organ transplantation. The clinical availability of currently used pharmaceutical dosage forms is severely limited by the insolubility of the drug. That is, the bioavailability of oral dosage forms is low, and there are variations in intra and inter patient absorption between patients themselves and between patients. The phospholipid may be a natural phospholipid or a synthetic phospholipid, such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidyl acid, lysophosphatilipid, egg or soybean phospholipid, or There are combinations of these. Phospholipids may be in salt form or desalted, hydrogenated or partially hydrogenated, or may be natural, semi-synthetic, or synthetic. .. Examples of some other suitable surface modifiers are (a) natural surfactants such as casein, gelatin, tragacant rubber, wax, enteric resins, paraffin, arabic rubber, gelatin, cholesterol esters, and triglycerides; b) Polyoxyethylene fatty alcohol ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, sorbitan ester, glycerol monostearate, polyethylene glycol, cetyl alcohol, cetostearyl alcohol, stearyl alcohol, poloxamers, polaxamines, Nonionic surfactants such as methylcellulose, hydroxycellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, non-crystalline cellulose, polyvinyl alcohol, polyvinylpyrrolidone, and synthetic phospholipids; (c) potassium laurate, triethanolamine stearate, lauryl sulfate Sodium, alkyl polyethylene sulfate, sodium alginate, sodium dioctyl sulfosuccinate, negatively charged phospholipids (phosphatidylglycerol, phosphatidylinosite, phosphatidylserine, phosphatidic acid, and salts thereof), negatively charged glyceryl ester, sodium carboxymethyl cellulose , And anionic surfactants such as carboxymethyl cellulose calcium; (d) cationic surfactants such as quaternary ammonium compounds, benzalkonium chloride, cetyltrimethylammonium bromide, chitosan, and lauryldimethylbenzylammonium chloride; and (e). There are colloidal clays such as bentnite and veegum; A detailed description of these surfactants is "<u style="single">Remington's Pharmaceutical Science,</u> And Theory and Practice of Industrial Pharmacy, Lachman et al., 1986 . Further examples of other suitable surface denaturants include one or a combination of the substances listed below: polaxomers [eg Pluronic^TM) F68, F108, and F127 (these are block copolymers of ethylene oxide and propylene oxide, commercially available from BASF)], poloxamines [eg Tetronic^TM) 908 (T908) (a tetrafunctional block copolymer obtained by sequential addition of ethylene oxide and propylene oxide to ethylenediamine, commercially available from BASF)], Triton^TM) X-200 (alkylaryl polyether sulfonate, commercially available from Roam &amp; Haas), Tween 20, 40, 60, and 80 (these are polyoxyethylene sorbitan fatty acid esters, from ICI Specialty Chemicals). (Commercially available), Carbowax^TM) 3550 and 934 (these are polyethylene glycols, commercially available from Union Carbide), hydroxypropylmethyl cellulose, dimyristyl phosphatidyl sodium salt, sodium dodecyl sulfate, sodium deoxycholate, and cetyltrimethylammonium bromide. The particles obtained by the method of the invention are generally at most 500 nm (usually less than 300 nm) in size, preferably less than 200 nm, preferably less than about 100 nm, and in the range 0.1-100 nm. There are also many. These particles have a narrow distribution in that 99% of them are less than 500 nm (preferably less than 400 nm) and the half width of the peak is about 200 nm (preferably less than 100 nm). The particles can be recovered from the suspension by any conventional means (eg, spray drying, lyophilization, diafiltration, dialysis, or evaporation). The solvent properties of supercritical fluids are strongly influenced by the fluid density near the critical point of the fluid. Rapid expansion from a supercritical solution dissolves the non-volatile solute in the supercritical fluid. Rapid expansion of supercritical fluid causes nucleation and crystallization by reducing the density of the solution to atmospheric conditions. To achieve this, supercritical fluids are typically sprayed with a nozzle of 10-50 microns (inner diameter) in an aspect ratio of 5-100. The fluid approaches the terminal velocity at the tip of the nozzle, resulting in a high level of supersaturation, resulting in faster nucleation and restricted crystal growth. The combination of rapidly spreading physical perturbations and high levels of supersaturation is a hallmark of rapid expansion from supercritical solutions. Under these conditions, very small particles with a narrow particle distribution are formed. The first extensive study of rapid expansion from supercritical solutions was reported by Krukonis (1984) [VJ Krukonis: AIChE Annual Meeting San Francisco (1984) , Supercritical Fluid Engineering Science, Chapter 19, Chapter 19, by JWTom et al. Cited in P.238 (1993)], he formed microparticles with certain sequences of organic, inorganic, and biological substances, such as robastatin, polyhydroxyic acid, and so on. And most of the particle sizes reported for mevinolin) ranged from 5 to 100 microns. Nano β-carotene by expanding ethane into a viscous gelatin solution to suppress particle aggregation due to post-expansion. Particles (300 nm) were formed. Most studies of rapid expansion from supercritical solutions on organic matter use supercritical carbon dioxide. However, for β-carotene, ethane is preferred over carbon dioxide due to certain chemical interactions. In general, carbon dioxide is preferably used alone or in combination with an auxiliary solvent. The addition of a small amount of co-solvent can significantly increase the solubility of certain solutes. When using an auxiliary solvent for rapid expansion from a supercritical solution, care must be taken to prevent the dissolution of particles by the solvent condensing in the nozzle. This is usually achieved by heating the supercritical fluid to a temperature at which no condensate (mist) is observed at the nozzle tip before expansion. Similar problems occur when carbon dioxide is used alone. During adiabatic expansion (cooling), carbon dioxide becomes two phases if sufficient heat is not supplied to the nozzle to maintain the gas state. Most researchers have a clear understanding of this phenomenon and increase the pre-expansion temperature to prevent condensation and freezing in the nozzle. A considerable amount of heat input is required to keep carbon dioxide in a gaseous state (40 to 50 kcal / kg). If this energy is supplied by increasing the pre-expansion temperature, the density will decrease and therefore the solvation power of the supercritical fluid will decrease. This results in premature precipitation and nozzle clogging. There are many advantages when using compressed carbon dioxide in liquid and supercritical fluid states as a solvent or non-solvent for forming substances with the characteristics of submicron particles. The diffusion coefficient of an organic solvent in carbon dioxide, which is a supercritical fluid, is generally one to two orders of magnitude higher than that in a conventional liquid solvent. Carbon dioxide is also a small linear molecule that diffuses into a liquid faster than other non-solvents diffuse. In the non-solvent precipitation process, the promoted mass transfer in both directions facilitates very rapid phase separation, thus facilitating the production of materials with submicron characteristics. It is easy to recirculate the supercritical fluid solvent at the end of the process simply by reducing the pressure. Since supercritical fluids do not have surface tension, they can be taken out without causing structural collapse due to capillary forces. The product dries significantly faster. Carbon dioxide does not remain in the product and has many other desirable properties (eg, non-toxic, non-flammable, and inexpensive). Moreover, since the typical non-solvent to solvent ratio is 30: 1, the amount of waste solvent is significantly reduced. Carbon dioxide has wide applicability as a non-solvent in that it reduces the cohesive energy of almost all organic solvents. In 1992, DJ Dixon (dissertation, University of Texas, Austin) said that liquid solutions obtained by dissolving a polymer in a solvent were sprayed into compressed carbon dioxide to form microspheres and fibers. Reported the method. In this method (so to speak, precipitation using a compressed fluid non-solvent), the polymer is insoluble in carbon dioxide and the organic solvent is completely mixed with carbon dioxide. Using this idea, the formation of biologically active insulin particles (4 microns) [Formation of Microparticulate Protein Powders using a Supercritical Fluid Anti-Solvent Biotechnol. And Bioeng. By Yeo, SD, Lim, GB and Debenedetti. 1993, 341 ], Formation of biodegradable L-poly (lactic acid) particles of several micron size [Micron Sized Biodegradeable Particles of Poly (L-lactic Acid) via the Gas by Randolph, TWB, RA, and Johnston, KP Antisolvent Spray Precipitation Process. Biotechnology Progress. 1993, 9, 429 ], and the formation of methylprednisolone acetate particles (&lt;5 microns) [WJ Schmitt, MCS, GGShook, and SMS speaker Finely-Divided Powders by Carrier Solution Injection into a Near or Supercritical Fluid. Am.Inst.Chem.Eng.J.1995, 41, 2476-2486 ]. Somewhat surprisingly, the time for decompression in rapid expansion from supercritical solutions is probably faster than for reciprocal mass transfer in compressed fluid non-solvent methods. However, the particle size is as small as that produced by rapid expansion from supercritical solutions. The compressed fluid non-solvent method can not only produce PS particles, but also solid fibers, hollow fibers, highly oriented microfibrils, It is possible to generate 100 nm microballoons with biocontinuous networks and porous shells. To date, submicron particles have not been produced by the compressed fluid non-solvent method without particle agglutination and floculation. The object of the present inventors is a surface modifier [surfactant. Also called stabilizers)] [For example, phospholipids, salts of cholic acid and deoxycholic acid, tween (polyoxysorbitan ester), Pluronic F-68, Tetronic-908, hydroxypropylmethylcellulose (HPMC) Triton X-100, odor The use of cetyltrimethylammonium silicate, PEG-400, or a combination of these compounds (see above for details)] is to eliminate these restrictions. Due to the different surface properties of these small particles, it must be taken into account that the identities and types of phospholipids and especially surfactants vary considerably depending on the water-insoluble or sparingly soluble biologically active material selected. It doesn't become. The most advantageous surfactants for insoluble compounds will be apparent from the following tests to identify surfactants or surfactant systems / combinations, and with these surfactants the required particle size and particle size stability for long-term storage Sex is obtained. Proper selection of stabilizers prevents flocculation in the aqueous phase. Surfactants are selected to be active at the compound-water interface but not at the carbon dioxide-organic solvent or carbon dioxide-drug interface. Stabilizer is CO₂Does not have to be soluble in CO₂As long as it is active at the interface of the solute, it only needs to be soluble in the liquid to be sprayed. The present invention provides a supercritical fluid / compressed fluid based method for obtaining suspensions of water-insoluble drugs with an average particle size of less than 100 nm and a narrow particle size distribution. An essential element is the use of phospholipids and other surfactants to denature the surface of the drug particles to prevent particle agglomeration, thereby improving the storage stability and pharmacokinetic properties of the drug particles. Is to use.<u style="single">Detailed description of the invention</u>Substances and methods: Submicron Particle Sizer-Autodilute Model 370 (NICOMP Particle Sizing Systems, Santa Barbara, Calif.), Based on the principles of photon correlation spectroscopy Particle sizing was performed. This instrument provides a particle size distribution of number weighting, strength weighting, and volume weighting, as well as the multimodality of the particle size distribution, if any. Cyclosporine was separated and quantified using a Waters HPLC system using reverse phase chromatography. The drug was extracted from the sample using methanol and injected into the C-18 analytical column at 60-80 ° C for analysis (the mobile phase now consists of acetonitrile, methanol, and water). Specimens were examined by absorbance at 214 nm. Chromatography system and data processing operations are waters millenium (Waters) Millennium) v2.1 software. Since there is no literature on chemical interactions with cyclosporine, carbon dioxide was used to make rapidly expanding supercritical solutions. Carbon dioxide was used as a solvent for cyclosporine in fermentation recovery and HPLC. The relative solubility of cyclosporine in a solvent that expands with compressed carbon dioxide is required. When the gas is inflated in the nozzle, it approaches the speed of sound at the end. Therefore, it is important to determine the maximum nozzle diameter and aspect ratio (L / D) that maintain these conditions at a constant ratio. It has been reported that nozzle diameters of 10 to 50 microns and aspect ratios of 5 to 200 are used in combination. The device for rapid expansion from supercritical solutions shown in Figure 1 is drug / CO.₂Contains a high pressure container 1 for compounding the solution. The concentration of the drug is constant during spraying as the drug solution is isolated from the pressurized fluid by piston 2 and valve 2a. The solution is mixed using the stir bar 14a and the magnetic stirrer 14. The temperature is controlled by heating tape. The pressure exerted on the piston and thus on the drug solution is controlled via line 3 by an automated syringe pump (ISCO model 100DX) 5 containing high purity carbon dioxide. The preheater shown in FIG. 2A is a shaft along the center of a copper rod with an outer diameter of 2 × inner diameter of 0.030 × length of 4 for preheating the solution to the desired temperature before expansion. Includes directionally hollowed holes (inner diameter 0.030 and length 4 ) 8a. The preheater assembly 8 and the expansion valve 7 are connected to the high pressure container 1 via an outlet tube 6. Heat the assembly 8 and the expansion valve 7 with the high-temperature heating tape 12 to sufficiently insulate them. To monitor the temperature, the thermocouple 13 is placed directly near the orifice of the preheater assembly. The inflatable nozzle, detailed in Figure 2B, contains a laser-drilled orifice 11 (length to diameter ratio ~ 8.5) with a thickness of 0.254 mm and a diameter of 30 microns, and this orifice has two copper gaskets 15 (outside). It is located between (diameter 10 mm, inner diameter 6 mm, thickness 1 mm) and is sealed in a 1/4 tube assembly. The downstream end of the orifice is widened in a V-shape with a drilling machine, as shown in Figure 2B, to prevent the expansion jet from hitting the wall and distorting the morphology of the settling solute. A 0.5 micron metal filter 9 with a diameter of 1/4 is inserted upstream of the nozzle preheater assembly to prevent clogging of the orifice (Fig. 1). In addition, prior to each spray, the preheater assembly is made of high-purity solvent (CO) using bypass line 10.₂) To prepress. If this is not done, the initial pressure drop before and after the filter will cause the drug to settle and clog the orifice 11. After expelling the high purity solvent from the preheater, the orifice is immersed in 25 ml of aqueous solution to capture and stabilize the precipitating drug microparticles. The high kinetic energy of the jet forces it to be sprayed 2 cm below the surface of the aqueous phase. The equipment used to perform compressed fluid non-solvent spraying is shown in Figure 3. Precipitate the drug using a 300 ml high pressure vessel 16 [equipped with a magnetically coupled stirrer (Parr) outlined above the vessel 16]. Before spraying the drug solution, add 50 ml of aqueous solution to this precipitator. This aqueous solution is an aqueous solution containing high-purity water, 1.0% by weight of Tween 80, an aqueous dispersion of 10% by weight of phospholipid, or an aqueous dispersion containing 10% by weight of phospholipid and 2.0% by weight of Tween 80. It is a liquid. The phospholipid dispersion and the dispersion containing phospholipid and Tween 80 are used in a microfluidizer (model M110EH, model M110EH,). It is made by high shear homogenization of an aqueous suspension by passing it through Microfluidics). Tween 80 is commercially available from ICI and egg phospholipids are commercially available from Pfansthiel. Adjust the pH of these dispersions to 7.5 using aqueous sodium hydroxide solution (1N). Carbon dioxide is compressed with a Haskel pneumatically driven gas booster 17 (model AC-152), adjusted with a Tescom pressure regulator (model 26-1021) 18, and monitored with a pressure gauge 19. CO₂Monitor the pressure within ± 0.2 bar. A water bath equipped with a recirculator 30 is used to control the temperature of the settler. The solution is sprayed through a quartz glass capillary 27 (Polymicro Technology) with an inner diameter of 50 microns at a length / diameter ratio of 2800. To maintain a constant flow rate, an automated syringe pump 20 (ISCO model 100DX) is used to pump the solution to the capillary atomizer through the solution valve 28. CO of 0.5 μm filter 21₂Installed in the outflow line 22 to prevent water-insoluble compounds from being lost from the settling vessel. The filter assembly includes an in-line sintered filter element (Swagelok F series) welded to an NPT mounting component with an inner diameter of 1/4 . The spill valve 23 (Whitey, SS-21RS4) connected to the rotor meter 24 is heated to at least 50 ° C in the water bath 29 and is expanding CO.₂Prevents freezing. While precipitation is occurring, a 45 ° pitch blade impeller 26 is used to stir a known amount of aqueous solution 25. After the precipitation is completed, the stirring is stopped, the container is separated, and the pressure is reduced for 30 to 45 minutes. Then, the aqueous solution is recovered and the particle size is analyzed. Unless otherwise stated, all parts and percentages described herein are based on weight per unit volume (w / v), where the volume in the denominator represents the total volume of the system. The diameter dimension is millimeters (mm = 10)^-3Meters), micrometers (μm = 10)^-6Meters), nanometers (nm = 10)^-9It is written in meters) or angstrom units (= 0.1 nm). Volume is liter (L), milliliter (mL = 10)^-3L) or microliter (μL = 10)^-6It is described in L). Dilution is by volume. All temperatures are listed in degrees Celsius. The composition of the present invention may contain the described substance, may substantially consist of the described substance, or may consist of the described substance. In addition, the process or method of the present invention may include a described step using such a substance, may substantially consist of a described step using such a substance, or may comprise this. It may consist of the described steps using such substances. Although the present invention has been described with respect to the most practical and preferred embodiments at this time, the invention is not limited to the disclosed embodiments, and various modifications and equivalent assemblies are also claimed. Needless to say, it is included in the range. Hereinafter, the present invention will be described in more detail with reference to examples.<u style="single">Example 1</u><u style="single">Formation of cyclosporine microparticles from supercritical solution by rapid expansion method</u>Cyclosporine supercritical CO₂The homogeneous solution inside was rapidly expanded from a supercritical solution into various aqueous solutions to study the stabilization of microparticles. The aqueous solution was high-purity water, an aqueous solution containing 1.0% by weight of Tween 80, a dispersion containing phospholipids, or a dispersion containing 2.0% by weight of Tween 80 and phospholipids. Place 0.0480 g of cyclosporine in a variable volume view cell and add 20 mL of CO to it.₂Was added to prepare a 0.25 wt% solution. Cyclosporine / CO after the solution reaches thermal equilibrium (T = 35 ° C)₂The solution was sprayed into aqueous solution at 3000 psia through a 0.30 μm orifice (L / D 8) for 25 seconds. The pre-expansion temperature was 40 ° C. The volume-weighted particle size of the cyclosporine microparticles expanded in the high-purity phospholipid was 153.7 nm (peak 2) as shown in FIG. Most of the substances constituting Peak 1 having a diameter of 20 to 50 nm are derived from phospholipids. However, this population also contains some particles containing cyclosporine. The average particle size of the volume-weighted cyclosporine microparticles expanded in the dispersion containing 2.0% by weight of Tween 80 and phospholipid was 80.9 nm (peak 2) as shown in FIG. Again, the smaller peaks (26.8 nm) are largely derived from the phospholipid and tween 80-containing dispersion and a small fraction of cyclosporine-containing granules. A control standard experiment was conducted in which high-purity carbon dioxide was sprayed into a phospholipid dispersion at 3000 psia. The average diameter of the granules in the dispersion was 9 nm. Therefore, the particles larger than 100 nm in Figures 4 and 5 were clearly drug microparticles, not derived from phospholipids. Similarly, for a phospholipid dispersion containing 2% by weight Tween 80, the average diameter of the granules was 28 nm.<u style="single">Example 2</u><u style="single">Compressed CO</u>_{<u style="single">2</u>}<u style="single">Behavior of water-insoluble compound phase in</u>Solubility of the study drug in carbon dioxide was measured to assess whether a particular water-insoluble compound should be treated by rapid expansion from a supercritical solution or by rapid expansion from a compressed fluid non-solvent. .. Cyclosporine, nifedipine, piroxicam, carbamazepine, indomethacin, and tetracaine HI were investigated. Measured doses of drug and CO to make a solution using a constant molar composition₂Was charged into the variable volume view cell from Example 1. A co-solvent (ie, acetone or ethanol) was added to the view cell to increase solubility. The temperature was changed from 25 ° C to 45 ° C and the pressure was changed from 1200 psia to 4500 psia. The behavior of the phase was examined with the naked eye by observing when phase separation occurred as the pressure gradually decreased at a rate of 1-2 pisa / sec. Table 1 shows CO₂It gives an overview of the solubility behavior for. Cyclosporine CO up to 0.5% by weight₂Dissolved in. Solutions containing 0.01% by weight carbamazepine, tetracaine HI, nifedipine, and piroxicam are CO.₂Was insoluble in. With the addition of 2.40% by weight acetone, at least CO₂0.026 wt% piroxicam CO at 25 ° C for any pressure up to vapor pressure (930 psia)₂Dissolved in. Solutions containing 0.028% by weight nifedipine and 2.26% by weight acetone auxiliary solvent are CO at 25 ° C.₂Was insoluble in. Nifedipine was solvated at 45 ° C and no phase separation was observed up to a minimum of 2000 psia.<img file="JP5038552B2_D0001.tif" /><u style="single">Example 3</u><u style="single">Formation of indomethacin microparticles by compressed fluid non-solvent method</u>A 9.9 wt% acetone solution of indomethacin was sprayed into carbon dioxide with the aqueous solution using the compressed fluid non-solvent method. The spraying time was 30 seconds at 1 mL / min. The average particle size of the phospholipid dispersion liquid by volume weighting was 26 nm (peak 1) as shown in FIG. For indomethacin particles, a two-mode particle size distribution was observed, with average diameters of 143.0 nm (peak 2) and 1088.9 nm (peak 3), respectively. Particles having such a size difference are easily separated by filtration. In the case of microparticles precipitated in the phospholipid dispersion in the presence of 2.0% by weight Tween 80, the average volume-weighted particle size was 126 nm, as shown in FIG.<u style="single">Example 4</u><u style="single">Formation of tetracaine HI microparticles by compressed fluid non-solvent method</u>A 0.97 wt% acetone solution of tetracaine HI was sprayed into a precipitator containing carbon dioxide and high-purity water. The volume-weighted average particle sizes of the tetracaine HI microparticles were 31.8 nm, 193.4 nm, and 2510.1 nm, respectively (Fig. 8). This indicates that the compressed fluid non-solvent method can produce extremely small particles without a surfactant stabilizer. When 1.0 wt% Tween 80 was added to water, three peaks were observed, with average diameters of 9.5 nm, 38.3 nm, and 169.1 nm, respectively (Fig. 9). Figure 10 shows the particle size distribution for 1.0 wt% tetracaine HI stabilized using a phospholipid dispersion and 2.0 wt% Tween 80. A monomode distribution was observed between 8 and 200 nm, with an average diameter of 27.3 nm. This peak contains detergent aggregates and drug particles. No drug particles larger than 200 nm were observed.