Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
  • C01F7/34—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/04—X-ray contrast preparations
  • A61K49/0433—X-ray contrast preparations containing an organic halogenated X-ray contrast-enhancing agent
  • A61K49/0447—Physical forms of mixtures of two different X-ray contrast-enhancing agents, containing at least one X-ray contrast-enhancing agent which is a halogenated organic compound
  • A61K49/0476—Particles, beads, capsules, spheres
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
  • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
  • A61K9/1682—Processes
  • A61K9/1688—Processes resulting in pure drug agglomerate optionally containing up to 5% of excipient

Definitions

• Particles of compounds having low solubility in a dispersing medium are commonly used in a wide variety of applications, including pharmaceuticals, ceramics, paints, inks, dyes, lubricants, pesticides, insecticides, fungicides, fertilizers, chromatography columns, cosmetics, lotions, ointments, and detergents.
• Aqueous dispersions of particles are used in many cases to avoid hazards such as flammability and toxicity associated with organic solvents. Such dispersions typically have a broad range of particle size.
• Particle size is one important factor affecting the release rate of these drugs.
• Those skilled in the art can discern other examples for using particle size to control product performance for the substances listed above.
• Drugs that are insoluble in water can have significant benefits when formulated as a stable suspension of particles of less than three microns diameter.
• the drug can be injected intravenously, circulate in blood, and be preferentially accumulated in, for example, the reticuloendothelial system, where it can facilitate normal reticuloendothelial functions such as detoxification.
• the drug can reside in the reticuloendothelial cells where it is stored until solubilized or metabolized into an active form which circulates in blood to other tissues for efficacy.
• This "slow" release of active drug can provide more constant drug concentrations in plasma over a period of hours, days, weeks, or months, resulting in improved therapeutic efficacy.
• Biodegradable particles which are radiopaque or labelled with a radioisotope are useful for diagnostic imaging of organs, such as liver and spleen, with high concentrations of fixed reticuloendothelial function.
• Obvious drug classes appropriate for formulation as particulate suspensions include: antineoplastics, antimicrobials, antivirals, anticoagulants, antihypertensives, antihista ines, antimalarials, male and female contraceptives, antiepileptics , depressants and antidepressants, adrenocortical steroids, hormones and hormone antagonists, cardiac glycosides, immunosuppressants, beta-blockers, water-insoluble vitamins, sympathomimetics , hypoglycemic agents, hyperglycemic agents, analgesics, tranquilizers, mood altering drugs, and others.
• the treatment of deficiency diseases, alcohol abuse, drug abuse, and many others could be improved with intravenous administration of particulate suspensions of the appropriate drug
• Particles must be less than three microns in diameter to safely pass through capillaries without causing emboli. This is critical for intravenous administration since the particles must pass through lung capillaries before reaching the fixed reticuloendothelial cells of liver and spleen. Restriction to particle diameters of 0.01- 0.1 micron could result in selective accumulation of these particles in certain tissues, eg., neoplastic tissue, where capillaries are somewhat more porous than capillaries of normal tissues. Suspensions of particles with diameters greater than 10 microns could be useful for selective intra-arterial administration to purposely e bolize vessels feeding abnormal tissue such as a neoplasm. Accurate and precise control of particle diameters is essential for efficacy while minimizing or avoiding adverse effects in each of these applications.
• the invention involves a method of making uniformly sized particles of a solid compound by, first, preparing a solution of the solid compound in a suitable solvent for the compound, second, infusing a precipitating liquid into the solution at a temperature between about -50"C and about 100"C and at an infusion rate of from about 0.01 ml per minute to about 3000 ml per minute per unit volume of 50 ml, the solid compound having essentially little solubility in the precipitating liquid and the solvent being miscible in the precipitating liquid, so as to produce a suspension of precipitated solid compound in the form of substantially non-aggregated particles with a substantially uniform mean particle diameter selected from the range of up to about 10 microns, such that the particle size is directly related to the solution temperature and inversely related to infusion rate, and then separating the particles from the solvent and washing in a suitable washing liquid.
• additional precipitating liquid is added to the suspension before the particles are separated from the solvent. Separation can be accomplished, for example, by centrifugation, membrane filtration, reverse osmosis, or other methods.
• the mean particle diameter of the particles can be up to about 10 microns, preferably in a range of 0.01 microns to about 5 microns.
• Particles made according to this invention will typically have a particle size distribution with a maximum relative standard deviation of 30%, for example 95% of the particle having a mean size of 1.0 micron will be within the size range of 0.5 to 1.5 microns.
• the present invention is useful for compounds which preferably have essentially little solubility in a precipitating liquid, i.e. a solubility of less than about one part per ten thousand in the precipitating liquid.
• a solubility of less than about one part per ten thousand in the precipitating liquid i.e. a solubility of less than about one part per ten thousand in the precipitating liquid.
• any compound that meets the other requirements of the invention is suitable, including many drugs.
• the compound may be organic or inorganic.
• the solvent may be organic or inorganic, as long as the solubility of the compound in the solvent is greater than about 10 mg/ml. Also, the solvent must be miscible with the precipitating liquid.
• the washing liquid can be the same as or different than the precipitating liquid. In certain instances it may be advantageous for the compound to have a lower solubility in the washing liquid than in the precipitating liquid in order to maximize yield.
• the precipitating liquid can be water, a solution of a mineral salt, a surfactant solution, or an organic solvent in which the compound is poorly soluble.
• Suitable aqueous surfactant solutions include 5% polyvinylpyrrolidone C-30, 0.1% polyvinylpyrrolidone C- 15, 0.1% human serum albumin, 0.1% Pluronic F-68 (poloxamer 188), and 0.33% gelatin, alone or combined with 0.6% hetastarch, 0.02% propylene glycol, or 2% sucrose.
• the organic solvent can be dimethyl sulfoxide, dimethyl formamide, N,N'-dimethyl acetamide, phenol, isopropanol, or other solvents.
• the solid compound has poor aqueous solubility, i.e. an aqueous solubility from about one part per ten thousand to about one part per one hundred.
• a precipitating and washing liquid may be chosen in which the compound is even less soluble than water.
• the solvents which may be used include the organic solvents previously identified, among others.
• the precipitating liquid is at least substantially non ⁇ aqueous.
• Suitable non-aqueous solutions include alcohols such as ethanol, and alcoholic surfactant solutions such as 1% (w/v) polyvinylpyrrolidone in ethanol, other lower aliphatic alcohols, acids, amides, aldehydes, ketones, and glycols.
• the method includes the additional step of diluting the solution in which the compound is dissolved with a non-solvent, i.e. a liquid in which the compound is poorly soluble but does not cause the compound to precipitate, such that the ratio of non- solvent to solvent is between about 100:1 and about 1:100, after preparing the solution and before the infusion step, so that the particle size is directly related to the ratio of non-solvent to solvent.
• a non-solvent i.e. a liquid in which the compound is poorly soluble but does not cause the compound to precipitate
• the solid compound is iodipamide ethyl ester, an ethyl ester of a triiodobenzoic acid derivative, and is dissolved in dimethyl sulfoxide and diluted with ethanol. The compound is thereafter precipitated with an aqueous surfactant solution. If the ratio of ethanol to dimethyl sulfoxide is greater than about two, the mean particle diameter is greater than about one micron, and if the ratio of ethanol to dimethyl sulfoxide is less than about two, the mean particle diameter is less than about one micron.
• the solid compound is mitindomide, an anticancer drug having the molecular formula c i 4 H 12 N 2 ° 4 and m °lecular weight of 272.3.
• the mitindomide is dissolved in dimethyl sulfoxide and the precipitating liquid used is 1% (w/v) polyvinylpyrrolidone in 99% ethanol.
• the solid compound is aluminum chloride hexahydrate. It is dissolved in ethanol (99%) , and thereafter diluted with acetone. The compound is then precipitated with an aqueous surfactant solution.
• Figure 1 is a graph of free energy of the various phases of the compounds used in the invention.
• Figure 2 is a graph of the relationship between size distribution of particles and time interval between onset and completion of precipitation.
• Figure 4 is a graph showing iodipamide ethyl ester particle size as a function of temperature at a constant ratio of infusion rate of aqueous precipitating liquid to [stir rate (rpm) x volume of organic solution];
• Figure 5 is a graph demonstrating the effect on particle size of varying the infusion rate of aqueous precipitating liquid at constant temperature and stirring rate of an iodipamide ethyl ester solution.
• Figure 6 is a schematic diagram of preferred steps in the inventive method.
• This invention concerns the preparation of uniform particles of a predetermined size.
• One aspect of the invention concerns the preparation of uniform particles of a predetermined size in a vehicle in which the concentration of the compound in the vehicle is greater than the solubility of the compound in that vehicle.
• the particles are formed by a carefully controlled precipitation of the compound into a suitable precipitating liquid from a solvent in which the compound is soluble.
• Figure 1 shows that the free energy of the system is higher when the compound is dissolved in the organic solvent than when the compound exists in the particulate or crystalline state. During precipitation the compound will naturally convert to the crystalline form—the lowest free energy state—unless it is trapped in the metastable particulate form, a condition where its free energy is intermediate between the solution and the crystalline phases.
• this invention enables the trapping of a compound in the metastable particle state, precluding transformation to the crystalline state.
• the size distribution of particles formed during precipitation can be correlated with the time interval between onset and completion of precipitation. As shown in Figure 2, a very short time interval results in the production of uniformly sized particles (A) , while a very long time interval results in a broad particle size distribution (B) . Intermediate conditions produce intermediate particle size distributions.
• an important parameter for utilization of this invention is the solubility of the compound in the precipitating liquid.
• compounds having essentially little aqueous solubility i.e. compounds which have an aqueous solubility of less than one part in ten thousand, may be precipitated in an aqueous solution in order to obtain an "excellent yield.
• Compounds which are more water- soluble can also use an aqueous precipitating liquid.
• the higher the solubility of the compound the greater the probability that some of the compound will dissolve in the aqueous phase and transform to the more stable crystalline state.
• redissolution in the aqueous phase can lead to a broadening of the particle size distribution.
• an aqueous precipitating liquid be used for compounds having a water-solubility of less than one part in ten thousand.
• a solution of the solid compound in a suitable solvent is prepared.
• the solution may be diluted with a non-solvent that does not cause the drug or other compound to precipitate.
• a precipitating liquid is also prepared, preferably with a surfactant, in su ficient quantity to both precipitate the drug or other compound and stabilize the resulting suspension of particles of the compound against aggregation.
• the precipitating liquid may be used alone when compounds which do not aggregate are used.
• the precipitating liquid is infused into the solution in which the compound is dissolved under carefully controlled conditions, including: the rate of stirring of the organic solution, the rate of infusion of the aqueous solution, the volume of the organic solution and the temperature of the solutions and the suspension.
• the precipitating liquid may be infused, for example, through a needle of standard gauge.
• the uniformly sized particles are washed to remove the solvent, i.e. by centrifugation, filtration, etc. In most cases, the particles should be separated from the solvent quickly to prevent transformation to a crystalline form.
• Aqueous precipitating liquids are useful for many compounds, including but not limited to organic compounds such as iodipamide ethyl ester, iothalamate ethyl ester, iosefamate ethyl ester, 2,2', 4,4' - tetrahydroxybenzophenone, RS nitrocellulose, progesterone, beta-2,4,6-triiodo-3-dimethyl formamidinophenyl propionic acid ethyl ester, isopropylpyrrolizine derivative (NSC-278214) , N- (trifluoroacetyl) Adrimycin 14 valerate, 1,2 diaminocyclohexane malinate platinum (II) , norethisterone, a ⁇ etyl salicylic acid, wafarin, heparin-tridodecyl methyl ammonium chloride complex, sulfamethoxazole, cephalexin, predni
• Compounds which are better suited for precipitation using a non-aqueous precipitating liquid include organic compounds such as mitindomide, hydrolytically unstable compounds such as isopropylpyrrolizine (IPP, or carbamic acid, (1-methylethyol)-, (5-(3,4-dichlorophenol)-2,3- dihydro-l,H-pyrrolizine-6,7-diyl) bis(methylene ester) ;and inorganic compounds such as iron citrate, iron iodate, calcium pyrophosphate, calcium salicylate, platinum dichloride and sodium pyrophosphate.
• organic compounds such as mitindomide, hydrolytically unstable compounds such as isopropylpyrrolizine (IPP, or carbamic acid, (1-methylethyol)-, (5-(3,4-dichlorophenol)-2,3- dihydro-l,H-pyrrolizine-6,7-diyl) bis(methylene ester) ;
• the first step is to prepare a solution of the compound of interest in a suitable solvent for that compound. This can occur as the compound is synthesized as a dissolved solid, or it can be done by simply dissolving the compound in the solvent of choice.
• the solvent is chosen to suit the compound.
• dimethylformamide (DMF) is a solvent for iothalamate ethyl ester (IEE) and iosefamate ethyl ester (IFE)
• di ethylsulfoxide (DMSO) is a solvent for iodipamide ethyl ester (IDE) and IEE.
• DMSO is also a suitable solvent for compounds such as mitindomide.
• Another suitable solvent for many compounds, and especially IPP is tetrahydrofuran (THF) .
• the solution is then optionally diluted with a non- solvent that does not cause the compound to precipitate.
• the non-solvent causes greater dispersion of the dissolved molecules of the compound in the liquid phase. Greater dilution of the solution with non-solvent produces larger particles, and less dilution of the solution with non-solvent produces smaller particles.
• the non-solvent should not precipitate the compound when it is added to the solution.
• Lower aliphatic alcohols such as ethanol, are effective non-solvents for solutions of IDE and IEE in DMSO.
• proportions of non-solvent to solvent at a ratio of 2 or more can produce 1 to 3 micron sized particles (depending on other parameters) ; and ratios of less than 2 can produce sub-micron particles, at least as applied to DMSO solutions diluted with ethanol.
• a solution of a surfactant is prepared in sufficient quantity to effect complete precipitation of the compound and to stabilize the resulting suspension of particles of the compound against aggregation.
• the surfactant provides the stabilization against aggregation, while a suitable precipitating agent causes the precipitation of the compound. Presence of extra surfactant solution is advisable to ensure stabilization so that precipitated particles suspended in liquid do not aggregate, forming agglomerates of an improperly large size.
• surfactants are used in most cases, some compounds appear to form stable, substantially non-aggregated particles without the use of surfactants. Examples of such non-aggregrating compounds are certain heparin complexes.
• the surface charge of a particle is sometimes referred to as its zeta potential, a measurement of charge which falls off with distance.
• the zeta potential is directly correlated with the polarity or net charge of a compound.
• the need for surfactant in the precipitating solution may be predicted from the extent of the charge or polarity of the compound employed in the method of the invention. For example, heparin complexes are highly charged, and form stable non-aggregated particles when precipitated with water.
• a precipitation may first be performed with water, and if aggregation occurs, then a precipitation in the presence of surfactant is indicated.
• surfactants are chosen for their compatibility with the compound and their ability to stabilize a suspension of compound particles.
• a solution of 5% polyvinylpyrrolidone (C-30) , 0.1% polyvinylpyrrolidone (C-15) , or 0.1% human serum albumin is preferred.
• Pluronic F-68 [Poloxamer 188, a poly(oxyethylene- co-oxypropylene) polymer], a 0.33% gelatin, 0.33% gelatin plus 0.6% Hetastarch, 0.33% gelatin plus 0.002% propylene glycol, and 0.33% gelatin plus 2% sucrose, or other surfactants known to one skilled in the art can be used.
• the precipitating liquid and the solution are combined under controlled conditions of temperature, ratio of infusion rate to stirring rate, and the proportion of non-solvent to solvent in the dispersed solution.
• the solution being infused with precipitating liquid is agitated.
• This can be accomplished by stirring, shaking, by the infusion itself and by other techniques known to those skilled in the art.
• This effect can also be achieved by combining a stream of precipitating liquid with a stream of the solution.
• the precipitation of the compound occurs exothermically, heating the solution and the resulting suspension.
• the temperature of the solution and resulting suspension is controlled to achieve the particle size of precipitate that is desired. Higher solution temperatures during precipitation produce larger particles, and lower solution temperatures during precipitation produce smaller particles. Since many compounds are less soluble at lower temperatures, it is generally preferred to conduct the infusion of precipitating liquid at a low temperature in order to maximize yield.
• the lower limit of the temperature at which precipitation can be conducted is, of course dependent upon the freezing point of the solvent, precipitating liquid, as well as economic concerns.
• FIGS. 3-5 show the effects on particle size of varying parameters during precipitation of IDE from a DMSO solution diluted with 1 part solution to 2 parts ethanol using an aqueous solution of 5% polyvinylpyrrolidone at different infusion rates and temperatures.
• FIG. 4 shows that at a constant ratio of infusion rate to [stir rate x volume], increased precipitation temperature produces larger particles.
• FIG. 5 plots 3 points from the 20"C temperature line of FIG. 3 for rate of infusion of the precipitating liquid into the organic solution to approximate the curve by which larger particles are formed from slower injection rates, showing that at a constant ratio of temperature to [stir rate x volume], particle size is inversely related to the rate of infusion of the precipitating liquid.
• FIGS. 3-5 show clearly that higher temperatures and slower mixing rates produce larger particles, and lower temperatures and faster mixing rates produce smaller particles.
• Another parameter that can be varied to affect particle size is the amount of dilution of the solution before precipitation occurs.
• extra surfactant solution can be added to further stabilize the suspended particles against agglomeration.
• the extra solution can be added at a rapid rat , since essentially all the compound is now precipitated in uniformly sized particles.
• the precipitated particles are promptly separated from the solvent to prevent redissolving and reprecipitation of particles at undesirable sizes. Centrifuging is a preferred way to perform the separation. Other methods, including membrane filtration, reverse osmosis, and others known to persons skilled in the art may also be used to remove undesired substances.
• the particles are washed or rinsed with normal saline solution to remove solvent and excess surfactant. Where an aqueous precipitating liquid is used, normal saline solution may be used for this purpose.
• the particles prepared according to the method outlined above may be resuspended in an appropriate suspension vehicle which may be aqueous or non-aqueous solution, as the situation requires.
• an appropriate suspension vehicle which may be aqueous or non-aqueous solution
• the particles are ultimately resuspended in an aqueous solution such as sterile water.
• the particles may be suspended in a carrying agent such as an ointment, gel, or the like.
• the compound has the same range of solubility in the suspension vehicle as in the precipitating liquid.
• Examples 1 to 19 are presented in Table I.
• the solid organic compound was dissolved in the organic solvent and then diluted (except where indicated) by the non- solvent.
• the aqueous precipitating liquid was then infused through a needle at the given rate into the solution, at the given temperature and while stirring at the given stirring rate.
• the size of the particles obtained is shown for each example.
• Example Example 7 solid organic 100 mg beta-2,3,6 100 mg beta-2,3,6 compound triod-3-dimeth l triod-3-dimethyl formamidino-phenyl formamidino-phenyl propionic acid ethyl propionic acid ethyl ester ester
• Example Example 13 14 solid organic 120 mg iodipamide 10 mg isopropyl compound ethyl ester pyrrolizine derivative (NSC-278214) organic 2.0 ml dimethyl 0.4 ml dimethyl solvent sulfoxide sulfoxide
• Example Example 19 20 solid organic 200 mg heparin-benzal- 10 mg organic compound* compound konium chloride (see list) complex
• Examples 1 to 19 show how the process can be used to produce aqueous dispersions of a wide variety of compounds that have low aqueous solubility and for which particle size can be controlled with substantial precision and predictability. Conditions would be varied from compound to compound according to the invention in order to optimize results. This may in some cases include chemical modification of the compound to achieve the desired solubility.
• Example 20 is also presented in Table I. This example should be performed in the same manner as examples 1 to 19, and would make particles of the listed compounds within the scope of the invention.
• Examples 21 to 28 are presented in Table II.
• the given quantity of iodipamide ethyl ester was dissolved in the given volume of dimethyl sulfoxide, then diluted with the given volume of ethanol.
• the aqueous precipitating liquid was prepared from polyvinylpyrrolidone then infused at the given infusion rate through a needle with the given gauge into the solution while the solution was stirred at the given stir rate. The precipitation was carried out in the given vessel at the given temperature. After precipitation, the given amount of saline was added to further stabilize the dispersion.
• the mean particle diameter was about 1.0 micron and substantially uniform.
• IDE iodipamide ethyl ester
• Particles of iodipamide ethyl ester may be prepared for administration to a patient.
• IDE is the water-insoluble ethyl ester of iodipamide, a water-soluble radiopaque compound used clinically for radiographic examination of the gallbladder.
• the synthesis of iodipamide ethyl ester is known in the art (for example, esterification by alcohol and acid or by a Schotten-Bauman reaction) .
• IDE s only minimally soluble in water (10 —5 M) and can be precipitated easily from the dimethyl sulfoxide (DMSO)/ethanol solvent mixture.
• DMSO dimethyl sulfoxide
• the simple addition of water to this solution results in IDE particles with extremely rough contours; these particles vary in size from less than one micron to greater than 300 microns in diameter.
• the method of this invention provides a more refined procedure for controlling particle size and shape.
• Particle Precipitation Procedure Physical methods for modifying and controlling particle size, such as ball milling, grinding or sonication result in preparations with a very broad range of particle diameters. These methods are commonly used to eliminate large particles (greater than 4-5 microns) which could embolize in the pulmonary capillary bed, but generally some particles of réelle., contradict duplicate PCT/US90/ 3380
• a chemical precipitation procedure for producing particles of a given size was developed to avoid these problems.
• aqueous solution of polyvinylpyrrolidone By adding an aqueous solution of polyvinylpyrrolidone, at controlled rates and temperatures, to IDE dissolved in a dimethyl sulfoxide/ethanol solvent, apparently spherical, amorphous particles can be produced with an extremely narrow size distribution.
• the total range of particle diameters is 0.4 to 2.0 microns with 90 per cent of the particles ranging in size between 0.5 and 1.5 microns, as determined by microscopy.
• the IDE particles produced using this methodology are stable in whole blood with little apparent tendency toward aggregation. When suspended in whole blood, there is essentially no tendency for one micron IDE particles to aggregate with themselves or with formed elements of blood. The IDE particles have smooth contours.
• a 10% solution of aluminum chloride hexahydrate (A1C1_.6H 2 0) is prepared by adding 1 gram of this compound to 10 ml of 99% ethanol. This mixture is heated to approximately 50°C until substantially all of the AlCl_.6H.-0 is dissolved. The solution was then allowed to cool to room temperature. Subsequently, 5 ml of acetone is added to 2.5 ml of A1C1 3 .6H_0/ethanol solution in 25 ml beaker and cooled to 4°C. This solution is stirred rapidly using a magnetic stirrer.
• the suspension is then centrifuged at 10,000 RPM for 15 minute and the pellet is resuspended in aqueous 0.1% PVP/0.9% NaCl solution. Laser light scattering analysis of this suspension reveals a mean particle diameter of 285 nm.
• Mitindomide a pharmaceutical intended for parenteral administration, has a solubility in water of 70 ug/ml at room temperature. Although this normally is considered to be water-insoluble, we encountered PCI 3380
• a mitindomide solution of 30 mg/ml in DMSO is prepared and filtered through an 0.2 micron nylon filter immediately prior to use.
• a 1% (w/v) polyvinylpyrrolidone (PVP) solution in 99% ethanol is prepared and filtered through an 0.2 micron filter immediately prior to use.
• the mitindomide particles are prepared by mixing the 1% PVP/ethanol solution at a rate of six (6) liters/minute with the mitindomide/DMSO solution at a rate of 250 ml/minute at a temperature of 0°C. After 90 minutes of recirculation at this temperature, laser light scattering analysis reveals a mean particle diameter of approximately 400 n .
• the suspension can be transferred to a 500 ml bottle for storage at -20 ⁇ C until further processing is desired or one may proceed directly to the following procedures.
• the suspension Before use, the suspension must be washed to remove DMSO. This is accomplished by centrifugation, filtration or by any other means known to one skilled in the art.
• the wash fluid can be water. However, to maximize yield, it is preferred to wash with the 99% ethanol. -33-
• the particles may be resuspended in ethanol and stored at -20"C.
• the suspension When the suspension is to be prepared in final form, the suspension is centrifuged and the separated mitindomide particles are resuspended in aqueous PVP solution.
• This suspension vehicle may contain other additives such as buffer, preservatives, or other excipients as may be deemed necessary.
• the resultant "concentrated" suspension is then lyophilized to remove the ethanol and most of the water.
• the lyophil can be reconstituted by adding sterile water just prior to use.

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• 1985
  • 1985-05-17 CA CA000481799A patent/CA1282405C/en not_active Expired - Lifetime
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  • 1985-05-21 EP EP85201206A patent/EP0169618B2/de not_active Expired - Lifetime
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