Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
  • B01J13/02—Making microcapsules or microballoons
  • B01J13/04—Making microcapsules or microballoons by physical processes, e.g. drying, spraying
• • 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
  • A61K9/1694—Processes resulting in granules or microspheres of the matrix type containing more than 5% of excipient
• • 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
  • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
  • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
  • A61K9/5089—Processes

Definitions

• the present invention relates to an encapsulation process in the form of microcapsules of fine solid particles such as in particular proteins. It also relates to the micro-capsules obtained according to such a process.
• microcapsules when their diameter is less than approximately 100 ⁇ m, when the active agent must be protected from the environment during its conservation and / or its use. Such microcapsules are thus used in reprographic inks, in many cosmetic and dermatological preparations, and in certain pharmaceutical products.
• the pharmaceutical industry but also the cosmetics industry, requires new dosage forms in order to improve the service rendered by certain molecules of therapeutic or dermatological interest.
• it is looking for ways to achieve effective protection of certain molecules which would be destroyed as soon as they are absorbed by the digestive enzymes, or which would not be stable when stored in the presence oxygen or air humidity, or light.
• Micro-capsules respond well to this need.
• micro-spheres or micro-capsules the core of which consists of an active agent formed of proteins of therapeutic interest within an excipient, due to the large fragility of these proteins.
• proteins are complex and fragile buildings whose biological activity is closely linked to their three-dimensional conformation which can be easily affected by the environment of the molecule, which has the effect of causing destruction generally irreversible of its biological activity.
• Such fragility is particularly great for many proteins of high therapeutic interest whose production is beginning to be implemented according to new biotechnologies, but whose therapeutic implementation is proving to be extremely delicate.
• the object of the present invention is precisely to describe a process for obtaining microcapsules with heart-shell structure or with matrix structure otherwise called microspheres, and more particularly of microcapsules making it possible in particular to include proteins in the within an excipient.
• SAS supercritical, or the anti-solvent process called either SAS, SEDS, PCA or ASES, which consists in spraying a solution of a product to be atomized in an organic or aqueous solvent in a stream of fluid in supercritical state .
• ASES high pressure
• the anti-solvent process inevitably involves the use of at least one organic solvent or co-solvent. This results in a certain number of drawbacks and in particular significant problems of recovery of the solvent and purification of the microcapsules obtained. This process also has a major drawback, namely that of not being usable for carrying out the encapsulation of fragile bio-molecules, such as in particular proteins, insofar as most of these are irreversibly denatured on contact. of an organic solvent.
• Another method consists in carrying out the coacervation of the coating agent initially dissolved in an organic solvent within which the particles to be coated are kept in dispersion, said coacervation being caused by an effect anti-solvent caused by the dissolution of a supercritical fluid or a liquefied gas in said organic solvent.
• the capsules obtained are recovered after complete extraction of the organic solvent by a stream of supercritical fluid or liquefied gas, then decompression of the container in which the encapsulation was carried out. This process therefore also has the drawback of requiring the use of an organic solvent within which the particles of active agent will be dispersed.
• patent application WO-98/15348 describes the application of the previous concept to the manufacture of microcapsules consisting of particles of an active agent encapsulated in a polymer, using a supercritical fluid which, by dissolving in the polymer, liquefies it at a temperature below the melting temperature of the polymer and allows the setting suspension of the particles of the active agent within this saturated liquid phase itself in supercritical fluid, which suspension is then expanded at atmospheric pressure with the formation of microcapsules due to the solidification of the polymer around the particles of active agent .
• this process uses carbon dioxide at supercritical pressure and that the temperature for processing the mixture in the first container is generally close to the melting or glass transition temperature of the polymer. It is easily understood that such a method cannot be used to encapsulate fragile particles such as in particular proteins.
• the object of the present invention is to provide a method for making microcapsules made up of particles of an active agent with a diameter generally less than 20 ⁇ m, and often less than 10 ⁇ m, dispersed within a coating agent, these microcapsules having an adjustable mean diameter which is preferably between a value minimum equal to 2 to 3 times the average diameter of the encapsulated particles and a maximum value equal to approximately 200 ⁇ m, and allowing in particular to include proteins within an excipient.
• the present invention thus has for an object method for encapsulation 1 in the form of microcapsules of fine solid particles, characterized in that it comprises the steps of:
• the present invention is particularly intended for encapsulating very fine solid particles with a size of less than 20 ⁇ m and most often less than 10 ⁇ m in order to obtain microcapsules intended for preparations for therapeutic use in human or veterinary pharmacy , cosmetic or phytosanitary.
• an aqueous or organic solvent can be added to the coating agent.
• the gaseous fluid can entrain the solvent and the total elimination of this can be obtained by means of a “stripping” of the microcapsules by a fluid brought to a supercritical pressure.
• the particles can be suspended at a temperature of the order of 50 ° C to 60 ° C and at a pressure of the order of 5 Mpa to 6 Mpa and the pressure during collection will be close of atmospheric pressure.
• the present invention also relates to the microcapsules obtained according to the process of the invention.
• the particles may consist of an active agent of food, pharmaceutical, cosmetic, agrochemical or veterinary interest. These particles may in particular consist of a protein associated or not with a stabilizing agent.
• This invention is advantageous in that it makes it possible to use a wide range of coating agents and not only polymers, and, even more surprisingly, that the fluid can be dissolved in quantity significant in the suspension of active agent dispersed in the coating agent at a pressure significantly lower than its critical pressure.
• Figure 1 is a schematic view showing the principle of implementation of the method according to the invention.
• Figure 2 is a curve showing the release kinetics of an active agent enclosed in a coating agent when the microcapsule is placed in water. It represents, as a function of time, the percentage of active agent which has dissolved in water relative to its quantity present in the particles.
• FIG. 1 a device for implementing the method according to the invention.
• This device comprises an enclosure 1, the bottom 2 of which is conical and inside which is mounted for rotation about a vertical axis, a stirrer 3.
• the enclosure 1 is provided with an inlet 5 and a lower axial outlet 7 which is in communication with a nozzle spray 9 arranged in the upper part of a collecting container 11.
• this collecting container will be of the cyclonic type and will comprise, for this purpose, a cylindrical tube 12 creating an upper annular zone in which the gas flow charged with particles will be allowed to tangentially.
• the collecting container 11 comprises an extraction orifice 13 disposed in the bottom thereof through which the microspheres produced will be extracted.
• the method according to the invention is implemented as described below.
• the enclosure 1 contains a light phase consisting essentially of the fluid at subcritical pressure within which the coating agent and the active agent are almost insoluble, and a heterogeneous heavy phase which consists of a suspension of the active agent particles within the coating agent saturated with fluid.
• This heavy phase is extracted through the orifice 7 and admitted, through the spray nozzle 9, into the collecting container 11, which is maintained at a pressure close to atmospheric pressure, which subjects this heavy phase to a abrupt decompression which allows the spray into fine droplets which are strongly cooled by the degassing of the fluid brought back at low pressure, so that they solidify in the form of microcapsules.
• Such an implementation can advantageously be carried out periodically.
• the coating agent can be placed in the liquid phase at a temperature below the degradation temperature of the active agent, it is possible, in another particularly advantageous embodiment of the invention, to suspend the the active agent in a coating agent which has been previously melted.
• the suspension thus produced and the fluid at subcritical pressure are introduced continuously into the enclosure 1 and the heavy phase obtained is drawn off to bring it continuously within the enclosure 1, while maintaining constant the amount of heavy phase present in it.
• a small amount of organic solvent is used to put the coating agent in the liquid phase at a temperature below its melting temperature, either at atmospheric pressure or when it is saturated with fluid at subcritical pressure.
• Such an embodiment is particularly advantageous when the active agent is very sensitive to temperature, which is particularly the case for proteins.
• organic solvents preferably very volatile, non or not very toxic, such as ethanol, n-propanol, isopropanol, acetone or ethyl acetate.
• other alcohols such as methanol, ketones or esters, or even light hydrocarbons or halocarbons having between 3 and 8 carbon atoms.
• microcapsules thus obtained contain very low contents of residual solvent, in particular for the reason that the gaseous phase resulting from the decompression of the heavy phase entails almost all of this solvent, and all the more so as 'it has a greater volatility.
• this organic solvent content must be reduced to minute levels, it will be possible without particular difficulty, to extract the residual solvent by subjecting the microcapsules to a brief treatment (so-called “stripping” extraction) by a stream of fluid brought to supercritical pressure, taking care however to maintain the temperature of this fluid below the melting temperature of the coating agent at the pressure considered.
• a brief treatment so-called “stripping” extraction
• the equipment used to carry out the examples presented below is of pilot size. It used carbon dioxide as a subcritical pressure fluid, with an operating pressure of 8 MPa and a range of temperature ranging from 0 ° C to 150 "C.
• the pressure vessel 1 had a total volume of 4 liters, and was fitted with an anchor-type agitator 3 driven by an electric motor with variable speed between 100 and 800 revolutions per
• This enclosure 1 consisted of a container terminated by a conical bottom with an angle of 45 ° and a diameter of 0.10 m, with a double jacket traversed by a heat-transfer fluid making it possible to maintain the temperature of the assembly at the desired value.
• the collecting container 11 consisted of a cylindrical cyclone with a diameter of 0.20 m and a height of 1 m, the atomizing nozzle had an orifice with a diameter of 300 ⁇ m and was placed at the top of the container with a tangential orientation inducing a movement of rotation with the gas flow generated in the annular space included between the external wall of the cyclone and the internal cylinder 12 with a diameter of 0.16 m and 0.40 m high.
• EXAMPLE 1 In the equipment thus described, very fine particles of L-ascorbic acid, which were obtained by an anti-solvent process, and whose mean diameter by mass is 2.3 ⁇ m, are encapsulated in an agent of lipid texture conventionally used in the food industry, consisting of hydrogenated vegetable oil, and marketed by the cios Industrielle des Oléagineux under the code GV 60, the fusion of which takes place at atmospheric pressure between 58 ° and 61 ° C.
• an agent of lipid texture conventionally used in the food industry, consisting of hydrogenated vegetable oil, and marketed by the cios Industrielle des Oléagineux under the code GV 60, the fusion of which takes place at atmospheric pressure between 58 ° and 61 ° C.
• the suspension is produced at atmospheric pressure at 62 ° C by stirring 2 kg of a mixture comprising 1,800 kg GV60 and 0.200 kg of L-ascorbic acid for 15 minutes in enclosure 1, the jacket of which is traversed by water at 60 ° C. and the agitator is rotated at 200 revolutions per minute. Carbon dioxide is then introduced at 60 ° C until the pressure is stabilized at 6 MPa. After 20 minutes of stirring, to achieve perfect balancing, the enclosure 1 is placed in communication with the nozzle 9 and the heavy phase present in the enclosure 1 is sprayed into the collecting container 11. During this phase, the pressure is maintained by the arrival of fluid in one enclosure and one stirring is also maintained. After 10 • inutes, 0.320 kg of white powder is collected, the analysis of the characteristics of which leads to the following results: - Particle size distribution between 5 ⁇ m and 19 ⁇ m with an average mass diameter of 12 ⁇ m;
• composition of the particles obtained after dissolution of the coating agent in heptane and of the vitamin in water, by HPLC on a C18 silica column with UV detection (254nm): 9.5% mass of L acid - ascorbic.
• Example 1 The test carried out in example 1 is reproduced under slightly different conditions. This time the temperature in enclosure 1 is maintained at 50 ° C only, so that this temperature is insufficient to obtain a liquid phase even in the presence of the fluid at 6 Mpa. 0.360 kg of pure ethanol was therefore added, prior to its introduction, to the coating agent and 2.160 kg of this mixture is introduced into enclosure 1. All the other parameters were kept equal, moreover, to those used in Example 1, and 0.338 kg of powder was obtained, the analysis of the characteristics of which led to results very close to those obtained on the powder described in Example 1:
• Average composition of the particles obtained by HPLC 9.7% by mass of L-ascorbic acid.
• Example 2 The test carried out in Example 2 is reproduced under almost identical conditions, with the difference that the organic solvent added to the coating agent is acetone and not ethanol. 0.360 kg of pure acetone was therefore added, prior to its introduction, to the coating agent, and 2.160 kg of this mixture was therefore introduced into enclosure 1. All the other parameters were kept equal to those elsewhere. used in Example 2, and 0.332 kg of powder were obtained, the analysis of the characteristics of which led to results very close to those obtained for the powders described in Examples 1 and 2:
• Example 2 The test carried out in Example 2 is reproduced under the same conditions using another coating agent, namely a silicone wax of the AMS-C30 type from Dow Corning, commonly used as an excipient in cosmetic products.
• the temperature in enclosure 1 is maintained at 50 ° C, and the pressure at 6 Mpa. 0.600 kg of pure ethanol was added before its introduction to the coating agent, and 2.400 kg of this mixture was therefore introduced into enclosure 1. All the other parameters were kept equal, moreover, to those used for Example 2, and 0.319 kg of powder were obtained, the analysis of the characteristics of which led to results very close to those obtained on the powder described in Example 1:
• Example 1 The test carried out in Example 1 is reproduced under almost identical conditions except that the active agent consists of fine albumin particles obtained from egg, also called ovalbumin, with a particle size centered on 5 ⁇ m. 1.800 kg of GV60 coating agent and 0.180 kg of albumin were therefore introduced into enclosure 1. All the other parameters were maintained equal to those used in Example 1, in particular the temperature was maintained at 60 "C and the pressure at 6 MPa in the enclosure 1. 0.310 kg of powder was obtained, of which 1 • analysis of the characteristics led to results very close to those obtained on the powder described in Example 1:
• Example 6 The test carried out in Example 5 is reproduced under almost identical conditions with the difference that the agent active consists of fine particles of a protein called lactase with a particle size centered on 6 ⁇ m. 1.800 kg of GV60 coating agent and 0.180 kg of lactase were therefore introduced into enclosure 1. All the other parameters were kept equal to those of Example 5, in particular the temperature was kept at 60 °. C and the pressure at 6MPa. 0.305 kg of powder was obtained, the analysis of the characteristics of which led to results very close to those obtained on the powder described in 1 •
• Example 1 Example 1:
• Measurements relating to the biological activity of the protein were carried out according to the protocol generally used for measuring the enzymatic activity of lactases:
• the reaction implemented is the hydrolysis of 1 O-nitrophenyl-galactopyranoside (ONPG) in O-nitrophenol and D-galactose, the production of O-nitrophenol being followed by spectrophotometry at 420 nm.
• the activity of the starting lactase was found to be equal to 542,000 units / gram (+ 15,000) and the activity of the lactase after encapsulation to 454,000 units / gram ( ⁇ 28,000), ie a loss of activity of about 16%.
• Measurements relating to the dissolution of the protein in physiological saline were also carried out at 37 ° C. with monitoring of the concentration in water by UV spectrophotometry.
• the release curve of the protein as a function of time is of the same type as that shown in FIG. 2, showing that the protein was effectively encapsulated within the coating agent without immediate release effect during contacting with the aqueous phase. On the contrary, there was a very regular progressive release of the protein for 8 hours.
• Example 6 The test carried out in Example 6 is reproduced under almost identical conditions with the same active agent and the same excipient, the temperature being maintained at 50 ° C and the pressure at 6 Mpa in enclosure 1. But, as described in Example 2, there were introduced into enclosure 1 both 1,800 kg of coating agent GV60 and 0.420 kg of ethanol, as well as 0.180 kg of lactase. 0.320 kg of powder was obtained, the analysis of the characteristics of which leads to results very close to those obtained on the powder described in Example 1:

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• 2000
  • 2000-07-19 FR FR0009473A patent/FR2811913B1/fr not_active Expired - Lifetime
• 2001
  • 2001-07-19 CA CA002416004A patent/CA2416004A1/fr not_active Abandoned
  • 2001-07-19 JP JP2002511872A patent/JP2004503603A/ja active Pending
  • 2001-07-19 EP EP01956607A patent/EP1370352A1/de not_active Ceased
  • 2001-07-19 AU AU2001278538A patent/AU2001278538A1/en not_active Abandoned
  • 2001-07-19 WO PCT/FR2001/002350 patent/WO2002005944A1/fr not_active Application Discontinuation
  • 2001-07-19 US US10/333,038 patent/US20030157183A1/en not_active Abandoned

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