MXPA99011540A - Novel liposome vectors of active principles - Google Patents

Abstract

The invention concerns liposome vectors, in powder form, of active principles, and more particularly active principles sensitive to digestive and/or plasmatic degradation, such as proteins, and their application as medicine. Said liposome vectors of active principles consist of a powder composition essentially constituted of unilamellar liposomes comprising an external lipid phase consisting of class 4 lipids (phospholipids), optionally associated with class 2 substances, class 3 substances and/or class 5 substances and an internal aqueous nucleus consisting of a mixture M of at least two different non-polymerisable gelling agents (G1 and G2) whereof the gel-sol phase transition is not less than 37°C, G1 being selected among gelatines and carrageenans and G2 being selected among carrageenans with properties different from the carrageenans selected for G1, and celluloses, which liposomes have a diameter ranging between 20 nm and 1 mm, preferably between 20 nm and 500 nm;said composition having the form of particulate units with an average particle diameter between 10 mm and 1000 mm, formed by one or several of said liposomes, enclosed in a sheath selected in the group consisting of a dehydrated thermoreversible aqueous gel identical to said internal nucleus aqueous gel, dextrins or a mixture thereof, such that they contain, on an average, 1016 to 1018 liposomes per gram of powder;and at least an active principle contained, as the case may be, either in the gelled internal nucleus or in the external lipid phase.

Description

N U EVOS VECTORS LI POSOMAT1COS DE PRI NCI P ACTIVOS The present invention relates to stable liposomal vectors, in powder form, of active principles, and more particularly to active principles sensitive to digestive and / or plasma degradation, such as proteins, as well as their application as medicaments. Numerous vectors have been proposed to protect such brittle active ingredients; among these, liposomes should be mentioned, which have been considered as a selection vector. The first oral administration studies of liposomes were inconclusive (DESH MU KH DS, et al., Life Sciences, 1981, 28, 239-242). The results obtained showed that the iiposomes of the formulation: diether-phosphatidylcholine (non-digestible analogs of PC) / cholesterol-7: 1 allowed a gastrointestinal protection of the encapsulated peptide, but did not allow its passage through the intestinal barrier. Many reasons can be advanced to explain this lack of step: very large and uncalibrated liposome size, poor stability of the structure or leakage of the encapsulated compound towards the extra-liposomal medium. Recently, the team of Robert Greenwood (Drug Dev. And ind. Pharm., 1 993, 19, 11, 1303-1315), of the Campbell University in the USA, was successful in showing that duodenal intubation of liposomes that vectorize insulin causes a hypoglycemic effect superior to that obtained after duodenal intubation of a free insulin solution. Numerous tests have been carried out to obtain liposomes which have good capacities for transporting the active principles, in particular as regards the action on the percentage of capture of the active principle, the stability of the liposomes and the bioavailability of the active principle. Mention may be made, for example, by way of indication: - SB Kulkarni et al. (J. Microencapsulatión, 1995, 12, 3, 229-246) who pointed out the point about the factors involved in the microencapsulation of drugs in liposomes: Liposome size, liposome type, liposome surface charge, bilayer stiffness, addition of encapsulation aids. It is clear from this evaluation that MLVs (multilamellar vesicles) containing several bilayers and with a diameter between 100 nm and 20 mm are desirable for the encapsulation of hydrophobic drugs that interact with the bilayers, while the LUVs (large unilamellar vesicles) that they contain a single bilayer and of a size between 100 and 1, 000 nm are considered as the most appropriate for the encapsulation of hydrophilic medicaments. - I. De Miguel et al., (Biochimica et Biophysica Acta, 1995, 1237, 49-48), who propose nanoparticles composed of an internal nucleus formed of cross-linked polysaccharides, grafted externally by fatty acids and surrounded by a layer of phospholipids; - P. S. Uster et al., (FEBS Letters, 1996, 386, 243-246) who propose inserting phospholipids modified with a poly (ethylene glycol) in preformed liposomes to improve bioavailability. Series of experiments have been conducted regarding the administration of peptides by oral route and different methods of liposomal encapsulation have been used, either the modification of the lipid active principle by grafting lipophilic functions. In any case, the objective is to transform the lipid active ingredient into "prodroga"; This prodrug has the property of resisting gastrointestinal transit, that is, resistance to gastric pH, to physiological detergents (bile salts), to proteases (exo- and endo-peptidases intestinal) and to metabolization by the intestinal flora. For example, the bridging in position 2 of a 1,3-diglyceride on a pentapeptide allowed conferring these qualities to the drug thus modified. However, these different liposomes of the prior art do not allow to have at the same time a good stability, an encapsulation yield of the acceptable active principle and a significantly improved bioavailability per os of said active principle, without modifying the active principle, which thus preserves all its functions and properties. "Bio-availability" is understood as the fraction of the dose that reaches the systemic circulation under the pharmacologically active form and the speed with which it achieves it. J. C. Hauton, has described liposomes with a gelatinized inner core (lipogelosomas®) in suspension in aqueous medium containing gelling substances. He has developed, in particular, a process that allows to manufacture such liposomes (European Patent 0 393 049), which differ from classical liposomes in that the encapsulated aqueous phase is presented in the semi-solid form of gel and not under the liquid form, and this prevents fusions of liposomes during collisions. Such lipogelosomas® are produced only from natural substances, which minimize the risk of intolerance. In particular, in European Patent 0 393 049, these lipogelosomes® are constituted by a bilayer interfacial phase in the case of unilamellar lipogelosomes® or a plurality of concentrically overlapping bilayer phases, in the case of lipogelosomes® multi- laminates and by a gelled encapsulated internal aqueous polar phase, in which the gelled substance polymerizable or not is selected from polysaccharides, polypeptides or polyacrylamides; for example, the non-polymerizable gelatinizable substance is selected from gelatin, agarose or carrageenans and the polymerizable gelatinizable substance is selected from polyacrylamide gels. These lipogelosomes® have a significantly increased stability, by comparison with the liposomes of the prior art, particularly by the absence of inter-particle fusion during the crashes. However, they have the drawback of being presented in the form of a dispersion of liposomes in liquid phase, not adapted for the preparation of solid formulations, which are not easy to store and administer.

Accordingly, the Applicant has set himself the objective of providing a new vector, which effectively allows both to obtain a sufficient encapsulation efficiency and a significantly improved bioavailability per os of said active principle, in comparison with the liposomes of the art. previous, while presenting great stability both in storage and in vivo. Such vectors are adapted for oral administration; the aqueous solution is adapted for other routes of administration: transdermal, pulmonary, nasal, genital, intravenous, subcutaneous, or ocular, for example, depending on the selected excipient. Said vectors are characterized in that they consist of: a powder composition consisting essentially of unilamellar liposomes comprising an external lipid phase consisting of class 4 lipids (phospholipids), possibly associated with substances of class 2 (long chain triglycerides) , cholesterol esters), substances of class 3 (cholesterol, long-chain non-ionized fatty acids) and / or substances of class 5 (bile salts, derived from fusidic acid) and an internal aqueous core that forms a thermal, aqueous gel. reversible which irradiates only to the outer lipid phase, said inner aqueous core is constituted essentially of a mixture M of at least two non-polymerizable gelatinizing agents G1 and G2, different and where the gel-sol phase transition point is higher or equal to 37 ° C, with G 1 being a gelatinizing agent selected from gelatins and carrageenans, such as Kappa-carrageenans and G2 sie A selected group of carrageenans having properties different from the carrageenans selected for G 1, such as iota-carrageenans and celluloses, such as hydroxypropylmethylcellulose, said liposomes having a diameter comprised between 20 nm and 1 mm, preferably comprised between 20 nm and 500 nm and which are presented in the form of particulate units having an average diameter comprised between 10 mm and 1000 mm, formed of one or more of said liposomes, surrounded by a matrix selected from the group consisting of an aqueous thermal gel dehydrated reversible identical to the aqueous gel of said inner core, dextrins or a mixture thereof, such that it comprises, on average, 1016 to 1018 liposomes / g of powder, and - at least one active ingredient included, depending on the case, either in the gelatinized inner core, or in the outer lipid phase of the said composition. Surprisingly, such vectors overcome the drawbacks associated with conventional liposomes. Indeed, they allow: - increase the stability of the liposomes, due to the absence of inter-particle fusion during collisions, - increase the bioavailability of the active principle (protection in the gastrointestinal tract and passage through the intestinal barrier); in particular, in rats, the passage time of the vectors according to the invention (LGS) through the intestinal barrier from its administration by the oral route can be comprised between two and four hours: that is, one hour of gastric emptying and one to three hours of passage of the intestinal lumen towards the systemic circulation; thus, an active principle whose cellular internalization capacity is low or null can effectively be incorporated into a differentiated intestinal epithelial cell, when it is encapsulated in a vector (LGS) according to the invention, without modification of the activity or the composition of the active substance. - decrease the toxicity of the encapsulated active principles, and - result in less leakage of the encapsulated products, due to the lower molecular mobility in the gelatinized encapsulated aqueous phase. Unexpectedly, by selecting gelatinizing agents, it is possible to obtain liposomes (SUVs or small unilamellar vesicles), suitable for use in a dry form (powder) and having particularly interesting properties as active ingredient vectors.; in fact surprisingly, the bioavailability of the said active ingredients, preferably the active principles, sensitive to digestive degradation, poorly absorbed or very toxic, is significantly increased, when they are encapsulated or combined with the vector according to the present invention. In addition, such vectors in the form of powder retain all the integrity of the liposomes they contain and that remain stable over time, either in the form of powder and when in suspension, in order to maintain the integrity of the constituent lipids ( no degradation product) and maintenance of the integrity of the characteristics of the gelatinizing agents, in particular of the mixture G1 and G2 (viscosity, gel strength and rupture, molecular masses). The interest of the use of lipogelosomes® (LGS) in this context is to benefit from a stabilized liposomal form (JC Hauton et al., Eur. J. Surg., 1 994 suppl. 574, 1 17-1 19) in view of the administration of active principles orally. The mode of manufacture of the LGS allows obtaining, on average, degrees of encapsulation of the gelatinized hydrophilic phases close to 10%. This percentage varies, in particular as a function of the molecular weights of the active principle, and is calculated according to the ratio of amounts of encapsulated active principle / amount of active principle used. For example, at least 5% encapsulation is observed for a 500 Da molecule and at least 50% encapsulation for a molecule of at least 20 kDa. With respect to the peptides, for example 10 to 50% of encapsulation is observed, while generally for the group of active ingredients, the percentage of encapsulation varies from 5 to 80% depending on the case. The gelating agents G 1 and G 2 differ in particular as regards the viscosity, the molecular mass and the gel-sol transition point (ie, the melting temperature). For gelling agents G1, this temperature is less than or equal to 45 ° C, while it is greater than or equal to 45 ° C for gelling agents G2. The mixture M of at least two gelatinising agents G 1 and G 2, as defined above, present texturometric characteristics (gel strength and rupture) that are particularly interesting from the point of view of the stability of the liposomes obtained and the bioavailability of the encapsulated active principle. Thus, preferably, the mixture M of at least two gelatinising agents G1 and G2 has, at 5 ° C, relaxation characteristics comprised between 70 and 100%, preferably 81-89%, and a breaking force comprised between 1000 and 1600 g, preferably 1 109-1503 g. According to another advantageous embodiment of said composition, said inner aqueous core of the liposomes also comprise at least one stabilizing agent of glycosidic nature, and / or at least one agent for regulating the osmolarity of the medium and / or less a surfactant, such as a bile salt and / or a nonionic surfactant. Advantageously, said vectors comprise in% (m / m): to 75% of class 4 lipids, 5 with 45% gelatinizing agents, 0 to 70% of glycosidic stabilizing agent, 0 to 15% of osmorality regulating agent of the medium, 0 to 20% of surfactants and 0 to 15% dextrins, preferably 8 to 12%; this formulation does not include the active ingredients. According to another advantageous embodiment of said powder composition according to the invention, said aqueous inner core comprises from 70 to 95% of gelatinising agent G 1 and from 5 to 30% of gelling agent G2. According to another advantageous embodiment, said powder composition according to the invention, the stabilizing agent of the glycosidic nature is sucrose, trehalose or any other protection agent.

The subject of the present invention is also a method for preparing powder vectors according to the invention, in which the external matrix of the particulate units comprises a thermo-reversible aqueous gel fraction, characterized in that it comprises the following steps: (1) preparation of a dispersion of liposomes with gelatinized inner core (lipogelosomas®) in aqueous phase by (a) preparing a solution of at least one suitable gelatinizing agent, in particular a mixture M of gelatinising agents G1 and G2, by dissolution of said gelatinizing agents, under slow stirring, at a temperature above the gel-sol phase transition temperature of said gelatinizing agents in an aqueous solution with pH compatible with the active ingredient to be encapsulated, (b) incorporation of the principle active to the solution obtained in (a), (c) incorporation of the lipids in the solution obtained in (b), under slow agitation of the mixture, for a period of less than 5 hours, preferably under vacuum, and the formation of an emulsion, and (d) obtaining said dispersion of liposomes with gelatinized inner core (lipogelosomas®) in an aqueous phase containing the said gelling agents, m This is followed by rapid stirring of the emulsion obtained in (c), preferably under vacuum, and (2) obtaining the powder product by means of the appropriate drying of the dispersion obtained.

According to an advantageous embodiment of said process, the drying is carried out by atomization, coacervation, thin layer or granulation. The subject of the present invention is also a process for the preparation of powder vectors according to the invention, in which the external matrix of the particulate units comprise a thermo-reversible aqueous gel fraction and / or a dextrin, characterized in that it comprises the following steps: (1) preparation of a dispersion of liposomes with gelatinized inner core (lipogelosomas®) in aqueous phase by (a) preparation of a solution of at least one suitable gelatinizing agent, in particular a mixture M of gelatinizing agents G1 and G2, by dissolving said gelatinizing agents, under slow stirring, at a temperature higher than the gel-sol phase transition temperature of said gelatinizing agents in an aqueous solution with pH compatible with the active ingredient to be encapsulated, (b) ) incorporation of the active principle into the solution obtained in (a), (c) incorporation of the lipids into the solution ob held in (b), under slow stirring of the mixture, for a period of less than 5 hours, preferably under vacuum, and the formation of an emulsion, and (d) obtaining said dispersion of liposomes with gelatinized inner core (lipogelosomas®) in an external aqueous phase containing said agents gelatinizers, by rapid stirring of the emulsion obtained in (c), preferably under vacuum, (2) removal of at least a part of the aqueous liquid phase containing the said gelatinizing agents, in which the liposomes are dispersed, ( 3) the addition of at least one suitable dextrin, and (4) obtaining the powder product by spray drying the product obtained in (3). According to an advantageous embodiment of said process, the step (2) of elimination of at least a part of the aqueous liquid phase containing the said gelatinizing agents is carried out by dissolution and / or by filtration. According to the preparation processes according to the invention, the aqueous solution of step (a) further comprises an agent for regulating the osmolarity of the medium (0.9% NaCl, for example) and / or a stabilizing agent of nature glycosidic acid and / or a surfactant, preferably of the substances of class 5 (bile salts). As a variant, the active principle is added in the external lipid phase, before its incorporation into the mixture obtained in (a). For example, calcitonin is incorporated at pH 5, AZT at pH 7.5 and doxorubicin at pH 3. Surprisingly, such procedures make it possible to obtain a powder-form vector based on liposomes with stable geiatinized internal core (lipogelosomas®) in the course of a single stage comprising a phase of maturation (in the sense of maturation) of the constituents in aqueous phase, a slow speed, followed by a dispersion phase (formation of lipogelosomes®) with rapid speed, comprises a stage in which a stable dispersion of lipogelosomas® in liquid phase is obtained, of homogeneous morphology, which is apt to be subjected to the drying stage; such a dispersion of liposomes with gelatinized inner core presents, in effect, the following morphology: vesicular structure with a diameter comprised between 20 nm and 500 nm, preferably between 20 and 80 nm, • microscopic observations in negative coloration, cryofracture, cryotransmission and atomic force : vesicles or vesicle assemblies of characteristic aspects of phospholipid bilayers; the negative coloration makes it possible to observe the more or less marked presence of mixture M of gelatinizing agents surrounding the external phospholipid layer, and polydispersity of the liposomes with gelatinized internal phase comprised between 10 and 55%, preferably between 10 and 30%. Such a method has the advantage of being reproducible and perfectly adaptable to the industrial scale. It also has the advantage of being less heavy to be implemented than the prior art processes in which a sonication, extrusion or removal of detergents step is necessary, as described in the patent 0 393 049. According to a modality advantageous of said processes, step (c) is preferably carried out at a cutting speed lower than 200 s "1; generally, the cutting speed is given by the following ratio: speed of the stirring module / space between the internal wall of the reactor and the distal end of the stirring blade (also called "air space") The present invention also has as its objective a pharmaceutical composition, characterized in that it comprises a liposomal vector in powder form of active principle as defined herein and at least one pharmaceutically acceptable carrier According to an advantageous embodiment of said composition, presents in solid form (capsule of compressed gel, powder to dissolve in water). According to another embodiment of said composition, it also comprises an activator of cAMP. In addition to the foregoing provisions, the invention also includes other provisions, which will become apparent from the description that follows, which refers to the examples of implementation of the process object of the present invention as well as to the attached drawings, in which: Figure 1 represents the variations of the calcemia as a function of time (-D- = free calcitonin; -B- = LGS-calcitonin vector according to the invention); Figure 2 represents the difference of AUC between the calcemia obtained with the free calcitonin and that obtained after oral administration of the LGS-calcitonin vectors according to the invention; Figure 3 represents the variations of calciuria as a function of time (--------- = vector LGS calcitonin 500 kDa, - D- = free calcitonin, - a- = vector LGS calcitonin 300 kDa); Figure 4 represents the evaluation of phosphataemia as a function of time (-D- = free calcitonin; --------- = LGS-calcitonin vector according to the invention); Figure 5 represents the difference of AUC between the phosphathemia obtained with the free calcitonin and that obtained after oral administration of the LGS-calcitonin vectors according to the invention; Figure 6 represents the variations of phosphaturia as a function of time (-U- = LGS vector calcitonin (construction (PA-vector) of molecular weight at least above 500 kDa, equivalent to the lipogelosomes® that encapsulate calcitonin in diameter at least above 40 nm, - D- = free calcitonin, -O- = LGS vector calcitonin (construction (PA-vector) of molecular weight at least above 300 kDa, equivalent to the lipogelosomes® that encapsulate calcitonin Figure 7 represents the variations of the SGOT (UI / 1) as a function of time (-D- = free calcitonin; - • * - = LGS-calcitonin vector according to the invention); Figure 8 represents the variations of the SGPT (IU / 1) as a function of time (- D- = free calcitonin; - • * - = LGS-calcitonin vector according to the invention); Figure 9 represents the differences in AUC of the SGPT contents between the groups treated with free calcitonin and those treated with an LGS-calcitonin vector according to the invention. It should be well understood, however, that these examples are given solely by way of illustration of the purpose of the invention, therefore they do not constitute in any way a limitation. EX EMPLO 1: Mixing texturometry measurements of the gelatinising agents G 1 and G 2 a) Material and methods The measurements are made on a TA-XT2I apparatus of the Rhéo society. The study concerns the behavior of gels constituted by a mixture of gelatin, iota and kappa carrageenans during rupture and relaxation tests. • Sample concentration: Mix gelatin / iota / kappa carrageenan (80 / 17.5 / 2.5) at 7.5% w / V, in a medium of 5mM Na2HPO4 and 0.9 or 2% NaCl. - Preparation of a gelatinizing solution: Dissolve the sodium chloride in a mixer coupled with a turbine and a planetary and containing purified water (15 minutes at 10 turns / minute), increase the temperature of the mixer to 75 ° C (stirring at 10 turns per minute for 45 minutes), the gelatinizing agents (gelatin, iota carraghenanes, kappa carraghenanes) are added to the mixer at 75 ° C, the agitator speed is set to 1,500 rpm; the duration of the dissolution stage is approximately 30 minutes; The solution is complete when the solution is clear and does not contain particles in suspension. • Preparation of the samples: For the relaxation test, 45 ml of gel are poured hot into a petri dish with a flat bottom of 92 ± 2 mm external diameter. For the rupture test, 30 ml of gel are poured hot into a flat bottom crystallization vessel of 50 ± 2 mm external diameter. The gel is obtained by cooling to a temperature less than or equal to 37 ° C. The maturation temperatures of the gels, which correspond to a maximum hydration of the gels, is 2.5 days at the study temperature and at rest. • Operating conditions: For the relaxation test, a compressive force is applied to the gel for a certain time. The mobile element used is a 25 mm diameter aluminum cylinder with a pre-speed of 1.0 mm / s, a speed of 0.5 mm / s and a post-speed of 10.0 mm / s. The displacement of the moving element is 1.0 mm for 30 seconds. For the rupture test, the mobile element used is a 10 mm diameter ebonite cylinder with a pre-speed, a speed and a post-speed of 1.0 mm / s. The displacement of the mobile element is 12 mm. b) Results of a study at 5 ° C, with a NaCl content of 0.9% Relaxation% Minimum value: 81 ± 2.2 Maximum value: 89 ± 0.8 Bursting force (g) Minimum value: 1 109 + 25 Maximum value: 1503 ± 35 c) results as a function of temperature and different NaCl contents The operating conditions are identical to those described in a), except as regards the displacement of the mobile element used in the relaxation test (displacement of 20). % of the total thickness of the gel). Relaxation (%) at 5 ° C NaCl 0.9%: 89 ± 0.8 NaCl 2%: 90 ± 0.2 at 25 ° C NaCI 0.9%: 32 ± 3.9 NaCl 2%: 38 ± 4.4 at 37 ° C NaCI 0.9%: 36 ± 3.7 NaCI 2%: 40 ± 4.9 Bursting force (g) at 5 ° C NaCl 0.9%: 1413 ± 66 NaCl 2%: 1 1 14 ± 143 at 25 ° C NaCI 0.9%: 21 1 ± 2.7 NaCl 2%: 173 ± 1.5 at 37 ° C NaCl 0.9%: 25.7 ± 2.4 NaCl 2%: 45.7 ± 3.9 EXAMPLE 2: Preparation procedure for a powder vector according to the invention containing calcitonin 1) Preparation of a liposome dispersion with internal gelatinized phase (lipogelosomas®): - Constituents: Soy lecithins 1 1 .915 kg (7.943%) Gelatin B 150 7,149 kg (4,766%) Iota carrageenans 1,565 kg (1 .043%) Kappa carrageenans 0.222 kg ( 0.148%) Sucrose 8,936 kg (5,957%) Sodium chloride 1 .073 kg (0.715%) Purified water 1 19.15 kg (79.43%) TOTAL MATTER 150.01 kg (100%) a) Preparation of a dispersion of liposomes a mixture of: - Gelatin B 150 7.1 49 kg - Iota carrageenans 1,565 kg - Kappa carrageenans 0.222 kg - Sucrose 8,936 kg - Sodium chloride 1 .073 kg - Na + -chenodeoxycholate 1 .131 kg - Purified water 1 19.15 kg (cbp 150 kg) Pre-mixed in a mixer at a speed of 10 revolutions / minute, where the planetary rotates at the speed of 1500 revolutions / minute for 1.5 hours, under vacuum. b) Incorporation of calcitonin: With the help of concentrated acetic acid (6 N), the pH of the mixture is lowered by successive additions until a stable pH of 4.5 is reached. The addition of 4,075 g of salmon calcitonin (Bachem California), whose specific activity is 7017 IU / mg, is followed. c) Incorporation of the phospholipids to the solution obtained in a): The soy lecithins (1 1 .915 kg) are added to the pre-mix, in a mixer at the speed of 10 revolutions / minute, in which the planetarium rotates at the speed of 1500 revolutions / minute, for 5 hours, under vacuum (? formation of an emulsion). Final dispersion by increasing the agitation speeds of the planetary (25 revolutions / minute) and the turbine (2500 revolutions / minute) a sufficient time to obtain a polydispersity lower than 40%. A dispersion of lipogelosomes® in aqueous phase is obtained. Microscopic observations in negative coloration, cryofracture, cryotransmission and atomic force microscopy: vesicles or assemblies of vesicles of characteristic aspects of phospholipid bilayers; the negative coloration makes it possible to observe the more or less marked presence of external gelatinizer according to the selected manufacturing and / or separation process, d) Tangential filtration A volume of the lipogelosome® dispersion, obtained in the course of the preceding steps, is dilute in 20 volumes of NaCl to 0.9%, with heating, with agitation. The diluent (NaCl 0.9%) will be supplemented with 8.25x10"4% chenodeoxycholate, according to the presence of this surfactant, in the previous dispersion.The non-encapsulated phase is eliminated by tangential ultrafiltration continued with heat. filtration is carried out on a selective porosity membrane of 300 or 500 kDa, depending on the desired granulometry, of the lipogelosomes® The product obtained is a suspension of lipogelosomes®, which encapsulates at least 17% of salmon calcitonin, in the the diameters of the liposomes vary from 20 nm to 500 nm, when the suspension is ultrafiltered on 300 kDa and from 40 nm to 500 nm, when the suspension is ultrafiltered on 500 kDa.) 2) Drying of the obtained dispersion: The dispersion of the lipogelosomes® in the obtained aqueous phase is transferred to a vacuum dryer (50-100 mbars) for approximately 4 hours, obtaining a very homogeneous, pale yellow powder, very light, containing grains with a diameter of 0.1 mm and 1 mm. At the level of the electron microscopy observations, a retraction of the lipid vesicles on themselves was observed, due to the dehydration. Furthermore, it is noted that, while in the liquid state, the LGS are often added to a homogeneous gelatinized matrix in an environment of numerous isolated vesicular structures, the drying step transforms this gelatinous matrix into filaments of dry gelatinizer in the surface of aggregates, but also on the surface of isolated vesicular structures. As a variant, the drying is carried out as follows: the dispersion of lipogelosomes® in aqueous phase is distributed directly on a rotary cylinder dryer (cylinder temperature: 120-150 ° C, rotation speed 3-6 turns / min. ). The obtained "chips" are then grown and calibrated in a suitable screen. In this way, a powder of lipogelosomes® (hereinafter referred to as LGS) is obtained, which have the characteristics defined above. Drying can be used by the addition of a filler excipient, for example maltodextrin or β-cyclodextrins.EXAMPLE 3: Comparative effects of free or encapsulated calcitonin on the vectors obtained according to Example 2, after oral administration to rats. The effects of a preparation according to Example 2, on calcemia, calciuria, phosphatiaemia, and phosphaturia, are analyzed comparatively with the oral administration of calcitonin in free form. The pharmacokinetics obtained by the two forms of calcitonin administered are likewise compared.

Other parameters are also analyzed: transaminases (SGOT and SGPT) and glycemia. It is important to note that the effect of calcitonin in rats or in normocalcemic man is difficult to demonstrate, and that responses to this hormone are much more accurate when treating pathological (hypercalcemic) subjects. Experimental protocol - Preparation of LGS-Calcitonin. See Example 2 Animals and pharmacological treatment. Animals 10 groups of 10 Wistar Ico rats (IOPS AF / Han, I FFA CREDO) that is, 100 rats in total, ages of 6 weeks and weighing between 160 and 180 g, were constituted. The weight of the animals was measured at the beginning of the experiment in order to ensure, as a level of this parameter, a homogeneous distribution of the rats within each of the groups. The 6 experimental groups were pre-fed for 7 days with a sterile "AO4" -based base regimen (UAR = Usine d'Alimentation Rationnelle). The rats are fasted and on an ad libitum glucose regime 24 hours before the administration of the experimental doses. The weight of the animals is controlled before the administration of the experimental doses. Experimental scheme Groups A, B, C, D, E, F, G, H, I, J are carried out as follows: • group A: 10 controlled rats from which plasma and urine are taken at time 0. • Group B: 10 rats are intubated and 1.8 ml of LGS-Cal-500 kDa suspension is administered to each individual (approximate concentration in calcitonin: 54 IU / rat, ie 330 U l / kg). Plasma and urine are taken within 45 min. • Group C: 10 rats are intubated and 1.8 ml of LGS-Ca / 500 kDa suspension (approximate concentration in calcitonin: 54 U / rat, ie 330 IU / kg) is administered to each individual. Plasma and urine are taken within 90 min. • group D: 10 rats are intubated and each individual is administered 1.8 ml of LGS-Cal-500 kDa suspension (approximate calcitonin concentration: 54 IU / rat, ie, 330 IU / kg). The plasma and urine are taken in the time of 180 min. • group E: 10 rats are intubated and 1.8 ml of LGS-Cal-500 kDa suspension (approximate concentration in calcitonin: 54 U / rat, ie 330 IU / kg) is administered to each individual. The plasma and urine are taken in the time of 300 min. • group F: 10 rats are intubated and 1.8 ml of free calcitonin suspension (concentration: 54 U / rat, ie 330 IU / kg) is administered to each individual. Plasma and urine are taken within 45 min. • group G: 10 rats are intubated and 1.8 ml of free calcitonin suspension is administered to each individual (concentration: 54 IU / rat, ie, 330 U l / kg). Plasma and urine are taken within 90 min. • group H: 10 rats are intubated and 1.8 ml of free calcitonin suspension is administered to each individual (concentration: 54 IU / rat, ie, 330 IU / kg). The plasma and urine are taken in the time of 180 min. • group I: 10 rats are intubated and 1.8 ml of free calcitonin suspension is administered to each individual (concentration: 54 U / rat, ie 330 U l / kg). The plasma and urine are taken in the time of 300 min. • group J: 10 rats are intubated and administered to each individual 1.8 ml suspension of LGS-Cal-300 kDa (approximate concentration in calcitonin: 36 U / rat, ie 228 U l / kg). Plasma and urine are taken within 90 min. Anesthesia: anesthesia is performed with the help of Rompun® (Xylazine 2%, 10 mg / kg) / lmalgéne® Kétamine 10%; 60 mg / kg) by intraperitoneal injection according to the chronology indicated in the experimental scheme. Sampling Blood samples at the level of the abdominal aorta by catheterization under anesthesia are performed at time zero for group A; time 45 minutes for groups B and F; 90 minute time for groups C, G and J; 180 minute time for groups D and H; 300 minutes time for groups E and I; The gallbladder is also swallowed and the urine collected according to the same times as those used for blood sampling. The total plasma will be obtained after the separation of the blood samples by centrifugation at 3000 VPM, 15 minutes, in tubes containing 3.8% EDTA (non-protein anticoagulant). Analysis The calcémia, the phosphatémia, the transminasas will be assayed by colorimetry in each sample of plasma. Statistical treatment of the data The results of the measurements are expressed as an average ± SEM for the 10 rats in each group. The data will be compared through statistical tests appropriate to this type of experimental protocol (study of parameters and pharmacokinetics). The statistical test chosen is the ANOVA test or analysis of variance, the meanings of the differences are determined by the Fisher test and the Scheffe test which is more discriminant. Two methods of expression of the results were used: the graphical representation of the averages of 10 values relative to the considered parameter as well as the comparative analysis of the AUC (areas under the curve). This mode of expression allows us to appreciate the differences in amplitudes of the responses obtained.

The results obtained are represented according to the pharmacokinetic technique: variation of the degree of the parameter considered as a function of time. In this case, it is not an investigation of a dose effect. Results • Pharmacokinetics of the effect of free calcitonin or encapsulated in the form of LGS-Calc, on the calcemia. Figure 1 represents the variations of calcemia as a function of time. The tests used to determine the concentrations in calcium have been made by the colorimetric method consigned in the Pharmacopoeia. The base values of the calémies (at time 0) are well correlated with the previous data. Each point represents the average of 10 values, that is, 9 groups of 10 independent rats. The means are expressed ± SEM. The results are compared by analysis of variance (ANOVA), for odd values. The significant differences are symbolized by **. This symbol corresponds to a significance of the highly discriminating Scheffe test. There is a transient decrease in calcemia after oral administration of free calcitonin. It is explained by the fact that in the course of a massive administration of calcitonin-like peptide, a small percentage crosses the intestinal barrier (1%), without being denatured. In this case 330 ul was administered, which corresponds to a lymphatic passage of 3.3 U l (passage from the intestinal lumen to the plasma, via the lymphatic channel route). However, the IV effect of calcitonin starts at 0.9 U l. It is then normal to observe this effect of free calcitonin. The hypocalcemia observed after oral administration of calcitonin decreases with the course of time to return to normal after 90 minutes. As regards the LGS-Calc, the same effect is observed at 45 minutes, but this hypocalcemic effect is twice as important at 180 minutes. This fact indicates that the LGS formulation, with an equivalent concentration in calcitonin, is more effective in terms of pharmacological effect than free calcitonin. This bi-phasic phenomenon can be attributed to the activity of calcitonin bound to the outer layer of the LGS (first action), and the second effect could be due to the calcitonin contained within the LGS. A double retarded effect is then observed in an increase in the activity of the PA of a factor 2. Figure 2 represents the difference of AUC between the calcemia obtained with the free calcitonin and that obtained after the oral administration of the LGS- Calc. The difference observed is highly significant in the Scheffe test. The AUC corresponds to a cluster of all the values obtained in the course of the experiment; these values are integrated, and then compared. The AUC corresponds to the area under the curve of the variations of calcemia as a function of time. The smaller this AUC is, the greater the hypocalcemic effect (since the curve then approaches the axis of the abscissa).

• Pharmacokinetics of the effect of free calcitonin or encapsulated in the form of LGS-Calc, on calciuria. The restrictions mentioned with respect to the plasma results obtained by atomic absorption are confirmed by the analysis of the values obtained on the urine of rats treated with free or encapsulated calcitonin. Indeed, Figure 3 corroborates the values of Figure 1, since a hypocalcemia is always followed by an increase in calciuria. • Pharmacokinetics of the effect of free calcitonin or encapsulated in the form of LGS-Calc, on phosphataemia. (Figure 4) LGS-Calc and free calcitonin induce a hypophosphatemia (colorimetric test) which continues only in the case of the groups treated with LGS-Calc. The results are significant in Fisher's test. The comparison shown in Figure 5 of the respective AUCs confirms very clearly the pharmacokinetic data. The difference between the two AUCs is significant in the Scheffe test. • Pharmacokinetics of the effect of free calcitonin or encapsulated in the form of LGS-Calc, about phosphaturia. (Figure 6) The tests in the urine samples were performed by atomic absorption as in the case of calciuria (see above). These results are less significant than in the case of calciuria. Thus, it is difficult to reach a conclusion. However, it seems that in the time of 180 minutes, the effect of the LGS-Cale has a tendency to be higher than that of the non-encapsulated drug. - Toxicological aspect of the study. By means of the sampling carried out, it was possible to carry out the tests of the transminates in the course of the administration of the two active principles. The analysis of the contents of SGOT over time shows a tendency to hypotoxicity (Figure 7) of the encapsulated form of calcitonin compared to the free form. This difference is very significant in the Fisher test in the time of 300 minutes. However, the AUC comparisons do not show significant differences with respect to the variations of the SGOT contents over time. This tendency towards a moderation in the increase of transminates ("hypotoxicity") is confirmed by the analysis of the SGPT contents over time (Figure 8). These data show a strong hypotoxicity of the encapsulated form of calcitonin compared to the free form. Figure 9 shows the differences in AUC of the SGPT contents between the groups treated with free calcitonin and those treated with encapsulated calcitonin. The difference between the two areas is significant in the Scheffe test. This effect can be used particularly in the context of administration of highly toxic active ingredients, in order to reduce the hepatotoxic impact of such substances.Conclusion - The encapsulation of calcitonin in the LGS form potentiates the passage of the intestinal barrier. - The compared effect of oral administration shows a genuine potential of the LGS form, which is all the greater since it is now possible to stabilize this structure in powder form. - The bi-phasic hypocalcemic effect of LGS-Calc is explained by the distribution of calcitonin on the surface and in the center of the LGS. - This experimentation allows to measure in value the hypotoxicity of the LGS-Calc form in comparison with the free form, which seems more toxic. - Data demonstrating the superiority of the LGS-Calc vs free calcitonin form were acquired using the test method recommended in the pharmacopoeia. - The two peaks of hypocalcemia caused after oral administration of the two forms of PA were specified: 45 and 180 after administration. - The "delayed" effect of LGS-Calc could be due to a progressive release at the intestinal level of microspheres released from a mother matrix: the LGS-Calc concentrates, which penetrate little by little the intestinal barrier. EXAM PLO 4: Increased bioavailability of the encapsulated principles in the lipogelosome and derivative forms; comparison between liposomes and lipogelosomes®. 1 . Comparison of resistance or stability of the classic lipogelosomes® (LGS) and liposome (LS) forms. The LGS allow the realization of galenic forms (dust) impossible to perform with classical liposomal forms; alone, the LGS are resistant to physiological conditions: pH, temperature, intestinal motility, enzymes, which confers the ability to be administered orally or pulmonarily, while LS are destroyed, when administered by such routes. a) Resistance to pH and intestinal bile salts: series of LGS and LS incubations were carried out, one hour at 37 ° C in presence of bile salt (taurodeoxicholato) with detergent power, and thus destroyer front-to-front of the vesicles l ípidas. The results show that for a concentration of 0.25 mM in bile salt, LGS are three times more resistant than LS. The strength of the structures is analyzed by laser granulometry (variation of the level of counting of the particles, indicated by the variation of the diffraction of a laser, in Khz). The comparison of the structure (observed in laser granulometry) of the LGS and of the LS after one hour of incubation with the variable pH, shows that the LGS are stable from pH = 2.5 to 9 while the LS are mostly intact, only at pH = 6.3. The LGS are more resistant than the LS to the pH and to the concentrations in detergent, found in the stomach; this allows to deduce that the LS are degraded in the stomach, while the LGS resist more time. b) Resistance to the serum medium, temperature and agitation: LGS and LS incubation series were carried out for 24 hours at 37 ° with shaking. The lipid phases of the LGS and LS, rigorously identical in composition, were marked in the same way by an isotope (-C14). The products derived from the degradation of the two types of structures: LS or LGS were analyzed in the course of time. It seems, in light of the results, that the lipid constituents of the LS are released more easily than the lipid constituents of the LGS. These results show that the LGS form is more stable than the LS form. c) Comparison of the leakage of active ingredients encapsulated from the LGS and the LS: A small active principle (PA) (500 Da) was encapsulated in the LGS and the LS, in the same amount. Then, the two preparations were shaken at 37 ° C in a serum medium, and the release of the encapsulated PA was measured. The amount of PA released from the LS is 60% higher than the amount of PA released from the LGS (1.6 units of PA per LS, 1.01 units of PA for the LGS). By virtue of this significantly higher stability of the LGS, solid galenic (pharmaceutical) forms are feasible and oral administration is possible, while these can not be conceived with liposomes of conventional formulation. 2. Comparison of the bioavailability of conventional lipogelosomes® and liposome forms, in a cellular model.

The differences of cellular internment of a marker or a PA were analyzed when these molecules were encapsulated in the LGS (lipogelosomas®) or the LS (liposome) forms. a) Comparison of the cellular internals of the Hposomae and the lipogelosomes®: the LSs and the LGS were marked with the help of radioactive probes or fluorescent probes and, after a period of incubation in a medium in the presence of human macrophages (strain THP1) in culture at 37 ° C, the comparative hospitalization of the two types of structures (LS and LGS) at the end of the incubation was analyzed, the incubation durations being identical. The analysis of hospitalizations was carried out using various analytical methods. A. Fluorescence microscopy The images show an internalization of the LS and the LGS, but in the case of the LS the signal distribution is homogeneous, while the distribution of the LGS signal is localized in the intracellular punctate structures . This result shows that LGS are degraded less rapidly intracellularly than LS structures (where the signal diffuses more rapidly in the cell). Thus, there appears a slow diffusion effect of the active ingredients encapsulated in the LGS, while it does not exist for the LS. B. Radiolabelling The intracellular count of the labeled LGS radio and the marked LS radio shows that the LGS are 2.5 times more interned than the LS in the same experimental conditions. The LGS are hospitalized in larger quantity than the LS: this fact shows that the cellular bioavailability of the LGS is greater than that of the LS, this fact is due to the difference between the two liposomal structures: the presence of a thermoreversible gel In particular, in the internal phase of LGS, which radiates up to the surface of the particle, it gives the LGS a property of preferential cellular uptake. C. Flow cytometry These experiments rest on the compared cellular endocytosis of LGS and LS marked by a fluorescent probe. After incubation, the cells are cultured and then passed to flow cytometry, which quantifies the fluorescent signal within each cell. The obtained spectra show that the cells incubated with the LGS emit 2.5 times more fluorescent signal than the cells incubated with the LS. The LGS are hospitalized 2.5 times more than the LS: this fact shows that the cellular bioavailability of the LGS is greater than that of the LS. b) comparative cellular pharmacology of free lipogelosomes®-PA / PA: A. AZT and 3TC, effects on macrophages in culture: In these experiments, the LGS that encapsulate AZT or 3TC were incubated with human macrophage cells. The cytotoxicities of the free or encapsulated products in the LGS were analyzed. The results show that the encapsulated PAs are 150 times more effective than free AZT or 3TC, in terms of cytotoxicity against the macrophages in culture. These experiments show that, at equal doses, encapsulated PA is 150 times more active against macrophages than free PA, probably due to its better cellular internment. B. Doxorubicin and PEG 4000, effects on hepatocytes and differentiated intestinal epithelial cells, in culture: The cellular internment of two molecules was compared: doxorubicin and PEG 4000, according to whether their form is free or encapsulated in the form of LGS. In the same experimental conditions in time and concentration, the fact that the molecule is encapsulated causes an increase in its cellular incorporation or its pharmacological activity against cells of hepatic or intestinal origin, a factor that fluctuates from 1 .5 to 3. These experiments show that the bioavailability of the encapsulated molecules in the form of LGS is increased in comparison with their free form in intestinal epithelial cells or in hepatic parenchymal cells. c) Explanation of the modified bioavailability of molecules when they are in the form of LGS: Liposomes (LS) are usually internalized at the cellular level by a membrane fusion process, known as passive diffusion, that is, it does not involve secondary messengers responsible for the expression of a membrane receptor. However, the LGS different from the LS by the presence of a particular thermoreversible gel in the internal phase of the LGS, which radiates to the surface of the particle as well as by the presence of a gel film on its external surface. This gel is of the nature of a prothe-saccharide (a mixture of gelatin, carrageenans K and i). The differences of cellular internments and therefore of bioavailability between the LS and the LGS according to the invention reside essentially in the presence and composition of this gel. Differentiated or undifferentiated intestinal cells (strains: HT29, HT29gal, T84) were cultured on a semi-porous filter (diffusion chamber). The LGS were incubated with these cells in the presence or in the absence of cpt-cAMP. In the presence of cpt-cAMP, the hospitalization of LGS increased by a factor of two. This experiment shows that the entry of LGS is a phenomenon that depends on cAMP. In addition, the hospitalization curve of the LGS according to the dose shows that the phenomenon of hospitalization of the LGS is saturable. These two essential facts show that the internment of LGS is measured by a receiver. This inpatient procedure therefore differs from the processes of endocytosis by fusion of conventional liposomes, which do not depend on a receptor. Thus, the optimized bioavailability of the drugs encapsulated in LGS is explained by the involvement of a specific receptor for LGS. d) Bioavailability of forms lipogelosomas® in vivo in the rat: see example 3 e) Bioavailability of the forms lipogelosomas® in the diffusion chamber model: The intestinal epithelial cells were grown in confluence on a semi-porous filter to obtain a system of two compartments, which separate a "plasmatic" medium from a "intestinal lumen" medium. The LGS were placed next to the "intestinal lumen", after a period of incubation, the "plasma" medium was analyzed. In this compartment, structures that have the same characteristics as the LGS deposited at the beginning of the experiment in the "intestinal lumen" compartment are found by laser granulometry. The addition of a proportion of CDCA (chenodeoxycholate) in the LGS formulation increases the number of particles found in the "plasma" compartment. These experiments show that a proportion of LGS pass through the intestinal epithelium probably through a paracellular or transient passage process. This step is increased when the LGS formulation is modified by the addition of CDCA. Thus, it is possible to optimize the intestinal transepithelial passage (after oral administration, for example) of molecules encapsulated in the LGS; The LGS form allows to increase the intestinal bioavailability of the encapsulated molecules, this property is exacerbated when chenodeoxycholate is included in the LGS formulation. As it emerges from the preceding text, the invention is not limited in any way to the methods of implementation and application that have just been described more explicitly; on the contrary, it covers all the variations that can be made within the spirit of the person skilled in the art, without departing from the context, nor from the scope of the present invention.

Claims (10)

1. REIVI N DICATIONS 1. Liposomatic vectors of active principles, characterized in that they consist of: - a powder composition consisting essentially of unilamellar liposomes comprising an external lipid phase constituted by class 4 lipids (phospholipids), possibly associated with substances of class 2 (long-chain triglycerides, cholesterol esters), class 3 substances (cholesterol, non-ionized long-chain fatty acids) and / or substances of class 5 (bile salts, derived from fusidic acid) and an internal aqueous core that forms a thermoreversible aqueous gel that radiates up to the external lipid phase, said internal aqueous core is constituted essentially by a mixture M of at least two non-polymerizable gelatinization agents G 1 and G 2, different and whose gel-sol phase transition point is greater than or equal to 37 ° C, with G1 being a gelatinization agent selected from gelatins and carrageenans and s G2 selected from carrageenans having properties different from the carrageenans selected for G1, and celluloses, said liposomes having a diameter comprised between 20 nm and 1 mm, preferably between 20 nm and 500 nm and which is presented in the form of units in particles having an average diameter comprised between 10 mm and 1000 mm, formed by one or more of said liposomes, surrounded by a matrix selected from the group consisting of a dehydrated thermoreversible aqueous gel identical to the aqueous gel of said inner core , of dextrins or a mixture thereof, such that it comprises, on average, from 1016 to 1018 liposomes / g of powder, and - at least one active ingredient included, depending on the case, whether in the inner gelled core , or in the external lipid phase.
2. 2. Liposomatic vectors of active ingredients according to claim 1, characterized in that they also comprise, in their internal aqueous core, at least one stabilizing agent of glycosidic nature, and / or at least one agent for regulating the osmolarity of the medium and / or at least one surfactant, such as a bile salt and / or a nonionic surfactant.
3. 3. Liposomal active ingredient according to claim 1 or claim 2, characterized in that they comprise in% (m / m): 25 to 75% of class 4 lipids, 5 to 45% of gelatinizing agents, 0 to 70 % of stabilizing agent of glycosidic nature, 0 to 15% of regulation agent of the osmolarity of the medium, 0 to 20% of surfactants and 0 to 15% of dextrins.
4. 4. Liposomal active ingredient according to any one of claims 1 to 3, characterized in that said aqueous inner core comprises 70 to 95% gelatinising agent G 1 and 5 to 30% gelling agent G2.
5. 5. Liposomal active ingredient vectors according to any one of claims 2 to 4, characterized in that the stabilizing agent of glycosidic nature is sucrose, trehalose or any other protection agent.
6. 6. Method for preparing powder vectors according to any of claims 1 to 5, wherein the external matrix of the particulate units comprise a dehydrated thermoreversible aqueous gel fraction, characterized in that it comprises the following steps: (1) preparation of a dispersion of liposomes with gelatinized inner core (lipogelosomas®) in aqueous phase by (a) preparing a solution of at least one suitable gelatinizing agent, in particular a mixture M of gelatinising agents G1 and G2, by dissolving the said gelatinizing agents, under slow stirring, at a temperature above the gel-sol phase transition temperature of said gelatinizing agents in an aqueous solution with pH compatible with the active ingredient to be encapsulated, (b) incorporation of the active principle into the solution obtained in (a)(c) incorporation of the lipids in the solution obtained in (b), under slow agitation of the mixture, for a period of less than 5 hours, preferably under vacuum, and the formation of an emulsion, and (d) obtaining of the said dispersion of liposomes with gelatinized inner core (lipogelosomas®) in an aqueous phase containing the said gelatinizing agents, by rapid stirring of the emulsion obtained in (c), preferably under vacuum, and (2) obtaining the product in powder by proper drying of the dispersion obtained.
7. 7. Process according to claim 6, characterized in that the drying is carried out by atomization, coacervation, thin layer or granulation.
8. 8. Procedure for preparing the powder vectors according to any of claims 1 to 5, wherein the external matrix of the particulate units comprise a thermoreversible aqueous gel fraction and / or a dextrin, characterized in that it comprises the following steps: (1) preparation of a dispersion of liposomes with gelatinized inner core (lipogelosomas®) in aqueous phase by (a) preparing a solution of at least one suitable gelatinizing agent, in particular a mixture M of gelatinizing agents G1 and G2, by dissolving said gelatinizing agents, under slow stirring, at a temperature above the gel-sol phase transition temperature of said gelatinizing agents in an aqueous solution with pH compatible with the active ingredient to be encapsulated, (b) incorporation of the active principle to the solution obtained in (a), (c) incorporation of the lipids to the solution obtained in (b), under agi slow mixing of the mixture, for a period of less than 5 hours, preferably under vacuum, and the formation of an emulsion, and (d) obtaining said dispersion of liposomes with gelatinized inner core (lipogelosomas®) in an external aqueous phase containing the said gelatinizing agents, by rapid stirring of the emulsion obtained in (c), preferably under vacuum, (2) elimination of at least a part of the aqueous liquid phase containing the said gelatinizing agents, in which they are dispersed the liposomes, (3) the addition of at least one suitable dextrin, and (4) obtaining the powder product by spray drying the product obtained in (3).
9. 9. Process according to claim 8, characterized in that the step (2) of elimination of at least a part of the aqueous liquid phase containing the said gelatinizing agents is carried out by dissolution and / or by filtration.
10. 10. Process according to any of claims 6 to 9, characterized in that the aqueous solution of step (a) further comprises an agent for regulating the osmolarity of the medium (0.9% NaCl, for example) and / or a stabilizing agent of glycosidic nature and / or a surfactant, preferably of substances of class 5 (bile salts). 1. Preparation method according to any one of claims 6 to 10, characterized in that step (b) of incorporation of the active principle is carried out in the external lipid phase, before the incorporation of the latter in the mixture obtained in (to). Method according to any of claims 6 to 11, characterized in that step (c) is preferably carried out at a cutting speed of less than 200 s "1. 13. Pharmaceutical composition, characterized in that it comprises a liposomal vector of active ingredient according to any one of claims 1 to 5, and at least one pharmaceutically acceptable carrier 14. Composition according to claim 1, characterized in that it also comprises an activator of cAMP. Composition according to claim 13 or claim 14, characterized in that it is presented in solid form (gel capsule, tablet, powder to dissolve in water,) 16. Dispersion of liposomes with gelatinized inner nuclei in an aqueous solution containing the A mixture of gelatinizing agents as defined in claim 1, wherein said liposomes have the following morphology: structure. icular in diameter comprised between 20 nm and 500 nm, preferably between 20 and 80 nm, and polydispersity of the liposomes with gelatinized internal phase comprised between 10 and 55%, preferably between 10 and 30%. SUMMARY Stable liposomatics, in the form of powder, of active principles, and more particularly of active principles sensitive to digestive and / or plasma degradation, such as proteins, as well as their application as medicaments. The said liposomal active ingredient vectors consist of a powder composition consisting essentially of unilamellar liposomes comprising an external lipid phase consisting of class 4 lipids (phospholipids), optionally associated with substances of class 2, substances of class 3 and / or substances of class 5 and an internal aqueous core consisting essentially of a mixture M of at least two non-polymerizable gelatinization agents G 1 and G 2, and whose gel-sol phase transition point is greater than or equal to 37 ° C , G1 being a gelatinization agent selected from gelatins and carrageenans and G2 being selected from carrageenans having properties different from the carrageenans selected for G1, and celluloses, said liposomes having a diameter comprised between 20 nm and 1 mm, preference between 20 nm and 500 nm; said composition is presented in the form of particulate units having an average diameter comprised between 10 mm and 1000 mm, formed by one or more of said liposomes, surrounded by a matrix selected from the group consisting of an identical dehydrated thermoreversible aqueous gel. to the aqueous gel of said inner core, of dextrins or a mixture thereof, such that it comprises, on average, from 1.06 to 10 liposomes / g of powder and at least one active ingredient included, depending on the case, either in the internal gelled core, or in the external lipid phase.