EP1372730A1

EP1372730A1 - Use of lipoaminoacids as absorption promoters in a pharmaceutical composition

Info

Publication number: EP1372730A1
Application number: EP02724387A
Authority: EP
Inventors: Nicolas Calvet
Original assignee: Physica Sarl
Current assignee: Physica Sarl
Priority date: 2001-03-28
Filing date: 2002-03-28
Publication date: 2004-01-02
Also published as: WO2002076506A1; CA2441824A1; FR2828102B1; US20040147578A1; FR2828102A1

Abstract

The invention concerns the use, in a pharmaceutical composition comprising at least an active principle, of at least a lipoaminoacid consisting of the combination between a fatty acid and an amino acid, the fatty acid comprising 4 to 40 carbon atoms and the amino acid may be a natural, synthetic or modified amino acid, in native or salified form; the lipoaminoacid being either an intestinal absorption promoter, or a pulmonary absorption promoter, depending on whether the composition is respectively in galenic form for oral administration or in galenic form for pulmonary administration. The invention also concerns a dispersed system comprising such a lipoaminoacid, the dispersed system being in galenic form adapted to the mode of delivery.

Description

USE OF LIPOAMINOACIDS AS ABSORPTION PROMOTERS IN A PHARMACEUTICAL COMPOSITION

Technical area

The present invention relates to the field of pharmaceutical compositions and more particularly the use of lipoamino acids in pharmaceutical compositions as absorption promoters.

State of the prior art

A large part of the research carried out in the pharmaceutical field concerns the discovery of new active molecules, also called active principles. For a long time, the main source of new molecules was nature. In fact, most of the molecules were extracted from plants.

The evolution of technologies has made it possible to use new means of obtaining molecules. The first of these means is chemical synthesis. More recently, "drug design" and combinatorial chemistry have greatly increased the number of molecules of interest.

However, pharmaceutical research is not limited to the discovery of new molecules. Other lines of research have developed considerably. One of the other major areas of research is that of galenics.

Indeed, we now know that the pharmacological activity of an active principle does not depend solely on its chemical structure and therefore on its physicochemical properties, but also on its ability to reach its active site, that is to say the place where it acts and this in sufficient quantity. This property is called "bioavailability". The bioavailability of an active ingredient strongly depends on the route used to administer it. In fact, depending on the route of administration, the active principle will undergo more or less degradation. It is therefore important to choose the best route of administration for a given active ingredient. The most widely used route of administration is the oral route. This choice is clearly explained by the ease of swallowing a drug and by the fact that the digestive tract represents an interesting absorption site. Other routes of administration are also used: the cutaneous route, the pulmonary route and the route relating to the mucous membranes such as the mouth, the nose, the conjunctiva (inside of the eyelids), the vagina or the rectum. The cutaneous way is more and more used. It is the route of choice for topical drug applications, especially in the form of creams, ointments, gels or patches. This route allows the plasma compartment to be reached in certain cases through the skin barrier: this is called transdermal passage.

Administration at the level of the oral, nasal, conjunctiva (inside the eyelids), vaginal and rectal mucosa is also advantageous. These mucous membranes have in common to be constituted by a membrane lining the cavities of the organism and which is directly attached to the skin.

The pulmonary administration has other particularities. The constitution of the pulmonary alveoli is very specific and allows the active ingredient to pass directly into the blood, hence the interest of the method. The pulmonary administration is therefore distinguished from the administrations at the level of the mucous membranes as previously mentioned, as well as the cutaneous or oral administrations. However, the bioavailability of the active ingredients, when the drugs are administered by these routes, is often limited.

When it comes to the oral route, the gastrointestinal tract is the site of many enzymatic reactions. Also, the active ingredients, like food, undergo degradations which decrease strongly their concentration. An important step in this tract is the passage of the intestinal barrier, called resorption. The absorption of the active ingredients depends on their physico-chemical characteristics. Similarly, in the case of transdermal preparations, the active ingredients must cross the different layers of the epidermis. This absorption is a limiting step which is at the origin of a more or less important bioavailability. The method of administration by mucosal route, that is to say at the level of the mucous membranes directly attached to the skin, has additional characteristics compared to the cutaneous application. The pH levels in the mucous membranes are different. Different enzymes that can degrade certain active products are also present.

As for the pulmonary route, the presence of specific enzymes and mucosal cells in large numbers, imply a particular dosage form to allow the active principle to be absorbed.

It appears that, whatever the route of administration, only a fraction of the amount of active ingredient administered is found in the blood and reaches its site of action. In addition to the problems inherent in the route of administration, there are other factors which influence the bioavailability of the drug. Liver function is an important factor. In fact, the liver, which plays a filtering role in the body, plays a major role in the transformation of molecules. Thus, the fraction of active principle which arrives at the liver by the circulatory system, in free form or linked to plasma molecules, is often greater than that which leaves it. The action of the drug is all the more limited. It has been thought for a long time to combine in a formulation the active principles with other compounds, called excipients, making it possible to shape the drug, but also to protect the active principle in order to limit its degradation as much as possible.

The evolution of technologies has made it possible to set up new research avenues. Thus, we went from the simple combination of excipients and active ingredients, to the development of more complex systems, comprising several phases with different physico-chemical properties. Most of this research is aimed at improving the solubility of poorly soluble molecules. In fact, in the case of active principles administered orally, resorption can only be carried out properly when the molecule is dissolved in the digestive tract. The formulation plays a preponderant role because it makes it possible to choose compounds which, associated with the active principle, will improve its solubility.

Several approaches have been considered to improve the solubility of poorly soluble compounds. The first approach consisted in the association of surfactant compounds in solid or liquid state (such as sodium lauryl sulfate “SLS” or Polysorbate 80) with active principles in solid state, in very variable quantities, in tablets or capsules. However, these combinations only slightly improve the solubility of these compounds and require large amounts of surfactant. Such systems can lead to poor local tolerance.

A second approach consisted in the administration, directly in a liquid form, of very poorly soluble compounds already solubilized, organized in emulsified systems preferentially of the oil in water type. These systems were originally developed to provide parenteral nutrition (Intralipid ^® systems of the type, Japanese Patent No. 55 476) have been extended to the oral route, for the solubilization of hydrophobic insoluble active compounds. Such systems mainly concern active lipop iles molecules and have the drawback of being difficult to adapt to oral unit presentations. Recently, more sophisticated systems, constituting a "pre-concentrate" of surfactants and co-solvent have been developed. These systems form, in situ with gastric fluids, fine emulsions which make it possible to administer orally, active ingredients sparingly soluble in water, presented in unit form. These systems such as SEDDS ^® (Self Emulsifying Drug Delivery System) or SMEDDS ^® (Self Micro-Emulsifying Drug Delivery System, European patent EP-A-0 670 715) exist either in solid or liquid state. These systems are essentially intended to improve the solubility of hydrophobic active ingredients, by forming a fine emulsion with gastric fluids.

One of the drawbacks of such systems lies in the fact that the active compounds are capable of interacting with gastrointestinal fluids (effects of gastric juice, pH, bile salts, blood, pancreatic lipases).

Other encapsulation systems, semi-solid to solid, have been developed in order to improve the protection of the active ingredients in the gastrointestinal environment. These are micro or nanoparticulate systems called liposomes. These systems are formed by a stack of one to several layers of phospholipids, which contain either in their center or in the entire structure, the active ingredient (s). Such systems do not increase the solubility of the active ingredients but can improve the absorption of the latter.

It has been found that after oral absorption, these systems can be sensitive to pH, pancreatic lipases and digestive juices. They then become permeable and let diffuse external layers, the or active ingredients. Their use seems difficult in a unit form, suitable for the oral route. It has more particularly developed for the injectable or topical route. Other dispersed systems, of the oil-in-water type, form solid lipid particles which prevent leakage of active principle. In fact, by their essentially lipid composition and their solid character, these structures are less permeable and therefore limit the diffusion processes. Given their mainly lipid composition, the quantity of solubilized molecules is relatively small. This characteristic limits the applications to lipophilic molecules. It can also lead to a decrease in the speed of absorption of the active ingredients. Such compositions seem poorly suited to the oral unit form, given the aqueous nature of the dispersing phase.

American patent US-A-5, 897, 876 presents emulsified systems of the H / L type, that is to say made up of a hydrophilic phase dispersed in the lipophilic phase. These systems allow protection of the active ingredients against the destabilizing action of proteolytic enzymes and gastrointestinal fluids. However, these systems do not make it possible to improve the absorption of the active ingredients. In fact, the reduced proportion of the dispersed phase (less than 10%) limits the amount of active principle capable of being dissolved. In addition, the presence of ethanol in the hydrophilic part can lead to destabilization of the system and cause irritant effects at the cellular level.

As a result, the composition of these systems is not sufficiently adapted to allow the improvement of the absorption of the active molecules.

With regard to the cutaneous route, certain systems which have been developed consist of a preferentially oily vehicle in which the active principle is dissolved and of an adhesive part ensuring a prolonged cutaneous contact of the oily part. Because of their structure, these systems only apply to molecules that are active in low doses and easily cross the skin barrier. Other systems use lipo amino acids or acyl amino acids. Thus, in application EP 0552405A1, the acylamino acids are used as promoters of skin absorption in pharmaceutical compositions. These absorption promoters are not used in dispersed systems, but directly mixed with the composition. To improve the absorption of the compositions comprising these absorption promoters, the authors use an adhesive strip which is applied directly to the skin. In application EP 0418642A1, the acylamino acids are used as absorption promoters in the context of a transvaginal application. Again, these are not dispersed systems.

In the oral route, which represents the main route of administration, the aforementioned systems focus their approach on improving a single parameter. Indeed, some systems only act on the stability of the active ingredients by limiting the destabilizing effect of gastric juices and bile salts. Others focus on improving the solubility or absorption of the active ingredients.

Applications EP 0552405A1 and EP 0418642A1 are based only on the effect of the lipoamino acid improving the transmembrane passage of the active principle. Such compositions do not exhibit resistance to enzymatic degradations.

No composition is used for pulmonary use.

However, despite their interests, many molecules cannot be used as principles active in these systems due to their poor physicochemical properties (solubility, reactivity ...).

SUMMARY OF THE INVENTION The aim of the present invention is therefore to provide an original system using a compound capable of improving the absorption of the active pharmaceutical ingredients in a pharmaceutical composition, which can be administered in particular by oral route, by transdermal route. , or pulmonary. This improvement is observed in particular when the compound is intimately incorporated with other constituents, thus forming a system according to the present invention.

More specifically, the invention relates to the use in a pharmaceutical composition comprising at least one active principle, of at least one lipoamino acid constituted by the association between a fatty acid and an amino acid, the fatty acid comprising from 4 to 40 carbon atoms and the amino acid may be a natural, synthetic or modified amino acid, which may be in native or salified form; the lipoamino acid being either a promoter of intestinal absorption or a promoter of pulmonary absorption, depending on whether the composition is respectively in a galenic form suitable for oral administration or in a galenic form suitable for administration in the lungs.

Another subject of the invention is a dispersed system for pharmaceutical use comprising:

- at least one active ingredient,

- at least one lipoamino acid constituted by the association between a fatty acid and an amino acid, as an absorption promoter,

- a dispersing phase,

- a dispersed phase immiscible with the dispersing phase,

- at least one emulsifying agent, and - a free or esterified fatty acid; the fatty acid associated with the amino acid comprising from 4 to 40 carbon atoms and the amino acid may be a natural, synthetic or modified amino acid, which may be in native or salified form; the lipoamino acid being either a promoter of intestinal absorption or a promoter of pulmonary absorption, depending on whether the dispersed system is respectively in a galenic form suitable for oral administration or in a galenic form suitable for administration in the lung. The main function of the invention is to improve the absorption of the active ingredients in the body following oral administration, pulmonary administration or skin application.

The unexpected nature of the invention lies in the fact that the lipoamino acids can be used in dispersed systems without losing their property of absorption promoters. Another unexpected characteristic is that these lipoamino acids, when they are made up of 4 to 40 carbon atoms can also serve as absorption promoters at the pulmonary level and especially at the intestinal level.

Detailed description of the invention More specifically, the applicant has observed that the lipoamino acids constituted by the association of an amino acid and a fatty acid comprising from 4 to 40 carbon atoms, preferably from 4 to 22, constitute promoters of absorption particularly advantageous in the case of intestinal absorption or pulmonary absorption. These absorption promoters can therefore be used in the context of a pharmaceutical composition intended for oral or pulmonary administration. They can be used directly mixed with the active principle, the pharmaceutical composition then being in the form of a homogeneous phase. The dosage form of the composition is suitable for the mode of administration.

These lipoamino acids ci can also be used as absorption promoters in dispersed systems for pharmaceutical use comprising: at least one active principle, at least one of these lipoamino acids, a dispersing phase, a dispersed phase immiscible with the dispersing phase, - at less an emulsifier, and

- a fatty acid in the free or esterified state.

The advantage compared to a homogeneous composition, is that the dispersed systems make it possible to protect the active principle from enzymatic attacks, in particular at the pulmonary level and especially at the intestinal level. On the other hand, in the dispersed systems described by the prior art the active principle is protected from enzymatic attacks, but the passage of the active principle at the level of the tissue is reduced, despite sometimes the presence of an absorption promoter; thus the transmembrane passage is made less easily than in a homogeneous composition. However, the Applicant has observed that the lipoamino acids retain their absorption properties within a dispersed system. The dispersed systems according to the present invention therefore make it possible to combine the advantages of increased resistance to enzymatic degradation and of a high transmembrane passage.

The effects of lipoamino acid absorption promoters being preserved or improved within the dispersed systems, dispersed systems comprising these lypoamino acids can be used in particular for oral and pulmonary administration, but also cutaneous and mucosal administrations, that is to say concerning the mucous membranes of the mouth, nose, conjunctiva (inside the eyelids), vagina and rectum. For each of these administrations, the dispersed system must be presented in a dosage form appropriate to each administration. For oral administration, the dispersed system will be in the form of capsules or syrup. In this case, the lipoamino acid is used as a promoter of intestinal absorption. In the case of pulmonary administration, the dispersed system may in particular be administered in the form of a spray. In this case, the lipoamino acid is used as an absorption promoter in the lungs.

For skin or mucosal applications, such as the mouth, nose, conjunctiva (inside the eyelids), vagina or rectum, the dispersed system may be used in the form of a cream or gel. In this case, the lipoamino acid is used as an absorption promoter in these mucous membranes. In homogeneous compositions as in dispersed systems, the amino acid constituting the lipoamino acid is included in the group of synthetic or modified natural amino acids. In the group of natural amino acids, there may be mentioned by way of example, aspartic acid, glutamic acid, alanine, arginine, carnitine, choline, cysteine, glycine, histidine , Isoleucine, leucine, lysine, methionine, phenylalanine, proline, ornithine, taurine, threonine, tryptophan, tyrosine, serine or valine.

Also concerned by the invention are the lipoamino acid salts. The term “lipoamino acid salts” is intended to mean any derivative resulting from the ionic interaction between an organic or inorganic molecule with one or more reactive functions carried by the lipoamino acid.

In the case of a dispersed system, the lipoamino acid is present in a proportion of between 0.01 and 50% by weight.

In the dispersed system, the lipophilic phase comprises at least one lipophilic compound of natural, synthetic or modified origin. By way of example, we can cite, vegetable and mineral oils, waxes, fatty acids and their derivatives, fatty alcohols and their derivatives, cholesterol and its derivatives, lecit ines, phospholipids, derivatives of condensation of fatty substances with sugars, polyols and ethylene oxide or propylene oxide. This lipophilic compound preferably consists of a free or esterified fatty acid, present in a proportion of between 0.1 to 70% by weight. Depending on its composition, this lipophilic phase occurs in a liquid, semi-solid or solid state at room temperature.

Likewise, the hydrophilic phase comprises at least one hydrophilic compound of natural, synthetic or modified origin. By way of example, mention may be made of water, alcohols, hydrophilic compounds such as derivatives of propylene glycol, glycerol, glycols, polyols, polymers derived from the condensation of ethylene oxide or propylene oxide, hydrocolloids. Depending on its composition, this hydrophilic phase occurs in a liquid, semi-solid or solid state at room temperature. The dispersed system comprises at least one emulsifying agent, of natural, synthetic or modified origin. By way of example, mention may be made of the group of Sorbitan derivatives, alkylpolyglycosides, ethoxylated castor oil derivatives, glycerol and fatty acid esters, glycol and fatty acid esters, esters polyethylene glycol and fatty acid, esters of polyglycerol and fatty acid, ethers of polyethylene glycol and fatty alcohol, polymers based on ethylene oxide and propylene, acrylic, vinyl polymers.

Examples 1 to 8 describe formulations of dispersed systems comprising one or more lipoamino acids (in bold) and their preparation process. These dispersed systems are more particularly of the water in oil type (Examples 2 to 7), that is to say with a hydrophilic dispersed phase and a lipophilic dispersing phase. While Example 8 describes an oil-in-water dispersed system, that is to say with a lipophilic dispersed phase and a hydrophilic dispersing phase.

Four of these compositions were the subject of an in vitro permeation study. These are systems including progesterone, aciclovir and ciclosporin A.

These studies were carried out using the model most commonly used in in vitro permeation studies. This is the Franz cell consisting of two compartments separated by a membrane:

- a donor compartment in which the composition to be studied is deposited,

- a membrane previously impregnated with a lipid solution, consisting of a mixture of phospholipids,

- a receptor compartment containing an aqueous solution buffered to pH 7.4 under constant agitation, in which the active principle is recovered, at regular times. Depending on the case, the composition of the medium can vary depending on the physicochemical characteristics of the molecule.

These permeation studies were carried out by comparing each dispersed system comprising the lipoamino acid (s), with a simple solution of active principle. The results of these studies are presented in the form of a comparative table, following the formulations of the dispersed systems.

Permeation expresses an amount of active principle which diffuses through a membrane per unit of area and time (μg / cm ² / h).

The examples presented below are in no way limiting. Example 1; Process for the preparation of dispersed systems

The dispersed systems presented in Examples 2 to 7 are prepared according to the principle of a reverse emulsion. Example 8 is in turn prepared according to the principle of a direct emulsion.

The two phases are prepared independently:

A hydrophilic phase consisting of at least one hydrophilic compound and of the active ingredient (s), heated between 40 and 80 ° C.,

- A lipophilic phase consisting of at least one lipid compound, of the hydrophilic / lipophilic emulsifier or surfactant, generally a vegetable oil, natural or modified, heated between 40 and 80 ° C. Depending on the melting temperatures of the phases, we preferentially obtain

- a liquid / liquid dispersion

- a solid / liquid dispersion

- A solid dispersion such that these different dispersions are prepared according to conventional emulsification methods.

- Example 2: Dispersed system comprising an anti-acne compound, isotretinoline - Isopropyl myristate 31.5%

- 4.5% oleic acid

- Oleic lysine 4%

- 35% monopropylene glycol

- Demineralized water 3% - NaOH 32% 2.5%

- Magnesium sulfate 1%

- isotretinoin 5%

- PEG 30 polyhydroxystearate 13.5% - Example 3; Dispersed system for the oral route, comprising a hormone, progesterone

- Isopropyl myristate 9%

- Monopropylene glycol 50%

- Palmitic acid 2.5%

- Undecylenic glycine 10%

- NaOH 32% 6.3%

- Progesterone 0.2%

- Magnesium sulfate 1%

- Polyglycéril-2 polyhydroxystéarate 15%

- Demineralized water 6%

Results of the permeation study

Example 4 A dispersed system intended for the transdermal route, comprising a hormone, progesterone.

Soybean oil 31, 4% Oleic acid 10% lauroyl methionine 5%

Monopropylene glycol 30% progesterone 0.5%

NaOH 32% 3.1%

Magnesium sulfate 1%

PEG 30 polyhydroxystearate 15%

Demineralized water 4% Results of the permeation study

- Example 5; Dispersed system for the oral route, comprising an antiviral, aciclovir

- Soybean oil 20.3%

- 3.5% oleic acid

- Capryloyl glycine 6.5% - Monopropylene glycol 45%

- Aciclovir 0.5%

- 0.7% magnesium sulfate

- PEG 30 polyhydroxystearate 14.5%

- NaOH 32% 4% - Demineralized water 5%

Example 6; Dispersed system for the topical route, comprising an antiviral, aciclovir. - 1.8% oleic acid

- Capryloyl glycine 12%

- 9.5% monopropylene glycol

- Aciclovir 0.5%

- Magnesium sulfate 0.7% - PEG 30 polyhydroxystearate 4.5%

- NaOH 32% 21%

- Demineralized water 50% Results of the permeation study

- Example 7: Dispersed system intended for the oral route, comprising an immunosuppressant, ciclosporin A

- 6.3% sesame oil

- Oleic acid 4.5% - Capryloyl glycine 3.5%

- 40% monopropylene glycol

- Magnesium sulfate 0.5%

- 15% glucose syrup

- Alpha tocopherol 0.05% - Ciclosporin A 2%

- PEG 30 polyhydroxystearate 25%

- 1% demineralized water

- Sodium hydroxide 32% solution 2.15%

- Example 8; Oil-in-water dispersed system for the oral route, comprising an immunosuppressant, ciclosporin A

- Capryloyl glycine 15%

- 5% oleic acid

- Monopropylene glycol 50%

- Ciclosporin A 2%

- NaOH 32% 9%

- polysorbate 80 6.5%

- Demineralized water 12.5% Results of the permeation study

- Analysis of the results of the perm ation study;

It is found that, whatever the active ingredient tested, the permeation is significantly higher when the active ingredient is contained in a dispersed system comprising one or more lipoamino acids. These results therefore make it possible to conclude that a lipoamino acid preferably formulated in a dispersed system makes it possible to improve the transmembrane passage of an active principle and its absorption. Such a compound can therefore be used as a promoter of intestinal or pulmonary absorption. It can also be used in a dispersed system while retaining its absorption promoter properties.

It is likely that lipoaminnoacids come to organize themselves at the hydrophilic-lipophilic interface of emulsions because of their amphihpile property.

In addition, the nature of the amino acid (free or basic acid function) involved in the lipoamino acid, can promote the formation of ionic bonds with functions carried by the active ingredients, which makes it possible to strengthen the stability of the system, but also to contribute to the solubilization of the active ingredients.

The use of a dispersed system avoids the destabilizing action of pancreatic lipases and digestive juices, leaks and degradation of active ingredients. Indeed, and in some cases, the oily phase external of the dispersed system prevents the migration of gastrointestinal juices through it, to degrade the active ingredient and destabilize the dispersed system.

On the other hand, the cohesion of these dispersed systems allows intimate contact with the intestinal, pulmonary or dermal cells, which improves the availability of the discontinuous phase, in which the active principle is organized.

Claims

1. Use, in a pharmaceutical composition comprising at least one active principle, of at least one lipoamino acid constituted by the association between a fatty acid and an amino acid, said fatty acid comprising from 4 to 40 carbon atoms and said amino acid possibly being a natural, synthetic or modified amino acid, which may be in native or salified form; said lipoamino acid being either a promoter of intestinal absorption or a promoter of pulmonary absorption, depending on whether the composition is respectively in a galenic form suitable for oral administration or in a galenic form suitable for administration in the lungs.

2. Use according to claim 1, wherein said fatty acid associated with said amino acid comprises from 4 to 22 carbon atoms.

3. Use according to claim 1, wherein said amino acid is a natural amino acid selected from the group consisting of aspartic acid, glutamic acid, alanine, arginine, carnitine, choline, cysteine, glycine, histidine, isoleucine, leucine, lysine, methionine , phenylalanine, proline, ornithine, taurine, threonine, tryptophan, tyrosine, serine, valine.

4. Dispersed system for pharmaceutical use comprising:

- at least one active ingredient,

- a dispersing phase,

- a dispersed phase immiscible with the dispersing phase,

- at least one emulsifying agent, and - a free or esterified fatty acid; said fatty acid associated with said amino acid comprising from 4 to 40 carbon atoms and said amino acid may be a natural, synthetic or modified amino acid, which may be in native or salified form; said lipoamino acid being either a promoter of intestinal absorption or a promoter of pulmonary absorption, depending on whether the dispersed system is respectively in a galenic form suitable for oral administration or in a galenic form suitable for administration in the lungs.

5. A dispersed system according to claim 4, in which said fatty acid associated with said amino acid comprises from 4 to 22 carbon atoms.

6. A dispersed system according to claim 4 or 5, said amino acid is a natural amino acid chosen from the group consisting of aspartic acid, glutamic acid, alanine, arginine, carnitine, choline, cysteine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, ornithine, taurine, threonine, tryptophan, tyrosine, serine, valine.

7. Dispersed system according to any one of claims 4 to 6, wherein said dispersing phase is a lipophilic phase and said dispersed phase a hydrophilic phase.

8. Dispersed system according to any one of claims 4 to 7, in which said dispersing phase is a hydrophilic phase and said dispersed phase is a lipophilic phase.

9. Dispersed system according to any one of claims 4 to 8, in which the lipophilic phase comprises at least one natural, synthetic or modified lipophilic compound taken from the group consisting of oils. vegetable and mineral, waxes, fatty acids and their derivatives, fatty alcohols and their derivatives, cholesterol and its derivatives, lecithins, phospholipids, derivatives of condensation of fatty substances with sugars, polyols and ethylene and or propylene oxide, said compound being in a liquid, semi-solid or solid state at room temperature.

10. Dispersed system according to any one of claims 4 to 9, in which the hydrophilic phase comprises at least one natural, synthetic or modified hydrophilic compound taken from the group consisting of water, alcohols, hydrophilic compounds such as derivatives of propylene glycol, glycerol, glycols, polyols, polymers derived from the condensation of ethylene oxide or propylene oxide, hydrocolloids, said hydrophilic phase being in a semi-liquid state solid or solid at room temperature.

11. A dispersed system according to any one of claims 4 to 10, in which said natural, synthetic or modified emulsifying agent belongs to the group consisting of Sorbitan derivatives, alkylpolyglycosides, ethoxylated castor oil derivatives, esters of glycerol and fatty acid, glycol and fatty acid esters, polyethylene glycol and fatty acid esters, polyglycerol and fatty acid esters, polyethylene glycol and fatty alcohol ethers, polymers based on ethylene oxide and propylene, acrylic, vinyl polymers.

12. Dispersed system according to any one of claims 4 to 11, wherein said lipoamino acid is present in a proportion of between 0.01 and 50% by weight.

13. A dispersed system according to any one of claims 4 to 12, wherein said free fatty acid is present in a proportion of between 0.1 to 70% by weight.

14. A dispersed system according to any one of claims 4 to 13, in which said lipoamino acid is also a promoter of skin absorption when said dispersed system is in a galenical form suitable for skin application.

15. A dispersed system according to any one of claims 4 to 13, wherein said lipoamino acid is also an absorption promoter in the mucous membranes such as the mouth, nose, vagina, rectum or conjunctiva, when said dispersed system is in a dosage form suitable for administration at the level of these mucous membranes.