DE10244503A1 - Method for the preparation and stabilization of micro and nano suspensions with amphiphiles and polyelectrolytes - Google Patents

Abstract

The present invention describes the representation of stable suspensions of water-insoluble or water-insoluble organic compounds, in particular of pharmaceutical active substances, diagnostic substances or substances for food supplements. The particles produced by means of known grinding, precipitation or crystallization processes and having an average diameter of less than 5 μm are stabilized according to the invention with a capsule shell which is gradually built up from up to 8 layers of oppositely charged polyelectrolytes. In addition to the polyelectrolytes, the shell can also contain charged amphiphiles and, due to the special coordination between the thickness of the shell and its permeability, does not lead to any significant delay in the diffusion of dissolved active substance molecules out of the capsule. These capsules ensure that the release of the active substance takes place much faster than the dissolution of the active substance, starting from the state of an auxiliary substance-free powder. The capsules or their stable suspensions can be used to prepare new pharmaceutical preparations, in particular for the production of rapidly disintegrating lyophilisates, films and tablets.

Description

The present invention describes the representation and stabilization of aqueous micro or nano suspensions of poorly water soluble or water-insoluble, in particular pharmacologically active substances and their further processing to resuspendable dry powders. The crystalline produced here or spherical amorphous substance particles preferably have an average diameter less than 5 μm and show, especially in the nanometer range, an increased solution speed and an increased saturation solubility in the lower nanometer range. You are stabilized through the step-by-step, called LbL technology Encapsulation with at least two layers of oppositely charged electrolytes, at least one of which is a polymer. The capsule wall is conditional the stability of the suspension and provides for the encapsulated substance does not represent an essential obstacle to diffusion.

The application is less water-soluble or more insoluble in water Drugs and their bioavailability continues to pose a general problem in pharmaceutical Formulation (R. H. Müller, S. Benita, B. Bohm (Eds.) "Emulsions and Nanosuspensions for the Formulation of Poorly Soluble Drugs ", Medpharm Scientific Publishers, Stuttgart, 1998; C. Jacobs, O. Kayser, R.H. Müller, International Journal of Pharmaceutics (2000), 196, 2, 161-164; R. H. Müller, C. Jacobs, O. Kayser, Advanced Drug Delivery Reviews (2001), 47, 1, 3-19). Due to the low water solubility of such pharmacologically effective substances is a sufficiently quick and quantitative sufficient absorption in the gastrointestinal tract can hardly be achieved. The increase of bioavailability through direct intravenous or intraparenteral application is, however, also in many cases problematic.

In this regard, has already been shown that the increase the surface such poorly water-soluble or water-insoluble substances, i.e. the reduction of particle sizes to an increased dissolution rate and saturation solubility leads (B. H. L. Böhm, R.H. Müller, Pharmaceutical Science & Technology Today (1999), 2, 8, 336-339). By wording accordingly disperse systems with particle sizes smaller 1 μm and in particular less than 500 nm on the one hand, sufficient bioavailability can be achieved, on the other hand these formulations intravenously be administered and lead not to block the capillary system (K. Peters, The Journal of Antimicrobial Chemotherapy (2000), 45, 1, 77-83; K. Peters, R. H. Müller, European Journal of Pharmaceutical Sciences (1996), 4, 1, S44).

For the representation of such micro- or nanodisperse particles were different methods established. In addition to mechanical grinding techniques, such as dry grinding (ball mills, bead mills, air jet grinding) and wet grinding (Premier Mill Mill, Ball or pearl mill, Jet milling), also different precipitation techniques, such as Example the “via humida paratum "- the precipitation by pouring one drug solution in a non-solvent (Hager's Handbook of Pharmaceutical Practice, Springer-Verlag, Heidelberg, 1994).

All methods have in common that the micro- and nanodisperse particles produced in this way, in particular their aqueous suspensions, do not have sufficient stability without the addition of additives and are therefore already prepared in the presence of these additives ( DE3013839 . EP0499299 . EP0275796 . US6048550 , WO0151196, DE3579385D . DE4440337 ). They reduce the tendency towards aggregation and Ostwald ripening as the particle size decreases, and they also ensure the resuspendability of the corresponding dry powder. The additives used here are generally emulsifiers. Depending on the substance properties and application of the disperse particles, these are charged and uncharged surfactants, such as sodium dodecyl sulfate, quaternary ammonium salts or Tween derivatives, or else charged and uncharged protective colloids , such as polyvinyl alcohol, polyvinyl pyrollidones, gelatin, pectins or polyacrylates. They are generally used in such a quantity that a more than adequate surface coverage of the nanodisperse particles is ensured. Herein lies a decisive disadvantage of the technologies mentioned for the production and stabilization of disperse systems: The presence of considerable amounts of such amphiphilic substances or surfactants, polymers and other additives can lead to considerable “vehicle-associated toxicities” and due to the lower stability of such surface loading, aggregation can occur easily, especially when diluting and resuspending.

With regard to this problem, the present invention describes a new method for the preparation and stabilization of micro- and nanodisperse suspensions of organic compounds. These organic compounds are in particular from the groups of poorly water-soluble or water-insoluble pharmaceutical active substances, diagnostic substances and substances for food supplements and are also particularly characterized in that their solubility in saliva, gastric or small intestinal juice at 37 ° C is not greater than about 1 mg / ml. The use of oppositely charged natural or synthetic polymer electrolytes in the sense of LbL technology encapsulates and stabilizes the disperse particles. The fiction proper encapsulation ensures suspension stability and resuspendability. Due to the special coordination between the thickness of the shell and its permeability, it does not significantly delay the diffusion of dissolved active substance molecules out of the capsule and also leads to an increased dissolution rate and saturation solubility in the aqueous phase for particle sizes in the lower μm and especially in the nm range , In addition to improved bioavailability, this invention also ensures improved biocompatibility.

According to the invention, this is stabilized micro- and nanodisperse particles less water-soluble or water-insoluble organic substances, through the gradual build-up in layers a particle shell. This shell consists of at least one charged natural and / or synthetic Polyelectrolytes and at least one counterion, these in the Are able to build a sparingly water-soluble complex or a sparingly soluble To form salt. In particular can the counterions to be used here also belong to the class belong to the polyelectrolytes.

The representation of the encapsulated Particles of such an organic substance with average particle diameters less than 5 μm, especially with an average particle diameter of less than 1 μm and particularly preferably with an average particle diameter of less than 500 nm, can be done according to the known methods. These include in particular grinding the organic substance using dry or wet processes as well by precipitation or crystallization processes, such as by dilution or Removal of a solvent or solvent mixture, in which the poorly or insoluble active ingredient was previously dissolved. This will start with dependent on from the net surface charge a primary stabilization of the resulting substance particles Suspension carried out. This is done by coating with an opposite to particle surface charged polyelectrolyte or a monomeric or polymeric charged Amphiphile by removing the substance particles already during their manufacturing process by means of one of the methods mentioned or also after the manufacturing process in an aqueous solution a corresponding polyelectrolyte or amphiphiles suspended become.

The coating with an opposite to the particle surface charged polyelectrolytes take place here in particular if the micro- or nanodisperse substance particles generated via a for the Coating step have sufficient net surface charge. This is at least one ionizable chemically functional Group within the molecule of the given organic substance, this chemical-physical Property especially by setting a suitable one pH of the aqueous Suspension of this chemical substance can be regulated. The Coating with a loaded amphiphile takes place in particular when if the micro- or nanodisperse substance particles generated have a for the further coating steps are insufficient or none at all Net surface charge feature. This is primarily the case in the presence of a difficult to ionize or if there are no ionizable chemically functional ones Groups in the molecule of organic matter. In this case, the particle surface not due to electrostatic interactions but due to the hydrophobic nature Interaction, being a net surface charge caused by coating with a charged amphiphile results.

The stabilized in this way, that is, with a polyelectrolyte or a loaded amphiphile coated particle, will now by centrifugation, filtration or dialysis from the solvent or solvent mixture as well as the excess separated on charged amphiphile or polyelectrolyte. In a aqueous solution the particles thus obtained are then resuspended and again from solvent or solvent mixture Centrifugation, filtration or dialysis separated. This process step is optional and can be repeated several times after each coating step become. It ensures that excess polyelectrolytes or ampholytes that do not occupy the particle surface are completely washed out become. The further construction of the capsule layer takes place in such a way that the particles in an aqueous solution one contrary to the resulting net surface charge of particles charged polyelectrolytes - in case of a positive surface charge the solution a polyacid, in the case of a negative surface charge the solution one Polybase - resuspended become. This occurs due to electrostatic interactions between particle surface and the oppositely charged and dissolved in the aqueous phase polyelectrolyte to form a new polyelectrolyte layer and analogously to it, opposed to the formation of polyelectrolyte complexes between the charged electrolyte.

On the one hand, this leads to a substantial stabilization of the capsule shell and, due to the non-stoichiometric composition of the polyelectrolyte complexes formed, to a polarity reversal of the net surface charge of the particles. Both effects bring about the stabilization of the particle suspension according to the invention. Analogously to this process step, further polyelectrolyte layers can now be applied to the particle surface. In order to ensure a rapid release of the encapsulated organic compound, capsule walls with no more than 8 layers, in particular with no more than 5 layers and very particularly preferred with no more than 2 layers, the resulting capsule shells likewise being able to contain one or more lipids or lipoids.

For the purposes of this invention, an amphiphilic substance is a substance that has both a hydrophobic and an ionizable or ionic hydrophilic residue in its molecular structure. The presence of at least one ionizable or ionic chemical-functional group ensures that the particles coated with such an amphiphilic substance have a positive or negative net electrical surface charge. The group of positively charged amphiphiles described here includes, inter alia: quaternary ammonium salts (R ₄ N ⁺ X ^- ), tertiary ammonium salts (R ₃ NH ⁺ X ^- ) and N-alkylpyridinium salts. The group of negatively charged amphiphiles described here includes, among others: alkyl sulfonates (RSO ₃ ^- M ⁺ ), alkyl sulfates (RSO ₄ ^- M +), carboxylates (RCO ₃ ^- M ⁺ ), such as fatty acids and their salts or phosphoric acid esters, such as Example phosphoglycerides and phosphatides. In addition to the monomeric amphiphiles listed, however, polymeric amphiphiles can also be used which have both hydrophobic molecular residues and charged molecular residues, in particular proteins such as gelatins and synthetic polymers such as polystyrene sulfonates.

As a polyelectrolyte in the sense of the invention is a substance that is made up of those molecules in which a kind or several kinds of atoms or atomic groupings regular or also repeated irregularly are lined up and the ionizable or dissociable chemical functional groups and an average molecular mass of from a few hundred to a few million. Dependent on on the type of ionized or ionizable chemically functional Groups are generally differentiated between polymeric acids, polymeric Bases and polymeric ampholytes.

Polymeric acids in the sense of the invention in particular have the property that they are dependent from the pH of the surrounding aqueous Medium can release protons and then exist as a polymeric anion. According to this property one differentiates between weak and strong polymeric acids, whereby these are both synthetic and naturally occurring polymers can represent. examples for Are polyacids polyacrylic acids, polyvinylsulfonic, polyvinylphosphonic, polyphosphoric acids, polymaleic, polystyrenesulfonic polylactic acids, polyglycolic acids, Carboxymethylcelluloses, carboxymethyldextrans, hyaluronic acid, chitosan sulfates, Cellulose sulfates, sulfoethyl celluloses, chondroitin sulfates, dextran sulfates, Carageenans, pectins, gum arabic, lignin sulfates, nucleic acids, alginic acids also corresponding copolymers. in the For the purposes of the invention, the term polyacids also includes the corresponding ones Polyanions of polyacids.

Polymeric bases in the sense of the invention in particular have the property that they are dependent from the pH of the surrounding aqueous Medium can hold protons and then exist as a polymeric cation. According to this property one differentiates between weak and strong polymeric bases, these being both synthetic and naturally occurring polymers can represent. examples for Polybases are polyvinylamines, polyvinylpyridines, polyallylamines, Polyethyleneimines, ammonium salts of polyacrylates, aminated dextrans, aminated celluloses, aminated pectins, chitosan, polylysine, spermine also corresponding copolymers. Included in the sense of the invention the term polybases also the corresponding polycations the polybases. For the purposes of the invention, polymeric substances also count the quaternaries Have ammonium groups, such as polydiallyldimethylammonium chlorides or trimethylchitosan chlorides, to the group of the polymeric bases, because they have a permanent positive charge.

Have polymeric ampholytes in the sense of the invention in particular the property that they are dependent on the pH of them surrounding watery Medium preferred as polyacids or can occur as polybases. In particular, here are examples, such as proteins, such as serum albumins and mention gelatin.

The capsules described in the sense of the invention are thus particularly characterized in that the layers the shell surrounding the core, individually one after the other by adsorption or electrostatic self-assembly be generated. This allows precise control of the number of layers inside the capsule wall and thus also the control of the average Capsule wall thickness. Capsules are preferred in the context of this invention, which are made up of 2 to 8 layers, making the capsule shells one average thickness of no more than about 20 nm and preferably have no more than about 10 nm. Through the adsorption of polyelectrolytes they are additional characterized by a positive or negative zeta potential with an amount of at least 10 mV, preferably at least 20 mV. That through the capsule shell resulting stability of this Suspensions allow these particles to be dissolved in suitable aqueous solutions Phases are suspended and subjected to freeze drying can be.

The special property of these capsules is the combination of small particle size, high suspension stability, controllable capsule wall thickness and high permeability as well as a high dissolution rate of the sparingly water-soluble or water-insoluble organic substance. This combination ensures that the described capsules release at least 90 percent by weight of their active ingredient within 15 minutes under “sink conditions”. This release takes place much faster than the active ingredient dissolution starting from the state of an auxiliary-free powder.

The capsule described consists of a core that contains poorly soluble organic substances, especially of poorly soluble active ingredients, of at least 50 percent by weight. These capsules or the stable suspensions of these particles are used in particular for Manufacture of pharmaceutical preparations of these active ingredients. in this connection are oral, parenteral, pulmonary, nasal, ophthalmic, dermal or transdermal applications preferred. In addition to representing pharmaceutical Suspensions, they are particularly suitable for the production of solid, quick-release Preparations of the slightly soluble Active ingredient for oral applications suitable. These include, among others for use in the production of rapidly disintegrating lyophilisates, rapidly disintegrating films and also rapidly disintegrating tablets, which in particular for the treatment of acute illnesses or symptoms are suitable.

Claims (36)

Capsule with an average particle size of not more than 5 μm, characterized by a core containing an active ingredient which is sparingly soluble in water, and an envelope with high permeability for the Active ingredient, the shell at least one polyelectrolyte and at least one counter ion to Contains polyelectrolyte, and wherein the polyelectrolyte and the counter ion are able one that is sparingly soluble in water Complex or a poorly soluble salt to form with each other. Capsule according to claim 1, characterized in that the counter ion to the polyelectrolyte is also a polyelectrolyte. Capsule according to claim 1 and 2, characterized in that that the or one of the polyelectrolytes is a positively charged substance selected from the group comprising the natural and / or synthetic polybases or their corresponding salts, especially from the group of polyvinylamines, polyvinylpyridines, Polyallylamines, polyethyleneimines, ammonium salts of polyacrylates, aminated dextrans, aminated celluloses, aminated pectins, chitosans, Polylysine, spermine, spermidine but also corresponding copolymers as well as polymeric substances with quaternary ammonium groups, such as Example polydiallyldimethylammonium chloride or trimethylchitosan chloride, is. Capsule according to claims 1-3, characterized in that the or one of the polyelectrolytes is a negatively charged substance selected from the group comprising the natural and / or synthetic polyacids or their corresponding salts, in particular from the group polyacrylic acids, polyvinylsulfonic, polyvinylphosphonic, polyphosphoric acids, polymaleic, polystyrenesulfonic polylactic acids, polyglycolic acids, Carboxymethylcelluloses, carboxymethyldextrans, hyaluronic acid, chitosan sulfates, Cellulose sulfates, sulfoethyl celluloses, chondroitin sulfates, dextran sulfates, Carageenans, pectins, gum arabic, lignin sulfates, nucleic acids, alginic acids also corresponding copolymers belong, is. Capsule according to claims 1-4, characterized in that the shell composed of several layers and preferably of 2 to 8 layers is. Capsule according to claims 1-5, characterized in that the layers of the shell on the core one by one by adsorption or electrostatic Self-assembly are generated. Capsule according to one of the preceding claims, characterized characterized that the envelope additionally contains one or more lipids or lipoids. Capsule according to one of the preceding claims, characterized characterized that the envelope is a low molecular or polymeric ionic amphiphilic substance with contains which with the surface of the core is in direct contact. Capsule according to one of the preceding claims, characterized in that the low-molecular ionic amphiphilic substance selected from the group comprising the quaternary ammonium salts (R ₄ N ⁺ X ^- ), tertiary ammonium salts (R ₃ NH ⁺ X ^- ), N-alkylpyridinium salts or a mixture this, alkyl sulfonates (RSO ₃ ^- M ⁺ ), alkyl sulfates (RSO ₄ ^- M ⁺ ), carboxylates (RCO ₃ ^- M ⁺ ), such as, for example, fatty acids and their salts or phosphoric acid esters, such as, for example, phosphoglycerides and phosphatides, or a mixture thereof , is. Capsule according to one of the preceding claims, characterized characterized in that the polymeric ionic amphiphilic substance selected from the group comprising proteins, such as gelatins or synthetic Polymers, such as polystyrene sulfonates and their copolymers, is. Capsule according to one of the preceding claims, characterized characterized that the envelope is a average thickness of no more than about 20 nm and preferably has no more than about 10 nm. Capsule according to one of the preceding An Sayings, characterized in that the average thickness of the shell is matched to its permeability so that it does not significantly delay the diffusion of dissolved drug molecules out of the capsule. Capsule according to one of the preceding claims, characterized characterized that under sink conditions it is at least 90% by weight releases its active ingredient within 15 minutes. Capsule according to one of the preceding claims, characterized characterized that their drug release under sink conditions happens faster than the drug dissolution based on the condition of an excipient-free powder. Capsule according to one of the preceding claims, characterized by an average particle size of not more than 5 μm, preferably not more than 1 μm, and in particular not more than 500 nm. Capsule according to one of the preceding claims, characterized by a positive or negative zeta potential with an amount of at least 10 mV, preferably of at least 20 mV. Capsule according to one of the preceding claims, characterized characterized that the core has a content of poorly soluble Active ingredient of at least 50 wt .-%. Capsule according to one of the preceding claims, characterized characterized that solubility of the sparingly soluble Active ingredient in saliva, gastric or small intestinal juice is not greater at 37 ° C than about 1 mg / ml. Capsule according to one of the preceding claims, characterized characterized in that the active ingredient is a pharmaceutical active ingredient, is a diagnostic or nutritional supplement. A method of manufacturing capsules according to claim 1, characterized by the steps: (a) Providing one Slightly soluble suspension Active substance with an average particle size of no more than 5 μm; (B) Coating the suspended from step (a) Active substance particles by adsorption of a polyelectrolyte; (C) Coating of the polyelectrolyte obtained in step (b) Active substance particles by adsorption of a counter ion to the polyelectrolyte. A method according to claim 20, characterized in that the or one of the polyelectrolytes is a positively charged substance selected from the group comprising the natural and / or synthetic polybases or their corresponding salts, especially from the group of polyvinylamines, polyvinylpyridines, Polyallylamines, polyethyleneimines, ammonium salts of polyacrylates, aminated dextrans, aminated celluloses, aminated pectins, chitosans, Polylysine, spermine, spermidine but also corresponding copolymers as well as polymeric substances with quaternary ammonium groups, such as Example polydiallyldimethylammonium chloride or trimethylchitosan chloride, is. A method according to claim 20 and 21, characterized in that the or one of the polyelectrolytes is a negatively charged substance selected from the group comprising the natural and / or synthetic polyacids or their corresponding salts, in particular from the group polyacrylic acids, polyvinylsulfonic, polyvinylphosphonic, polyphosphoric acids, polymaleic, polystyrenesulfonic polylactic acids, polyglycolic acids, Carboxymethylcelluloses, carboxymethyldextrans, hyaluronic acid, chitosan sulfates, Cellulose sulfates, sulfoethyl celluloses, chondroitin sulfates, dextran sulfates, Carageenans, pectins, gum arabic, lignin sulfates, nucleic acids, alginic acids also belong to corresponding copolymers. A method according to claim 20-22, characterized in that the suspension provided in step (a) is previously precipitated of the active ingredient was manufactured. Method according to claims 20-23, characterized in that precipitation through the dilution or removal of a solvent or solvent mixture in which the sparingly soluble Active ingredient previously dissolved Template. A method according to claim 20-22, characterized in that the suspension provided in step (a) beforehand by grinding of the active ingredient was manufactured. A method according to claim 20-25, characterized in that the suspension provided in step (a) as a stabilizer contains an amphiphilic substance. Method according to claims 20-26, characterized by An additional Step between step (a) and step (b), in which the in Step (a) provided, suspended active ingredient particles first Adsorption coated with an ionic amphiphilic substance become. A method according to claim 20-27, characterized in that the or one of the ionic amphiphiles selected a low molecular weight substance from the group comprising the quaternary ammonium salts (R ₄ N ⁺ X ^- ), tertiary ammonium salts (R ₃ NH ⁺ X ^- ), N-alkylpyridinium salts or a mixture of these, alkyl sulfonates (RSO ₃ ^- M ⁺ ), alkyl sulfates (RSO ₄ ^- M ⁺ ), Carboxylates (RCO ₃ ^- M ⁺ ), such as, for example, fatty acids and their salts or phosphoric acid esters, such as, for example, phosphoglycerides and phosphatides, or a mixture of these. Method according to claims 20-28, characterized in that the or one of the ionic amphiphiles is a polymeric substance selected from the group comprising proteins, such as gelatins or synthetic polymers such as polystyrene sulfonates and whose copolymers. Method according to claims 20-29, characterized by An additional Step after step (b) and / or step (c), in which the coated Active ingredient particles are washed. Method according to claims 20-30, characterized by an average particle size of no more than 5 μm, preferably not more than 1 μm, and in particular not more than 500 nm. Use of capsules according to one of the preceding Expectations for the preparation of a pharmaceutical preparation of the active ingredient for oral, parenteral, pulmonary, nasal, ophthalmic, dermal or transdermal application. Use of capsules according to one of the preceding Expectations for the production of a solid, quick-releasing preparation of the slightly soluble Active ingredient for the oral application. Use according to one of the preceding claims Production of a rapidly disintegrating lyophilisate, a rapidly disintegrating one Film or a rapidly disintegrating tablet. Use according to one of the preceding claims Preparation of a preparation for the treatment of acute diseases or symptoms. Use of capsules according to one of the preceding Expectations to produce a stable suspension or nanosuspension of the slightly soluble Active ingredient.