CH686226A5 - Slow release micro:particles contg. peptide hormone - Google Patents

Abstract

Prepn. of new microparticles, contg. an active ingredient (I) in a biodegradable, biocompatible polymeric carrier (II) comprises (1) dissolving (II) in solvent in which (I) does not dissolve; (2) dispersing in this soln. a soln. of (I) in a solvent in which (II) does not dissolve; (3) adding a phase-inducing agent to form microparticles (MP); (4) adding an oil-in-water emulsion to harden MP, then (5) isolating MP.

Description

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description

This invention relates to slow release formulations of active ingredients, particularly water soluble peptides, e.g. Somatostatin or somatostatin analogues such as octreotide in a biodegradable and biocompatible polymeric carrier material, e.g. as a matrix or envelope, which can be present as an implant or preferably as a microparticle (is also indicated as a microcapsule or micro-gei).

The invention also relates to formulations which have a satisfactory peptide release profile for a certain period of time.

Peptide drugs often show low bioavailability in plasma when given orally or parenterally, which is due to the short biological half-life due to metabolic instability. When administered orally or nasally, there is usually little mucosal absorption. For this reason, a therapeutically relevant blood level is difficult to achieve over a long period of time and the parenteral use of peptide active ingredients as depot formulations in a biodegradable polymer, e.g. as microparticles or implants, has been proposed, which enable their slow release after a stay in a polymeric carrier. This carrier protects the active ingredient against enzymatic and hydrolytic influences of the biological media in which it is located.

Although parenteral depot formulations of peptide active substances in a polymer carrier in microparticles "or implant form are known from the literature, satisfactory peptide releases are obtained in practice only in very few cases. Special measures must be taken in order to enable a continuous peptide release which is therapeutic effective level and still does not allow such high plasma concentrations that undesirable pharmacological side reactions occur.

The peptide drug delivery professional! depends on various factors, e.g. of the peptide type and whether the peptide is in its free form or another form, e.g. the salt form, which affects its water solubility. Another important factor is the choice of polymers, an extensive list of which is described in the literature.

Each type of polymer has its characteristic rate of degradation. During the breakdown, free carboxyl groups can be formed which influence the pH in the polymer and thereby the water solubility of the peptide and, as a result, its release profile.

Other factors that influence the release profile of the depot formulation are the degree of drug loading of the polymeric carrier material, the drug distribution in the polymer, the particle size of the polymer and, in the case of an implant, its shape. Furthermore, the place in the body where the formulation is located is also a determining factor.

So far, no slow release somatostatin compositions have appeared on the market for parenteral use, perhaps because no compositions with a satisfactory plasma level profile could be obtained.

DESCRIPTION OF THE PRIOR ART

Polymer formulations with slowed or delayed active ingredient release are known. U.S. Patent No. 3,773,919 describes controlled release formulations in which the active ingredient, e.g. a water soluble peptide dispersed in a biodegradable and biocompatible linear polylactide or polylactide-co-glycolide polymer. However, no drug release profiles have been described and no evidence of somatostatin has been given. U.S. Patent No. 4,293,539 describes antibacterial formulations in the form of microparticles.

U.S. Patent No. 4,675,189 describes formulations of the decapeptide LHRH analog Nafa-relin and analog LHRH relatives in polylactide-co-glycolide polymers. No release profiles were described.

T. Chang, J. Bioeng., Vol. 1, pp 25-32, 1976, describes the slow release of biological products, enzymes and vaccines from microparticles. Polymers / copolymers of lactic acid and lactide / glycolyd copolymers and related products for surgical use and for slow release and biodegradation are disclosed in U.S. Patent Nos. 3,991,776; 4,076,798 and 4,118,470.

European Patent Application No. 0 203 031 describes a number of somatostatin octapeptide analogs, e.g. Compound RC-160 with the formula

* *

D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2,

which has a bridge between the two Cys units, in columns 15-16.

The possibility of microencapsulating somatostatins with polylactide-co-glycolyd polymers is

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Proverb 18 described, but no information is given on how to achieve a continuous, therapeutically effective plasma level.

U.S. Patent No. 40 111 312 describes that continuous release of an antimicrobial agent, e.g. of the water-soluble polymyxin B from a polylactide-co-glycolyd matrix with a low molecular weight (below 2000) and a relatively high glycolyd content in the form of an implant can be obtained when the implant is pushed into the udder tube of a cow. The active ingredient is then released within a short period of time thanks to the high glycolide content and the low molecular weight of the polymer. These factors stimulate rapid polymer degradation and associated rapid release. A relatively high level of active ingredient also contributes to rapid release. However, no somatostatins and no drug release profiles have been described.

European Patent No. 58,481 describes that a continuous release of a water-soluble peptide from a polylactide polymer implant by lowering the molecular weight of at least some of the polymer molecules, by incorporating glycolide units into the polymer molecule, by enhancing the block polymer character of the polymer when polylactide-co- Glycol molecules are used, stimulated by increasing the degree of drug loading of the polymer matrix and by increasing the surface area of the implant. Although somatostatins are mentioned as water-soluble peptides, no somatostatin release profiles have been described, nor have indications been given on how to combine all of these parameters to achieve a continuous somatostatin release profile for at least one week, e.g. one month.

European Patent No. 92,918 describes that continuous release of peptides, preferably hydrophilic peptides, can be obtained over a longer period of time when the peptide is in a conventional hydrophobic polymeric matrix, e.g. of a polylactide, which has been made more accessible to water, by means of which a hydrophilic unit, e.g. a polyethylene glycol, polyvinyl alcohol, dextran or a polymethacrylamide is added. The hydrophilic contribution to the amphipathic polymer is provided by the ethylene oxide groups in the case of a polyethylene oxide unit, by free hydroxyl groups in the case of a polyvinyl alcohol unit or a dextran unit and by the amide group in the case of a polymethacrylamide unit. The presence of a hydrophilic unit in the polymer molecules gives the implant the properties of a hydrogel after it has absorbed water. Somastotatin is indicated as a hydrophilic peptide, but no release profile has been described and no indication has been given as to which type of polymer is suitable for this peptide and which molecular weight and how many hydrophilic groups it should have.

UK Patent GB 2 145 422 B describes that slow release of various types of active ingredients, e.g. Vitamins, enzymes, antibiotics, antigens can be achieved over a longer period of time if the active ingredient is in an implant, e.g. of microparticle size is incorporated and that from a polymer of a polyol, e.g. Glucose or mannitol is constructed, which contains one or more, preferably at least three, polylactide ester groups. The polylactide ester groups preferably contain e.g. Glycol units. No peptides, e.g. Somatostatins are named as active ingredients and no plasma level profiles are described.

SUMMARY OF THE INVENTION

This invention relates to slow release formulations, e.g. Microparticle formulations of an active ingredient, especially a hormonally active, water-soluble somastotatin or a somatostatin analog, such as octreotide, with a sufficient plasma level and e.g. in a biodegradable biocompatible polymer, e.g. in an enveloping polymeric matrix. The matrix can consist of a synthetic or natural polymer.

The invention relates to a pharmaceutical formulation with slowed release of active ingredient, which contains a peptide active ingredient from the group of a calcitonin, lypressine or a somatostatin in a linear 40/60 to 60/40 polylactide-co-glycolide polymer which contains polymer chains with a molecular weight Mw from 25,000 to 100,000 and a polydispersity Mw / Mn from 1.2 to 2 and the degree of peptide loading of the polymer is 0.2 to 10 percent by weight.

A pharmaceutical formulation with a star-shaped polylactide-co-glycolide polymer is the subject of patent CH 685 230 A5.

The pharmaceutical formulation can be made using conventional techniques, e.g. the organic phase separation method, the spray drying method or the triple emulsion method can be obtained. According to the first and third methods, the polymer is precipitated together with the active ingredient as microparticles and the resulting product is cured. If desired, however, the formulations can also be prepared in the form of an implant. We have developed a special, useful modification of the phase separation method, according to which microparticles can be produced with every active ingredient. The invention also relates to a phase separation method for producing the pharmaceutical formulation in the form of microparticles according to which

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a) the polymeric carrier material is dissolved in a suitable solvent in which the active ingredient is not soluble,

b) a solution of the active ingredient in a suitable solvent, e.g. an alcohol which cannot dissolve the polymer is dispersed in the solution of step a),

c) a phase-inducing agent is added to the dispersion of step b), whereby microparticles are formed,

d) an oil-in-water emulsion is added to the mixture of step c), whereby the microparticles are hardened and e) the microparticles are deposited.

We have also developed a particularly useful modification of the triple emulsion technique which is also the subject of the invention, namely a process for the preparation of the above pharmaceutical formulation by

(i) a water-in-oil emulsion of an aqueous medium and a water-immiscible solvent, which contain the active ingredient in one phase and a biodegradable, biocompatible polymer in the other, intensely with an excess of an aqueous medium which is an emulsifier or contains a protective colloid, is mixed into a water-in-oil-in-water emulsion without adding any active substance-retaining substance to the water-in-oil emulsion or without taking any viscosity-increasing measures,

(ii) removing the solvent therefrom and

(iii) the microparticles formed are isolated and dried.

The invention also relates to the above-mentioned pharmaceutical formulation according to the invention with octreotide pamoate as active ingredient.

We have found that the new salt octreotide pamoate is very stable in such formulations. The invention therefore relates to octreotide pamoate as an agent for use in the methods and pharmaceutical formulations according to the invention. If they contain octreotide pamoate as a peptide active ingredient, the pharmaceutical formulations according to the invention are used especially for the treatment of acromegaly or breast cancer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The active substances which are used in the processes according to the invention are preferably water-soluble active substances, e.g. water soluble peptides.

The peptide active ingredients which are used in the methods and formulations according to the invention can be a calcitonin, such as salmon calcitonin, lypressin and the natural somatostatin and its synthetic analogs.

The natural somatostatin is one of the preferred active ingredients and is a tetradecapeptide with the structure:

Ala-Gly-Cys-Lys-Asn-Phe-Phe-Trp

Cys-Ser-Thr-Phe-Thr-Lys

This hormone is produced both by the hypothalamic gland and by other organs, e.g. the digestive tract, produces and mediates, together with GRF, the neuroregulation of growth hormone release in the pituitary gland. In addition to inhibiting the growth hormone release in the pituitary gland, somatostatin also vigorously inhibits other systems, such as the central and peripheral nervous system, the gastrointestinal system and the smooth muscle vessels. It also inhibits the release of insulin and glucagon.

The term somatostatin encompasses the analogs and the derivatives.

Derivatives and analogs are straight-chain polypeptides characterized by internal or external disulfide bridges, in which one or more amino acid units have been omitted and / or replaced by one or more other amino radicals and / or one or more functional groups by one or more other functional groups and / or one or several groups have been replaced by one or different other isosteric groups. In general, the term encompasses all modified derivatives of a biologically active peptide which have a qualitatively comparable effect to that of the unmodified peptide.

Somatostatin agonist analogs are useful in the replacement of natural somatostatin in regulating its effect on physiological functions. Preferred known somatostatins are:

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a) (D) Phe-Cys-Phe- (D) Trp-Lys-Thr-Cys-Thr-ol (Common name: Octreotide)

*

b) (D) Phe-Cys-Tyr- (D) Trp-Lys-Val-Cys-ThrNH2

# *

c) (D) Phe-Cys-Tyr- (D) Trp-Lys-Val-Cys-TrpNH2

# *

d) (D) Trp-Cys-Phe- (D) Trp-Lys-Thr-Cys-ThrNH2

# *

e) (D) Phe-Cys-Phe- (D) Trp-Lys-Thr-Cys-ThrNH2

# #

f) 3- (2- (Naphthyl) - (D) Ala-Cys-Tyr- (D) Trp-Lys-Val-Cys-ThrNH2

* *

g) (D) Phe-Cys-Tyr- (D) Trp-Lys-Val-Cys- / 3-Nal-NH2

* *

h) 3 ~ (2-naphthyl) -Ala-Cys-Tyr- (D) Trp-Lys-Val-Cys- / 3-Nal-NH2

»#

i) (D) Phe-Cys- / 9-Nal- (D) Trp-Lys-Val-Cys-Thr-NH2

In each of the compounds a) to i) there is a bridge between the amino acid units which are marked with an *. The bridge is shown in the formula below.

Other preferred somatostatins are:

* »

H-Cys-Phe-Phe- (D) Trp-Lys-Thr-Phe-Cys-OH

(See Vale et al "Metabolism, 27, Supp.1, 139 (1978)).

* *

Asn-Phe-Phe- (D) Trp-Lys-Thr-Phe-Gaba

(See European Patent Publication No. 1295 and Application No. 78 100 994.9).

MeAla-Tyr- (D) Trp-Lys-Val-Phe

(See Verber et al., Life Sciences, 34, 1371-1378 (1984) and European Patent Application No. 82 106 205.6 (published as No. 70 021) also known as cyclo

(N-Me-Ala-T yr-D-T rp-Lys-Val-Phe).

NMePhe-His- (D) Trp-Lys-Val-Ala

(See R.F. Nutt et al.,. Klin.Wochenschr. (1986) 64 (Suppl.VII)

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* #

H-Cys-His-His-Phe-Phe- (D) Trp-Lys-Thr-Phe-Thr-Ser-Cys-OH

(see EP-A-200,188).

* #

X-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2 and

# *

X-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol In this formula, X is a cationic anchor group

* *

Ac-hArg (Et2) -Gly-Cys-Phe-D-Trp-Lys-Thr-Cys-NHZ (see EP 0363589A2)

In the compounds mentioned above, too, there is a bridge between the amino acid units which are marked with an *.

The content of all the publications mentioned above, especially the specifically listed somatostatins, is considered to belong to this description.

The term “derivative” also includes the corresponding derivatives that have a sugar residue. If somatostatins have a sugar residue, this is preferably connected to an N-terminal amino group and / or to at least one amino group in a peptide side chain, but preferably to an N-terminal amino group. Such compounds, including their preparation, have been described, e.g. in WO 88/02756.

The name "octreotide derivatives" includes those with the rest * "

-D-Phe-Cys-Phe-DTrp-Lys-Thr-Cys- with a bridge between the Cys units.

Particularly preferred derivatives are: Na- [a-glucosyl (1-4-deoxyfructosyl] -DPhe-Cys-Phe-DTrp-Lys-Thr-Cys-Thr-ol and

N ^ iß-deoxyfructosyl-DPhe-Cys-Phe-DTrp-Lys-Thr-Cys-Thr-ol, each with a bridge between the Cys units, preferably in the form of the acetate salt and in Examples 2 and 1 of the above-mentioned patent application described.

The somatostatins can e.g. are in free form, salt form or in the form of their complexes. Acid addition salts can be e.g. organic acids, polymeric acids and inorganic acids. Acid addition salts are e.g. the hydrochloride and acetate salts. Complexes are e.g. from somatostatins by addition with inorganic substances, e.g. inorganic salts or hydroxides, such as the calcium and zinc salts and / or formed by addition of polymeric organic substances. The acetate salt is preferred for formulations, especially microparticles, which show a reduced incipient release of active ingredient, as is the pamoate salt, which is also particularly useful for implants. The pamoate can be obtained in a conventional manner, e.g. by embonic acid (Pamoic Acid) with octreotide e.g. is implemented in free base form. The reaction can be carried out in a polar solvent e.g. be carried out at room temperature. The somatostatins are suitable for use in the treatment of diseases when long-term drug application is targeted, e.g. for disorders that are caused by excessive GH secretion, e.g. in the treatment of acromegaly, gastrointestinal disorders, e.g. in the treatment or prophylaxis of gastric ulcers, enterocutaneous and pancreaticocutaneous fistulas, intestinal inflammation, dumping syndrome, watery diarrhea syndrome, acute pancratitis and gastrointestinal, hormone-secreting tumors, e.g. Vipomas, GRFomas, glucagonomas, insulinomas, gastrinomas and carcinoid tumors, as well as gastrointestinal bleeding, breast cancer and complications associated with diabetes.

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The polymeric carrier material can be produced from biocompatible and biodegradable polymers such as linear polyesters or branched polyesters with linear chains which are esterified with a central polyol, such as glucose. Other esters are those of polylactic acid, polyglycolic acid, polyhydroxybutyric acid, polycaprolactone, polyalkylene oxalate or are polyalkylene glycol esters of cancer cycle acids, e.g. of the citric acid cycle and its copolymers.

The preferred polymers of the invention are the linear polyesters and the branched polyesters with linear chains (star polymers). The linear polyesters can be obtained by condensation from the alpha-hydroxycarboxylic acids, e.g. Lactic acid and glycolic acid or by polymerizing the lactone dimers, see e.g. U.S. Patent No. 3,773,919.

Polylactide-co-glycolides which can preferably be used suitably have a molecular weight between 25,000 and 100,000 and a polydispersibility Mw / Mn e.g. from 1.2 to 2.

Branched polyesters which can preferably be used can be derived from polyhydroxy compounds such as a polyol such as e.g. Glucose or mannitol can be produced as an initiator. These polyol esters are known and have been described in UK Patent GB 2 145 422 B. The polyol contains at least 3 hydroxyl groups and has a molecular weight of up to max. 20,000 and at least 1, preferably at least 2, e.g. an average of 3 hydroxyl groups in the form of ester groups consisting of polyactide or copolylactide chains. In order to start the polymerization, 0.2 weight percent glucose is used for a representative polyol ester. The structure of the branched polyester has the shape of a star. The preferred polyester chains of the linear and star polymer compounds are copolymers from the alpha-carboxylic acid units of lactic acid and glycolic acid or from the lactone dimers. The molar ratios of lactide and glycolide are preferably from 75:25 to 25:75, e.g. 60:40 to 40:60, especially from 55:45 to 45:55, e.g. 55:45 to 50:50 as the most preferred ratios. The star polymers can be produced by reacting a polyol with a lactide and preferably also with a glycolide at elevated temperature in the presence of a catalyst which enables polymerization by opening of the lactone ring.

We have found that the advantage of a star polymer is that its molecular weight can be relatively high, giving physical stability, e.g. implants and microparticles are somewhat hard, which prevents them from sticking together. Nevertheless, its polylactide chains are relatively short, which leads to a rapid, controllable biodegradation rate of the polymers. The dismantling is sufficient e.g. from a few weeks to a month or two, which, if the polymer contains a peptide, is accompanied by a corresponding peptide release and a depot formulation, e.g. for a month-long release. The star polymers preferably have an average molecular weight Mw of about 10,000 to 200,000, particularly 25,000 to 100,000, especially 35,000 to 60,000 and a polydispersity e.g. from 1.7 to 3.0, such as 2.0 to 2.5.

The intrinsic viscosities of star polymers with Mw 35,000 and Mw 60,000 are 0.36 and 0.51 dl / g in chloroform. A star polymer with an Mw 52,000 has a viscosity of 0.475 dl / g in chloroform.

The terms microsphere, microcapsule and microparticle are considered to be interchangeable in the context of the invention and relate to the encapsulation of the peptides in the polymers, the peptide preferably being distributed in the polymer and representing a matrix for the peptide. In this case, the terms microsphere or, more generally, microparticles are preferably used.

When using the phase separation technique of the present invention, the resulting formulations can be prepared by dissolving the polymeric carrier material in a solvent in which the peptide cannot dissolve, after which a solution of the peptide is dispersed in the polymer-containing solution. In order to encapsulate the peptide by the polymeric carrier, a phase induction agent, such as silicone oil, is added.

The strong release of active ingredient that often occurs at the start of the application can be considerably reduced by in-situ production of ultrafine active ingredient particles by adding the active ingredient solution to the polymer solution prior to phase separation.

However, dry fine particles of active ingredient can also be added directly to the polymer solution.

According to the invention, the therapeutic peptide effect can be extended by hardening and washing the microparticles with an emulsion of buffer / heptane. The methodology is known, whereby one hardens without washing afterwards or only with an aqueous medium. An oil-in-water (= o / w) type emulsion can be used for washing and curing the microparticles, removing unencapsulated, remaining peptide. Washing also removes non-encapsulated peptide particles adhering to the microparticle surface. The removal of these excess peptides lowers the high plasma levels at the beginning of the application, which are characteristic of many conventionally encapsulated products, and also promotes a more uniform release of active ingredients. The buffer heptane emulsion also removes the solvent used to dissolve the polymer and the phase inductor such as the silicone oil.

The emulsion can be added to the polymer / peptide mixture or the mixture to the emulsion. The last variant is preferred.

If stability is required, the o / w emulsion can be prepared with the aid of an emulsifier such as Sor-bitanmonooleate (Span 80 ICI Corp.). It can be buffered with a buffer which is not harmful to the peptide and the polymer matrix. The buffer can be one with pH 2

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to 8, preferably pH 4, and may be of the acidic buffer type, such as a phosphate buffer or an acetate buffer. Water can also be used instead of a buffer.

Solvents such as heptane or hexane can be used as the organic phase of the emulsion. The emulsion can contain dispersants such as silicone oil. The preferred emulsion contains heptane, phosphate buffer pH 4, silicone oil and sorbitan monooleate. If immediate drug release is desired, curing / washing the emulsion can be replaced by curing with the organic solvent such as heptane or hexane.

Other alternatives than the o / w emulsion for curing the microparticles are:

The use of a solvent with emulsifier for curing without washing, or the use of a solvent with emulsifier for curing, after which a separate washing treatment can be switched on.

The o / w emulsion can be used without a dispersant. The advantage of a disperser is that it prevents the build-up of dry microparticles by static electricity and helps to reduce the amount of residual solvent. Examples of solvents for the polymeric matrix material are methylene chloride, chloroform, benzene, ethyl acetate. The peptide is preferably in an alcoholic solvent, e.g. Dissolved methanol, which is immiscible with the solvent of the polymer.

The phase induction agents (coacervation agents) are solvents which are miscible with the polymer / active ingredient mixture. They create embryonic microparticles, which are then hardened. Silicone oils are the preferred phase inductors.

The o / w emulsion can be prepared in a conventional manner using solvents such as heptane or hexane for the organic phase.

The microparticles according to the invention can also be produced by using the generally known spray drying method. For this, the somatostatin or a solution of this peptide in an organic solvent, e.g. Methanol, or in water or in a buffer, e.g. at pH 3 to 8 and a solution of the polymer in an organic solvent which is immiscible with the first, e.g. with methylene chloride, mixed well.

The solution, suspension or emulsion formed is then sprayed in an air stream. The air is preferably warm. The microparticles that form are collected, e.g. in a cyclone and, if desired, washed. The washing liquid is e.g. a buffer solution with e.g. pH 3.0 to 8.0, preferably pH 4.0 or distilled water. The microparticles are dried in a vacuum, e.g. at temperatures of 20-40 ° C.

Washing can be used if the microparticles at the start of an application would show a sudden sharp increase in the released active ingredient, which is undesirable. As a buffer e.g. an acetate buffer can be used.

The pharmaceutical formulations of the invention exhibit an improved somatostatin release profile.

Compared to microparticles manufactured using the phase separation method, they do not contain any silicone oil, not even in traces, since no silicone oil is used in spray drying technology.

The formulations according to the invention can also be prepared using the triple emulsion process. In a representative procedure e.g. a peptide such as octreotide in a suitable solvent, e.g. Water, dissolved and the solution intensely in a solution of the polymer, e.g. 50/50 poly (D, L-lactide-co-glycolide) glucose in a solvent that cannot dissolve the peptide, e.g. emulsified in methylene chloride. As a solvent for the polymeric matrix material, e.g. Methylene chloride, chloroform, benzene, ethyl acetate can be used. The resulting water-in-oil (w / o) emulsion is then dissolved in an excess of water containing an emulsifier, e.g. contains an anionic or nonionic detergent or lecithin or a protective colloid such as gelatin or dextrin, carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol. This procedure allows the triple (w / o / w) emulsion to be continuously formed. By now removing the organic solvent from this emulsion by evaporation, microparticles are formed and cured by spontaneous precipitation of the polymer. Gelatin is preferably used to prevent the microparticles from clumping together. After sedimentation of the microparticles, the supernatant liquid is decanted off and the microcapsules are washed with water and with acetate buffer. The microparticles are finally filtered off and dried.

The peptide can also be added directly to the polymer solution without first dissolving it, after which the resulting suspension is mixed with the gelatin-containing aqueous phase.

The triple emulsion process is known from U.S. Patent No. 4,652,441. According to this patent, in a first step an active ingredient solution (1) i in a solvent, e.g. Somatostatin in water (column 2, lines 31-32) detailed with an excess of a polylactide-co-glycolide solution (2) in another solvent in which the first solvent is not soluble, e.g. Methylene chloride, mixed, whereby a water-in-oil type (w / o) emulsion (3) of droplets of fine active substance containing (1) in solution (2) is formed. In solution (1) there is also a so-called active substance retaining substance (column 1, line 31), e.g. Gelatin, albumin, pectin or agar dissolved. In a second step, the viscosity of the inner phase (1) is determined by suitable measures, such as heating, cooling, pH change, adding metal ions or crosslinking, e.g. of gelatin with an Al8

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increased dehydration. In a third step, an excess amount of water is completely mixed with the w / o emulsion (3), (column 7, lines 52-54), whereby a three-layer emulsion of the w / o / w type is formed. In the excess amount of water there can be a so-called emulsifier (column 7, line 56) which is selected from the group consisting of an anionic or non-ionic detergent, or e.g. Polyvinylpyrrolidone, polyvinyl alcohol or gelatin is chosen. In a fourth step, the w / o / w emulsion is subjected to a treatment which is presented as “drying in water” (line 52). In this step, the organic solvent is "desorbed" (removed), whereby microparticles are formed. Desorption is carried out in a known manner (column 8, lines 3-5), e.g. by reducing the pressure during stirring (column 8, lines 5-7) or by blowing nitrogen gas through the emulsion, the oil layer of which is composed of methylene chloride (line 19). The microparticles formed are isolated by centrifugation or filtration (lines 26-27). Components that have not been incorporated into the polymer are removed by washing with water (line 29). If desired, the microparticles are heated under reduced pressure, whereby the water and solvent adhering to the particles, e.g. Methylene chloride, can be removed better (lines 30-32). Although the process described above is satisfactory for the formulations according to the invention, the so-called active substance retaining substance, e.g. Gelatin, albumin, pectin or agar are still present in the microparticles. If, we found, the addition of the restraining substance (in solution 1) and the increase in the viscosity of the inner phase are avoided, but the measure is an emulsifier or a protective colloid, such as gelatin, to the excess water of the further w / o / w -Emulsion are maintained, it remains possible to obtain high quality microparticles. The advantage of these microparticles is that they contain no active substance-retaining substance and only a very small amount of solvent, such as methylene chloride.

The triple emulsion process of the invention is preferably carried out in such a way that a) a solution of an active ingredient, preferably a somatostatin, especially octreotide, in an aqueous medium, preferably water or a buffer, preferably in a weight / volume ratio of 0.8 to 4.0 g / 1-120 ml, preferably 2.5 / 10 and in a buffer with pH 3-8, preferably an acetate buffer, and b) a solution of a polymer, preferably a polylactide-co-glycolide, as mentioned above, in an organic Solvents which are not miscible with an aqueous medium, such as methylene chloride, preferably in a weight / volume ratio of 40 g / 90-400 ml, particularly 40/100, are mixed intensively with one another, preferably in such a way that the weight / Weight ratio of the active ingredient to the polymer is 1 / 10-50, preferably 1/16 and the volume / volume ratio of the aqueous medium to the organic solvent is 1 / 1.5-30, preferably 1/10 and the w / o-emulsion of a) in b) intensive with c) an excess of an aqueous medium, preferably water or a buffer, e.g. an acetate or phosphate buffer, preferably at pH 3-8, which contains an emulsifier or a protective colloid, preferably in a concentration of 0.01-15.0%, particularly gelatin, preferably in a concentration of 0.1-3%, especially 0.5% by weight, preferably in a volume / volume mixing speed ratio of ab / c of 1 / 10-100, especially 1/40

without adding any active substance-retaining substance to the water-in-oil emulsion or using a viscosity-increasing measure, after which the embryonic microparticles in the w / o / w emulsion formed are preferably removed by removing the organic solvent, which preferably consists of methylene chloride are hardened by evaporation and the microparticles are isolated and possibly washed and dried afterwards.

The invention also includes the process variant according to which the active ingredient is dispersed directly in the polymer solution and the dispersion formed is mixed with the gelatin-containing water phase.

Like the microparticles, which are produced according to the spray drying technique, they contain no silicone oil. Compared to the microparticles that are produced using the well-known triple emulsion technique, the new microparticles do not contain any protective colloid.

The slow release formulations can also be prepared according to other known methods. E.g. if the peptide agent is stable enough for the manufacture of an implant, microparticles which contain the peptide, e.g. contain a somatostatin in a polylactide-co-glycol-id, or a mixture of polymer and peptide, at a temperature of e.g. 70 to 100 ° C are heated and extruded, after which the compact mass is cooled, the extrudate is cut and possibly washed and dried.

The formulations according to the invention are expediently prepared under aseptic conditions.

The formulations can be in depot form, e.g. can be used as injectable microparticles or as an implant. They can be used in a conventional manner, e.g. Apply subcutaneously or intramuscularly for indications in which the peptide active ingredients are used.

The slow release formulations of octreotide can be used in all known indications where octreotide or its salts or derivatives are used, e.g. for those who in

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GB 2 199 829 A, pages 89 to 96 have been described or are applied to agromegaly or breast cancer.

The microparticles of this invention can range in size from about 1 to 250 microns, preferably 10 to 200, e.g. 10 to 130, such as 10 to 90 microns.

Implants can have a size of 1 to 10 mm3.

The amount of active ingredient in the formulations depends on the desired daily release amount and therefore on the rate of biodegradation of the polymer. The exact amount of peptide can be determined by means of bioavailability determinations, but the formulations generally contain an amount of peptide of at least 0.2, preferably 0.5 to 20 percent by weight, based on the polymeric matrix material, particularly 2.0 to 10, especially 3.0 to 6 percent by weight.

The peptide release period can range from 1 to 2 weeks to about 2 months.

The slow release formulations are conveniently those containing a somatostatin, e.g. Contain octreotide in a biodegradable, biocompatible polymeric carrier material and which, when administered subcutaneously to a rat in an amount of 10 mg of somatostatin per kg of body weight, has a plasma concentration of somatostatin of at least 0.3 ng / ml and preferably less than 20 ng / ml for 30 days or conveniently for 60 days. The slowed-release formulations according to the invention are also those which contain a somatostatin, e.g. Contain octreotide in a biodegradable, biocompatible polymeric carrier material which, when administered to a rabbit intramuscularly in an amount of 5 mg / kg body weight, has a plasma concentration of somatostatin of at least 0.3 ng / ml and expediently a maximum of 20 ng / ml during 50 Days.

Other preferred properties of somatostatin, e.g. Depot formulations containing octreotide are, depending on the manufacturing process used, the following:

Phase separation method

Rabbit 5 mg somatostatin / kg, intramuscular

Retardation

(0-42

Days)

76%

Average plasma level (Cp, ideal)

(0-42

Days)

4ng / ml

AUC

(0-42

Days)

170 ng / ml x days

Spray drying wet process:

Rat 10 mg somatostatin / kg, subcutaneously

Retardation

(0-42 days)

> 75%

Average plasma level (Cp, ideal)

(0-42 days)

4-6 ng / ml

AUC

(0-42 days)

170-210ng / ml x days

Rabbit 5 mg somatostatin / kg, intramuscular

Retardation

(0-43

Days)

> 75%

Average plasma level

(0-43

Days)

4-6 ng / ml

AUC

(0-43

Days)

200-240ng / ml x days

Triple emulsion process:

Rat 10 mg somatostatin / kg, subcutaneously

Retardation

(0-42

Days)

> 75%

Average plasma level (Cp, ideal)

(0-42

Days)

4-6.5 ng / ml

AUC

(0-42

Days)

170-230 ng / ml x days

Rabbit 5 mg somatostatin / kg, intramuscular

Retardation

(0-42 / 43 days)

> 74%

Average plasma level (Cp, jdeai)

(0-42 / 43 days)

3.5-6.5 ng / ml

AUC

(0-42 / 43 days)

160-270 ng / ml x days

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The invention thus also relates to compositions containing somatostatin, preferably octreotide and octreotide analoga, which have the following properties:

1. a retardation of at least 70%, preferably at least 74%, e.g. at least 75%, 80%, 88% or at least 89% for a period of 0 to 42 or 43 days and / or

2. an average plasma level (ideal Cp) of 2.5 to 6.5, preferably 4 to 6.5 ng / ml during a period of 0 to 42 days in the rat when 10 mg of the somatostatin is administered subcutaneously and / or an average Plasma levels from 3.5 to 6.5, e.g. 4-6.5 ng / ml for a period of 0 to 42 or 43 days, in rabbits when 5 mg of somatostatin is administered intramuscularly and / or

3. an AUC for a period of 0 to 42 days of at least 160, preferably 170 to 230 ng / ml x days, for the rat when 10 mg of somatostatin is administered subcutaneously and / or an AUC for a period of 0 to 42 or 43 Days of at least 160, preferably from 180 to 275, e.g. from 200 to 275 ng / ml x days for the rabbit when 5 mg somatostatin is administered intramuscularly.

For the quantitative characterization of the formulations according to the invention, we use the method of area deviation (AD) by F. Nimmerfall and J. Rosenthaler, published in Intern. J. Phar-maceut. 32, 1-6 (1986).

In short, the AD method determines the deviation of the area of an experimental plasma profile from an ideal profile in the form of a constant average plasma concentration (= Cp, ideal) by converting the experimental surface under the plasma curve (AUC) into a rectangle with the same surface. The retardation in percent is now calculated from the percentage surface deviation based on the AUC using the following formula:

% Retardation = 100 x (1 - AD / AUC)

According to this method, the entire plasma profile, measured over a predetermined period of time, is numerically recorded by a single index.

In Proc. nat. Acad.Sci. USA 25 (1988) 5688-5692, Fig. 4 was a plasma profile of the Octapeptida nalog of somatostatin of the formula

* «

D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 in the rat.

However, no clear comparison can be made with the plasma profile data of the compositions according to the invention shown above in the rat, since the plasma profile described is based on a different application method (intramuscular injection) and - more importantly - the degree of loading (between 2 and 6%) and the dosage amount for the application (25 to 50 mg portions of microparticles for 30 days, although determinations were carried out for at least 45 days) were not precisely specified. In addition, the poly (DL-lactide-co-glycolide) type has not been described in detail. The disclosure content of the publication is therefore too low to consider the publication as a pre-publication which could impair the invention.

The following examples illustrate the invention.

The molecular weight Mw of the polymer is the average molecular weight determined by GPC using polystyrene as the standard.

Example 1;

1 g of poly (DL-lactide-co-glycolide) (50/50 molar, Mw = 45000; polydispersity about 1.7) was dissolved in 15 ml of methylene chloride with stirring using a magnetic stirrer, after which a solution of 75 mg of octreotide acetate in 0.5 ml of methanol and then 15 ml of silicone oil (brand Dow 360 Medicai Fluid 1000 es) (silicone fluid) was added. The resulting mixture was added with stirring to an emulsion of 400 ml of n-heptane, 100 ml of pH 4 phosphate buffer, 40 ml of Dow 360 Medicai Fluid, 350 es and 2 ml of Span 80 (emulsifier) and the stirring was continued for at least 10 minutes. The microparticles formed were isolated by vacuum filtration and dried in a vacuum oven overnight. The yield was about 90% of microparticles in the diameter range from 10 to 40 micrometers.

The microparticles were suspended in a carrier and administered intramuscularly in a dose of 4 mg octreotide to white New Zealand rabbits. Blood samples were taken periodically, in which RIA analyzes (RIA = Radio Immuno Assay) measured plasma levels of 0.5 to 1.0 ng / ml for 30 days.

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Example 2:

1 g of poly (D, L-lactide-co-glycolide) glucose (Mw = 45,000, 55/45 molar; prepared according to method GB 2145 422 B from 0.2% glucose, polydispersity about 1.7) was stirred dissolved in 25 ml of ethyl acetate with a magnetic stirrer, after which 75 mg of octreotide in 3 ml of methanol and then 25 ml of silicone oil (brand Dow 360 Medicai Fluid 1000 es) were added. The mixture was added to the emulsion described in Example 1. Stirring was continued for at least 10 minutes, the resulting microparticles were isolated by vacuum filtration and dried overnight in a vacuum oven. The yield exceeded 80% microparticles. The diameter range was from 10 to 40 micrometers.

The microparticles were suspended in a carrier and administered intramuscularly in a dosage of 4 mg octreotide to white New Zealand rabbits. Blood samples were taken periodically, in which RIA analysis (RIA = Radio Immuno Assay) was measured over 21 days plasma levels of 0.5 to 2 ng / ml.

Example 3:

A solution of 1.5 g octreotide acetate in 20 ml methanol was added to a solution of 18.5 g poly (D, L-lactide-co-glycolide) glucose (50:50 molar, Mw 45,000) in 500 ml methylene chloride with stirring added. Thereafter, 500 ml of Dow 360 Medicai Fluid (1000 es) and 800 ml of Dow 360 Medicai Fluid (350 es) were added to the peptide-polymer suspension, whereby a phase separation took place. The resulting mixture was added with stirring to an emulsion of 1800 ml of n-heptane, 200 ml of sterile water and 40 ml of Span 80. After stirring for a further 10 minutes, the microsphere was isolated by vacuum filtration. Half of the product was dried in a vacuum oven at 37 ° C overnight. The residual methylene chloride content was 1.2%. The other half of the product was washed with stirring with 1000 ml of methanol containing 1 ml of Span 80. After stirring for a further hour, the ethanol layer was decanted and the microparticles were stirred for a further hour with 1000 ml of n-heptane, which contained 1 ml of Span 80. The microparticles were isolated by vacuum filtration and dried overnight in a vacuum oven at 37 ° C. The residual methylene chloride content of the microparticles washed in this way was reduced from 1.2% to 0.12%. The overall yield of the product was 18.2 g (91%) microparticles containing 5.6% octreotide. Average diameter 24 microns, residual heptane content 1.5%.

The microparticles were suspended in a carrier and administered intramuscularly to white rabbits in a dose of 5 mg / kg octreotide. Blood samples were taken periodically in which plasma levels of 0.3 to 7.7 ng / ml were measured for 49 days using RIA analysis.

Example 4:

1 g of poly (D, L-lactide-co-glycolide) glucose (Mw 46,000, 50:50 molar, prepared from 0.2% glucose by the process according to GB 2 145 422 B, polydispersity about 1.7) was added Stirring with a magnetic stirrer dissolved in 10 ml of methylene chloride, after which a solution of 75 mg of octreotide in 0.133 ml of methanol was added. The mixture was e.g. intensively stirred by means of an Ultra-Turax at 20,000 revolutions per minute, which resulted in a suspension of very small octreotide crystals in the polymer solution. The suspension was spray dried using a high speed turbine (Niro Atomizer); the small droplets were dried to microparticles in a warm air stream. They were collected in a cyclone and dried overnight at room temperature in a vacuum oven, washed for 5 minutes with a 1/15 acetate buffer pH 4.0 and dried again at room temperature in a vacuum oven. After 72 hours, the microparticles were sieved (0.125 mm mesh). The sieved microparticles were suspended in a carrier and administered intramuscularly in a dose of 5 mg octreotide / kg body weight to white rabbits (chinchilla bastard) and in a 10 mg / kg dose subcutaneously to male rats. Blood samples were taken periodically in which plasma levels of 0.3 to 10.0 ng / ml (5 mg dose) were measured in rabbits and 0.5-7.0 ng / ml in rats over 42 days (RIA analysis) .

Example 5:

Microparticles were produced by spray drying in the same manner as described in Example 4. Only in the present case the octreotide was suspended directly in the polymer solution without the use of methanol. The microparticles were suspended in a carrier and administered subcutaneously in a dose of 10 mg octreotide per kg body weight to male rats. In blood samples, which were taken periodically over 42 days, plasma levels of 0.5-10.0 ng / ml could be measured by means of RIA analysis.

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Example 6:

1 g of poly (D, L-lactide-co-glycolide) glucose (Mw 46,000, 50:50 molar; prepared according to the process according to GB 2 145 422 B from 0.2% glucose, polydispersity about 1.7) was used in 2.5 ml of methylene chloride dissolved, after which 75 mg of octreotide in 0.125 ml of deionized water was added. The resulting mixture was mixed intensively by means of an Ultra-Turax for 1 minute at 20,000 revolutions / minute (internal w / o phase). Ig gelatin A was dissolved at 50 ° C. in 200 ml of deionized water; the solution was cooled to 20 ° C. (outer w phase). The w / o and w phases were mixed intensively. During this process, the inner w / o phase was homogeneously dispersed as small droplets in the outer w phase. The resulting triple emulsion was slowly stirred for 1 hour, whereby the methylene chloride evaporated and cured microcapsules emerged from the droplets of the inner phase. After sedimentation of the microparticles, the excess liquid was drawn off by filtration. The microparticles were isolated by vacuum filtration and rinsed with water, whereby the gelatin was removed. The microparticles were then dried, sieved, washed and dried a second time as described in Example 4. The microparticles were suspended in a carrier and administered intramuscularly in a dose of 5 mg octreotide per kg body weight to white rabbits (chinchilla bastard) and in a dose of 10 mg per kg body weight subcutaneously to male rats. In blood samples taken periodically, RIA analysis measured plasma levels of 0.3 to 15.0 ng / ml (5 mg dose) in rabbits and 0.5 to 8.0 ng / ml in rats over 42 days.

Example 7:

Microparticles were produced using the triple emulsion technique as described in Example 6, but with the following process changes:

1. Instead of 0.125 ml water, 0.25 ml acetate buffer pH 4.0 was used to produce the inner W / O phase

2. After the isolation of the microparticles, the rinsing was carried out with a 1/45 molar acetate powder pH 4 instead of with water

3. The further washing of the microparticles was dispensed with.

Example 8:

Microparticles were produced using the triple emulsion technique in the same manner as described in Example 7, with the difference that the inner W / O phase was produced by using water which contained 0.7% (weight / volume) sodium chloride instead of acetate powder.

Example 9:

Microparticles were produced in the same way as described in Example 6, with the difference that the active ingredient was dispersed directly in the polymer solution and the dispersion obtained was mixed with the gelatin-containing water phase.

Example 10;

Octreotide pamoate

10.19 g of the free base of octreotide (10 mM) and 3.8 g of embonic acid (10 mM) are dissolved in 1 l of water / dioxane (1: 1). The reaction mixture is filtered and lyophilized and yields a yellow powder [et] d1 = + 7.5 (C = 0.35, in DMF) from octreotide pamoate hydrate. The factor is 1.4. The weight of the lyophilisate / the weight of the octreotide contained is indicated as a factor. The octreotide acetate in Examples 1 to 9 can be replaced by the octreotide pamoate and has excellent stability.

Example 11:

A solution of 1 g of poly (DL-lactide-co-glycolide) (50:50 molar, MW = 36,100) in 20 ml of methylene chloride was added with stirring to a solution of 100 mg of calcitonin in 1.5 ml of methanol and the phase separation accomplished by adding 20 ml of silicone oil (Dow 360 Medicai Fluid, 1000 es). The resulting mixture was added with stirring to an emulsion of 100 ml pH 4 phosphate buffer, 400 ml n-heptane, 4 ml Span 80 and 40 ml silicone fluid (Dow 360 Medicai Fluid, 1000 es). After stirring for a further 10 minutes, the microspheres were isolated by vacuum filtration and dried overnight in a vacuum oven at 37 ° C. The yield was 1.1 g of microspheres containing 5.9% calcitonin.

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Example 12:

A solution of 9.9 g of poly (DL-lactide-co-glycolide) (50/50 molar; Mw 44 300 = in 140 ml of methylene chloride was added to 100 mg of lypressine. The dispersion was magnetically stirred for 1 hour, after which 140 ml of silicone oil (Dow 360 Medicai Fluid, 1000 es) and 2.5 ml Span 80. The mixture was added to 2000 ml heptane and stirred for 10 minutes The resulting microcapsules were isolated by vacuum filtration, washed three times with heptane and 10 minutes Half of the product obtained was washed in water for 10 minutes and the other half was not washed Both samples were dried overnight in a vacuum oven at 30 ° C. The overall yield was 10.65 g of microparticles Sample was 0.5% and 0.6% lypressin was present in the unwashed sample.

Claims (16)

Claims 1. Pharmaceutical formulation with slowed release of active ingredient, which contains a peptide active ingredient from the group of a calcitonin, lypressine or a somatostatin in a linear 40/60 to 60/40 polylactide-co-glycolide polymer which contains polymer chains with a molecular weight Mw of 25 000 to 100,000 and a polydispersity Mw / Mn of 1.2 to 2 and the degree of peptide loading of the polymer is 0.2 to 10 percent by weight. 2. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight, when administered subcutaneously in an amount of 10 mg of active ingredient per kg of body weight on a rat, a plasma level of the active ingredient of at least 0.3 ng / ml and less than 20 ng / ml for 30 days. 3. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight when applied subcutaneously in an amount of 5 mg of active ingredient per kg of body weight to a rabbit, a plasma level of at least 0.3 ng / ml and at most 20 ng / ml for 50 days. 4. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight in order to have a retardation of at least 70% for 43 days when administered intramuscularly in an amount of 5 mg of active ingredient per kg of body weight to a rabbit. 5. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight when applied subcutaneously in an amount of 10 mg of active ingredient per kg of body weight to a rat, an average plasma level of 2.5 to 6.5 ng / ml to show for 42 days. 6. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight when applied intramuscularly in an amount of 5 mg of active ingredient per kg of body weight to a rabbit, an average plasma level of 3.5 to 6.5 ng / ml for 43 days. 7. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight in order to have an AUC of 160 to 230 ng / ml x days for 43 days when administered subcutaneously in an amount of 10 mg per kg body weight to a rat . 8. Pharmaceutical formulation according to claim 1 with an active ingredient content of 0.2 to 20 percent by weight when applied intramuscularly in an amount of 5 mg of active ingredient per kg of body weight to a rabbit, an AUC of 160 to 275 ng / ml x days for 43 days to show. 9. A process for the preparation of formulations according to claim 1, which contain an active ingredient in a biodegradable, biocompatible polymeric carrier, according to which a) the polymeric carrier material is dissolved in a suitable solvent in which the active ingredient is not soluble, b) a solution of the active ingredient in a suitable solvent which cannot dissolve the polymer is added to the solution of step a) and dispersed therein, c) a phase-inducing agent of the dispersion agent of step b) is added, whereby microparticles are formed, d) an oil-in-water emulsion is added to the mixture of step c), whereby the microparticles are hardened and e) the microparticles are isolated. 10. A process for the preparation of formulations according to claim 1, which contain an active ingredient in a biodegradable, biocompatible carrier, in which i) a water-in-oil emulsion of an aqueous medium and a water-immiscible solvent, in one phase the active ingredient and in the other a biodegradable, biocompatible polymer is intensively mixed with an excess of an aqueous medium, which contains an emulsifier or a protective colloid, to form a water-in-oil-in-water emulsion, without any substance retaining substances added to the water-in-oil emulsion or any measures to increase the viscosity are taken, 14 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 686 226 A5 ii) the solvent is removed therefrom and iii) the microparticles formed are isolated and dried. 11. A process for the preparation of formulations according to claim 1, which contain an active ingredient in a biodegradable, biocompatible carrier, in which i) an active ingredient suspension comprising an active ingredient and a water-immiscible organic solvent which contains a biodegradable, biocompatible polymer in solution is mixed with an excess of an aqueous medium containing an emulsifier or a protective colloid to form an oil-in-water emulsion which contains the active ingredient dispersed in the oil component without any active ingredient-retaining substances or any viscosity-increasing substances being present in the oil component Measures are taken ii) the solvent is removed therefrom and iii) the microparticles formed are isolated and dried. 12. A process for the preparation of formulations according to claim 1, in which a) a solution of an active ingredient in an aqueous medium and b) a solution of a polymer in an organic solvent which is not miscible with the aqueous medium are mixed intensively with one another and the Water-in-oil emulsion from a) in b). c) is intensively mixed with an excess of an aqueous medium which contains a protective colloid, without adding any active substance-retaining substances to the water-in-oil emulsion or without taking any viscosity-increasing measures which embryonic microparticles in the water-in-oil formed Oil-in-water emulsion hardened by removing the solvent and the microparticles formed are isolated. 13. The method according to claim 12, with a somatostatin as active ingredient. 14. The method according to claim 12, in which a) a solution of a somatostatin in water or a buffer in a weight / volume ratio of 0.8 to 4.0 g / l to 120 ml and b) a solution of a polylactide-co- glycolids in an organic solvent that is not miscible with the aqueous medium, in a weight / volume ratio of 40 g / 90 to 400 ml, are mixed intensively in such a way that the weight / weight ratio of the active ingredient to the polymer 1 / 10 to 50 and the volume / volume ratio of the aqueous medium to the organic solvent is 1 / 1.5 to 30 and the water-in-oil emulsion of a) in b) intensive with c) an excess of water or buffer , containing a protective colloid, is mixed in a volume / volume speed ratio of ab) / c) from 1/10 to 100 without any active substance-retaining substances being added to the water-in-oil emulsion or any measures to increase the viscosity be taken, the embryonic microparticles in the water-in-oil-in-water emulsion formed are hardened by evaporation of the organic solvent and the microparticles formed are isolated. 15. Octreotide pamoate for performing the method according to one of claims 9 to 14. 16. octreotide pamoate as active ingredient for the production of formulations according to claim 1. 15