HRP940838A2 - Long-acting biodegradable microparticles and process for preparation - Google Patents

Abstract

Long-acting biodegradable microparticles containing therapeutically active peptides as active ingredient and poly(lactide-co-glycolide) as vehicle, which are obtained by spray drying at temperatures below 60 DEG C with a spray flow above 500 l(STP), are described.

Description

The invention relates to biodegradable micro particles of long-term action based on poly(lactide-co-glycolide) = (PLGA), which as active substances contain therapeutically effective peptides, i.e. their physiologically tolerable salts, and the process for the production of such micro particles.

For drugs that are enzymatically broken down in the gastrointestinal tract, such as proteins or peptides, apart from nasal and dermal application - with often only a slight resorption ratio - parenteral forms are important above all. For the long-term treatment of certain diseases, it would be desirable to develop parenteral forms of a depot form of the drug, from which the drug would be continuously released over several weeks. In addition to implants, microcapsules/microspheres are also described in the literature for this purpose (compare e.g. EP-B-0 058 481).

In order to avoid surgical removal of such forms of injections, biodegradable polymers are used. In addition to polyamides, polyanhydrides, poly(ortho)esters, polyacetates, polyesters are primarily used. Most describe polyesters based on monomers and glycolic acid or copolymers thereof as suitable polymers.

For the production of microcapsules/microspheres, various processes are considered, such as phase separation (EP-B-0 052 510), solvate extraction (EP-B-0 145 240) or spray drying (EP-A-0 315 875 = ZA patent file 88/8396, CH 666 406, A5, compare Derwent Ref No. 88-228036/33). Spray drying has an advantage over other methods in that the encapsulation efficiency is generally higher than any of the other mentioned methods and that no additional encapsulation aid is needed, which would then lead to possible contamination in the product. The disadvantage is that spray drying must be carried out at higher temperatures, i.e., as a rule, far above the boiling point of the solvent in question. If a suspension, emulsion or solution of a copolymer of lactic and glycolic acid (PLGA) is subjected to spray drying under normal conditions, no microparticles are obtained, but fibrous formations that are not suitable for injectable deposit forms (EP-A-0 315 875). Microcapsules, described in CH 666 496 A5, obtained by spray drying at 59°C, as a biodegradable carrier material do not contain PLGA but D,L-oligolacoil-N-(L)-phenyl-alanine.

It has now surprisingly been found that PLGA polymer solutions and corresponding aqueous suspensions and emulsions can be sprayed if the spray temperature is lower than 60°C and the spray flow is above 500 NL/h. In comparison with the micro particles produced by the above-mentioned processes, these micro particles are also characterized by an insignificant content of residual solvent (organic solvent, water), which is below 1%. The content of the residual solvent is of particular importance in the case of injections, because there are high requirements for the purity of the drug.

The invention therefore relates to microparticles, which contain a peptide as an active substance and poly(lactide-co-glycolide) (PLGA) as a carrier material, characterized by the fact that spray drying is carried out at temperatures below 60°C at a spray flow rate above 500 NL /h. (1 NL = 22,415 liters).

In the previous and following versions, micro-particles also mean micro-capsules and micro-spheres, so also particles in which the active substance is completely or partially surrounded by a polymer, as well as particles in which the active substance is divided in a PLGA-matrix.

Peptides are natural and synthetic peptides and their physiologically tolerable salts.

The invention further relates to a process for the production of microparticles that contain a peptide as an active substance and PLGA as a carrier material, characterized in that the peptide is suspended in a carrier material solution or dissolved or an aqueous solution of the peptide is emulsified in a carrier material solution and the suspension, solution or the emulsion is sprayed at a temperature below 60°C at a spray flow rate greater than 500 NL/h.

The micro particles according to the invention primarily contain water-soluble peptides. The molecular weight of the peptide is preferably above 800. Particularly suitable peptides are LHRH agonists and antagonists such as buserelin, HOE 013 (Ac-D-Nal-p-Cl-D-Phe-D-Trp-Ser-Tyr-D-Ser (α-L-Rha)-Leu-Arg-Pro-Azagly-NH2, compare EP-A-0 263 521), nafarelin, triptorelin, leuprorelin and goserelin. Peptides of a different type are also suitable, such as TRH, vasopressin, calcitonin, insulin or HOE 427 (= ebiratides, [4-methionine dioxide, 8-D-lysine, 9-phenylamine]-α-MSH-(4-9) - (8-amino-octyl) amide triacetate, compare EP-A-0 179 332).

The biodegradable carrier material is PLGA. The release of the active substance from micro particles is not only influenced by the physico-chemical properties of the active substance, but also by the properties of the polymer or polymer mixture, such as molecular weight, molar composition, sequence of repetitions of lactic acid and unit of glycolic acid in the polymer. The carrier material can consist, for example, of a mixture of PLGA 50:50 and PLGA 40:60. The higher the molecular weight, i.e. the inherent viscosity, the longer the release of the active substance takes. The inherent viscosity (20°C, chloroform, 0.1%) is preferably 0.1 to 0.8 dl/g. The molar ratio of lactide to glycolide units is in the range, for example, from 85:15 to 40:60, preferably poly(d,l-lactide-co-glycolide) 50:50, which has a viscosity of 0.1 to 0.7 dl/g, especially from 0.1 to 0.5 dl/g.

Depending on the properties of the polymer, the micro-particles produced by the process according to the invention release the active substance during a time period of preferably 2 weeks to 3 months. The degree of filling, although not of primary importance, also affects the duration of release of the active substance. The method according to the invention produces microparticles with a peptide loading level of less than 20%, preferably less than 12%. The size of the particles, which also affects the release, of the particles produced by the process according to the invention is less than 200 µm, preferably less than 100 µm. In particular, the particle size is less than 50 µm.

The production of micro particles takes place by spraying from a solution, emulsion or suspension of an active substance in a polymer solution. For example, chloroform, methylene chloride, DMF, acetone, ethyl acetic acid ester, glacial acetic acid and water or their mixture can be used as solvents. Methylene chloride, glacial acetic acid and water are primarily used.

According to the method according to the invention, the peptide is first dissolved in water and added to a solution of PLGA, for example in methylene chloride. The resulting emulsion is sprayed. Spraying can also be carried out after the addition of, for example, methanol, whereby a solution is then formed.

The temperature is preferably at 50°C to 30°C, especially at 40°C to 30°C. The spray flow must not be too low, otherwise threads may form. It amounts primarily to approximately 800 NL/h, because a higher spray flow is associated with better drying properties.

The pressure of the spray medium, for example air or nitrogen, when using a laboratory spray device (eg Buchi Mini Spray Dryer 190) must be in the range of 3-8 bar. The pump output of the spray device must be adapted to the circumstances (3 - 20 ml/min). With a proper adjustment of the aspirator, for example, to 18 scale units, all the air, i.e. nitrogen, that is in the spray medium can be extracted.

The PLGA polymer should be dissolved in a minimal amount of solvent, whereas polymers with a high lactide content need larger amounts of solvent. In principle, the concentration of the polymer in the solution, emulsion, suspension for spraying should be selected so that under the selected conditions spraying is possible. The concentration of PLGA in methylene chloride is preferably less than 15% based on methylene chloride.

The invention is explained by the following examples.

The viscosity for PLGA given in the examples is the inherent viscosity of a 0.1% solution in chloroform at 20°C determined by conventional methods.

The spray parameters, a) aspirator and b) pump effect, in all examples are set to 18 (for the aspirator) and 6 (for the pump effect) scale units.

Example 1: Dispersed medium - glacial acetic acid

a) 0.064 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution was mixed with a solution of 1.936 g of PLGA 50:50 (IV = 0.4 dl/g) in 40 g of glacial acetic acid and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 50°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

1.2 g = 60% of the theoretical.

Content of active substance (degree of filling): 3%.

Residual solvent content: glacial acetic acid: 0.8%.

b) In the same way, micro particles were produced using 0.192 g of buserelin acetate and 1.808 g of PLGA 50:50 (IV = 0.4 dl/g). Gain: 1.2 g = 60% of the theoretical.

Active substance content (filling level); 9%.

Residual solvent content: glacial acetic acid: 0.8%,

For 20 mg of micro particles, the released meals were determined in vitro as follows:

20 mg of microparticles are placed in 2.0 ml of phosphate buffer solution pH 7.4 and washed for 24 hours at +37°C. After separation of the eluate from micro particles, the content of buserelin in the eluate is determined using HPLC. The remaining microparticles are placed again in 2.0 ml of phosphate buffer and washed again for 24 hours at 37°C. This procedure continues analogously for 56 days.

The amounts of buserelin determined in the eluate are listed as extracts in the following table:

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Example 2: Dispersing medium - chloroform

a) 0.108 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.892 g PLGA 50:50 (IV =0.4 dl/g) in 92 g chloroform and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.9 g = 45% of the theoretical. Active substance content: 5%.

b) Microparticles were produced in the same way using 0.152 g of buserelin acetate and 1.848 g of PLGA 50:50 (IV =0.4 dl/g). Gain: 1 g = 50% of the theoretical. Active substance content: 7%

For 20 mg of microparticles, the release rates were determined in vitro analogously to example 1 for 35 days:

The amounts of buserelin determined from the eluate are listed as extracts in the following table:

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Example 3: Spray medium - methylene chloride/water/methanol

a) 0.128 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution was mixed with a solution of 1.872 g of PLGA 50:50 (IV =0.4 dl/g) in 46 g of methylene chloride. 9 g of methanol is added to this mixture. A clear solution is formed which is sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

1.2 g = 60% of the theoretical. Active substance content: 6%. Residual solvent content; water 0.9%,

methylene chloride 0.06%, methanol <0.01%.

For 20 mg of microparticles, the release rates were determined in vitro analogously to example 1 over 28 days.

The amounts of buserelin determined from the eluate are listed as excerpts in the following table;

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Example 4: Spray medium - methylene chloride/water/methanol

a) 0.084 g of buserelin acetate is dissolved in 4.0 g of water. The aqueous solution was mixed with a solution of 1.916 g of PLGA 50:50 (IV = 0.42 dl/g) in 65 ml of methylene chloride. 25 g of methanol is added to this mixture. A clear solution is formed which is sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain: 0.8 g = 40% of the theoretical.

Active substance content: 4%.

b) In the same way, micro particles were produced using 0.168 g of buserelin acetate and 1.832 g of PLGA 50:50 (IV = 0.42 dl/g). Gain: 0.8 g = 40% of the theoretical.

Active substance content: 8%.

For 20 mg of microparticles, the release rates were determined in vitro as follows:

20 mg of microparticles are placed in 2.0 ml of phosphate buffer solution pH 7.4 and washed for 24 hours at +37°C. After separating the eluate from micro particles, the content of buserelin in the eluate is determined by radioimmunoassay (RIA). The remaining microparticles are placed again in 2.0 ml of phosphate buffer and washed again for 24 hours at 37°C. This procedure continues analogously for 63 days.

The amounts of buserelin determined in the eluate are listed as extracts in the following table:

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Example 5: Spray medium - methylene chloride/water/dimethylformamide

a) 0.13 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.87 g of PLGA 50:50 (IV =0.4 dl/g) in 41.4 g of chloroform and 4.6 g of dimethylformamide and dispersed in a laboratory drying device scattering.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h

Micro particles fall as a white, loose powder. Gain:

1.2 g = 60% of the theoretical.

Active substance content: 6%.

For 20 mg of microparticles, the release rates were determined in vitro analogously to example 4 for 63 days.

The amounts of buserelin determined in the eluates are listed in extracts in the following table:

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Example 6: Dispersing medium - methylene chloride

a) 0.13 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.915 g PLGA 50:50 (IV =0.4 dl/g) in 46 g methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1- inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.6 g = 30% of the theoretical.

Active substance content: 4%.

b) In the same way, micro particles were produced using 0.128 g of buserelin acetate and 1.872 g of PLGA 50:50 (IV =0.4 dl/g)

Gain: 0.7 g = 35% of theoretical.

Active substance content: 6%.

c) and using 0.170 g of buserelin acetate and 1.872 g of PLGA 50:50 (IV = 0.4 dl/g).

Gain: 0.4 g = 20% of the theoretical.

Active substance content: 8%.

For 20 mg of microparticles, the release rates were determined in vitro analogously to example 4 for 63 days;

The amounts of buserelin determined in the eluates are listed in the excerpts in the following table;

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Example 7: Spray medium - methylene chloride/water

0.032 g of buserelin acetate is dissolved in 1.0 g of water. The aqueous solution was emulsified using a rotor-stator homogenizer in a solution of 0.968 g PLGA 85:15 in 23 g methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature; 40°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.7 g = 70% of the theoretical.

Active substance content: 3%.

Example 8; Dispersing medium - methylene chloride/water

0.064 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.936 g of PLGA 50:50 (IV=0.7 dl/g) in 92 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 40°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.9 g = 45% of the theoretical.

Active substance content: 3%.

Determination of the release of the active substance is analogous to example 1.

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Example 9: Spray medium - methylene chloride/water

0.106 q of buserelin acetate is dissolved in 1.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 0.894 g of PLGA 50:50 (IV=0.1 dl/g) in 23 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 40°C,

2. spray flow; 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.3 g = 30% of the theoretical.

Active substance content: 10%.

Determination of the release of the active substance is analogous to example 1.

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Example 10: Dispersing medium - methylene chloride/water

0.13 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.87 g of PLGA 75:25 (IV=0.5 dl/g) in 46 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

1.2 g = 60% of the theoretical.

Active substance content: 6%.

Example 11: Spray medium - methylene chloride/water

0.128 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.872 g of PLGA 75:25 (IV=0.8 dl/g) in 138 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow; 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.9 g = 55% of the theoretical.

Active substance content; 6%.

Example 12: Dispersing medium - methylene chloride/water

0.13 g of buserelin acetate is dissolved in 2.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 1.87 g of PLGA 47:53 (IV=0.5 dl/g) in 46 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Profit;

1.3 g = 65% of the theoretical.

Active substance content: 6%.

Example 13: Dispersing medium - methylene chloride

0.13 q of buserelin acetate is suspended in a solution of 1.87 g of PLGA 50:50 (IV=0.4 dl/g) in 46 g of methylene chloride using a rotor-stator homogenizer. The suspension is sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 40°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.5 g = 25% of the theoretical.

Active substance content: 6%.

Example 14: Spray medium - methylene chloride/water

a) 0.2 g of Hoe 427 is dissolved in 1.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 3.3 g of PLGA 50:50 (IV=0.4 dl/g) in 92 g of methylene chloride and sprayed in a laboratory spray drying device.

The scattering parameters are set as follows:

1. inlet temperature: 40°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

1.9 g = 48% of the theoretical.

Active substance content: 5%.

b) In the same way, micro particles were produced using 0.6 g of Hoe 427 and 3.4 g of PLGA 50:50 (IV=0.4 dl/g), gain: 2.8 g = 70% of the theoretical.

Active substance content: 15%.

c) and with the use of 0.4 g of Hoe 427 and 3.6 g of PLGA 50:50 (IV=0.4 dl/g), gain: 2 g = 50% of the theoretical. Active substance content: 10%.

Example 15: Dispersing medium - methylene chloride/water

a) 0.08 g of Hoe 013 is dissolved in 1.0 g of water. The aqueous solution is emulsified using a rotor-stator homogenizer in a solution of 0.92 g of PLGA 50:50 (IV==0.4 dl/g) in 23 g of methylene chloride and sprayed in a laboratory spray dryer.

The scattering parameters are set as follows:

1. inlet temperature: 30°C,

2. spray flow: 800 NL/h.

Micro particles fall as a white, loose powder. Gain:

0.5 g = 50% of the theoretical.

Active substance content: 6%.

Determination of the release of the active substance is analogous to example 1.

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Claims (7)

1. Biodegradable micro-particles of long-term action, which contain a peptide as an active substance and poly(lactide-co-glycolide) (PLGA) as a carrier material, indicated by the fact that spray drying is carried out at temperatures below 60°C at a spray flow rate above 500 NL/h. 2. Process for the production of biodegradable micro-particles of long-term action, which contain a peptide as an active substance and PLGA as a carrier material, characterized in that the peptide is suspended or dissolved or an aqueous solution of the peptide is emulsified in a solution of the carrier material and the suspension, solution or emulsion is spray at a temperature below 60°C at a spray flow rate greater than 500 NL/h. 3. Micro particles according to claim 1, characterized in that they contain water-soluble peptides. 4. The procedure according to claim 2, characterized in that one or more of the following conditions are respected: a) the peptide is an LHRH-agonist or LHRH-antagonist, b) the supporting material is PLGA 50:50, c) the inherent viscosity of PLGA is 0.1 to 0.5 dl/g (20°C, chloroform, 0.1%), d) the solvent is chloroform, methylene chloride, glacial acetic acid, methanol, dimethylformamide, or water, or a mixture of at least 2 listed solvents and e) the spray flow is approximately 800 NL/h. 5. The procedure according to claim 2, characterized in that one or more of the following conditions are respected: a) the peptide is buserelin acetate or HOE 013, b) the supporting material is PLGA 50:50, c) inherent viscosity of PLGA is 0.1 to 0.5 dl/g (20°C, chloroform, 0.1%), d) the solvent is methylene chloride, glacial acetic acid, or water, or a mixture of at least 2 listed solvents and e) the spray flow is approximately 800 NL/h. 6. Mikoro particles, indicated by the fact that they are produced by the process according to claim 4. 7. Mikoro particles, indicated by the fact that they are produced by the process according to claim 5.