Injection preparation

Abstract

Provided is an injection preparation for the treatment of Parkinson's disease or restless legs syndrome, the injection preparation comprising microparticles each containing a free dopamine receptor agonist and a biodegradable polymer. The volume average particle diameter D50 of the microparticles is 50 μm or less, and the concentration of the dopamine receptor agonist in plasma of a subject to which the injection preparation has been administered is retained for 1 month or longer.

Description

Injectable preparations

[0001] The present invention relates to an injectable preparation.

[0002] Dopamine receptor agonists include pramipexole, ropinirole, and rotigotine. Commercially available oral formulations of pramipexole and ropinirole are Bi-Sifrol (registered trademark) and Requip (registered trademark), respectively. Oral administration is subject to the first-pass effect, resulting in low bioavailability, and high doses are unavoidable to achieve sufficient efficacy.

[0003] Transdermal formulations currently on the market include Neupro® Patch, a sustained-release formulation of rotigotine, and Haruropi® Tape, a sustained-release formulation of ropinirole. The sustained-release period of these transdermal formulations is limited to one day. This is because transdermal formulations typically have low bioavailability due to low permeability through the skin, and to avoid skin disorders such as rashes that may occur when applied for more than one day. While transdermal formulations are highly non-invasive to patients, there are concerns about decreased medication compliance, particularly in patients with severe Parkinson's disease, such as forgetting to apply or remove the transdermal formulation due to memory impairment or unintentional removal of the transdermal formulation due to movement disorders.

[0004] Injectable formulations, which can avoid the first-pass effect of oral administration, have relatively high bioavailability and can be expected to have high efficacy at lower doses. In addition, injectable formulations are administered by a physician, which is expected to improve compliance, which is a concern with transdermal formulations.

[0005] As disclosed in Patent Document 1 and Non-Patent Document 1, microparticle preparations that sustain the release of rotigotine for a long period of time, for example, two weeks to one month, are known.

[0006] Furthermore, Patent Document 2 discloses that when a pharmaceutical composition containing rotigotine behenate, in which rotigotine is bound to a linear saturated fatty acid, was injected intramuscularly into rats, rotigotine was detected in the blood for 42 days.

[0007] Special table No. 2008-513524 Publication No. 2019-523297

[0008] Ying Xue et al., Studying spatial drug distribution in golf ball-shaped microspheres to understand drug release, Journal of Controlled Release, 2023, 357, 196-209

[0009] The microparticle formulation disclosed in Patent Document 1 has a rotigotine sustained-release time of up to one month, but experiments using beagle dogs have shown that the blood drug concentration is relatively low, hardly meeting the blood drug concentration requirement (>0.5 ng / mL) for the treatment of Parkinson's disease, particularly during the evaluation period. Furthermore, the microparticle formulation disclosed in Non-Patent Document 1 can only sustain a rotigotine sustained-release time of two weeks, which is hardly long enough. No microparticle formulation capable of sustained-release of a dopamine receptor agonist for more than one to two months and maintaining the required blood drug concentration has yet been known.

[0010] Furthermore, the microparticle formulations disclosed in Patent Document 1 and Non-Patent Document 1 have an average particle size of 70 μm to 90 μm. Therefore, when administering the microparticle formulations via intramuscular or subcutaneous injection, it is necessary to select an injection needle with a large diameter, which causes pain during administration and may require anesthesia, which inevitably places a burden on the patient.

[0011] Furthermore, in the case of the pharmaceutical composition disclosed in Patent Document 2, if a subject of administration experiences serious side effects, there is no treatment other than emergency administration of an antagonist, which may be a burden on the subject of administration.

[0012] The present invention has been made in view of the above circumstances, and aims to provide an injectable preparation that can sustainably release a dopamine receptor agonist for a longer period of time and reduce the burden on the patient to whom it is administered.

[0013] The injectable preparation for treating Parkinson's disease or restless legs syndrome according to the present invention comprises microparticles containing a free dopamine receptor agonist and a biodegradable polymer, and the microparticles have a volume average particle diameter D ５０ and the concentration of the dopamine receptor agonist in the plasma of the administered subject is maintained for one month or longer.

[0014] The volume average particle diameter D of the microparticles ５０ may be 1 to 50 μm.

[0015] The maintenance period may be two months.

[0016] The dopamine receptor agonist may be rotigotine free base or ropinil free base, and the content of the dopamine receptor agonist in the microparticles may be 5 to 50% by weight.

[0017] The biodegradable polymer may be a lactic acid polymer or a lactic acid-glycolic acid copolymer having a molecular weight of 5,000 to 150,000.

[0018] According to the present invention, a dopamine receptor agonist can be sustainedly released for a longer period of time, thereby reducing the burden on the subject of administration.

[0019] FIG. 1 shows the particle size distribution of formulation 1. FIG. 2 shows the particle size distribution of formulation 2. FIG. 3 shows the particle size distribution of formulation 3. FIG. 4 shows the particle size distribution of formulation 4. FIG. 5 shows the particle size distribution of formulation 5. FIG. 6 shows the particle size distribution of formulation 6. FIG. 7 shows scanning electron microscope images of formulations 1 to 6. FIG. 8 shows the change over time in the subcutaneous rotigotine retention rate in rats subcutaneously administered with formulation 1 or any of formulations 3 to 6 in Test Example 1. FIG. 9 shows the change over time in the plasma rotigotine concentration in rats subcutaneously administered with an injectable formulation of formulation 2 in Test Example 2.

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals. It should be noted that the present invention is not limited to the following embodiments and drawings. It should be noted that in the following embodiments, the expressions "have," "include," or "contain" also include the meaning of "consisting of" or "consisting of."

[0021] The injectable preparation according to this embodiment is used to treat Parkinson's disease or restless legs syndrome. The injectable preparation may be a therapeutic agent for Parkinson's disease or restless legs syndrome.

[0022] The injectable formulation comprises microparticles containing a free dopamine receptor agonist and a biodegradable polymer. The dopamine receptor agonist is not particularly limited and may be any substance that agonizes or activates dopamine receptors. The term "free form" refers to a free form of a dopamine receptor agonist that is not a salt form and can take the form of a physiologically acceptable salt. Examples of the free dopamine receptor agonist include the free base of a dopamine receptor agonist when the dopamine receptor agonist is a basic dopamine receptor agonist, and the free acid of a dopamine receptor agonist when the dopamine receptor agonist is an acidic dopamine receptor agonist. Preferably, the injectable formulation contains the free base of rotigotine or the free base of ropinil as the dopamine receptor agonist.

[0023] The biodegradable polymer may be any polymer that has biodegradable properties. The biodegradable polymer is a polymer that is low in irritation and toxicity to the living body and is degraded and metabolized after administration. After administration to the living body, the biodegradable polymer remains in the living body, hydrates and swells, and gradually releases the dopamine receptor agonist as hydrolysis progresses.

[0024] The biodegradable polymer is, for example, a biodegradable polymer. The biodegradable polymer can be produced from a biodegradable polyester. The biodegradable polyester is, for example, a polyester synthesized by further copolymerizing a polymer of one or more monomers or dimers selected from D,L-lactide, D-lactide, L-lactide, D,L-lactic acid, D-lactic acid, L-lactic acid, glycolic acid, glycolide, ε-caprolactone, ε-hydrohexanoic acid, γ-butyrolactone, γ-hydroxybutyric acid, δ-valerolactone, δ-hydroxyvaleric acid, hydroxybutyric acid, malic acid, etc. The biodegradable polymer may be obtained by mixing the above-mentioned monomers or dimers in an appropriate ratio and polymerizing the mixture.

[0025] Preferably, the biodegradable polymer is a lactic acid polymer (PLA) or a lactic acid-glycolic acid copolymer (PLGA). The polymerization ratio of PLGA is not particularly limited. The polymerization ratio of PLGA is, for example, 1:99 (lactic acid:glycolic acid) to 99:1. The molecular weight of PLA and PLGA is, for example, 5,000 to 150,000. More preferably, the molecular weight of PLA and PLGA is 8,000 to 100,000. PLA and PLGA can be synthesized from a monomer or dimer by a general method such as a dehydration condensation method or a ring-opening polymerization method.

[0026] The particle size of the microparticles is 1 to 50 μm, more preferably 10 to 40 μm. If the particle size of the microparticles is too small, the ratio of surface area to volume increases, which can increase the adhesion and cohesion of the powder and deteriorate dispersibility and flowability. On the other hand, microparticles larger than 50 μm require a large-diameter needle when injected intramuscularly or subcutaneously, and in some cases the patient may be forced to administer the injection under anesthesia. Therefore, the particle size range of the microparticles is particularly a range (10 to 40 μm) that can be used with a thin injection needle of about 23 to 26 G that does not require local anesthesia and ensures sustained release.

[0027] The particle size of microparticles can be measured by sieving, sedimentation, microscopy, light scattering, laser diffraction / scattering, electrical resistance testing, observation with a transmission electron microscope, observation with a scanning electron microscope, etc. The particle size of microparticles can be expressed as a Stokes equivalent diameter, a circle equivalent diameter, a sphere equivalent diameter, etc., depending on the measurement method. Furthermore, the particle size of microparticles shown here may be expressed as an average particle size, particularly a volume average particle size or a mass average particle size, calculated as an average from a number distribution based on measurements such as laser diffraction / scattering, using multiple particles as the measurement subject.

[0028] For example, the particle diameter of the microparticles may be an average particle diameter calculated from a volume distribution based on measurements using a laser diffraction / scattering method. Specifically, when a cumulative curve is calculated assuming the total volume of a particle group to be 100%, the volume average particle diameter (50% diameter; D) is the particle diameter at the point where the cumulative curve is 50%. ５０ ) may be used as the particle diameter. ５０ can be determined using a commercially available particle size distribution analyzer. Examples of particle size distribution analyzers include a Microtrac particle size distribution and particle shape analyzer, Sync Analyzer (manufactured by Microtrac BEL). ５０ is 50 μm or less. Preferably, the D ５０ is 1 to 50 μm, more preferably 10 to 40 μm.

[0029] The span value of the microparticles is preferably 3.5 or less. ９０ -D １０ ) / D ５０ where D ９０ is the particle diameter at the point where the cumulative curve reaches 90%. １０ is the 10% diameter, which is the particle diameter at the point where the cumulative curve reaches 10%. ９０ and D １０ The span value of the microparticles can be determined using a commercially available particle size distribution analyzer. More preferably, the span value of the microparticles is 3.0 or less.

[0030] The content of the dopamine receptor agonist in the microparticles is not particularly limited, but is preferably 5 to 50% by weight, more preferably 5 to 30% by weight. If the content of the dopamine receptor agonist is less than 5% by weight, an effective plasma concentration of the dopamine receptor agonist cannot be ensured, whereas if the content is more than 50% by weight, the release of the dopamine receptor agonist is unstable, which may lead to side effects.

[0031] The injectable formulation of this embodiment may further contain an excipient to improve redispersibility during use and stability during storage. Any pharmaceutically acceptable excipient can be used. For example, the excipient is a sugar or an amino acid. More specifically, examples of the excipient include lactose, mannitol, trehalose, inositol, erythritol, sucrose, pullulan, sorbitol, starches, dextrin, dextran, sodium alginate, crystalline cellulose, methylcellulose, carmellose sodium, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), natural polymers, synthetic polymers, glycine, leucine, isoleucine, arginine, histidine, etc. Preferably, the excipient is mannitol.

[0032] Next, a method for producing an injectable formulation according to this embodiment will be described. The microparticles contained in the injectable formulation can be produced by any known production method, such as a phase separation method or an oil-in-water (O / W) emulsion method. In the O / W emulsion method, two types of solvents are used: a good solvent capable of simultaneously dissolving a free dopamine receptor agonist and a biodegradable polymer, and a poor solvent in which at least the biodegradable polymer is insoluble. Alternatively, an organic solvent in which the biodegradable polymer dissolves and which is miscible with the poor solvent can also be used as the good solvent. The types of the good solvent and poor solvent are not particularly limited.

[0033] Examples of good solvents include organic solvents that have a boiling point lower than that of water and are poorly water-soluble, such as dichloromethane, chloroform, halogenated alkanes, ethyl acetate, diethyl ether, hexane, and cyclohexane. Dichloromethane, chloroform, and the like are preferably used as good solvents because they are easily emulsified, have a low boiling point, and can easily reduce the amount of residual solvent. A small amount of a solvent such as methanol, ethanol, or acetone may be added to the good solvent to enhance the solubility of the dopamine receptor agonist in the good solvent.

[0034] The poor solvent may be water, to which a dispersant may be added. In principle, the dispersant is removed by washing during the preparation process. In poor solvents other than water, a dispersant may not be required.

[0035] Examples of dispersants include surfactants, polyethylene glycol, polyvinyl alcohol (PVA), polyvinylpyrrolidone, hydroxymethyl cellulose, hydroxypropyl cellulose, glycerin, fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, polyglycerin fatty acid esters, polysorbates, etc. The dispersant has both hydrophilic and hydrophobic functional groups and may function as a protective colloid or surfactant.

[0036] In the O / W emulsion method, a mixture of a dopamine receptor agonist and a biodegradable polymer dissolved in a good solvent is dropped into a poor solvent under stirring, causing the good solvent in the mixture to rapidly diffuse into the poor solvent. As a result, the good solvent is emulsified in the poor solvent, forming emulsion droplets of the good solvent.

[0037] As the organic solvent in the emulsion droplets continues to diffuse into the poor solvent, the solubility of the dopamine receptor agonist and biodegradable polymer in the emulsion droplets decreases, and if the organic solvent is further promoted by stirring under normal pressure, microparticles of the biodegradable polymer containing the dopamine receptor agonist are eventually produced. Subsequently, the emulsion is washed to remove the dispersant as needed, redispersed in water, and subjected to freeze-drying or other methods to obtain redispersible microparticles.

[0038] Alternatively, for hydrophilic dopamine receptor agonists that are insoluble in organic solvents, microparticles may be produced by a W / O / W emulsion method, in which a W / O emulsion containing an aqueous solution of the dopamine receptor agonist as the internal phase is prepared, and then the W / O emulsion is poured into a stirred aqueous phase to produce a W / O / W emulsion.

[0039] The injectable formulation according to this embodiment may contain, if necessary, other pharmaceutically acceptable components in addition to the microparticles, such as carriers, lubricants, binders, disintegrants, solvents, solubilizers, suspending agents, isotonicity agents, buffers, preservatives, antioxidants, and colorants.

[0040] The injectable preparation according to this embodiment is administered to humans and non-human animals, preferably mammals such as dogs, cats, cows, pigs, horses, sheep, and deer.

[0041] The administration route of the injectable preparation according to this embodiment is intramuscular, subcutaneous, intradermal, intraperitoneal, etc. The administration route of the injectable preparation is preferably intramuscular or subcutaneous injection.

[0042] The dosage of the injectable preparation according to this embodiment is determined appropriately depending on the age, sex, weight, symptoms, etc. of the subject to be administered so that the dopamine receptor agonist is an effective amount. Here, the effective amount is the amount necessary to treat Parkinson's disease or restless legs syndrome, or to prevent or delay the progression of the condition.

[0043] As shown in Test Examples 1 and 2 below, with the injectable formulation according to this embodiment, the dopamine receptor agonist concentration in the plasma of the administered subject is maintained for one month or more, for example, for two months. The administration interval of the injectable formulation according to this embodiment is appropriately determined so as to maintain a certain level of plasma drug concentration or higher. The on-off phenomenon, one of the symptoms that occurs during continuous drug treatment for Parkinson's disease, is a symptom that interferes with the daily or social life of Parkinson's disease patients and requires early treatment. Furthermore, a "wearing-off" phenomenon, in which the efficacy of a drug gradually decreases, is known to occur in the treatment of Parkinson's disease. In treatment using the long-lasting sustained-release injectable formulation according to this embodiment, in order to achieve a stable therapeutic effect, attention must be paid to adjusting the administration interval while observing not only the efficacy but also the occurrence of side effects, including the wearing-off phenomenon and the on-off phenomenon.

[0044] Furthermore, as shown in the following Test Example 1, when the injectable formulation according to this embodiment is administered subcutaneously, it is coated with a collagen coating or the like and remains around the administration site. Even if a subject who has received the injectable formulation subcutaneously develops a serious side effect, the source of sustained release of the dopamine receptor agonist can be extracted, making the injectable formulation safe and highly practical.

[0045] In another aspect of the present embodiment, there is provided a use of the microparticles for the manufacture of an injectable preparation for treating Parkinson's disease or restless legs syndrome. In another aspect of the present embodiment, there is provided a method for treating Parkinson's disease or restless legs syndrome, comprising the step of administering the microparticles to a subject. In another aspect of the present embodiment, there is provided the microparticles for use in treating Parkinson's disease or restless legs syndrome.

[0046] The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples.

[0047] [Preparation of microparticle formulations] Microparticles containing rotigotine and PLA or PLGA as a biodegradable polymer were prepared by the above-mentioned O / W emulsion method as follows. The preparation conditions for the oil phase of the microparticle formulations (Formulations 1 to 6) are shown in Table 1. Note that, hereinafter, PLA is represented as PLA-m, where m represents the weight-average molecular weight of PLA, and PLGA is represented as PLGA(x / y)-z, where x / y represents the polymerization ratio of lactic acid / glycolic acid, and z represents the weight-average molecular weight of the polymer.

[0048]

[0049] To optimize the particle size, the temperature of an oil phase solution containing rotigotine and a biodegradable polymer dissolved in dichloromethane was adjusted to 18°C. The solution was then poured into 1.0 L of 0.1% PVA aqueous solution over approximately 1 minute while vigorously stirring (room temperature, 6000 rpm) in a Clearmix (M Technique Co., Ltd.). Vigorous stirring continued for 3 minutes after the injection to emulsify the solution. The organic solvent was then removed by gentle stirring (room temperature, 1000 rpm, 3 hours). The resulting suspension was sieved through a 75 μm mesh sieve and centrifuged (4°C, 350 × g, 5 minutes) to recover the microparticles. The supernatant was removed, and the precipitated microparticles were washed with 100 mL of ultrapure water, thoroughly stirred, and then centrifuged (4°C, 350 × g, 5 minutes) to recover the released drug and dispersant. This washing step was repeated twice to obtain microparticles, which were then dispersed in 100 mL of ultrapure water and solidified by lyophilization to obtain Preparations 1 to 6. The ratio of the mass of the obtained microparticle preparation to the total mass of the charged amounts of the biodegradable polymer and rotigotine shown in Table 1 above was calculated as the preparation yield.

[0050] The particle size distribution of the obtained microparticle formulations was measured using a Microtrac particle size distribution and particle shape analyzer, Sync Analyzer (Microtrac BEL). The particle size distributions of Formulations 1, 2, 3, 4, 5, and 6 are shown in Figures 1, 2, 3, 4, 5, and 6, respectively. ５０ was calculated as the particle diameter here.

[0051] The microparticle preparations were observed using a tabletop microscope Miniscope TM4000PlusII (Hitachi High-Technologies Corporation), and scanning electron micrographs of Preparations 1 to 6 are shown in FIG.

[0052] The drug content of Formulations 1 to 6 was measured as follows: 5 mg of the microparticle formulation was precisely weighed into a conical tube, and acetonitrile was added to a concentration of 0.5 mg / mL. The mixture was then stirred in a vortex mixer for 1 minute and sonicated in an ultrasonic cleaner for 1 minute to prepare a sample solution for high-performance liquid chromatography (HPLC) analysis. The sample solution was then analyzed (n=3) under the following HPLC conditions, and the rotigotine content in the sample solution was calculated using the calibration curve of the standard solution. To prepare the standard solution, 5.0 mg of rotigotine reference standard was precisely weighed, and acetonitrile was added to a concentration of 0.5 mg / mL. The solution was then serially diluted to rotigotine concentrations of 3.125, 6.25, 12.5, 25, 50, and 100 μg / mL.

[0053] HPLC analysis conditions: Instrument: 1260 Infinity II (Agilent) Column: TSKgel ODS-100V 5 μm (Tosoh) Column size: 4.6 mm ID × 15 cm Column temperature: 40°C HPLC mobile phase: acetonitrile - 0.3% phosphoric acid aqueous solution (50:50, v / v) Flow rate: 1.000 mL / min Injection volume: 10.00 μL Detection: UV 241 nm Measurement time: 10.00 min

[0054] The ratio of the calculated mass of rotigotine to the mass of the microparticle formulation was defined as the content, and the ratio of the calculated mass of rotigotine to the amount of rotigotine charged shown in Table 1 was defined as the encapsulation rate.

[0055] The formulation yield, particle size distribution, formulation form, rotigotine content and encapsulation rate are shown in Table 2.

[0056]

[0057] Test Example 1: In vivo release test of microparticle formulations. 10 mg of each of Formulations 1 and 3-6 was suspended in 0.2 mL of a dispersion medium containing 5% mannitol, 0.5% carboxymethylcellulose sodium salt, and 0.1% polysorbate 80 to prepare an injectable formulation. Healthy male Crl:CD (SD) rats (Charles River Laboratories) aged 6 weeks, weighing between 175 g and 200 g, and kept with free access to food and water, were administered the injectable formulations. Specifically, the injectable formulations were subcutaneously injected into the occipital region of the SD rats under isoflurane inhalation anesthesia using 1 mL of a Terumo syringe equipped with a 23G injection needle. Immediately after subcutaneous administration, the puncture site was sealed with a medical soft tissue adhesive to confirm that the injectable formulations did not leak out of the body.

[0058] For Formulations 1, 3, and 4, at 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, and 6 weeks after administration of the injection formulation, and for Formulations 5 and 6, at 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks after administration of the injection formulation, anesthetized rats (n=3) were sacrificed by exsanguination by collecting blood from the inferior vena cava, an incision was made around the administration site, and the microparticle formulations together with the covering collagen coating were extracted. These were used as samples for measuring the amount of rotigotine remaining inside, placed in glass centrifuge tubes, and stored at −80°C until preparation of samples for HPLC analysis.

[0059] The measurement sample was thawed, and 20 mL of the above-mentioned HPLC mobile phase was added. The mixture was homogenized twice (10,000 rpm, 2 minutes) using a Hiscotron NS-56S (Microtec Nition) equipped with a generator shaft (NS-10). The suspension containing the disrupted tissue fragments was irradiated with ultrasound for 10 minutes using an ultrasonic cleaner, and the suspension was then centrifuged (room temperature, 1640 × g, 10 minutes). The supernatant was collected and filtered through a 0.2 μm syringe filter to prepare the sample for HPLC analysis. The sample for HPLC analysis was analyzed under the above-mentioned HPLC measurement conditions (n ​​= 3), and the rotigotine content in the sample for HPLC analysis was calculated from the calibration curve of the standard solution. The suspension of the dispersed microparticle formulation for administration to rats was thoroughly suspended in the same manner as for injection, and 0.2 mL of the suspension was collected in a glass centrifuge tube (n=3). Rotigotine was quantified in the same manner as in the preparation of samples for HPLC analysis, and this was taken as the amount of rotigotine injected (100%) at the start of release (0 hours).

[0060] Figure 8 shows the time course of the subcutaneous rotigotine retention rate in rats subcutaneously administered with Formulation 1 or any of Formulations 3 to 6. Regarding the in vivo rotigotine release rate, Formulations 1, 3, and 4 showed slight differences in the initial release from 12.6% to 24.7% on day 1 after administration, but there were no significant differences in the release trends up to 6 weeks after administration, with 78.3% to 83.0% of rotigotine released by 6 weeks after administration. Formulations 1, 3, and 4 all demonstrated release over 6 weeks associated with the hydration rate of the biodegradable polymer and changes in the physical properties of the polymer due to biodegradation. These results demonstrate that Formulations 1, 3, and 4 continuously release rotigotine for at least 6 weeks.

[0061] The in vivo rotigotine release rates for Formulations 5 and 6 were 18.1% to 21.2% after administration in the initial release, and there was no clear difference in the release trend up to 4 weeks after administration, with 98.9% to 99.4% of rotigotine released at 4 weeks after administration. For both Formulations 5 and 6, release was observed over about 4 weeks in accordance with the hydration rate of the biodegradable polymer and changes in the physical properties of the polymer associated with biodegradation. These results demonstrated that Formulations 5 and 6 provided continuous sustained release of rotigotine over a period of about 4 weeks.

[0062] Test Example 2: Measurement of plasma drug concentration in rats administered with a microparticle formulation The injection formulation was subcutaneously administered to SD rats in the same manner as in Test Example 1. The dose was based on the average body weight of SD rats, and an injection formulation prepared by suspending 84 mg of Formulation 2 (7.8 mg as rotigotine) in 0.2 mL of the dispersion medium was administered.

[0063] Blood samples were collected from the jugular vein of SD rats (n=6) before administration of the injectable formulation, on day 1 after administration, and weekly from week 1 to week 8. Using a heparinized syringe, 0.7 mL to 1.0 mL of blood was collected from the jugular vein. The plasma components were centrifuged (4°C, 1100 × g, 10 minutes) to obtain plasma samples. The samples were stored in a -80°C deep freezer until they were prepared for analysis by a high-performance liquid chromatograph triple quadrupole mass spectrometer (LC / MS).

[0064] 100 μL of the thawed plasma sample was transferred to a microtube, and 10 μL of an internal standard solution (2 μg / mL diazepam methanol-water (70:30, v / v) solution) was added. 10 μL of methanol-water (70:30, v / v) was then added and mixed uniformly. Next, 1 mL of a mixture of n-hexane-dichloromethane-isopropanol (20:10:1, v / v / v) was added, and the mixture was thoroughly stirred with a vortex mixer for 3 minutes. The organic phase separated by centrifugation (room temperature, 20,400 × g, 10 minutes) was transferred to a new microtube and dried by blowing with nitrogen gas. Finally, 200 μL of the LC / MS mobile phase described below was added to dissolve the dried product. After stirring with a vortex mixer for 2 minutes, the mixture was sonicated in an ultrasonic cleaner for 10 minutes, and filtered through a 0.2 μm syringe filter to prepare the sample for LC / MS analysis.

[0065] To 100 μL of blank plasma obtained from SD rats that had not been administered the injectable formulation, 10 μL of the internal standard solution and 10 μL of the above-mentioned standard solution were added to prepare plasma samples corresponding to plasma rotigotine concentrations of 0.03125, 0.0625, 0.125, 0.25, 0.5, 1.0, 2.0, 10.0, and 40.0 ng / mL. These samples were analyzed by LC / MS to obtain a standard curve.

[0066] LC conditions: Instrument: 1290 Infinity II, 6495 Triple Quad LC / MS (Agilent) Column: InertSustainSwift C18 HP 3 μm (GL Sciences) Column size: 4.6 × 100 mm Column temperature: 40°C Mobile phase for LC / MS: 0.1 mM ammonium acetate / methanol-0.05% formic acid aqueous solution (70:30, v / v) Flow rate: 0.700 mL / min Injection volume: 10.00 μL Measurement time: 6.00 min

[0067] MS conditions: Ion source: AJS ESI Source temperature: Gas 200°C, sheath gas 400°C Detection mode: Positive ion Scan type: MRM Ion pair: Rotigotine 316.2 / 147.1, Diazepam 285.1 / 193.0

[0068] The time course of rotigotine plasma concentrations in SD rats subcutaneously administered with Formulation 2 is shown in Figure 9. No initial burst was observed on day 1 after administration, and plasma rotigotine concentrations increased bimodally up to 3 weeks after administration (peaks of 8.3 ng / mL and 8.6 ng / mL), followed by a gradual decrease from 4 to 6 weeks after administration. The bimodal increase in plasma rotigotine concentrations is due to the release of rotigotine localized on the surface of the microparticles and the release of rotigotine associated with swelling and subsequent hydrolysis of the biodegradable polymer. Therefore, it was demonstrated that the injectable formulation of this example maintains plasma rotigotine concentrations for at least 8 weeks, which is thought to depend on the biodegradability of the biodegradable polymer.

[0069] The above-described embodiments are intended to explain the present invention and are not intended to limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not by the embodiments. Various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

[0070] This application is based on Japanese Patent Application No. 2024-82281, filed on May 21, 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-82281 are incorporated herein by reference.

[0071] The present invention is useful in sustained release injectable formulations.

Claims

1. A composition comprising microparticles containing a free dopamine receptor agonist and a biodegradable polymer, wherein the volume average particle diameter D of the microparticles is ５０ 1. An injectable preparation for treating Parkinson's disease or restless legs syndrome, wherein the dopamine receptor agonist has a particle size of 50 μm or less, and the concentration of the dopamine receptor agonist in the plasma of a subject to which the preparation is administered is maintained for one month or longer.

2. The volume average particle diameter D of the microparticles ５０ The injectable preparation according to claim 1, wherein the particle size is 1 to 50 μm.

3. The injectable preparation according to claim 1 or 2, wherein the maintenance period is 2 months.

4. The injectable formulation according to claim 1 or 2, wherein the dopamine receptor agonist is rotigotine free base or ropinil free base, and the content of the dopamine receptor agonist in the microparticles is 5 to 50% by weight.

5. The injectable preparation according to claim 1 or 2, wherein the biodegradable polymer is a lactic acid polymer or a lactic acid / glycolic acid copolymer having a molecular weight of 5,000 to 150,000.

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