Microspherical sustained-release injection containing escitalopram and method for preparing same

Abstract

The present invention relates to a biodegradable polymer microsphere-containing sustained-release injection containing escitalopram as an active ingredient, and to a method for manufacturing the same. In the case of escitalopram microspheres, there is a problem of low encapsulation rate, fracture due to weak strength, and initial over-release due to the phase separation of the liquid drug and the polymer inside the microspheres. In order to solve the problem, it is possible to maximize the encapsulation amount and the encapsulation efficiency of the escitalopram adding a hydrophobic solidifying agent to uniformize the non-uniform phase, to overcome the cracking of the microspheres at high loading conditions, and to properly control the initial release and release delay of the microspheres.

Claims

1. A sustained release injectable composition, comprising biodegradable polymer microspheres comprising escitalopram, wherein the microspheres further comprise a pharmaceutically acceptable hydrophobic solidifying agent to uniformly distribute the escitalopram in the microspheres, wherein the biodegradable polymer is selected from at least one of the group consisting of polylactide, polyglycolide, poly (lactide-co-glycolide), and poly (lactide-co-glycolide) glucose, and wherein the pharmaceutically acceptable hydrophobic solidifying agent is selected from the group consisting of dipalmitoyl phosphoric acid, stearic acid, lithocholic acid, hydroxy naphthoic acid, and a mixture thereof.

2. The sustained release injectable composition of claim 1, wherein the pharmaceutically acceptable hydrophobic solidifying agent is a hydroxy naphthoic acid.

Description

DESCRIPTION OF DRAWINGS

(1) The following drawings, which are to be incorporated in this specification, illustrate preferred embodiments of the invention and, together with the description of the invention, serve to further understanding the principles of the invention, and the invention is not to be construed as limited to the details set forth in such figures.

(2) FIG. 1 is an electron micrograph of microspheres prepared in Example 1, Example 2, and Example 3. The left photograph is the entire picture of the microspheres and the right photograph is a photograph of the inside of the crushed surface of the microspheres. The microspheres prepared in Examples 1-3 show the inside filled morphology and the particles were not broken or deformed after drying.

(3) FIG. 2 is a photograph of Comparative Example 1 in which the solidifying agent is not added in microspheres. Comparative Example 1 shows an emulsion in the form of an O/O/W emulsion, and the higher the content of the drug, the greater the number of small cells in which the liquid drug was present, resulting in a significant drop in the strength of the microspheres. As a result, after lyophilization, the broken form increased.

(4) FIG. 3 is a graph showing in vitro drug release pattern measured according to Experimental Example 3 of microspheres prepared in Example 1, Example 2, Example 3 (3-3) and Comparative Example 1 according to the present invention. When the phospholipid (DPPA) is contained in comparison with Comparative Example 1, the initial release is shown, but the release delay effect is high as the time passes, and when the fatty acid (stearic acid) is added, the initial release and the release delay effect appear to be weak. In the case of Example 3, in which the aromatic acid was added, the initial release inhibition and the release delay effect were good.

(5) FIG. 4 is a graph showing the results of comparison with Comparative Example 1 in Examples 3-1, 3-2, 3-3, and 3-4 according to the method of Example 3 of aromatic acid with good initial release inhibition and release delay effects. It can be seen that as the content of the aromatic acid increases, the initial release inhibition and the release delay effect are improved. This is because the O/O/W type non-uniform microsphere internal structure is changed into an O/W type uniform internal structure by the addition of a hydrophobic solidifying agent, thereby increasing the initial release inhibition and the release delay effect and preventing the microsphere from being broken even if the loading amount of escitalopram is increased.

MODE FOR INVENTION

(6) Hereinafter, embodiments of the present invention will be described in detail in order to help an understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

(7) Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Example 1 Preparation of O/W Type Microspheres Using Biodegradable Polymer PLGA, Escitalopram, and DPPA

(8) 1.5 g of biodegradable polymer PLGA (Evonik, Product Name: RESOMSER® RG504H), 1 g of escitalopram, and 0.5 g of dipalmitoyl phosphoric acid (DPPA) were added to 20 ml of dichloromethane and stirred vigorously for 1 hour to dissolve them. The uniformly dissolved solution was placed in a 200 ml aqueous solution of 5 (w/v) % polyvinyl alcohol (SIGMA ALDRICH®, 87-90% hydrogenated MW: 30,000-70,000) and dispersed at 1,000-2,000 rpm using a homogenizer (IKA™, Ultra-Turrax™ T8) over 2 minutes to obtain an O/W emulsion. Thereafter, the emulsion was vigorously stirred at room temperature and atmospheric pressure to a magnetic stirrer (900 rpm) for 5 hours to form microspheres, and microspheres were collected using a Whatman paper and washed 2-3 times with distilled water. The washed microspheres were first dried at room temperature and atmospheric pressure for 3 hours, and then freeze-dried at −35° C. for 12 hours to completely remove the solvent in the microspheres.

Example 2 Preparation of O/W Type Microspheres Using Biodegradable Polymer PLGA, Escitalopram and Stearic Acid

(9) 1.5 g of biodegradable polymer PLGA (Evonik®, product name: RESOMER® RG504H®), 1 g of escitalopram and 0.3 g of stearic acid were added to 20 mL of dichloromethane and stirred vigorously for 1 hour to dissolve. Thereafter, the microspheres were prepared in the same manner as in Example 1.

Example 3 Preparation of O/W Type Microspheres Using Biodegradable Polymer PLGA, Escitalopram and 1-Hydroxy-2-naphthoic Acid

(10) 1.5 g of biodegradable polymer PLGA, 1 g of escitalopram, and 0.5 g of 1-hydroxy-2-naphthoic acid were added to 20 ml of dichloromethane and stirred vigorously for 1 hour to dissolve. Thereafter, the microspheres were prepared in the same manner as in Example 1.

(11) Examples 3-1 to 3-4 were prepared in the same manner with varying amounts of 1-hydroxy-2-naphthoic acid. A representative example of Example 3 is Example 3-3.

(12) TABLE-US-00001 TABLE 1 Example Example Example Example 3-1 3-2 3-3 3-4 escitalopram 1 g 1 g 1 g 1 g Hydroxy 0.13 g 0.3 g 0.5 g 0.63 g naphthoic Acid PLGA(RG504H) 1.5 g 1.5 g 1.5 g 1.5 g

Comparative Example 1: Preparation of O/O/W Type Microspheres Using Biodegradable Polymer PLGA and Escitalopram

(13) 1.5 g of biodegradable polymer PLGA (Evonik, Product Name: RESOMER® RG504H), and 1 g of escitalopram were added to 20 mL of dichloromethane and stirred vigorously for 1 hour to dissolve. Thereafter, the microspheres were prepared in the same manner as in Example 1.

Experimental Example 1: Morphology Measurement of Microspheres

(14) The morphology of the microspheres obtained in Examples 1 to 3 and Comparative Example 1 was confirmed using an electron microscope. A sample for observing the crushing surface was prepared by adding 100 mg of microspheres and 5 ml of liquid nitrogen to the pestle and crushing the particles. About 5 mg of the prepared microspheres were coated with a platinum coating for 4 minutes using a coater (Quorum™ Q150 TES, 10 mA), and the morphology and surface of the microspheres were observed through a scanning electron microscope (sold under the trademark TESCAN® Mira™ 3, LMU FEG-SEM).

(15) The results are shown in FIGS. 1 and 2. According to the results, microspheres having a size of about 50-160 μm were identified in each of the Examples and Comparative Examples, and Comparative Example 1 showed the formation of sponge-shaped pores inside the microspheres by phase separation between the liquid escitalopram and the PLGA polymer, thereby significantly lowering the strength of the microspheres. Examples 1-3, on the other hand, were in the form of a filled solid and had little broken morphology. The stearic acid of Example 1 showed a soft and slightly distorted spherical shape due to the influence of lipid, and the phospholipid (DPPA; dipalmitoyl phosphoric acid) of Example 2 showed a shape in which the inner crushing surface was filled with a solid without pores or cracks, but the surface was somewhat rough. Example 3 was an aromatic hydroxy-naphthoic acid-containing particulate, the particle shape was spherical and the surface was homogeneous. The inner crushing surface was observed to have a small number of pores, but the number was not large.

Experimental Example 2: Determination of the Encapsulation Amount and Rate of Escitalopram of Microspheres

(16) About 30 mg of microspheres prepared in Examples 1-3 and Comparative Example 1 were completely dissolved in 3 ml of chloroform (SIGMA ALDRICH®), and then diluted to 400-fold to be used as a test solution. The absorbance was measured using an HPLC photometer to determine the content of escitalopram encapsulated in the microspheres. The encapsulation rate was calculated as the encapsulated amount relative to the added amount of the drug.

(17) HPLC analysis conditions were as follows:

(18) The mobile phase was prepared at a ratio of Acetonitrile 4:Methanol 5:Buffer 11; the detector was UV 240 nm; the separation column was 4.6-mm×25-cm; 5-um packing L1; the flow rate was 1.5 ml/min; the injection size was 20 uL; the analysis time was 15 min; and the assay range was measured in a concentration range of 1000 ug/ml to 7.8125 ug/ml.

(19) The results are shown in Table 2.

(20) TABLE-US-00002 TABLE 2 Content rate of drug (%) Encapsulation Efficiency (%) (Encapsulated amount of (Encapsulated amount of drug/weight of drug/Added amount of microsphere) × 100 (%) drug) × 100% Example 1 35.7 ± 0.6 75.5 ± 0.2 Example 2 34.4 ± 0.2 78.3 ± 0.4 Example 3 34.6 ± 0.4 84.2 ± 0.6 Comparative 12.5 ± 0.2 .sup. 46 ± 0.5 Example 1

(21) The encapsulation efficiency of escitalopram in Examples 1-3 has been as high as 75-80%. However, Comparative Example 1 had a relatively low encapsulation rate because the drug was lost in liquid phase. The content of the drug of Comparative Example 1 was also low, and it seems that it is because the microspheres of the sponge structure were broken or the non-ideal release happened.

(22) Experimental Example 3: Measurement of In Vitro Drug Release Behavior of Microspheres

(23) In order to measure the release behavior of the drug, the microspheres prepared in Examples 1-3 and Comparative Example 1 were weighed so that the amount of drug in the microspheres was 4.0 mg and stored in 100 ml of PBS (Phosphate Buffered Saline, pH 7.4) at 37° C. isotherm, and the amount of release was measured using a HPLC by diluting 1 ml of the PBS to 40-fold every hour. The concentration of the released drug was calculated by converting the absorbance value, and the amount of drug released for each time relative to the total drug (4 mg) of each sample was calculated as a cumulative percentage. The escitalopram stock solution was used as a control for this experiment. The results of these measurements are shown in FIGS. 3 and 4.

(24) FIG. 3 is a graph showing in vitro drug release behavior measured according to Experimental Example 3 of microspheres prepared in Example 1, Example 2, Example 3 (3-3) and Comparative Example 1 according to the present invention. As compared to Comparative Example 1, when the phospholipid (DPPA) was contained, the initial release was shown, but the release delay effect was increased over time. When the fatty acid (stearic acid) was added, the initial release and the release delay effect appeared to be weak. In the case of Example 3, which is the case where aromatic acid was added, the initial release inhibition and the release delay effect were good.

(25) FIG. 4 is a graph showing the results of comparison with Comparative Example 1 in Examples 3-1, 3-2, 3-3, and 3-4 according to the method of Example 3 of aromatic acid with good initial release inhibition and release delay effects. It can be seen that as the content of the aromatic acid increases, the initial release inhibition and the release delay effect are improved. This is because the O/O/W type non-uniform microsphere internal structure is changed into an O/W type uniform internal structure by the addition of a hydrophobic solidifying agent, thereby increasing the initial release inhibition and the release delay effect and preventing the microsphere from being broken even if the loading amount of the escitalopram is increased.