Solid dispersions of insoluble drug and preparation method thereof

Abstract

The present invention relates to a solid dispersion characterized in that it comprises carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester as an active ingredient and a water-soluble polymer having a glass transition temperature lower than the melting point of the active ingredient as a carrier, and it is prepared via melt extrusion. The solid dispersion of the present invention remarkably increases the solubility and dissolution rate of the active ingredient which is an insoluble drug to efficiently improve the bioavailability when it is orally administered.

Claims

1. A method for preparing a solid dispersion, comprising: mixing 10 to 50 wt % of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester or a pharmaceutically acceptable salt thereof, 45 to 85 wt % of a water-soluble polymer having a glass transition temperature lower than the melting point of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester, and 1 to 5 wt % of a plasticizer, and melt-extruding the mixture at a temperature lower than the melting point of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester, wherein the water-soluble polymer is selected from polyvinylpyrrolidone, hypromellose acetate succinate and a combination thereof, and the plasticizer is selected from the group consisting of D-alpha-tocopheryl polyethylene glycol 1000 succinate, polyethylene glycol 400, and a combination thereof.

2. The method of claim 1, wherein the mixture is melted when it passes through four (4) or more heating blocks, wherein a temperature of the heating blocks is sequentially lowered.

3. The method of claim 2, wherein the heating blocks consist of a first, a second, a third, and a fourth heating blocks, wherein a temperature of the first heating block is controlled to 160 to 145 C., wherein a temperature of the second heating block is controlled to 144 to 120 C., wherein a temperature of the third heating block is controlled to 119 to 80 C., and wherein a temperature of the fourth heating block is controlled to 79 to 70 C.

4. The method of claim 1, wherein the water-soluble polymer is contained in the amount of about 70 to 85 wt % based on the total weight of the mixture.

5. The method of claim 1, wherein the plasticizer is contained in the amount of about 1 wt % based on the total weight of the mixture.

6. The method of claim 1, wherein the mixture comprises 50 to 85 wt % of polyvinylpyrrolidone.

7. The method of claim 1, wherein the mixture comprises: about 30 wt % of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-lmethyl ester, about 69 wt % of polyvinylpyrrolidone, and about 1 wt % of D-alpha-tocopheryl polyethylene glycol 1000 succinate.

8. The method of claim 1, wherein the mixture comprises: about 30 wt % of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester, about 69 wt % of polyvinylpyrrolidone, and about 1 wt % of polyethylene glycol 400.

9. The method of claim 1, wherein the mixture comprises: about 15 wt % of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester, about 84 wt % of hypromellose acetate succinate, and about 1 wt % of polyethylene glycol 400.

Description

DRAWINGS

(1) FIG. 1 shows the results by Scanning Electron Microscopy for CBI obtained in Preparation 1 (left) and the CBI-containing solid dispersion of the present invention obtained in Example 1 (right).

(2) FIG. 2 shows the results of the dissolution test of the solid dispersion-containing tablet obtained in Example 7.

(3) FIG. 3 shows the pharmacokinetic profile observed after the solid dispersion of the present invention is orally administered to a Beagle dog.

BEST MODE FOR CARRYING OUT THE INVENTION

(4) <Preparation 1>

(5) Preparation of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester (CBI)

(6) The preparation of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester (CBI) is described in detail in Korean Patent Application No. 2010-0041436. Specifically, it was prepared as follows.

(7) 4-Benzyloxybenzaldehyde (4.24 g, 20 mmol) was dissolved in a solvent mixture of ethanol and water (3:1, 100 ml) in the concentration of 0.2 M while stirring. NH.sub.2OHHCl (2.78 g, 40 mmol) and sodium acetate (2.46 g, 30 mmol) were added thereto, which was then stirred for about 30 min at room temperature. The completion of reaction was confirmed by liquid chromatography, and water and ethanol were distilled off under reduced pressure to give a pale yellow solid compound. This solid compound was extracted three times with water and ethyl acetate, and the organic solvent layer was subjected to the condition of reduced pressure. The crude compound was recrystallized from hexane/ethyl acetate (10:1) to give a compound as a white solid. Thus obtained solid 4-benzyloxy-benzaldehydeoxime (2.27 g, 10 mmol; a compound of 92% purity) was dissolved in methylene chloride (40 ml, 0.25 M), and propargyl alcohol (1.77 ml, 30 mmol) was added thereto. To this solution was very slowly added in drops 10% NaOCl (13.7 ml, 20 mmol) at 0 C. by using a dropping funnel. After all NOCl was added, the mixture was stirred for about 5 h during which the temperature was slowly raised to room temperature. After the completion of reaction was confirmed by liquid chromatography, the reaction mixture was distilled under reduced pressure to evaporate methylene chloride. Water (200 ml) was added to the residue, and the resulting solid was filtered. The compound thus filtered was washed with excess water and then finally washed with diethyl ether. The solid compound thus obtained was recrystallized from ethyl acetate/hexane (1:2) to give [3-(4-benzyloxy-phenyl)-isoxazol-5-yl]-methanol as a white solid (Yield: 2.5 g). Chlorosulfonyl isocyanate (1.04 ml, 12 mmol) was slowly added to the THF solution (50 ml, 0.2 M) containing [3-(4-benzyloxy-phenyl)-isoxazol-5-yl]-methanol (2.813 g, 10 mmol) in a 250 ml flask at 78 C. After disappearance of all the starting materials was confirmed by liquid chromatography, water was added to the reaction solution. After 1 h, distillation under reduced pressure was carried out to evaporate THF. Water (100 ml) was added thereto, and the resulting solid was filtered. Thus filtered solid was washed with 100 ml of water and ethyl acetate/hexane (1:2) solution, and dried to give 3.4 g of the crude product (Purity: 95.9%). This crude product was recrystallized from ethyl acetate/hexane/methylene chloride (1:4:1) solution containing 1% methanol to give 2.743 g of carbamic acid 3-(4-benzyloxy-phenyl)-isoxazol-5-ylmethyl ester (CBI) in the purity of 99%.

EXAMPLES 1 to 6

(8) Preparation of Melt-Extruded Solid Dispersions

(9) Solid dispersions having the compositions of Tables 2 to 7 were prepared from a mixture of CBI, a water-soluble polymer and a plasticizer by using a twin screw having an 18 mm diameter. The mixtures were introduced into an extruder wherein four distinguished heating blocks (Zone 1Zone 4) were connected in series, and the solid dispersions obtained by melt-mixing and extruding were pulverized by a pulverizer to give the solid dispersions of Examples 1 to 6 as a powder. The detailed preparation condition is shown in Table 1. Polyvinylpyrrolidone PVP K30 was used as the water-soluble polymer. A photograph was taken of the CBI obtained in Preparation 1 (left) and the CBI-containing solid dispersion obtained in Example 1 (right) by Scanning Electron Microscopy as shown in FIG. 1. As can be seen from FIG. 1, in the solid dispersion CBI is uniformly dispersed in the polymer matrix mainly in the form of amorphous microstructure.

(10) TABLE-US-00001 TABLE 1 Parameter Result Extruder Leistritz 18-mm Screw Speed 250 rpm Die Single Bore, Round, 3.0 mm diameter Zone 4 Temperature 75 C. Zone 3 Temperature 110 C. Zone 2 Temperature 140 C. Zone 1 Temperature 150 C. Feed Speed of Powder 1.0 kg/hr Feeder Screw 20 mm single flight screw Pulverizer Fitzmill L1A Pulverizing Rate 9,000 rpm Standard Sieve 20

(11) TABLE-US-00002 TABLE 2 Ingredient Final Composition Ratio (wt %) CBI 15% Polyvinylpyrrolidone 85%

(12) TABLE-US-00003 TABLE 3 Ingredient Final Composition Ratio (wt %) CBI 30% Polyvinylpyrrolidone 70%

(13) TABLE-US-00004 TABLE 4 Ingredient Final Composition Ratio (wt %) CBI 30% Polyvinylpyrrolidone 69% TPGS 1%

(14) TABLE-US-00005 TABLE 5 Ingredient Final Composition Ratio (wt %) CBI 30% Polyvinylpyrrolidone 69% Polyethylene glycol 400 1%

(15) TABLE-US-00006 TABLE 6 Ingredient Final Composition Ratio (wt %) CBI 15% Hypromellose acetate succinate 84% Polyethylene glycol 400 1%

(16) TABLE-US-00007 TABLE 7 Ingredient Final Composition Ratio (wt %) CBI 50% Hypromellose acetate succinate 40% TPGS 10%

Comparative Example 1

(17) Preparation of Melt-Extruded Solid Dispersion

(18) The melt-extruded solid dispersion of Comparative Example 1 was prepared according to the same procedure as Example 1 except that the temperatures of heating blocks were set up as follows. Impurities were measured by using the high-performance liquid chromatography for the solid dispersions of Example 1 and Comparative Example 1. The column used in the present experiment was a 150 cm4.6 mm, 3.5 m C18 column, the flow rate was 1.0 mL/min, the column temperature was 30 C., and the detection was performed at 260 nm. The mobile phase was applied for 30 min under the following gradient condition with acetonitrile and 0.1% aqueous trifluoroacetic acid solution.

(19) TABLE-US-00008 TABLE 8 0.1% Aqueous trifluoroacetic Time (Min) Acetonitrile acid solution 0 Min 45 55 12 Min 45 55 20 Min 80 20 22 Min 45 55 30 Min 45 55

(20) As a result, in the case of the solid dispersion of Comparative Example 1 which was obtained by warming and melting in Zone 1 whose initial temperature was the melting point of CBI, decomposition products were generated during the procedure and impurities corresponding to the Relative Retention Times (RRTs) of 0.87 and 1.32, the total amount thereof being 6.5%, were detected. However, the total impurity of only 0.6% was detected in the solid dispersion of the present invention. From this result, it was confirmed that the preparation method of the present invention is a safe method wherein the active ingredient is hardly decomposed.

(21) TABLE-US-00009 TABLE 9 Comparative Example - Heating Block Condition 1 Zone 1 165 Zone 2 155 Zone 3 140 Zone 4 90 CBI Content (%) 93.5% Total Impurity (%) 6.5%

Example 7

(22) Preparation of the Solid Dispersion-Containing Tablet

(23) The solid dispersion thus prepared may be formulated into a tablet for the purpose of easy administration. The tablet was prepared by adding the pharmaceutically acceptable disintegrating agent, diluent and lubricant as excipients needed for the preparation of a tablet. Specifically, the solid dispersion obtained in Example 2, croscarmellose sodium as a disintegrating agent, magnesium stearate as a lubricant and microcrystalline cellulose as a diluent were used. The tablet was prepared by using SiO.sub.2 for the purpose of increasing fluidity, and the amounts of ingredients are shown in the following Table 10.

(24) TABLE-US-00010 TABLE 10 Unit Weight Ratio Ingredient (mg) (%) Function CBI solid 16.7 6.7 Main ingredient dispersion of Solid dispersion (CBI 30%, Example 2 water-soluble polymer 70%) Microcrystalline 217.1 86.8 Diluent Cellulose (Avicel PH102) Croscarmellose 12.5 5 Disintegrating Agent Sodium (Ac-Di-Sol) Magnesium Stearate 1.25 0.5 Lubricant SiO.sub.2 2.5 1 Fluidizer Total Amount 250 100

Experiment 1

(25) Identification of Solubility of the Active Ingredient CBI

(26) Under several solvent conditionsi.e., distilled water, methanol, ethanol, acetone and diethyl etherthe solubility of CBI was measured. Specifically, about 5 to 40 mg of CBI was introduced into a 1.5 mL microtube, and 1 mL of the test solvent was added thereto. The mixture was slowly stirred in a rotary stirrer for 24 h under the condition of room temperature until solvent equilibrium was reached. After stirring, the suspended solution was filtered through a 0.45 micrometer membrane filter. The supernatant was collected and diluted by two-fold with the same amount of diluent for analysis. The CBI concentration was analyzed by using high-performance liquid chromatography. The column used in the present experiment was a 150 cm4.6 mm, 5 m C18 column, and the mobile phase was a mixture of 35% acetonitrile, 20% methanol and 45% distilled water by volume. The flow rate was 1.0 mL/min, and the detection was performed at 255 nm. The results are shown in Table 11 wherein the values are represented as an average of three repeats standard deviation.

(27) TABLE-US-00011 TABLE 11 Solvent Solubility (mg/mL) Distilled Water Not detected Methanol 2.5 Ethanol 1.5 Diethyl Ether 0.7 Acetone 24.8

(28) From the above results, it is confirmed that CBI is an extremely insoluble compound that is hardly dissolved in water.

Experiment 2

(29) Thermal Analysis of CBI

(30) Evaluations of melting point and heat-dependent change of characteristics of CBI were performed by DSC (Differential Scanning calorimetry). The experimental procedure was briefly explained below. 1 to 2 mg of CBI weighed accurately and was introduced into a standard aluminum pan. The temperature was raised from 50 C. to 350 C. at the heating rate of 100 C./min. The thermal characteristics were analyzed under the nitrogen stream of 25 mL/min. The analysis results are shown in Table 12.

(31) TABLE-US-00012 TABLE 12 Melting Point ( C.) Starting Heat of Fusion Sample No. Temperature Peak Time H (J/g) First 164.15 167.94 155.692 Second 164.23 167.09 129.708 Average 164.19 167.52 142.700

Experiment 3

(32) Dissolution Test of the Solid Dispersion-Containing Tablet

(33) The solid dispersion-containing tablet obtained in Example 7 was subjected to a dissolution test according to the second method of United States Pharmacopoeia Dissolution Test (a paddle method) as follows and the results are shown in FIG. 2.

(34) [Dissolution Test]

(35) Method: The second method of United States Pharmacopoeia Dissolution Test (a paddle method)

(36) Dissolution media: 1.5% sodium lauryl sulfate (SLS)-containing distilled water 500 mL

(37) Stirring speed: 50 rpm

(38) Temperature of eluent: 370.5 C.

(39) As can be seen from FIG. 2, the tablet prepared from the solid dispersion of the present invention shows a dissolution rate that satisfies the criteria of Dissolution Test of Tableti.e., 80% or more dissolution for 45 min. From this result, it can be confirmed that the dissolution characteristic of the highly insoluble CBI has been improved very effectively.

Experiment 4

(40) Pharmacokinetic Test of the Solid Dispersion for a Beagle Dog

(41) Just before the test, three Beagle dogs were weighed respectively. The solid dispersion of Example 3 as the test group and CBI powder as the control group each weighed in the amount corresponding to 40 mg/kg, were filled into a gelatin capsule and then orally administered. Just before and at 0.5, 1, 2, 4, 6, 8 and 24 h after administration, the blood was collected from the popliteal vein. The plasma was separated from the blood sample by centrifugation and stored/kept at 20 C. until analysis thereof. For the analysis, the plasma sample (0.5 ml) was correctly transferred to a 1.5 ml polypropylene centrifuge tube. This mixture was vortexed for 30 sec and centrifuged at 400 rpm for 10 min. The concentration of CBI in the plasma was analyzed by LC-MS/MS. As the mobile phase, a mixed solution of 0.1% formic acid-acetonitrile/deionized water (60/40, v/v), as the flow rate 0.25 mL/min, and as the column XterrS C18 (3.050 mm, 2.5 micrometer, Waters, USA) were used. The peak was detected by MRM (multiple reaction monitoring) method using triple-quadrupole mass spectrometry. The ionization was analyzed in the positive mode by using electrospray ionization (ESI) wherein the ion spray temperature was set up at 500 C. In the MRM method, the protonated molecular ions of CBI and the internal standard compound were monitored to have the m/z values of 325.1 and 268.0, and the product ions thus produced were monitored to have the m/z values of 91.0 and 155.0, respectively. The area under the concentration-time curve (AUC) of the drug in the plasma was calculated by the linear trapezoidal method. The results are shown in the following Table 13 and FIG. 3.

(42) TABLE-US-00013 TABLE 13 Blood CBI Concentration (g/mL) Time (hours) Test Group Control Group 0 0.0 0.0 Below the 0.5 0.080 0.06 Sensitivity for 1 0.464 0.28 Quantification 2 0.692 0.33 4 0.183 0.10 6 0.065 0.04 8 0.059 0.05 24 Not Detected AUClast (g*hr/mL) 1.98 0.96 AUCInf (g*hr/mL) 2.14 1.04

(43) As can be seen from the above results, the control group to which CBI powder was administered shows the result of below the sensitivity for quantification in all the time zones, which confirms that the drug was not orally absorbed at all. On the contrary, the test group to which the solid dispersion of the present invention was administered shows the maximum blood concentration of 0.531 g/mL at 1 h after administration, which confirms that the absorption by oral administration and bioavailability of CBI have been conspicuously improved.