Method for preparing inclusion medicine by adopting spray drying process

Abstract

According to the method for preparing the clathrate medicine by adopting the spray drying process, CMC-Na and HPMC are combined for use, and under the heating condition, CMC-Na and HPMC entrapped with medicine molecules are further subjected to cross-linking clathration, so that the viscosity of a solution is reduced, new large-particle molecules are formed, the spray drying process is stable and controllable, and the clathrate medicine is prepared. The problems that when an HPMC inclusion drug is prepared through an existing spray drying technology, a spray head of spray drying equipment is prone to being blocked, and a finished product is caked and agglomerated and severely adheres to the wall are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of veterinary medicine, and in particular to a method for preparing inclusion medicine by adopting a spray drying process. Background Art

[0002] Tiamulin fumarate has a strong bitter taste and unpleasant odor, which can cause animals to resist eating or drinking, resulting in reduced food or water intake, which in turn affects drug intake and reduces therapeutic efficacy. Taste-masking can mask the drug's unpleasant odor and taste, making it more acceptable to animals and ensuring that the drug can enter the body and take effect. Taste-masking not only improves the drug's palatability but also enhances the stability and solubility of the formulation, making it more suitable for use in scenarios such as drinking water administration.

[0003] Existing taste-masking strategies for tiamulin fumarate primarily fall into two categories: directly mixing the API with excipients like sugar or flavorings, and encapsulating the drug using techniques like fluidized bed coating. Commercially available products have included the addition of flavoring agents and sweeteners to mask the bitterness and off-flavor of the drug. Inclusion-based taste-masking products, however, typically utilize HPMC, PEG6000, Tween-80, talc, and other coating materials, coating the tiamulin granules using fluidized bed coating technology.

[0004] Directly using flavors or sweeteners to mask the taste of tiamulin fumarate presents the following challenges: The tiamulin API is extremely bitter and irritating. Simply using flavors can only enhance the aroma and sweetness, but is ineffective in masking the bitterness and completely eliminating the drug's unpleasant taste. Therefore, using flavors alone for taste masking is not ideal for improving animal compliance.

[0005] There are the following problems in using fluidized bed coating technology to prepare taste-masked granules of tiamulin fumarate: if the bitter taste and irritating odor of the raw material drug need to be better masked, it needs to be coated multiple times. The particle size and weight of the product obtained after coating are significantly increased. The excessively large particle size of the product may result in failure to meet the particle size quality requirements of the soluble powder, and may also lead to uneven mixing when the included particles and excipients are further mixed, resulting in low content test results. Moreover, the current specification of tiamulin fumarate soluble powder commonly used in China is 45%. Excessive coating material may result in a low proportion of active ingredients.

[0006] Spray drying technology is an effective means of obtaining ultrafine dry powders from liquid feeds. Its basic principle is to use an atomizer to spray a liquid of a certain concentration into a mist of droplets. These droplets are then released into a hot air stream at a constant velocity, rapidly drying the droplets to produce a powdered product. Using spray drying technology, the solution dries within the equipment in just seconds, completing the mixing, granulation, and drying operations in one step. This simplifies the production process and shortens the production cycle. It also produces uniformly sized, spherical, and fluid particles, eliminating the need for secondary processing.

[0007] In recent years, the application of HPMC in the pharmaceutical industry has received considerable attention. Its good biocompatibility, strong load capacity and mechanical properties make it stand out among many cellulose derivatives, and it is made into various forms for drug delivery, encapsulation and inclusion. However, HPMC is often used as hydrogels, micellar particles, tablet skeletons, and thin films for tablets and capsules. It is generally not used in spray drying processes. This is because when using spray drying technology to prepare HPMC-encapsulated drugs, due to the high viscosity of the HPMC solution, direct spray drying of the HPMC-drug inclusion solution can easily cause the equipment nozzle to clog, the finished product to agglomerate, and severe wall adhesion. This leads to low powder collection rate and final product yield, increased risk of machine damage, and potential safety hazards. These problems have greatly limited the application of HPMC in the spray drying field.

[0008] Therefore, it is necessary to further explore and develop safe, convenient, cost-effective and improved HPMC spray drying technology to expand its application range in industrial production. Summary of the Invention

[0009] The present invention aims to address the problems of easy clogging of the nozzle of the spray drying equipment, agglomeration of the finished product, and severe wall sticking when HPMC-encapsulated drugs are prepared using the existing spray drying process. The present invention provides a method for preparing the encapsulated drug using the spray drying process. CMC-Na and HPMC are combined. Under heating conditions, the CMC-Na and the HPMC encapsulated with the drug molecules are further cross-linked and encapsulated, thereby reducing the viscosity of the solution and forming new large microparticle molecules, making the spray drying process stable and controllable.

[0010] According to a first aspect of the present invention, there is provided a method for preparing a drug inclusion complex using a spray drying process, comprising the following steps: Adding drug powder to deionized water, heating and stirring until completely dissolved, to obtain a first solution; wherein the first solvent is continuously maintained at a first temperature; Add sodium carboxymethyl cellulose (CMC-Na) into deionized water and stir at room temperature until completely dissolved to obtain a second solution; Adding Hydroxypropyl Methylcellulose (HPMC) to the first solution, continuing to maintain the first temperature and stirring for inclusion, to obtain a third solution; wherein the third solution is continuously maintained at the first temperature; adding the third solution to the second solution and continuing to stir and include the solution at the first temperature until the mixed solution forms an emulsion, thereby obtaining a fourth solution; The fourth solution is spray-dried and granulated by a spray drying process to obtain the included drug powder.

[0011] As an optional embodiment, the molar ratio of the drug to HPMC is less than 1.

[0012] As an optional embodiment, the molar ratio of HPMC to CMC-Na is (1-3):1.

[0013] As an optional implementation manner, the first temperature T≥50°C.

[0014] As an optional embodiment, HPMC is added to the first solution and stirred for at least 30 minutes at a stirring speed of 450-1000 rpm.

[0015] As an optional embodiment, the third solution is added to the second solution, and after the mixed solution forms a white emulsion, stirring is continued for at least 40 minutes to form an emulsion-like turbid solution.

[0016] As an optional embodiment, the spray drying process is configured to determine the air inlet temperature and the pump speed according to the parameters of the encapsulated drug powder.

[0017] As an optional embodiment, the parameters of the spray drying process include: an air inlet temperature of 145-160° C. and a pump speed of 16-25 rpm.

[0018] As an optional embodiment, the drug includes tiamulin fumarate.

[0019] According to a second aspect of the present invention, there is provided a tiamulin fumarate soluble powder preparation prepared by the aforementioned method.

[0020] From the above technical solutions of the present invention, it can be seen that the method of preparing the inclusion drug by using the spray drying process proposed by the present invention is that CMC-Na is further cross-linked with HPMC loaded with drug molecules. After HPMC is loaded with drug molecules, active sites that can interact with other molecules exist on its surface, and the carboxylmethyl groups (-COO - ) has strong hydrophilicity and reactivity, and will ionize sodium ions (Na +), so that the molecular chain has a negative charge, heating promotes the thermal motion of the molecules, increases the frequency and energy of collisions between CMC-Na and HPMC molecules, and enables the two to overcome the repulsive force between molecules, and cross-link and include through multiple intermolecular forces such as electrostatic interaction, hydrogen bond and van der Waals force, thereby building a larger molecular network structure and forming new particles; The new microparticles have more sites that can interact with drug molecules, which further increases the chances of drug molecules being included. At the same time, during the further inclusion process, the electrostatic interactions and hydrogen bonds between molecules not only stabilize the structure of the microparticles themselves, but also make the drug molecules included in them more stable. This stable structure can effectively prevent the drug molecules from escaping from the inclusion system under the influence of external environments (such as high temperature and high humidity), thereby improving the stability of drug inclusion and ensuring the effectiveness of the drug during subsequent processing and storage. When the drug is further included, the drug molecules can fill the gaps between HPMC and CMC-Na molecules, enhancing the interaction between molecules, reducing the depolymerization caused by molecular thermal motion, allowing the cross-linking reaction to proceed more smoothly, and contributing to the continuous growth and ultimate formation of new microparticles. In addition, the inclusion of drug molecules will induce conformational changes in HPMC and CMC-Na molecules, making them more susceptible to cross-linking and accelerating the formation of new microparticles. In this way, through the mutual promotion between HPMC and CMC-Na that encapsulate drug molecules, a precursor solution with low viscosity and containing new particles with larger and more stable structures is formed. Due to their large molecular weight and stronger intermolecular interaction, the new particles can precipitate in an orderly manner under a high-temperature environment with rapid evaporation of water, and the spray-drying precipitation process is stable and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart of a method for preparing a drug inclusion complex using a spray drying process.

[0022] Figure 2 It is a statistical diagram of the particle size of the samples in the examples of the present invention.

[0023] Figure 3 These are pictures related to the preparation process and products in the examples of the present invention.

[0024] Figure 4 These are pictures of API-HPMC solution, HPMC-CMC-Na solution, API-CMC-Na solution, and API-HPMC-CMC-Na solution in examples of the present invention. DETAILED DESCRIPTION

[0025] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0026] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to be comprehensive. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of a number of ways.

[0027] The present invention combines CMC-Na with HPMC without chemically modifying HPMC to obtain a precursor solution suitable for a spray drying process. The spray drying process can be used to directly prepare an HPMC inclusion compound with uniform texture, stable properties, no agglomeration, and no discoloration. The powder yield of the product is significantly improved, no nozzle clogging or finished product agglomeration occurs, and the quality of the spray-dried finished product is significantly improved.

[0028] Combine Figure 1 As shown, in a preferred embodiment of the present invention, a method for preparing a drug inclusion complex using a spray drying process is provided, comprising the following steps: Adding the drug powder to deionized water, heating and stirring until completely dissolved, to obtain a first solution; wherein the first solvent is continuously maintained at a first temperature; Add sodium carboxymethyl cellulose (CMC-Na) into deionized water and stir at room temperature until completely dissolved to obtain a second solution; Adding Hydroxypropyl Methylcellulose (HPMC) to the first solution, continuing to maintain the first temperature and stirring for inclusion, to obtain a third solution; wherein the third solution is continuously maintained at the first temperature; adding the third solution to the second solution and continuing to stir and include the solution at the first temperature until the mixed solution forms an emulsion, thereby obtaining a fourth solution; The fourth solution is spray-dried and granulated by a spray drying process to obtain the included drug powder.

[0029] As an optional example, the molar ratio of the drug to the HPMC is less than 1.

[0030] As an optional example, the molar ratio of HPMC to CMC-Na is (1-3):1.

[0031] As an optional example, the first temperature T is ≥ 50° C., and is particularly preferably 50-60° C.; it can be understood that the first temperature T is intended to reduce the viscosity of the CMC-Na solution, and this condition only needs to be met.

[0032] As an optional example, HPMC is added to the first solution, and the stirring time is at least 30 minutes at a stirring speed of 450-1000 rpm.

[0033] As an optional example, the third solution is added to the second solution, and after the mixed solution forms a white emulsion, stirring is continued for at least 40 minutes to form an emulsion-like turbid solution.

[0034] It is understandable that after the mixed solution forms a white emulsion, it can be stirred at the first temperature for at least 40 minutes, or the heating condition can be turned off and stirring can be continued for at least 40 minutes to form an emulsion.

[0035] It should be understood that the stirring time and stirring speed include but are not limited to the above parameters and can be set according to actual conditions.

[0036] As an optional example, the spray drying process is configured to determine the inlet air temperature and pump speed according to the parameters of the encapsulated drug powder.

[0037] As a preferred example, the parameters of the spray drying process include: inlet air temperature of 145-160°C and pump speed of 16-25 rpm.

[0038] As an optional example, the drug includes tiamulin fumarate; it is understandable that the drug includes but is not limited to tiamulin fumarate, which is suitable for drug powders that require taste masking, and the drug powders need to have good water solubility and not react with HPMC and CMC-Na.

[0039] Below, we provide a specific example, taking the inclusion of tiamulin fumarate (API) as an example, which is prepared using the aforementioned method, including the following specific steps: Weigh the API, add deionized water, stir and heat to 50-60°C to obtain the API solution, and keep the API solution at 50-60°C.

[0040] Weigh HPMC-E30 so that the molar ratio of drug to HPMC-E30 is less than 1. Add HPMC-E30 to the API solution maintained at 50-60°C. Continue stirring at 50-60°C for inclusion complexation to obtain an API-HPMC mixed solution. The API-HPMC mixed solution is continuously maintained at 50-60°C.

[0041] Weigh CMC-Na and HPMC in a molar ratio of (1-3):1 to CMC-Na, add CMC-Na into deionized water, and mechanically stir at room temperature until it is completely dissolved to obtain a CMC-Na solution.

[0042] Add the API-HPMC mixed solution to the CMC-Na solution and continue stirring at 50-60°C to form a white emulsion. Then turn off the temperature and continue stirring to form a white, stable and uniformly dispersed emulsion without suspended solids or precipitation.

[0043] The stirring was stopped and the emulsion was spray-dried at an inlet air temperature of 145-160°C and a pump speed of 16-25 rpm to obtain the encapsulated API powder.

[0044] In another exemplary embodiment of the present invention, a soluble powder preparation of tiamulin fumarate prepared by the aforementioned method is also provided. During the spray-drying process, the preparation does not experience nozzle clogging or finished product agglomeration, and the quality of the spray-dried finished product is significantly improved. The particle size D50 is 50~350 μm, D70 is 100~400 μm, and D90 is 150~500 μm. The preparation powder is fine and has a high powder yield.

[0045] It can be understood that the water in the present invention refers to deionized water.

[0046] For better understanding, the present invention is further described below with reference to several specific examples, but the preparation process is not limited thereto, and the content of the present invention is not limited thereto.

[0047] Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0048] The API is tiamulin fumarate soluble powder (abbreviated as Shuangyuanqing) produced by Shandong Shengli. Example 1

[0049] Weigh 10 g of API, add about 200 mL of water, and heat to 60°C with stirring to obtain the API solution (maintain at 60°C).

[0050] Weigh the amount of CMC-Na equal to that of the API and other substances, add about 200 mL of water, and mechanically stir at room temperature until the solution is completely dissolved to obtain a CMC-Na solution.

[0051] Weigh the amount of HPMC E30 equal to that of the API and other substances, add it to the API solution heated to 60°C, and continue stirring and inclusion at 60°C for 30 minutes to obtain the API-HPMC mixed solution (maintained at 60°C).

[0052] The API-HPMC mixed solution was added to the CMC-Na solution and stirred at 60 °C to form a white emulsion. The temperature was then turned off and stirring was continued for 40 min. At this time, the solution was a white, stable, and uniformly dispersed emulsion with no suspended solids or precipitation.

[0053] The stirring was stopped and spray drying was started with an inlet air temperature of 150°C and a pump speed of 18.0 rpm to obtain a sample. Example 2

[0054] The amount of HPMC was 3 times that of the API, and the amount of CMC-Na was the same as that of the API. The operation method was similar to that of Example 1. Example 3

[0055] The amount of HPMC is 3 times that of API, and the amount of CMC-Na is the same as that of HPMC. The operation method is similar to that of Example 1. Example 4

[0056] The amount of HPMC is 3 times that of API, and the amount of CMC-Na is 4 times that of API. The operation method is similar to that of Example 1. Comparative Example 1

[0057] Weigh 10 g of API, add about 200 mL of water, and heat to 60 °C with stirring to obtain API solution (maintain 60 °C).

[0058] Weigh the same amount of HPMC E30 as the API and add it to the API solution heated to 60°C. Continue stirring and inclusion complexing at 60°C for 30 minutes to obtain an API-HPMC mixed solution.

[0059] The stirring was stopped and spray drying was started with an inlet air temperature of 150°C and a pump speed of 18.0 rpm to obtain a sample. Comparative Example 2

[0060] The amount of API was 1.2 times that of HPMC, and the amount of CMC-Na was the same as that of HPMC. The operation method was similar to that of Example 1. Comparative Example 3

[0061] The amount of HPMC was 3 times that of the API, and the amount of CMC-Na was 0.75 times that of the API. The operation method was similar to that of Example 1. Comparative Example 4

[0062] The difference from Example 1 is that HPMC E30 and CMC-Na are added to the API solution at the same time.

[0063] The ratio of the amount of raw materials in each example is shown in Table 1.

[0064] Table 1

[0065] Particle size testing The particle size of the powders obtained from Examples 1-4 and Comparative Examples 1-4 was tested using a TOPSIZER laser particle size analyzer. The results are as follows: Figure 2 shown.

[0066] The results showed that the powder obtained by the method of the present invention had a smaller particle size, with a particle size D50 of 50-350 μm, a D70 of 100-400 μm, and a D90 of 150-500 μm, which were all lower than those of the original drug powder. However, the particle size of the drug obtained by only HPMC inclusion was significantly increased. Bitterness intensity and product form

[0067] The comparison of the bitterness intensity and product morphology of each example spray-dried product is shown in Table 2.

[0068] Table 2

[0069] Note: In the evaluation of bitterness intensity, the more asterisks there are, the bitterer it is.

[0070] Combined with Table 2 and Figure 2 、 3 As shown, it can be seen that: The spray-dried product in Comparative Example 1 (excluding CMC-Na) has an obvious bitter taste, the powder is white to light yellow particles, and there is a large amount of sticking to the wall and clogging the spray drying machine pipeline. However, in Example 1, there is no sticking to the wall and clogging the spray drying machine pipeline, and a fine white powder is obtained without agglomeration and caking, and the bitterness masking effect is obvious.

[0071] The spray-dried products in Comparative Example 2 and Example 1 have the same morphology, both being white powders. However, the spray-dried product in Comparative Example 2 is significantly more bitter than that in Example 1. Therefore, it is determined that the molar ratio of the drug to HPMC should not be greater than 1.

[0072] Although the spray-dried product in Comparative Example 3 has a good bitterness masking effect, the powder is a mixture of white to light yellow particles and white powder, and a small amount of product sticking to the wall. The spray-dried product in Example 2 is a white powder with no sticking to the wall. Therefore, it is determined that the molar ratio of HPMC to CMC-Na should be less than or equal to 3.

[0073] The spray-dried products of Example 3 and Example 4 have the same morphology, both are white powders, and both have good taste masking effects; Example 4 has no significant improvement in the bitterness masking effect compared to Example 3, and there is no significant difference in the bitterness intensity of the final product. Therefore, it is determined that the molar ratio of HPMC to CMC-Na should be greater than or equal to 1.

[0074] In Comparative Example 4, HPMC and CMC-Na were added to the API solution at the same time, and a small amount of wall sticking occurred. This indicates that HPMC loaded with drug molecules must be formed first. Only then can the HPMC loaded with drug molecules produce a mutual promoting effect with CMC-Na to form new particles, making the spray drying precipitation process stable and controllable. Content determination

[0075] The samples of Examples 1-4 were assayed using high performance liquid chromatography (HPLC) (determined according to the method described in Appendix 0512 of the 2020 Pharmacopoeia).

[0076] Chromatographic conditions: Octadecylsilane bonded silica gel was used as the filler; the mobile phase was methanol-ammonium carbonate solution (take 10 g of ammonium carbonate, add 800 mL of water to dissolve, add 24 mL of 6% perchloric acid solution (take 8.5 mL of perchloric acid, add water to 100 mL, shake well), dilute to 1000 mL with water, shake well, and filter)-acetonitrile (49:28:23), the column temperature was 30°C, the flow rate was 1.2 mL / min, and the detection wavelength was 212 nm.

[0077] The results are shown in Table 3.

[0078] Table 3

[0079] The test results of the content of the finished preparations after spray drying of the samples in the embodiment all met the requirements of the pharmacopoeia, ranging from 90% to 110%, and the RSD was less than 1%, indicating that the measured data were reliable. This shows that the inclusion drug obtained by the method of the present invention does not affect the raw material drug, and does not cause degradation of the raw material drug or reduction of the active ingredient. Process principle verification

[0080] (1) Weigh 10 g of API, add about 200 mL of water, and heat to 60 °C with stirring. Weigh the same amount of HPMC E30 as the API and add it to the API solution heated to 60 °C. Continue stirring at 60 °C for 30 min to obtain the API-HPMC solution.

[0081] (2) Weigh the same amount of CMC-Na as 10 g of API, add about 200 mL of water, and stir mechanically at room temperature until it is completely dissolved; weigh the same amount of HPMC E30 as API, add it to the CMC-Na solution heated to 60 °C, and continue stirring at 60 °C for 30 min to obtain HPMC-CMC-Na solution.

[0082] (3) Weigh 10 g of API, add about 200 mL of water, stir and heat to 60 °C to obtain API solution (maintain 60 °C).

[0083] Weigh the amount of CMC-Na equal to that of the API, add about 200 mL of water, and mechanically stir at room temperature until it is completely dissolved to obtain a CMC-Na solution. Add the API solution to the CMC-Na solution and continue stirring at 60°C for 30 min to obtain an API-CMC-Na solution.

[0084] (4) Obtain API-HPMC-CMC-Na solution according to the steps of Example 1.

[0085] from Figure 4 It can be seen that the API-HPMC solution, API-CMC-Na solution and HPMC-CMC-Na solution are all clear and transparent, while the API-HPMC-CMC-Na mixed solution is a white emulsion. Combined with the tests of Comparative Examples 1 and 4, it can be seen that only when the drug, HPMC and CMC-Na are co-present and the drug is first encapsulated with HPMC and then mixed with CMC-Na, will there be a mutual promotion effect between the HPMC and CMC-Na encapsulating the drug molecules, and the system will form a precursor solution with low viscosity and containing new particles with larger and more stable structures, thereby avoiding the problem of clogging the equipment pipeline during the spray drying process and changing the morphology of the final preparation obtained by spray drying from the original light yellow granules and agglomerated blocks to a fine white powder.

[0086] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A method for preparing a drug inclusion complex using a spray drying process, characterized in that: The following steps are involved: Adding drug powder to deionized water, heating and stirring until completely dissolved, to obtain a first solution; wherein the first solvent is continuously maintained at a first temperature; Add sodium carboxymethyl cellulose (CMC-Na) into deionized water and stir at room temperature until completely dissolved to obtain a second solution; Adding Hydroxypropyl Methylcellulose (HPMC) to the first solution, continuing to maintain the first temperature and stirring for inclusion, to obtain a third solution; wherein the third solution is continuously maintained at the first temperature; adding the third solution to the second solution and continuing to stir and include the solution at the first temperature until the mixed solution forms an emulsion, thereby obtaining a fourth solution; The fourth solution is spray-dried and granulated by a spray drying process to obtain the included drug powder.

2. The method for preparing a drug inclusion complex by spray drying according to claim 1, wherein: The molar ratio of drug to HPMC was less than 1.

3. The method for preparing a drug inclusion complex by using a spray drying process according to claim 1, characterized in that: The molar ratio of HPMC to CMC-Na is (1~3):

1.

4. The method for preparing a drug inclusion complex using a spray drying process according to claim 1, wherein: The first temperature T is ≥ 50°C.

5. The method for preparing a drug inclusion complex by using a spray drying process according to claim 1, characterized in that: Add HPMC to the first solution and stir for at least 30 min at a stirring speed of 450-1000 rpm.

6. The method for preparing a drug inclusion complex by spray drying according to claim 1, wherein: The third solution was added to the second solution, and after the mixed solution formed a white emulsion, stirring was continued for at least 40 min to form an emulsion-like turbid solution.

7. The method for preparing a drug inclusion complex using a spray drying process according to claim 1, wherein: The spray drying process is configured to determine the air inlet temperature and pump speed according to the parameters of the encapsulated drug powder.

8. The method for preparing a drug inclusion complex using a spray drying process according to claim 1, wherein: The parameters of the spray drying process include: inlet air temperature of 145-160°C and pump speed of 16-25 rpm.

9. The method for preparing a drug inclusion complex by using a spray drying process according to any one of claims 1 to 8, characterized in that: The drug includes tiamulin fumarate.

10. A tiamulin fumarate soluble powder preparation prepared by the method according to any one of claims 1 to 8.

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