Coated formulation

Abstract

The present invention relates to a coated formulation. The formulation contains silodosin, a sustained-release material, and an antioxidant. The sustained-release material is selected from hydrophilic matrix sustained-release materials, and the coating contains a plasticizer. The coated formulation of the present invention can effectively reduce the instability caused by the incompatibility between the silodosin and the sustained-release material, and the coating can further inhibit the continuous reduction of the content of the antioxidant.

Description

Coated formulations TECHNICAL FIELD

[0001] The present application belongs to the field of pharmaceutical preparations, and particularly relates to a sustained-release coated tablet containing a pharmaceutical active ingredient. BACKGROUND

[0002] Silodosin is an alpha 1-adrenergic receptor antagonist invented by Japan Tsumura & Co. It can improve urethral resistance by relaxing the smooth muscle in the prostate and bladder neck, and can be used for the treatment of benign prostatic hyperplasia (BPH). The marketed preparation is a tablet and a capsule, and the dosage is 4 mg each time, twice a day. Its chemical name is 1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide. The structure is shown as follows:

[0003] Patent document WO2004054574 describes a silodosin immediate-release preparation. Patent document CN102283816A discloses a silodosin sustained-release tablet, which uses a hydrophilic gel matrix material and a waxy matrix material as a mixed material matrix, and uses acrylic resin E100 as a release regulator.

[0004] Patent document US20240180871A1 discloses a capsule preparation containing silodosin sustained-release granules. So far, no silodosin sustained-release preparation has been approved for marketing or entered clinical research. SUMMARY

[0005] The present application provides a silodosin sustained-release preparation in a first aspect, which contains silodosin and a hydrophilic gel matrix sustained-release material.

[0006] The present application provides a silodosin sustained-release preparation in another aspect, which contains silodosin, a hydrophilic gel matrix sustained-release material, and an antioxidant.

[0007] The present application provides a coated preparation in another aspect, wherein the coating material contains a plasticizer, and when the preparation contains an antioxidant, the coating material can stabilize the existence of the antioxidant.

[0008] The present application provides a silodosin sustained-release preparation in another aspect, which contains silodosin, a hydrophilic gel matrix sustained-release material, an antioxidant, and a coating, and the coating material contains a plasticizer.

[0009] The present application provides the use of a silodosin sustained-release preparation in another aspect in the preparation of a drug for the treatment of benign prostatic hyperplasia (BPH) or symptoms and signs caused thereby. DETAILED DESCRIPTION

[0010] Explanation of terms

[0011] The "viscosity" mentioned in the present invention refers to the viscosity in a 1-2% aqueous solution at 20-25°C. "High viscosity" refers to a viscosity of 1000 mPa.s or above in a 1-2% aqueous solution at 20-25°C;

[0012] The "high-viscosity hydroxypropyl methylcellulose" herein refers to hydroxypropyl methylcellulose having a viscosity of 1000 mPa.s or above in a 2% aqueous solution at 20°C. High-viscosity hydroxypropyl methylcellulose includes, but is not limited to, hydroxypropyl methylcellulose K4M (viscosity 4000 mPa.s), hydroxypropyl methylcellulose K15M (viscosity 15000 mPa.s), hydroxypropyl methylcellulose K35M (viscosity 35000 mPa.s), hydroxypropyl methylcellulose K100M (viscosity 100000 mPa.s), and hydroxypropyl methylcellulose K200M (viscosity 200000 mPa.s).

[0013] The "low-viscosity hydroxypropyl methylcellulose" herein refers to hydroxypropyl methylcellulose having a viscosity of 200 mPa.s or less in a 2% aqueous solution at 20°C. Low-viscosity hydroxypropyl methylcellulose includes, but is not limited to, hydroxypropyl methylcellulose K100LV and hydroxypropyl methylcellulose E50.

[0014] The "weight (mg / mg) ratio" herein, when calculated, refers to the ratio of the weight of the uncoated ingredient in a unit dosage form to the total weight of the dosage form. For example, the "weight (mg / mg) ratio of the antioxidant" refers to the ratio of the weight of the antioxidant in a unit dosage form to the total weight of the uncoated unit dosage form.

[0015] The "coating weight gain" mentioned in the present invention refers to the ratio of the added weight of the coating material to the weight of the uncoated preparation.

[0016] The present invention is described in detail below by the following examples, but the present invention is not limited to the following examples. The chemical substances, reagents, experimental materials, etc. used in the examples of the present invention were obtained by conventional methods in the art.

[0017] The first aspect of the present invention provides a silodosin sustained-release preparation, which contains silodosin and a sustained-release material selected from a hydrophilic gel matrix sustained-release material.

[0018] The sustained-release preparation of the present invention can achieve a good sustained-release effect. The silodosin sustained-release preparation has at least one of the following release characteristics in a pH 6.8 phosphate buffer:

[0019] The time for dissolving 70% silodosin is not less than 4 hours and not more than 24 hours;

[0020] And / or, the time for dissolving 70% silodosin is not less than 4 hours and not more than 20 hours;

[0021] And / or, the time for dissolving 70% silodosin is not less than 4 hours and not more than 16 hours.

[0022] The hydrophilic gel matrix sustained-release material in the present application is a cellulose derivative, which is optionally selected from methyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose, sodium hydroxymethyl cellulose, ethyl cellulose or sodium carboxymethyl cellulose, etc. The hydrophilic gel matrix sustained-release material can be one or a combination of two or more.

[0023] The sustained-release material in the present application has a viscosity of 1000 mPa.s or more.

[0024] The hydrophilic gel matrix sustained-release material in the present application has a viscosity of 1000 mPa.s or more; preferably, the hydrophilic gel matrix sustained-release material is a cellulose derivative; further preferably, the hydrophilic gel matrix sustained-release material is a cellulose derivative with a viscosity of 1000 mPa.s or more.

[0025] In a preferred embodiment of the present application, the hydrophilic gel matrix sustained-release material is a cellulose derivative with a viscosity of 1000 mPa.s or more.

[0026] In a preferred embodiment of the present application, the hydrophilic gel matrix sustained-release material is a hydroxypropyl methyl cellulose with a viscosity of 1000 mPa.s or more, which is also referred to as high-viscosity hydroxypropyl methyl cellulose in the present application. The high-viscosity hydroxypropyl methyl cellulose includes hydroxypropyl methyl cellulose K4M, hydroxypropyl methyl cellulose K15M, hydroxypropyl methyl cellulose K35M, hydroxypropyl methyl cellulose K100M and hydroxypropyl methyl cellulose K200M. The high-viscosity hydroxypropyl methyl cellulose can be one or a combination of two or more.

[0027] In a preferred embodiment of the present application, the hydrophilic gel matrix sustained-release material is a high-viscosity hydroxypropyl methyl cellulose.

[0028] In a preferred embodiment of the present application, the hydrophilic gel matrix sustained-release material is composed of a high-viscosity hydroxypropyl methyl cellulose and a low-viscosity hydroxypropyl methyl cellulose.

[0029] In the sustained-release preparation of the present application, the weight ratio (mg / mg) of the sustained-release material in the sustained-release preparation is 10-90%; preferably, the weight ratio (mg / mg) of the sustained-release material in the sustained-release preparation is 10-80%; further preferably, the weight ratio (mg / mg) of the sustained-release material in the sustained-release preparation is 15-55%; further preferably, the weight ratio (mg / mg) of the sustained-release material in the sustained-release preparation is 25-55%.

[0030] In the preferred embodiment of the present application, the sustained-release material is a cellulose-based sustained-release material, and the weight ratio (mg / mg) of the cellulose-based sustained-release material in the sustained-release preparation is 10-90%; preferably, the weight ratio (mg / mg) of the cellulose-based sustained-release material in the sustained-release preparation is 10-80%; further preferably, the weight ratio (mg / mg) of the cellulose-based sustained-release material in the sustained-release preparation is 15-55%; further preferably, the weight ratio (mg / mg) of the cellulose-based sustained-release material in the sustained-release preparation is 25-55%.

[0031] In the preferred embodiment of the present application, the sustained-release material is high-viscosity hypromellose, and the weight ratio (mg / mg) of the high-viscosity hypromellose in the sustained-release preparation is 10-90%; preferably, the weight ratio (mg / mg) of the high-viscosity hypromellose in the sustained-release preparation is 10-80%; further preferably, the weight ratio (mg / mg) of the high-viscosity hypromellose in the sustained-release preparation is 15-55%; further preferably, the weight ratio (mg / mg) of the high-viscosity hypromellose in the sustained-release preparation is 25-55%.

[0032] In the preferred embodiment of the present application, the sustained-release preparation contains silodosin and a sustained-release material; the sustained-release material is hypromellose having a viscosity of 1000 mPa.s or above; and the weight ratio (mg / mg) of the hypromellose in the sustained-release preparation is 25-55%.

[0033] In the preferred embodiment of the present application, the sustained-release preparation is a tablet or a capsule.

[0034] In the preferred embodiment of the present application, the sustained-release preparation is a tablet.

[0035] In the prior art silodosin preparations, such as immediate-release preparations, no sustained-release material, such as no hydrophilic gel matrix sustained-release material, is contained, and thus there is no compatibility problem. When prepared into a sustained-release preparation, the sustained-release material and silodosin often have a certain degree of incompatibility problem, resulting in an increase in impurity content, and the increase in impurity content is more significant when PEO is used as the sustained-release material. The present application surprisingly found that the compatibility problem of the sustained-release material and silodosin, particularly the problem of the increase in impurity content, can be effectively solved by adding an antioxidant.

[0036] Therefore, in another aspect of the present application, there is provided a sustained release formulation of silodosin, the sustained release formulation comprising silodosin, a sustained release material and at least one antioxidant.

[0037] The antioxidant is selected from one or more than two combinations of ascorbic acid, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), propyl gallate, tocopherol, sodium sulfite, sodium bisulfite and the like; preferably, the antioxidant is selected from butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), vitamin C; further preferably, the antioxidant is selected from butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA).

[0038] In a preferred embodiment of the present application, the antioxidant is present in the sustained release formulation of silodosin in an amount of 0.01 to 2.0% by weight; further preferably, in an amount of 0.01 to 1.0% by weight; more preferably, in an amount of 0.01 to 0.5% by weight.

[0039] In a preferred embodiment of the present application, there is provided a sustained release formulation of silodosin, the sustained release formulation comprising silodosin, a hydrophilic gel matrix sustained release material and at least one antioxidant.

[0040] The hydrophilic gel matrix sustained release material is a cellulose derivative, optionally selected from methyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose, sodium hydroxymethyl cellulose, ethyl cellulose or sodium carboxymethyl cellulose and the like; the sustained release material can be one or more, or two or more combinations thereof.

[0041] The cellulose derivative has a viscosity of 1000 mPa.s or more; preferably, the sustained release material is hydroxypropyl methyl cellulose having a viscosity of 1000 mPa.s or more.

[0042] In the sustained release formulation of silodosin, the sustained release material is present in an amount of 10 to 90% by weight (mg / mg); preferably, the sustained release material is present in an amount of 10 to 80% by weight (mg / mg); further preferably, the sustained release material is present in an amount of 15 to 55% by weight (mg / mg); further preferably, the sustained release material is present in an amount of 25 to 55% by weight (mg / mg).

[0043] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, a sustained release material selected from cellulose derivatives and at least one antioxidant.

[0044] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, high viscosity hydroxypropyl methyl cellulose and at least one antioxidant.

[0045] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, 10-90% of a hydrophilic gel matrix sustained release material and 0.01-2.0% of an antioxidant.

[0046] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, 15-55% of a hydrophilic gel matrix sustained release material and 0.01-1.0% of an antioxidant.

[0047] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, 15-55% of a sustained release material selected from cellulose derivatives and 0.01-1.0% of an antioxidant.

[0048] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, 15-55% of high viscosity hypromellose and 0.01-1.0% of butylated hydroxytoluene (BHT).

[0049] In a preferred embodiment of the present application, the sustained release formulation comprises silodosin, 25-55% of high viscosity hypromellose and 0.01-1.0% of an antioxidant.

[0050] It has been further discovered by the present inventors that although the addition of an antioxidant improves the stability of the formulation, the amount of the added antioxidant decreases significantly over time in the formulation of the present application, and conventional coating often fails to effectively address the decrease of the antioxidant. It has been surprisingly discovered by the present inventors that the addition of a plasticizer in the coating material can effectively inhibit the decrease of the antioxidant content.

[0051] Accordingly, in a further aspect of the present application, there is provided a coating material comprising at least one film forming material and at least one plasticizer, which can inhibit the decrease of the antioxidant content in a formulation, in particular, the decrease of the antioxidant content in a silodosin sustained release formulation.

[0052] The film forming material is optionally selected from one or more of hydroxypropyl methylcellulose, hydroxypropyl cellulose, polyvinyl alcohol, acrylic resin, ethyl cellulose or polyvinyl pyrrolidone, etc. Preferably, the film forming material of the coating is hydroxypropyl methylcellulose.

[0053] The plasticizer is optionally selected from one or more of propylene glycol, glycerol, polyethylene glycol (PEG) or glyceryl triethylhexanoate. Preferably, the plasticizer is polyethylene glycol. The molecular weight of the polyethylene glycol is 1000-10000; suitable polyethylene glycols include PEG 2000, PEG 4000 or PEG 6000, etc.

[0054] In a preferred embodiment of the present application, the film forming material is optionally selected from hydroxypropyl methylcellulose and hydroxypropyl cellulose.

[0055] In a preferred embodiment of the present application, the plasticizer is polyethylene glycol, preferably PEG6000.

[0056] In a preferred embodiment of the present application, the coating material contains a film forming material selected from hydroxypropyl methylcellulose and a plasticizer polyethylene glycol.

[0057] In a preferred embodiment of the present application, the coating material contains a film forming material selected from hydroxypropyl methylcellulose and a plasticizer polyethylene glycol.

[0058] In a preferred embodiment of the present application, the coating material has a coating weight gain of not less than 1.0% in unit formulation; preferably, the coating material has a coating weight gain of not less than 1.5% in unit formulation; further preferably, the coating material has a coating weight gain of 1.5-6.0% in unit formulation; more preferably, the coating material has a coating weight gain of 2.0-6.0% in unit formulation.

[0059] In another aspect of the present application, a sustained release preparation is provided, which contains silodosin, a hydrophilic gel matrix sustained release material, an antioxidant and a coating containing at least one plasticizer.

[0060] In a preferred embodiment of the present application, the sustained release preparation contains, by weight ratio, silodosin; 10-90% of a hydrophilic gel matrix sustained release material; 0.01-2.0% of an antioxidant; and a coating material having a weight gain of not less than 1.5%, and the coating material contains at least one plasticizer.

[0061] In a preferred embodiment of the present application, the sustained release preparation contains, by weight ratio, silodosin; 10-90% of a cellulose derivative sustained release material; 0.01-2.0% of an antioxidant; and a coating material having a weight gain of not less than 1.5%, and the coating material contains at least one plasticizer.

[0062] In a preferred embodiment of the present application, the sustained release preparation contains, by weight ratio, silodosin; 15-55% of high viscosity hydroxypropyl methylcellulose; 0.01-2.0% of an antioxidant; and a coating material having a weight gain of not less than 1.5%, and the coating material contains at least one plasticizer.

[0063] In a preferred embodiment of the present application, the sustained release preparation contains, by weight ratio, silodosin; 15-55% of high viscosity hydroxypropyl methylcellulose; 0.01-2.0% of an antioxidant; and a coating material having a weight gain of not less than 1.5%, and the coating material contains polyethylene glycol.

[0064] The silodosin sustained release preparation of the present application is optionally a sustained release tablet or a sustained release capsule.

[0065] A preferred silodosin sustained release formulation according to the present application is a sustained release coated tablet.

[0066] In another aspect of the present application, there is provided a method for preparing a silodosin sustained release tablet, the method comprising the following steps:

[0067] Step 1: mixing silodosin, hydrophilic gel matrix sustained release material, antioxidant and other pharmaceutical excipients uniformly, and granulating;

[0068] Step 2: compressing the granules of Step 1 into tablets;

[0069] Step 3: coating the prepared tablets.

[0070] The granulation method in Step 1 is optionally dry granulation, wet granulation; preferably dry granulation. The sustained release formulation according to the present application can also be obtained by direct compression of powder.

[0071] The silodosin sustained release formulation according to the present application can optionally contain fillers, glidants, surfactants, lubricants, binders and other pharmaceutical excipients as needed.

[0072] Suitable fillers include mannitol, lactose or its hydrate, lactose-cellulose, starch, pregelatinized starch, microcrystalline cellulose, dextrin, sucrose, glucose, maltose, sorbitol, sugar powder, calcium sulfate, calcium hydrogen phosphate, calcium carbonate; preferred fillers according to the present application include mannitol, lactose, lactose-cellulose and the like.

[0073] Suitable surfactants include sodium dodecyl sulfate, sodium docusate and the like;

[0074] Suitable glidants include colloidal silicon dioxide, talc, stearic acid and the like;

[0075] Suitable lubricants include gelatinized starch, magnesium stearate, calcium stearate, colloidal silicon dioxide, fumed silicon dioxide, polyethylene glycol, talc, sodium docusate, sodium dodecyl sulfate, sodium stearyl fumarate, sodium carboxymethyl cellulose, glyceryl behenate and the like; preferred lubricants include magnesium stearate, calcium stearate, colloidal silicon dioxide, fumed silicon dioxide, talc, glyceryl behenate and the like.

[0076] Suitable binders include hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyvinyl pyrrolidone, copovidone, polyvinyl alcohol, ethyl cellulose, starch and the like;

[0077] In another aspect of the present application, there is provided a use of a silodosin sustained release formulation in the preparation of a medicament for treating benign prostatic hyperplasia (BPH) or symptoms and signs caused thereby.

[0078] The present application is specifically described below by the following examples, but the present application is not limited to the following examples. The chemicals, reagents, experimental materials, etc. used in the examples of the present application are obtained by the conventional methods in the art.

[0079] Example 1

[0080] Preparation method

[0081] Silodosin and mannitol are mixed in an equal amount increasing manner, the obtained mixture, high viscosity hydroxypropyl methyl cellulose, low viscosity hydroxypropyl methyl cellulose, colloidal silicon dioxide are added into a multi-directional motion mixer for mixing, and finally the dry granulation part of magnesium stearate is added for mixing uniformly. Dry granulation is performed, and the dry granules are taken and added with the additional part of magnesium stearate and glyceryl behenate for mixing uniformly to obtain total mixed granules. The sustained release granules are punched into sustained release tablets, each containing 8 mg of silodosin.

[0082] Coating is performed, and the coating material is hydroxypropyl methyl cellulose (HPMC), PEG6000, talc, and titanium dioxide.

[0083] Dissolution test

[0084] The preparation of Example 1-2 is taken, and the first method of the release rate determination method (Chinese Pharmacopoeia 2020 Edition Part II 0931) is used. The dissolution medium is 900 ml of pH 6.8 phosphate buffer, the medium temperature is 37℃±0.5℃, the rotation speed is 100 rpm, and the average value is taken. The results are as follows:

[0085] Example 2

[0086] Preparation method

[0087] Silodosin and mannitol are mixed in an equal amount increasing manner, the obtained mixture, high viscosity hydroxypropyl methyl cellulose, colloidal silicon dioxide are added into a multi-directional motion mixer for mixing, and finally the dry granulation part of magnesium stearate is added for mixing uniformly. Dry granulation is performed, and the dry granules are taken and added with the additional part of magnesium stearate, mixed uniformly, to obtain total mixed granules. The sustained release granules are punched into sustained release tablets, each containing 8 mg of silodosin. Coating is performed.

[0088] Example 3

[0089] Polyoxyethylene (PEO) (which has a viscosity of 2000-6000 mPa.s in a 1-2% aqueous solution at 20-25℃) is used as a sustained release material, and silodosin sustained release part is prepared according to the similar method of Example 1.

[0090] Example 4 Impurity content determination

[0091] Test condition: temperature 40°C, relative humidity 75%. The silodosin sustained release formulation was stored in high density polyethylene bottles with desiccant, and the related substance content was determined at 0 month and 6 months of storage, and the data are shown in the following table.

[0092] From the foregoing data, it can be judged that the content of the related substance of the silodosin sustained release formulation at 6 months has a relatively obvious increase relative to the value at 0 day. In particular, when PEO is used as the sustained release material, the impurity increase is more significant. The cellulose derivative with a viscosity of 1000 mPa.s and above has better formulation stability relative to the non-cellulose derivative, such as PEO.

[0093] The impurities of the sustained release tablets containing the antioxidant were determined under the same test conditions.

[0094] The addition of the antioxidant can significantly reduce the increase of the impurities in the formulation and improve the stability of the formulation.

[0095] Example 5

[0096] According to the formulation composition of Examples 1-2, BHT was used as the antioxidant, and the effect of the antioxidant addition amount on the impurity content under the test conditions (high temperature 60°C, 10 days) was investigated.

[0097] The antioxidant addition amount in the range of 0.05-0.2% of the total weight of the substrate tablet can achieve good impurity control.

[0098] Example 6

[0099] The silodosin sustained release tablets were prepared according to the method of Example 1, and were coated using three different coating materials. Coating powder 1 contains hydroxypropyl methylcellulose (HPMC), talc, and titanium dioxide; coating powder 2 contains hydroxypropyl methylcellulose (HPMC), PEG6000, talc, and titanium dioxide, and coating powder 3 contains hydroxypropyl methylcellulose (HPMC), glyceryl triethylhexanoate. The residual percentage content of the antioxidant after storage at 60°C for 0 days and 10 days was determined.

[0100] After the addition of the plasticizer to the coating material, the present application can significantly inhibit the reduction of the antioxidant.

[0101] Example 7

[0102] Coating powder 2 of Example 5 was used for coating, and the residual percentage content of the antioxidant after storage at 60°C for 0 days and 10 days was determined at different coating weight gain percentages.

[0103] Based on the above data, the coating weight gain of the present application is preferably 1.0% or more, more preferably 1.5% or more, which can effectively avoid the loss of antioxidant content.

[0104] Example 8

[0105] A tablet without active ingredient was prepared by referring to the similar method.

[0106] In pharmaceutical preparation adjuvants, when it is necessary to add antioxidant, the coating containing plasticizer of the present application can effectively inhibit the continuous decrease of antioxidant content.

Claims

1. A silodosin sustained-release preparation, comprising silodosin and a sustained-release material; the sustained-release material is selected from a hydrophilic gel matrix sustained-release material.

2. The sustained-release preparation according to claim 1, wherein the hydrophilic gel skeleton sustained-release material is a cellulose derivative with a viscosity of 1000 mPa.s or above.

3. The sustained-release preparation according to claim 1, wherein the weight ratio of the sustained-release material in the sustained-release preparation is 10-90%; preferably, the weight ratio is 10-80%; and further preferably, the weight ratio is 15-55%. The sustained-release preparation according to claim 1 , further comprising an antioxidant.

5. The sustained-release preparation according to claim 4, wherein the antioxidant is selected from ascorbic acid, butylated hydroxytoluene, butylated hydroxyanisole, propyl gallate, tocopherol, sodium sulfite, and sodium bisulfite.

6. The sustained-release preparation according to any one of claims 4 or 5, wherein the weight percentage of the antioxidant in the sustained-release preparation is 0.01-2.0%; more preferably, the weight percentage is 0.01-1.0%; and even more preferably, the weight percentage is 0.01-0.5%.

7. The sustained-release preparation according to any one of claims 4 or 5, wherein the antioxidant is butylated hydroxytoluene. The sustained-release preparation according to claim 1 , further comprising a coating comprising a film-forming material and at least one plasticizer.

9. The sustained-release preparation according to claim 8, wherein the plasticizer is selected from propylene glycol, glycerol, polyethylene glycol or triethylglycerol.

10. The sustained-release preparation according to claim 8, wherein the coating weight gain is not less than 1.5%. The sustained-release preparation according to claim 8 , wherein the plasticizer is polyethylene glycol.

12. A silodosin sustained-release preparation, comprising silodosin, 10-90% of a hydrophilic gel matrix sustained-release material, 0.01-2.0% of an antioxidant, and a coating material having a weight gain of not less than 1.5%, wherein the coating material contains at least one plasticizer.

13. Use of the silodosin sustained-release preparation according to any one of claims 1 or 12 in the preparation of a medicament for treating benign prostatic hyperplasia or symptoms and signs caused by it.

14. The silodosin sustained-release preparation according to any one of claims 1 or 12, which is in the form of a tablet or a capsule.

15. A coating material for inhibiting the reduction of antioxidant content in a preparation, wherein the coating material contains at least one plasticizer; the coating material has a coating weight gain of not less than 1.5% in the preparation. The coating material according to claim 15 , wherein the antioxidant is butylated hydroxytoluene.

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