JP2004175768A - Method for producing stabilized omeprazole enteric coated tablet - Google Patents

Method for producing stabilized omeprazole enteric coated tablet Download PDF

Info

Publication number
JP2004175768A
JP2004175768A JP2002347037A JP2002347037A JP2004175768A JP 2004175768 A JP2004175768 A JP 2004175768A JP 2002347037 A JP2002347037 A JP 2002347037A JP 2002347037 A JP2002347037 A JP 2002347037A JP 2004175768 A JP2004175768 A JP 2004175768A
Authority
JP
Japan
Prior art keywords
enteric
omeprazole
tablet
enteric coated
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2002347037A
Other languages
Japanese (ja)
Inventor
Keiichi Ikemoto
圭一 池本
Kazuyoshi Asada
和由 浅田
Maki Ikemoto
麻紀 池本
Yuko Maeda
優子 前田
Naomi Suda
尚美 須田
Michio Mamiya
美知雄 間宮
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Towa Pharmaceutical Co Ltd
Original Assignee
Towa Pharmaceutical Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Towa Pharmaceutical Co Ltd filed Critical Towa Pharmaceutical Co Ltd
Priority to JP2002347037A priority Critical patent/JP2004175768A/en
Publication of JP2004175768A publication Critical patent/JP2004175768A/en
Pending legal-status Critical Current

Links

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a stabilized omeprazole enteric coated tablet by coating a core tablet containing the omeplazole with an intermediate coating layer on the surface of the core tablet, then coating an enteric coating layer on the intermediate coated layer in this order without containing any alkali reactive compound in the core tablet and in the intermediate coated layer. <P>SOLUTION: This production method for stabilized omeprazole enteric coated tablets comprises (a) the step wherein the omeprazole, a vehicle, a disintegrator and a binder are mixed and granulated; (b) the step wherein a lubricant is added to the granules and the mixture is tableted to form the core tablet; (c) the step wherein the core tablet is coated with the intermediate coating layer of a water-soluble cellulose ether, then with the enteric coating layer. The core tablet and the intermediate coating layer are free from the alkali reactive compound and the granule prepared at the step (a) and the enteric tablet prepared in the step (c) are dried down less than 2% moisture content. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【技術分野】
本発明は、オメプラゾールの経口投与用製剤、詳しくは腸溶性皮膜を施したオメプラゾール錠の製造法に関する。
【0002】
【従来技術と課題】
胃酸分泌抑制作用を有するオメプラゾールは、胃潰瘍、胃炎、十二指腸潰瘍、十二指腸炎などの消化器病の予防および治療に使用されている。
【0003】
オメプラゾールは胃液のような酸性領域では極めて不安定であり、急速に分解されてその効力を失うことが知られている。従ってその経口投与用製剤は腸溶性でなければならない。
【0004】
周知のように腸溶性製剤は、胃液には溶解せず、中性ないし微アルカリ性の腸内消化液に溶解する腸溶性皮膜で被覆されている。ところが腸溶性皮膜を形成するポリマーは一般に遊離カルボキシル基のような酸基を含むので、これをオメプラゾールと接触するような態様で錠剤や顆粒などの固形製剤に直接コーティングすることは避けなければならない。
【0005】
特開昭62−258320およびその分割出願である特開平5−294831には、オメプラゾールとアルカリ化合物、オメプラゾールのアルカリ塩、またはオメプラゾールアルカリ塩とアルカリ化合物を含んでいる核部分に、場合によりアルカリ化合物を含む錠剤の賦形剤または水溶性ポリマーの中間層を被覆し、その上に腸溶性皮膜を被覆することにより、腸溶性皮膜とオメプラゾールとの接触を防止したオメプラゾールの腸溶性製剤を得る技術が開示されている。
【0006】
特表平9−511257には、オメプラゾール、不活性な水溶性ポリマーおよび賦形剤の水分散液を不活性コアに被覆し、これに水溶性ポリマーおよび賦形剤を含む中間被覆層と、その上に腸溶性皮膜を被覆して得られる顆粒状の腸溶性オメプラゾール製剤が開示されている。
【0007】
特表平10−511117には、上と同様にして得た造粒物を一旦錠剤に圧縮成形した後、中間被覆層および腸溶性皮膜を施してなるオメプラゾールの腸溶錠が記載されている。
【0008】
腸溶性ポリマーは多数のカルボキシル基を持っているので、これと反応するアルカリ反応性化合物をコア部分および/または中間層に存在させることは避けるのが好ましい。このためアルカリ反応性化合物を使用することなく、中間層によってオメプラゾールを含むコア錠と腸溶性皮膜が隔離された安定なオメプラゾール腸溶錠の製造法の提供が望まれる。
【0009】
【課題の解決手段】
上記課題を解決するため、本発明は、
a)オメプラゾール、賦形剤および崩壊剤を結合剤を用いて造粒する工程;
b)前記造粒物に滑沢剤を加えてコア錠に打錠する工程;
c)前記コア錠を最初に水溶性セルロースエーテルの中間皮膜、次いで腸溶性皮膜で被覆する工程よりなり、
前記コア錠および中間皮膜がアルカリ反応性化合物を含まず、かつa)工程において得た造粒物、およびc)工程において得た腸溶錠の水分が2%以下になるまで乾燥することを特徴とする安定なオメプラゾール腸溶錠の製造法を提供する。
【0010】
【好ましい実施態様】
本発明のオメプラゾール腸溶錠は、a)工程においてオメプラゾールと賦形剤と崩壊剤を結合剤を用いて造粒することを含む。造粒に使用される成分はいずれも医薬品製剤技術の分野において良く知られており、そのいずれかを使用することができる。例えばマンニトールを賦形剤に使用し、低置換度ヒドロキシプロピルセルロースを崩壊剤に使用し、流動層造粒装置を用いて両者の混合物に例えばポリビニルピロリドン(PVP)の水溶液を噴霧し、造粒する。このようにして得た造粒物は、同じ装置内で水分2%以下、好ましくは1%以下まで十分に乾燥する。
【0011】
乾燥した造粒物は、整粒後b)工程においてステアリン酸マグネシウムのような滑沢剤と混合して打錠される。
【0012】
このようにして得た未被覆の錠剤は、c)工程において中間皮膜および腸溶性皮膜で順次被覆される。中間被覆および腸溶性皮膜のコーティングは流動層コーティングまたはパンコーティングのような公知の技術を用いることができる。
【0013】
中間皮膜のためのコーティング液は、ヒドロキシプロピルセルロース、ヒドロキシプロピルメチルセルロースのような水溶性セルロースエーテルの水溶液に、タルクのような充填剤(体質顔料)と二酸化チタンのような着色顔料を分散して調製することができる。
【0014】
腸溶性皮膜を成形するポリマーは周知である。任意の腸溶性ポリマーを使用することができるが、中でも水または水とエタノールの混液を使ってコーティング液を調製することができる、ヒドロキシプロピルメチルセルロースアセテートサクシネート(信越化学工業(株)製AQOAT)またはメタクリル酸−メタクリル酸メチルコポリマー(オイドラギット L30D−55)が好ましい。コーティング液はこれら腸溶性ポリマーの水溶液または水分散液にタルクのような充填剤、二酸化チタンのような着色顔料および必要により可塑剤を分散して調製することができる。
【0015】
得られた腸溶錠は再び錠剤全体の水分が2%以下、好ましくは1%以下まで乾燥される。
【0016】
このように造粒物の段階および最終腸溶錠の段階で水分2%以下、好ましくは1%以下まで乾燥することにより、オメプラゾールを含むコア部分および中間皮膜層にアルカリ反応化合物を存在させることなく貯蔵中安定なオメプラゾール腸溶錠を製造することが可能である。
【0017】
以下の実施例は、限定を意図することなく本発明を例証する。
【0018】
【実施例】
オメプラゾール20重量部、マンニトール105.7重量部、および低置換度ヒドロキシプロピルセルロース7重量部を流動層造粒装置に仕込み、流動状態の混合物へPVP K−25の2.5重量部の水溶液を噴霧し、造粒した。噴霧終了後水分1%以下まで造粒物をよく乾燥し、整粒した。
【0019】
次に整粒した造粒物へステアリン酸マグネシウム0.7重量部を混合し、1錠あたりオメプラゾール20mgを含む錠剤に打錠し、素錠を得た。
【0020】
別にヒドロキシプロピルメチルセルロース3.78重量部およびヒドロキシプロピルセルロース0.63重量部を適量の水に溶解し、タルク0.3重量部および二酸化チタン1.29重量部を分散して中間コーティング液を調製した。
【0021】
腸溶コーティング液は、オイドラギットL30D−55の13.9重量部(固形分として4.17重量部)、クエン酸トリエチル0.42重量部、タルク0.42重量部、二酸化チタン0.04重量部を適量の水に分散して調製した。
【0022】
上で得た素錠に、上記中間コーティング液と腸溶コーティング液を順次コーティングし、最後に全体の水分が1%以下になるまで乾燥し、オメプラゾールの腸溶錠を得た。
【0023】
【安定性試験】
上で得た腸溶錠を乳鉢で粉砕し、その0.2gを秤取し、カールフィッシャー法により水分を測定したところ、0.6%であった。
【0024】
また、腸溶錠をPTP+アルミピロー(シリカゲル封入)、ガラス瓶(シリカゲル封入)、およびポリエチレン瓶(シリカゲル封入)にそれぞれ密閉包装し、40℃×75%RHの条件下で1ケ月および3ケ月間保存し、錠剤中のオメプラゾールの残存率を液体クロマトグラフィー(HPLC)によって測定した。結果を表1に示す。
【0025】

Figure 2004175768
[0001]
【Technical field】
The present invention relates to a preparation for oral administration of omeprazole, and more particularly to a method for producing an omeprazole tablet provided with an enteric coating.
[0002]
[Prior art and problems]
Omeprazole, which has a gastric acid secretion inhibitory action, has been used for the prevention and treatment of gastrointestinal diseases such as gastric ulcer, gastritis, duodenal ulcer, and duodenitis.
[0003]
Omeprazole is known to be extremely unstable in acidic areas, such as gastric juice, and is rapidly degraded to lose its efficacy. Therefore, the preparation for oral administration must be enteric coated.
[0004]
As is well known, an enteric preparation is coated with an enteric coating which does not dissolve in gastric juice but dissolves in neutral or slightly alkaline intestinal digestive juice. However, since the polymer that forms the enteric film generally contains an acid group such as a free carboxyl group, it must be avoided to directly coat it with a solid preparation such as a tablet or granule in such a manner as to come into contact with omeprazole.
[0005]
JP-A-62-258320 and its divisional application, JP-A-5-294831, disclose an omeprazole and an alkali compound, an alkali salt of omeprazole, or a core portion containing an omeprazole alkali salt and an alkali compound, and optionally an alkali compound. A technique for obtaining an enteric coating formulation of omeprazole in which an enteric coating and an omeprazole are prevented from contacting by coating an excipient of a tablet containing or an intermediate layer of a water-soluble polymer and coating an enteric coating thereon. Have been.
[0006]
Japanese Patent Application Laid-Open No. 9-511257 discloses that an aqueous dispersion of omeprazole, an inert water-soluble polymer and excipients is coated on an inert core, and an intermediate coating layer containing the water-soluble polymer and excipients, A granular enteric omeprazole preparation obtained by coating an enteric coating thereon is disclosed.
[0007]
Japanese Patent Application Laid-Open No. 10-511117 describes enteric coated tablets of omeprazole in which a granule obtained in the same manner as above is once compression-molded into tablets, and then an intermediate coating layer and an enteric coating are applied.
[0008]
Since enteric polymers have a large number of carboxyl groups, it is preferable to avoid the presence of alkali-reactive compounds that react with the carboxyl groups in the core portion and / or the intermediate layer. Therefore, it is desired to provide a method for producing a stable omeprazole enteric tablet in which the core tablet containing omeprazole and the enteric film are separated by an intermediate layer without using an alkali-reactive compound.
[0009]
[Means for solving the problem]
In order to solve the above problems, the present invention provides:
a) granulating omeprazole, excipient and disintegrant with a binder;
b) a step of adding a lubricant to the granules and compressing them into core tablets;
c) a step of first coating the core tablet with a water-soluble cellulose ether interlayer and then an enteric coating;
The core tablet and the intermediate film do not contain an alkali-reactive compound, and the granulated product obtained in the step a) and the enteric coated tablet obtained in the step c) are dried until the water content becomes 2% or less. To provide a stable method for producing omeprazole enteric coated tablets.
[0010]
[Preferred embodiment]
The omeprazole enteric coated tablet of the present invention includes granulating omeprazole, an excipient and a disintegrant in a step a) using a binder. All components used for granulation are well known in the field of pharmaceutical formulation technology, and any of them can be used. For example, mannitol is used as an excipient, low-substituted hydroxypropylcellulose is used as a disintegrant, and an aqueous solution of polyvinylpyrrolidone (PVP) is sprayed and granulated on a mixture of both using a fluidized bed granulator. . The granules thus obtained are sufficiently dried in the same apparatus to a water content of 2% or less, preferably 1% or less.
[0011]
The dried granules are mixed with a lubricant such as magnesium stearate and tableted in step b) after sizing.
[0012]
The uncoated tablet thus obtained is successively coated with an intermediate film and an enteric film in step c). For the coating of the intermediate coating and the enteric coating, known techniques such as fluidized bed coating or pan coating can be used.
[0013]
The coating liquid for the intermediate film is prepared by dispersing a filler (extender pigment) such as talc and a coloring pigment such as titanium dioxide in an aqueous solution of a water-soluble cellulose ether such as hydroxypropylcellulose and hydroxypropylmethylcellulose. can do.
[0014]
Polymers that form enteric coatings are well known. Any enteric polymer can be used. Among them, hydroxypropylmethylcellulose acetate succinate (AQOAT manufactured by Shin-Etsu Chemical Co., Ltd.) or a coating solution can be prepared using water or a mixture of water and ethanol, or Methacrylic acid-methyl methacrylate copolymer (Eudragit L30D-55) is preferred. The coating liquid can be prepared by dispersing a filler such as talc, a coloring pigment such as titanium dioxide, and if necessary, a plasticizer in an aqueous solution or dispersion of the enteric polymer.
[0015]
The obtained enteric coated tablet is dried again to a water content of 2% or less, preferably 1% or less of the whole tablet.
[0016]
By drying to a moisture of 2% or less, preferably 1% or less at the granulation stage and the final enteric-coated stage in this manner, the alkali-reactive compound is not present in the core portion containing omeprazole and the intermediate coating layer. It is possible to produce omeprazole enteric coated tablets that are stable during storage.
[0017]
The following examples illustrate the invention without intending to limit it.
[0018]
【Example】
20 parts by weight of omeprazole, 105.7 parts by weight of mannitol, and 7 parts by weight of low-substituted hydroxypropylcellulose are charged into a fluidized bed granulator, and an aqueous solution of 2.5 parts by weight of PVP K-25 is sprayed on the mixture in a fluidized state. And granulated. After the end of spraying, the granulated product was thoroughly dried to a moisture content of 1% or less and sized.
[0019]
Next, 0.7 parts by weight of magnesium stearate was mixed with the sized granules, and the mixture was compressed into tablets containing 20 mg of omeprazole per tablet to obtain uncoated tablets.
[0020]
Separately, 3.78 parts by weight of hydroxypropylmethylcellulose and 0.63 parts by weight of hydroxypropylcellulose were dissolved in an appropriate amount of water, and 0.3 part by weight of talc and 1.29 parts by weight of titanium dioxide were dispersed to prepare an intermediate coating solution. .
[0021]
The enteric coating solution was 13.9 parts by weight of Eudragit L30D-55 (4.17 parts by weight as solid content), 0.42 parts by weight of triethyl citrate, 0.42 parts by weight of talc, 0.04 parts by weight of titanium dioxide. Was prepared by dispersing in a suitable amount of water.
[0022]
The uncoated tablet obtained above was sequentially coated with the above intermediate coating solution and enteric coating solution, and finally dried until the total water content became 1% or less, to obtain an omeprazole enteric coated tablet.
[0023]
[Stability test]
The enteric coated tablet obtained above was pulverized in a mortar, 0.2 g of the tablet was weighed, and the water content was measured by the Karl Fischer method.
[0024]
Enteric coated tablets are sealed in PTP + aluminum pillow (silica gel), glass bottle (silica gel), and polyethylene bottle (silica gel), and stored at 40 ° C x 75% RH for 1 month and 3 months. Then, the residual ratio of omeprazole in the tablets was measured by liquid chromatography (HPLC). Table 1 shows the results.
[0025]
Figure 2004175768

Claims (5)

a)オメプラゾール、賦形剤および崩壊剤を結合剤を用いて造粒する工程;
b)前記造粒物に滑沢剤を加えてコア錠に打錠する工程;
c)前記コア錠を最初に水溶性セルロースエーテルの中間皮膜、次いで腸溶性皮膜で被覆する工程よりなり、
前記コア錠および中間皮膜がアルカリ反応性化合物を含まず、かつa)工程において得た造粒物およびc)工程において得た腸溶錠の水分が2%以下になるまで乾燥することを特徴とする安定なオメプラゾール腸溶錠の製造法。
a) granulating omeprazole, excipient and disintegrant with a binder;
b) a step of adding a lubricant to the granules and compressing them into core tablets;
c) a step of first coating the core tablet with a water-soluble cellulose ether interlayer and then an enteric coating;
The core tablet and the intermediate film do not contain an alkali-reactive compound, and the granulated product obtained in the step a) and the enteric coated tablet obtained in the step c) are dried until the water content becomes 2% or less. For producing stable omeprazole enteric coated tablets.
前記造粒物および腸溶錠の水分が1%以下である請求項1のオメプラゾール腸溶錠の製造法。The method for producing an omeprazole enteric tablet according to claim 1, wherein the water content of the granulated product and the enteric tablet is 1% or less. a)工程で使用する賦形剤がマンニトールであり、崩壊剤が低置換度ヒドロキシプロピルセルロースであり、c)工程で使用する水溶性セルロースエーテルがヒドロキシプロピルメチルセルロースとヒドロキシプロピルセルロースの混合物である請求項1または2のオメプラゾール腸溶錠の製造法。The excipient used in step a) is mannitol, the disintegrant is low-substituted hydroxypropylcellulose, and the water-soluble cellulose ether used in step c) is a mixture of hydroxypropylmethylcellulose and hydroxypropylcellulose. A method for producing the enteric coated tablet of 1 or 2 above. 前記中間皮膜および腸溶性皮膜がタルクおよび着色顔料を含んでいる請求項1ないし3のいずれかのオメプラゾール腸溶錠。4. The omeprazole enteric coated tablet according to claim 1, wherein the intermediate film and the enteric film contain talc and a coloring pigment. 請求項1ないし4のいずれかの製造法によって製造した安定なオメプラゾール腸溶錠。A stable omeprazole enteric coated tablet produced by the production method according to any one of claims 1 to 4.
JP2002347037A 2002-11-29 2002-11-29 Method for producing stabilized omeprazole enteric coated tablet Pending JP2004175768A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002347037A JP2004175768A (en) 2002-11-29 2002-11-29 Method for producing stabilized omeprazole enteric coated tablet

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002347037A JP2004175768A (en) 2002-11-29 2002-11-29 Method for producing stabilized omeprazole enteric coated tablet

Publications (1)

Publication Number Publication Date
JP2004175768A true JP2004175768A (en) 2004-06-24

Family

ID=32707756

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002347037A Pending JP2004175768A (en) 2002-11-29 2002-11-29 Method for producing stabilized omeprazole enteric coated tablet

Country Status (1)

Country Link
JP (1) JP2004175768A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016145242A (en) * 2016-04-06 2016-08-12 ニプロ株式会社 Solid pharmaceutical compositions containing calcium blocker
KR20180029035A (en) * 2015-07-17 2018-03-19 로께뜨프레르 Mannitol granules for direct compression
JP2019529525A (en) * 2016-08-05 2019-10-17 トーラス・ディベロップメント・カンパニー・エルエルシー Oral calcitonin preparation stable at room temperature
CN113367247A (en) * 2021-01-05 2021-09-10 安徽科技学院 Feed additive for preventing broiler chicken myogastric and glandular gastritis

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20180029035A (en) * 2015-07-17 2018-03-19 로께뜨프레르 Mannitol granules for direct compression
JP2018520192A (en) * 2015-07-17 2018-07-26 ロケット フレールRoquette Freres Mannitol granules for direct compression
US10828256B2 (en) 2015-07-17 2020-11-10 Roquett Freres Mannitol granules for direct compression
JP2021105035A (en) * 2015-07-17 2021-07-26 ロケット フレールRoquette Freres Mannitol granules for direct compression
JP7198860B2 (en) 2015-07-17 2023-01-04 ロケット フレール Mannitol granules for direct compression
KR102631002B1 (en) * 2015-07-17 2024-01-30 로께뜨프레르 Mannitol Granules for Direct Compression
JP2016145242A (en) * 2016-04-06 2016-08-12 ニプロ株式会社 Solid pharmaceutical compositions containing calcium blocker
JP2019529525A (en) * 2016-08-05 2019-10-17 トーラス・ディベロップメント・カンパニー・エルエルシー Oral calcitonin preparation stable at room temperature
JP7300793B2 (en) 2016-08-05 2023-06-30 パーク・セラピューティクス,インコーポレーテッド Oral Calcitonin Formulation Stable at Room Temperature
CN113367247A (en) * 2021-01-05 2021-09-10 安徽科技学院 Feed additive for preventing broiler chicken myogastric and glandular gastritis
CN113367247B (en) * 2021-01-05 2023-11-14 安徽科技学院 Feed additive for preventing stomach proventriculitis of broiler chickens

Similar Documents

Publication Publication Date Title
JP3699122B2 (en) New oral pharmaceutical use form
CA2251430C (en) Omeprazole formulation
EP0247983B1 (en) New pharmaceutical preparation for oral use
JP4638964B2 (en) Oral pharmaceutical dosage form comprising proton pump inhibitor and NSAID
JP4649001B2 (en) Omeprazole formulation
US20090208575A1 (en) Pharmaceutical Composition Of Acid Labile Substances
CZ2000344A3 (en) Oral pharmaceutical preparation containing compound exhibiting anti-ulcer activity and process for preparing thereof
SK18832000A3 (en) Enteric coated pharmaceutical tablet and method of manufacturing
JPH09502739A (en) Multiple unit tableted dosage form ▲ I ▼
AU5791900A (en) Solid oral pharmaceutical formulation of modified release that contains an acid labile benzimidazole compound
WO2009102172A2 (en) Pharmaceutical formulation containing choline alfoscerate
JP2011126912A (en) Dosage form containing pantoprazole as active ingredient
IL147232A (en) Stable benzimidazole formulation
WO2008129517A2 (en) A stabilized delayed release pharmaceutical composition of rabeprazole
WO2012001705A2 (en) Pharmaceutical compositions of (r)-lansoprazole
US6197347B1 (en) Oral dosage for the controlled release of analgesic
MXPA06000577A (en) Pharmaceutical compositions having a swellable coating.
JP2004175768A (en) Method for producing stabilized omeprazole enteric coated tablet
WO2015108392A1 (en) Small pharmaceutical tablet containing esomeprazole
WO2004098573A1 (en) An improved and stable pharmaceutical composition containing substituted benzimidazoles and a process for its preparation
JP2000212085A (en) Highly stable oral medicinal preparation containing omeprazole or othrer analog, and production thereof
WO2005034924A1 (en) Enteric coated pellets comprising esomeprazole, hard gelatin capsule containing them, and method of preparation
WO2007054565A2 (en) New stabilized galenic formulations comprising lansoprazole and their preparation
WO2006111853A2 (en) Stable solid dosage forms of acid labile drug
CA2547398A1 (en) Oral benzimidazole compositions comprising an active core, an optional separating layer and an enteric coating