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7. Tablets

7. Tablets. Contents. Types of tablets Compressed tablets Chewable tablets Molded tablets Tablet coating Impact of manufacturing changes on solid dosage forms Official and commercially available tablets Packaging and storing tablet.

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7. Tablets

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  1. 7. Tablets

  2. Contents • Types of tablets • Compressed tablets • Chewable tablets • Molded tablets • Tablet coating • Impact of manufacturing changes on solid dosage forms • Official and commercially available tablets • Packaging and storing tablet

  3. Tablets are solid dosage forms usually prepared with the aid of suitable pharmaceutical excipients.

  4. Tablets may vary in size, shape, weight, hardness, thickness, disintegration, and dissolution characteristics and in other aspects, depending on their intended use and method of manufacture. • Tablets can be administered orally, sublingually, buccally, or vaginally. • Tablets are prepared primarily by compression, with a limited number prepared by molding.

  5. 1. Types of tablets 1) Compressed tablets • Medicinal agent • Diluents or fillers, which add the necessary bulk to a formulation to prepare tablets of the desired size.

  6. 淀粉(starch) • 白色粉末、无臭、无味、不溶于水 • 迅速吸收空气中的水分，通常含水量在1014%范围 • 具有黏附性、粉体流动性与可压性较差 • 性质稳定、与大多数药物配伍 • 外观色泽好，价格便宜 • 常与可压性较好的蔗糖粉、糊精等混合使用。

  7. 蔗糖(sucrose) • 白色、无臭、有甜味、极易吸湿、溶于水、不溶于乙醇 • 在温度110145C时，或在酸性条件下引起糖转化（葡萄糖和果糖），在室温和中等湿度条件下稳定 • 粘合力强，可用来增加片剂的硬度，常与糊精、淀粉配合使用 • 应注意片剂长期贮存过程中由于蔗糖的吸湿和干燥使片剂的硬度变大，崩解或溶出不合格等问题 • 治疗糖尿病或其他糖代谢不良症的药物制剂中不宜加入。

  8. 乳糖(lactose) • 常用的乳糖是含有一分子结晶水的-乳糖 • 白色结晶性粉末、无臭、微甜，水中微溶，在乙醇中几乎不溶 • 无吸湿性，可压性较好，压成的药片光洁美观，性质稳定，可与大多数药物配伍。 • 有喷雾干燥法制得的乳糖为非结晶性、球形乳糖，其流动性、可压性良好，可供粉末直接压片。

  9. 预胶化淀粉(pregelatinized starch) • 白色粉末、无臭、微有特殊口感，在水中可溶10%-20% • 本品具有良好的流动性、可压性、自身润滑性和干粘合性，并有较好的崩解作用。 • 作为多功能辅料，常用于粉末直接压片

  10. 微晶纤维素(microcrystalline cellulose) • 本品为白色无味的多孔性颗粒状粉末 • 具有较强的结合力与良好的可压性，亦有干粘合剂之称 • 具有崩解作用（吸水膨胀，高于20％） • 压缩成型性很好，可用于粉末直接压片。

  11. 无机盐类： • 磷酸氢钙、碳酸钙及硫酸钙等。其中二水硫酸钙较为常用，其性质稳定，无臭、无味，微溶于水，可与多种药物配伍 • 制成的片剂外观光洁，硬度、崩解度均好，对药物也无吸附作用。

  12. 甘露醇 (mannitol)： • 本品为六碳醇，山梨醇的异构体，为白色细微粉末，甜度与葡萄糖相近，性质稳定，安全性好，吸湿性差（CRH为85％），可压性良好。 • 本品可溶于水，溶解时吸热有凉爽感，适于口含片及舌下片。

  13. Binders or adhesives, • which promote the adhesion of the particles of the formulation, enabling a granulation to be prepared and the maintenance of the integrity of the final tablet. • 蒸馏水 （distilled water) 当原、辅料有一定粘性时，加入水可制成性能符合要求的颗粒。

  14. 乙醇(ethanol)： • 当药物遇水能引起变质，或用水为润湿剂制成的软才粘性太强而较难制粒，或制成的干颗粒太硬时，可选用适宜浓度的乙醇为润湿粘合剂。 • 乙醇浓度越高，则润湿后产生的粘性越小，制的的颗粒较松散，片剂崩解较快。常用浓度为30-70%。 • 乙醇溶液作润湿剂时，应迅速混合进行制粒并迅速干燥，避免乙醇挥发而使软材结团不易制粒，或使已制得的颗粒变性结团。

  15. 淀粉浆： • 是将淀粉混悬于水中在一定温度下的糊化物，玉米淀粉糊化温度约70～75C。 • 粘合作用良好，国内外应用广泛，浓度5～15％，常用10％。 • 淀粉浆能均匀的润湿辅料，不易出现局部过湿现象，不影响制剂的崩解与溶出以及药物测定。

  16. 纤维素衍生物 甲基纤维素(methylcellulose, MC)： • 在冷水中溶解，在热水及乙醇中几乎不溶。 • 应用于水溶性和水不溶性物料的制粒中，颗粒压缩成形性好、且不随时间变硬。 羟丙基纤维素(hydroxypropylcellulose, HPC)： • 在低于38C水中可混溶形成润滑透明的胶体溶液，加热至50C形成高度溶胀的絮状沉淀。 • 既可做湿法制粒的粘合剂，也可做粉末直接压片的干粘合剂。

  17. 羟丙甲基纤维素（hydroxypropylmethylcellulose,HPMC）:羟丙甲基纤维素（hydroxypropylmethylcellulose,HPMC）: • 溶于冷水，不溶于热水与乙醇，但在水和乙醇的混合液中溶解。 • 用量一般占配方量的1～4％ • 压制成的片剂外观硬度和溶出度均良好。 羧甲基纤维素钠(carboxymethylcellulose sodium,CMC-Na)： • 在任何温度的水中易分散、溶解，形成透明的胶状溶液。 • 常用于可压性较差的药物 • 通常含水量少于10%，在高湿条件下可以吸收大量的水（〉50%），这一性质在片剂的贮存过程中会改变片剂硬度和崩解时间。

  18. 聚维酮（povidine,PVP) • 可溶于水，适宜浓度的水溶液为粘合剂，其用量常占片剂总重的0.52%。 • 也可溶于乙醇，并可用其醇溶液为润湿粘合剂，因此较适于对水敏感的药物； • 也适用于疏水性药物，有利于润湿药物易于制粒，又因改善了药物的润湿性而有利于药物溶出。 • 一步制粒机制粒的良好粘合剂。 • 是溶液片、泡腾片、咀嚼片等的优良粘合剂

  19. Disintegrants • which promote the breakup of the tablets after administration to smaller particles for more ready drug availability; 干淀粉： • 最常用的一种崩解剂，用量一般为配方总量5%20%，崩解作用较好； • 用量不宜太多，压缩成型性不好； • 对不溶性药物或微溶性药物较适用； • 水杨酸钠、对氨基水杨酸钠可使淀粉胶化，故可影响其崩解作用； • 用量太多，影响颗粒的粒度分布，因而影响片重差异。

  20. 羧甲基淀粉钠（sodium carboxymethyl starch, CMS-Na)： • 吸水膨胀作用显著，其吸水后膨胀率为原体积的300倍 • 性能优良的崩解剂 低取代羟丙基纤维素（low-substituted hydroxypropylcellulose, L-HPC）： • 近年来国内应用较多的一种崩解剂 • 具有很大的表面积和空隙率 • 有很好的吸水速度和吸水量

  21. 交联羧甲基纤维素钠（croscarmellose sodium, CCNa）： • 由于交联键的存在不溶于水，可吸水并有较强的膨胀作用， • 具有较好的崩解作用， • 与羧甲基淀粉钠合用时崩解效果更好，但与干淀粉合用时崩解作用降低。 交联聚维酮（crospovidone, PVPP）： • 是流动性良好的白色粉末，在水中不溶，但在水中迅速溶胀，无粘性，因而崩解性能优越， • 用量较L-HPC等少， • 本品为崩解剂的片剂崩解时间受压片力的影响较小。

  22. Glidants or lubricants which enhance the flow of the tableting material into the tablet dies, minimize wear of the punches and dies, prevent the sticking of fill material to the punches and dies and produce tablets having a sheen.

  23. 硬脂酸镁(magnesium stearate)： • 润滑作用良好 • 可显著地降低片剂的推片力 • 有防止粘冲作用 • 压片后片面光滑美观 • 用量0.11% • 由于本品为疏水性物质，用量过大，影响片剂的崩解

  24. 滑石粉(talc)： • 为优良助流剂，可用于抗粘剂和润滑剂 • 减低颗粒表面的粗燥性，从而达到降低颗粒间的摩擦力，改善颗粒的流动性 • 一般用量0.13% 微粉硅胶(fumed silicon dioxide)： • 为轻质白色无水粉末，比表面积大，对液体药物及挥发油有一定的吸收性， • 为优良的助流剂，可用于粉末直接压片， • 用量0.10.3%

  25. Colorants and flavorants • 应符合药用规格，口服所用色素必须是药用级或食用极 • 色素最大用量一般不超过0.05% • 把色素先吸附于硫酸钙、三磷酸钙、淀粉等主要辅料中可有效地防止颜色的迁移 • 香精的加入方法是将香精溶解于乙醇中，均匀喷洒在已经干燥的颗粒上。

  26. 2) Multiply compressed tablets • Multiply compressed tablets are prepared by subjecting the fill material to more than a single compression. • Layered tablets are prepared by initial compaction of a portion of fill material in a die followed by additional fill material and compression to form two- or three- layered tablets, depending on the number of separate fills.

  27. 3) Sugarcoated tablets • Compressed tablets may be coated with a colored or an uncolored sugar layer. • The sugarcoat protects the enclosed drug from the environment and provides a barrier to objectionable taste or odor. • The sugarcoat also enhances the appearance of the compressed tablet.

  28. Disadvantages: The time and expertise required in the coating process and the increase in size, weight, and shipping costs.

  29. 4) Film-coated tablets • Film-coated tablets are compressed tablets coated with a thin layer of a polymer capable of forming a skin-like film over the tablet. • The film is usually colored and has the advantage over sugarcoatings in that it is more durable, less bulky, and less time consuming to apply.

  30. 5) Gelatin-coated tablets A recent innovation is the gelatin-coated tablet. The innovator product, the gelcap, is a capsule-shaped compressed tablet that allows the coated product to be about one-third smaller than a capsule filled with an equivalent amount of powder.

  31. 6) Enteric-coated tablets • Enteric-coated tablets have delayed-release features. • They are designed to pass unchanged through the stomach to the intestines, where the tablets disintegrate and allow drug dissolution and absorption and/or effect.

  32. Enteric coatings are employed when the drug substance • is destroyed by gastric acid, • is particularly irritating to the gastric mucosa, • when bypass of the stomach substantially enhances drug absorption.

  33. 7) Buccal and sublingual tablets • Buccal and sublingual tablets are flat oval tablets intended to be dissolved in the buccal pouch or beneath the tongue for absorption through the oral mucosa. • They enable oral absorption of drugs that are destroyed by the gastric juice and/or are poorly absorbed from the gastrointestinal tract.

  34. Buccal tablets are designed to erode slowly, whereas those for sublingual use dissolve promptly and provide rapid drug effects.

  35. 8) Chewable tablets • Chewable tablets, which have a smooth, rapid disintegration when chewed or allowed to dissolve in the mouth, have a creamy base, usually of specially flavored and colored mannitol. • Chewable tablets are especially useful for administration of large tablets to children and adults who have difficulty swallowing solid dosage forms.

  36. 9) Effervescent tablets • Effervescent tablets are prepared by compressing granular effervescent salts that release gas when in contact with water.

  37. 10) Molded tablets • Certain tablets, such as tablet triturates, may be prepared by molding rather than by compression. The resultant tablets are very soft and soluble and are designed for rapid dissolution.

  38. 11) Tablet triturates • Tablet triturates are small, usually cylindrical, molded or compressed tablets containing small amounts of usually potent drugs. 12) Immediate-release tablets • Immediate-release tablets are designed to disintegrate and release their medication with no special rate-controlling features, such as special coatings and other techniques.

  39. 13) Instantly disintegrating or dissolving tablets • Instant-release tablets are characterized by disintegrating or dissolving in the mouth within 1 minute, some within 10 seconds. • Tablets of this type are designed for pediatric and geriatric patients or for any patient who has difficulty in swallowing tablets. • A number of techniques are used to prepare these tablets involving lyophilization, soft direct compression, and other methods.

  40. 14) Extended release tablets • Extended-release tablets are designed to release their medication in a predetermined manner over an extended period of time.

  41. 15) Vaginal tablets • Vaginal tablets, also called vaginal inserts, are uncoated and bullet- or ovoid-shaped tablets which are inserted into the vagina for localized effects. • They are prepared by compression and shaped to fit snugly on plastic inserter devices which accompany the product.

  42. 2. Compressed tablets Tablets diameters and shapes are determined by the die and punches used in the compression of the tablet.

  43. 1) Compressed tablet manufacture Compressed tablets may be made by three basic methods: • wet granulation • dry granulation • direct compression

  44. Wet granulation is a widely employed method for the production of compressed tablets. The steps required are: • weighing and blending the ingredients • preparing a damp mass • screening the damp mass into pellets or granules • drying the granulation • sizing the granulation by dry screening • adding lubricant and blending • tableting by compression

  45. ① Weighing and blending Specified quantities of active ingredient, diluent or filler, and disintegrating agent are mixed by mechanical powder blender or mixer until uniform. The fillers used are • Lactose(solubility, compatibility) • Microcrystalline cellulose (compactability, compatibility, and the consistent uniformity) • Starch • Powdered sucrose • Calcium phosphate

  46. Disintegrating agentsinclude • Croscarmellose （交联羟甲纤维素） • Corn and potato starches • Sodium starch glycolate （甘醇酸酯淀粉钠） • Sodium carboxymethylcellulose （羧甲纤维素钠） • Polyvinyl polypyrolidone (PVP) • Crospovidone • Cation-exchange resins • Alginic acid （海藻酸）

  47. ② Preparing the damp mass • A liquid binder is added to the powder mixture to facilitate the adhesion of the powder particles. • A damp mass resembling dough is formed and is used to prepare the granulation. • A good binder results in appropriate tablet hardness and does not negatively impact on the release of the drug from the tablet.

  48. ③ Screening the damp mass into pellets or granules The wet mass is pressed through a screen (usually No. 6- or 8-mesh) to prepare the granules. ④ Drying the granulation Granules may be dried in thermostatically controlled ovens which constantly record the time, temperature, and humidity.

  49. ⑤ Sizing the granulation by dry screening • After drying, the granules are passed through a screen of a smaller mesh than that used to prepare the original granulation. • In general, the smaller the tablet to be produced, the smaller are the granules used. • Sizing of the granules is necessary so that the die cavities for tablet compression may be completely and rapidly filled by the free-flowinggranulation.

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