Transcript chapter 7

7. Tablets
Contents
1.
2.
3.
4.
5.
6.
Types of tablets
Compressed tablets
Chewable tablets
Molded tablets
Tablet coating
Impact of manufacturing changes on solid
dosage forms
7. Official and commercially available tablets
8. Packaging and storing tablet
Tablets are solid dosage forms
usually prepared with the aid of
suitable pharmaceutical excipients.
• 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.
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.
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。
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。
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。
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
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。
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。
• 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。
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。
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。
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。
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。
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,CMCNa)：
• 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。
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
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。
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
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。
• 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.
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
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%
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。
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 threelayered tablets, depending on the number
of separate fills.
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.
Disadvantages:
The time and expertise required in
the coating process and the increase
in size, weight, and shipping costs.
4) Film-coated tablets
• Film-coated tablets are compressed
tablets coated with a thin layer of a
polymer capable of forming a skinlike 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.
5) Gelatin-coated tablets
A recent innovation is the gelatincoated 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.
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.
• 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.
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.
• Buccal tablets are designed to erode
slowly, whereas those for sublingual
use dissolve promptly and provide
rapid drug effects.
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.
9) Effervescent
tablets
• Effervescent tablets
are
prepared
by
compressing granular
effervescent
salts
that release gas when
in contact with water.
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.
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.
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.
14) Extended release tablets
• Extended-release
tablets
are
designed to release their medication
in a predetermined manner over an
extended period of time.
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.
2. Compressed tablets
Tablets diameters and shapes are
determined by the die and punches used
in the compression of the tablet.
1) Compressed tablet manufacture
Compressed tablets may be made by
three basic methods:
- wet granulation
- dry granulation
- direct compression
•
•
•
•
•
•
•
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
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
Disintegrating agents include
- 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）
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.
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.
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-flowing granulation.
• Voids or air spaces left by too large a
granulation would
result
in
the
production of uneven tablets.
⑥ Adding lubrication and blending
• After dry screening, a dry lubricant is
dusted over the spread-out granulation
through a fine mesh screen.
•
•
•
•
Lubricants contribute to the preparation of
compressed tablets in several ways:
They improve the flow of the granulation in
the hopper to the die cavity;
They prevent the adhesion of the tablet
formulation to the punches and dies during
compression;
They reduce friction between the tablet
and the die wall during the tablet’s ejection
from the tablet machine;
They give a sheen to the finished tablet.
The more commonly used lubricants are
- Magnesium stearate
- Calcium stearate
- Stearic acid
- Talc
- Sodium stearyl fumarate （富马酸硬脂酸钠）
The quantity of lubricant used from about
0.1% to 5% of the weight of the
granulation.
All-in-one granulation methods
Technologic advances now allow the
entire process of granulation to be
completed in a continuous fluid-bed
process, using a single piece of
equipment, the fluid-bed granulator.
The fluid-bed granulator performs the
following steps:
- preblending the formulation powder in
a bed by fluidized air,
- granulating the mixture by spraying
onto the fluidized powder bed, a
suitable liquid binder, as an aqueous
solution of acacia, hydroxypropyl
cellulose, or povidone,
- drying the granulated product to the
desired moisture content.
Dry granulation
• By the dry granulation method, the powder
mixture is compacted in large pieces and
subsequently broken down or sized into
granules.
• By this method, either the active
ingredient or the diluent must have cohesive
properties.
Dry granulation is especially applicable
to materials that can not be prepared
by wet granulation due to their
degradation by moisture or by the
elevated temperatures required for
drying the granules.
① Slugging
② Roller compaction
Direct compression tableting
• Some granular chemicals, like potassium
chloride, possess free flowing and
cohesive properties that enable them to
be compressed directly in a tablet
machine without need of wet or dry
granulation.
• For chemicals that do not possess this
quality, special pharmaceutical excipients
may be used which impart the necessary
qualities for the production of tablets by
direct compression.
2) Quality standards and
compendial requirements
•
•
•
•
•
In addition to the apparent features of
tablets, tablets must be met other physical
specifications and quality standards. These
include criteria for
tablet weight, weight variation
content uniformity, thickness
tablet hardness
tablet disintegration
drug dissolution
• These factors must be controlled during
production (in-process controls) and
verified after the production of each
batch to assure that established
product quality standards are met.
① Tablet weight and USP weight variation
test
• The quantity of fill placed in the die of
a tablet press determines the weight of
the resulting tablet.
• The volume of fill is adjusted with
the first few tablets produced to
yield tablets of the desired weight
and content.
• The USP contains a test for the
determination
of
dosage-form
uniformity by weight variation for
uncoated tablets.
• In the test, 10 tablets are weighed
individually and the average weight
calculated.
• The tablets are assayed and the
content of active ingredient in each
of the 10 tablets is calculated
assuming
homogeneous
drug
distribution.
② Content uniformity
• By the USP method, 10 dosage units are
individually assayed for their content
according to the assay method described
in the individual monograph.
• The requirements for content uniformity
are met if the amount of active
ingredient in each dosage unit lies within
the range of 85% to 115% of the label
claim and the relative standard deviation
is less than 6.0%.
③ Tablet thickness
- The thickness of a tablet is determined by
the diameter of the die, the amount of fill
permitted to enter the die ， the
compactability of the fill material ， and
the force or pressure applied during
compression.
- To produce tablets of uniform thickness
During batch production and between batch
productions for the same formulation, care
must be exercised to employ the same
factors of fill, die, and pressure.
④ Tablet hardness and friability
• Generally, the greater the pressure
applied,
the
harder
the
tablets,
although the characteristics of the
granulation also has a bearing on tablet
hardness.
• Tablets should be sufficiently hard to
resist breaking during normal handling
and yet soft enough to disintegrate
properly after swallowing.
• Special dedicated
or multifunctional
to measure the
required to break
hardness testers
systems are used
degree of force
a tablet.
• A force of about 4 kilograms is
considered
the
minimum
requirement for a satisfactory
tablet.
• A tablet’s durability may be
determined through the use of a
friabilator.
This
apparatus
determines the tablet’s friability.
• A maximum weight loss of not more
than 1% of the weight of the
tablets being tested generally is
considered acceptable for most
products.
第七节 片剂的质量检查
⑤ Tablet disintegration
• Tablet disintegration is important for
tablets containing medicinal agents (such
as antacids and antidiarrheals) that are
not intended to be absorbed but rather
to act locally within the gastrointestinal
tract.
• In these instances, tablet disintegration
provides drug particles with an increased
surface area for localized activity within
the gastrointestinal tract.
• Tablets usually must disintegrate 30
minutes, but varying from about 2
minutes for Nitroglycerin Tablets to up
to 4 hours for buccal tablets
• If one or more tablets fail to
disintegrate, additional tests
prescribed by the USP must be
performed.
• Enteric-coated tablets are similarly
tested, except that the tablets are
permitted to be tested in simulated
gastric fluid for one hour after which
no sign of disintegration, cracking, or
softening must be seen.
⑥ Tablet dissolution
In vitro dissolution testing of solid
dosage forms is important for a number
of reasons.
- It guides the formulation and product
development process toward product
optimization.
- The performance of the manufacturing
process may be monitored by dissolution
testing.
- Consistent in vitro dissolution testing
results assure bioequivalence from
batch-to-batch.
- As a requirement for regulatory
approval for product marketing for
products registered with the FDA
and regulatory agencies of other
countries.
A system has been developed which
relates combinations of a drug’s
solubility (high or low) and its
intestinal permeability (high or low)
as a possible basis for predicting the
likelihood of achieving a successful in
vivo-in vitro correlation (IVIVC).
•
•
•
•
High solubility and high permeability
Low solubility and high permeability
High solubility and low permeability
Low solubility and low permeability
For a high solubility and high
permeability drug, an IVIVC may be
expected if the dissolution rate is
slower than the rate of gastric
emptying.
• In the case of a low solubility and
high
permeability
drug,
drug
dissolution may be the rate limiting
step for drug absorption and an
IVIVC may be expected.
• In the case of a high solubility and
low permeability drug, permeability is
the rate-controlling step and only a
limited IVIVC may be possible.
• In the case of a drug with low
solubility and low permeability,
significant problems would be likely
for oral drug delivery.
•
•
•
•
A
number
of
formulation
and
manufacturing factors can affect the
disintegration and dissolution of a tablet
including:
The particle size of the drug substance in
the formulation;
The solubility and hygroscopicity of the
formulation;
The type and concentration of the
disintegrant, binder, and lubricant used;
The manufacturing method, particularly
the compactness of the granulation and
the compression force used in tableting.
3. Chewable tablets
• Chewable tablets are pleasant tasting
tablets
formulated
to
disintegrate
smoothly in the mouth with or without
active chewing.
• They are prepared by wet granulation and
compression, using only minimal degrees of
tableting pressure in order to produce a
soft tablet.
• Mannitol, a white crystalline hexahydric
alcohol, is used as the excipient in most
chewable tablets.
Per tablet
• Aluminum hydroxide
325.0mg
• Mannitol
812.0mg
• Sodium saccharin
0.4mg
• Sorbitol
32.5mg
• Magnesium stearate
35.0mg
• Mint flavor concentrate 4.0mg
Preparation: Blend the aluminum hydroxide, mannitol,
and sodium saccharin. Prepare a wet granulation
with the sorbitol solution. Dry at 120C and screen
through a 12-mesh screen.
Add the flavor and magnesium stearate, blend, and
compress into tablets.
4. Molded tablets
• Commercial preparation
of tablets by molding
has been replaced by
tablet compression.
• Molded tablets, or
tablet triturates, may
be prepared on a small
laboratory scale.
Molded tablets are
intended to dissolve
rapidly in the mouth.
They are not contain
disintegrants,
lubricants, or
coatings to slow
their rate of
dissolution.
5. Tablet coating
•
•
•
•
Tablets are coated for a number of
reasons, including to protect
the medicinal agent against
destructive exposure to air and/or
humidity;
to mask the taste of the drug;
to provide special characteristics of
drug release;
to provide aesthetics or distinction
to the product.
1) Sugarcoating tablets
The sugarcoating of tablets may be
divided into the following steps:
- waterproofing and sealing,
- subcoating,
- smoothing and final rounding,
- finishing and coloring if desired,
- polishing.
Waterproofing and sealing coats
• For tablets containing that may be
adversely affected by moisture, one or
more
coats
of
a
waterproofing
substance,
such
as
pharmaceutical
shellac or a polymer, is applied to the
compressed
tablets
before
the
subcoating application.
• The waterproofing solution is gently
poured or sprayed on the compressed
tablets rotating in the coating pans.
• Warm air is blown into the pan
during the coating to hasten the
drying and to prevent tablets from
sticking together.
Subcoating
• After the tablets are waterproofed
if needed, three to five subcoats of
a sugar-based syrup are applied.
• This bonds the sugar coating to the
tablet and provides rounding.
• The sucrose and water syrup also
contains
gelatin,
acacia,
or
polyvinylpyrrolidone (PVP) to enhance
coating.
• When the tablets are partially dry, they
are sprinkled with a dusting powder,
usually a mixture of powdered sugar and
starch but sometimes talc, acacia, or
precipitates chalk as well.
• Warm air is applied to the rolling tablets,
and when they are dry, the process is
repeated until the tablets are of the
desired shape and size.
Smoothing and final rounding
• After the tablets are subcoated, 5
to 10 additional coatings of a thick
syrup are applied to complete the
rounding and smooth the coatings.
• A dusting powder is often used
between syrup applications.
• Warm air is applied to hasten the
drying time of each coat.
Finishing and coloring
• To attain final smoothness and the
appropriate color to the tablets,
several coats of a thin syrup
containing the desired colorant are
applied in the usual manner.
• This step is performed in a clean pan,
free from previous coating material.
Imprinting
• Solid dosage forms may be passed
through a special imprinting machine
to impart identification codes and
other distinctive symbols.
Polishing
Coated tablets may be polished in several
ways
- Special drum-shaped pans or ordinary
coating pans lined with canvas or other
cloth impregnated with carnauba wax
and/or beeswax, may be used to polish
tablets as they tumble in the pan.
- Pieces of wax may be placed in a
polishing pan and the tablets allowed to
tumble over the wax until the desired
sheen is attained.
• A third method is light spraying of
the tablets with wax dissolved in a
nonaqueous solvent.
• Two or three coats of wax may be
applied, depending upon the desired
gloss.
2) Film-coating tablets
• The sugarcoating process is tedious,
time-consuming,
and
specialized,
requiring the expertise of highly
skilled technicians,
• It results in coated tablets that may
be twice the size and weight of the
original uncoated tablets,
• Sugarcoated tablets may vary slightly
in size from batch to batch and within
a batch.
• The film-coating process, which places
a thin, skin-tight coating of a
plasticlike material over the compressed
tablet, was developed to produce
coated tablets having essentially the
same weight, shape, and size as the
originally compressed tablet.
• The coating is thin enough to reveal any
identifying monograms embossed in the
tablet during compression by the tablet
punches.
• Film-coated tablets also are far more
resistant to destruction by abrasion than
are sugarcoated tablets.
• Film-coating solutions may be nonaqueous
or aqueous. The nonaqueous solutions
contain
- A film former
- An allowing substance
- A plasticizer
- A surfactant
- Opaquants and colorants
•
Sweeteners, flavors, and aromas
A glossant
A volatile solvent or water
Tablets are film-coated by application
or spraying of the coating solution on
the tablets in ordinary coating pans.
• The volatility of the solvent enables
the film to adhere quickly to the
surface of the tablets.
A typical aqueous film-coating
formulation contains
-
Film-forming polymer
Plasticizer
Colorant and opacifier
Vehicle
3) Enteric coating
• Enteric-coated solid dosage forms are
intended to pass through the stomach
intact to disintegrate and release their
drug content for absorption along the
intestines.
• Enteric-coating materials may be applied
to either whole compressed tablets or to
drug particles or granules used in the
fabrication of tablets or capsules.
4) Fluid bed or air suspension
coating
• Fluid bed coating, is spray coating
of powders, granules, beads, pellets,
or tablets held in suspension by a
column of air.
• Fluid bed processing equipment is
multifunctional and may also be
used
in
preparing
tablet
granulations.
• Both the top-spray and bottom-spray
methods may be employed using a
modified apparatus used for fluid bed
granulation.
• A third method, the tangential spray
technique, is used in rotary fluid bed
coaters.
• The three systems are increasingly used
for application of aqueous or organic
solvent-based polymer film coatings.
• The
top-spray
coating
method
is
particularly recommended for taste masking,
enteric release, and barrier films on
particles or tablets.
• It is most effective when coatings are
applied from aqueous solutions, latexes, or
hot melts.
• The bottom-spray method is recommended
for sustained-release and enteric-release
products.
• The tangential method is used for layering
coatings and for sustained-release and
enteric-coated products.
5) Compression coating
• It is similar to the preparation of multiple
compressed tablets having an inner core
and an outer shell of drug material, core
tablets
may
be
sugarcoated
by
compression.
• The coating material, in the form of a
granulation or powder is compressed onto a
tablet core of drug with a special tablet
press.
• Compression coating is an anhydrous
operation and thus may be safely employed
in the coating of tablets containing a drug
that is labile to moisture.
6. Impact of manufacturing
changes on solid dosage forms
The quality and performance of a
solid dosage form may be altered
by changes in formulation or by
changes
in
the
method
of
manufacture.
-
The changes in formulation may
arise from
the use of starting raw materials
the
use
of
different
pharmaceutical excipients
the use of different quantities of
the
same
excipients
in
a
formulation,
the addition of a new excipient to
a formulation.
-
-
-
The changes in the method of
manufacture may be
Use of processing or manufacturing
equipment of a different design,
A change in the steps or order in the
process or method of manufacture,
Different in-process controls, quality
tests, or assay methods,
Production of different batch sizes,
Employment of different product
reprocessing procedures,
Employment of a different manufacturing
site.
7. Official and commercially
available tablets
There are hundreds of tablets
recognized by the USP and literally
thousands of commercially available
tablet products from virtually all
pharmaceutical manufacturers.
8. Packaging and storing tablets
• Tablets are stored in tight containers,
in places of low humidity, and protected
from extremes in temperature.
• Products
that
are
prone
to
decomposition by moisture generally are
packaged with a desiccant packet.
• Drugs that are adversely affected by
light are packaged in light-resistant
containers.