Transcript Tablets - nubacad.com

Pharmaceutical Technology ll
Tablets - l
Presented by
Dr. Md. Harun Ar Rashid
Head
Department of Pharmacy
NUB
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“A tablet is a solid single unit dosage form
containing one or more active ingredients with
or without auxillary substances, prepared by
compression and molding.”
Intended mainly for oral administration
Most commonly are disk shaped with convex surfaces
Available in special shape like round, oval, oblong,
cylindrical, square, triangular
Widely used solid dosage form because they offer a
number of advantages to the patient, prescriber,
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manufacturer and manufacturing pharmacist
Essential qualities of a good Tablets
-They should be accurate and uniform in
weight
-The drugs should be uniformly distributed
throughout the tablets
-The size and shape should be reasonable for
easy administration
-The tablets should not be too hard that it may
not disintegrate in the Stomach
-There should not be any incompatibilities
-They should be chemically and physically
stable during storage . Cont.
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Essential qualities of a good Tablets
- They should not break during transportation
or crumble in the hands of the patient
- They should be attractive in appearances
- There should not be any manufacturing
defects like cracking, chipping discolouration
- After disintegration it should release the
drug readily
- They should be easy and economical in
production.
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Advantages
- Offer greatest dose precision and the least
content variability
- easy to be swallowed or administered
- easy to handle and carry by the patient
- economical, manufacturing cost are low,
manufacturing speed is quite high
- most stable with respect to physical, chemical
and microbiological attributes
- Bitter, unpleasant taste and nauseous odour of
medicaments can be easily masked by
administering in the form of coated tablet
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Advantage (Continued)
- product identification is probably the easiest
because of the variety of shapes and colours of
tablets that are possible
- the lightest and the more compact of all dosage
forms
- the easiest and the cheapest to pack and transport
- don’t require any measurement of dose
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Advantage (continued)
Can be divided into halves, quarters by drawing
lines during manufacture to facilitate breakage
whenever a fractional dose is required
Lend themselves to certain special release profile
such as enteric or delayed release products
Attractive and elegant in appearance
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In Summary Solid Dosage Forms, Most
Notably Tablets Provide Advantages
in storage, dispensing, and control
convenience of use
To the pharmacist
of product identification, dosage
accuracy and precision, improved
control and more reliable therapy
To the physician
cheaper due to mass production
and easier to manufacture,
simplicity, economy, stability,
and convenience
To the patient
To the
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manufacturer
Disadvantages
Amorphous and Low density drugs are difficult to
compress.
High doses are difficult to formulate as tablet dosage form.
Bitter tasting and objectionable odour drugs require
special treatment like coating or encapsulation and
increase the cost.
Drugs that are sensitive to oxygen or atmospheric
moisture may also require special coating as well as costly
packaging which may increase the overall cost of finished
product
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Disadvantage (Continued)
Drugs with poor wetting and slow dissolution properties
are difficult to convert into tablets which will provide full
drug bioavailability.
Drugs that are liquid at room temperature can not be
formulated in tablet dosage form
A major disadvantage with respect to convenience of
patients is the difficulty of swallowing specially by children
and ill patients
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Different Types of Tablets
Classified into a number of categories, based on
their
-Their methods of manufacture
-Type of drug delivery system
- Formulation and Functions
**Not all classes are entirely different but mostly
overlap each other, such as,
- Chewable and Effervescent tablets are single
layered uncoated tablets
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Classification (continued)
Table1. Classified based on the method of manufacture and
type of drug deliver system
(A) Tablets ingested orally:
--
Compressed tablet, e.g. Paracetamol tablet
–
Multiple compressed tablet
–
Delayed release tablet, e.g. Enteric coated Bisacodyl tablet
–
Sugar coated tablet, e.g. Multivitamin tablet
–
Film coated tablet, e.g. Metronidazole tablet
–
Chewable tablet, e.g. Antacid
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Classification (continued)
(B) Tablets used in oral cavity :
–
Buccal tablet, e.g. Vitamin-c tablet
–
Sublingual tablet, e.g. Vicks Menthol tablet
–
Troches or lozenges
–
Dental cone
(C) Tablets administered by other routes:
- Implantation tablet
- Suppositories or Inserts, e.g. Clotrimazole tablet
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(D) Tablets used to prepare solution:
– Effervescent tablet, e.g. Dispirin tablet (Aspirin)
–
Dispensing tablet, e.g. Enzyme tablet (Digiplex)
–
Hypodermic tablet
–
Tablet triturates e.g. Enzyme tablet (Digiplex)
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Standard compressed tablet
- Prepared by single compression
- employ any of the three basic methods of manufactures: wet
granulation, dry granulation and direct compression.
- most of the tablets containing drugs intended to exert a local
effect in the GIT are of this type (antacids and adsorbents)
- Other drugs in this group are intended to produce systemic
effect.
- Tablets break up and particle deaggregation are important
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Multiple compressed Tablet
Tablets of this category are usually prepared for one of
the two reasons:a. to separate physically or chemically incompatible
ingredients
b. to produce repeat action or prolonged action products
- layered tablets consist of parallel layers obtained by
successive compression of particles of different comp.
- press coated or dry coated tablets are prepared
by compressing a layer of granules over a previously
compressed tablets. (manesty drycota).
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The layered tablets are rapid, surface contact between
layers is lessened, production is simpler so preferred.
The shortcomings of this category of dosage form for
repeat – action products is that its performance is
highly dependant on gastric empting.
XX, If the second layer or core tablet quickly leaves the
stomach following release of the initial fast release
dose, an entirely different blood level profile results
than if there is a several hour or longer delay before
the second fraction is emptied.
- this is the reason that relatively few repeat –action or
controlled release products using this approach are
marketed.
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Repeat action tablets
In addition to compressed tablets, sugar coated tablet
may also employed.
The core tablet is usually coated with shellac or an
enteric polymer so that it will not release the loading
drug in the stomach.
The second dose of drug is then added in the sugar
coating.
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Delayed action and enteric coated tablet
The delay action tablet dosage form is intended to
release a drug after some time delay or after the
tablet has passed through the part of GI tract into
another.
The enteric coated tablet is the most common
example
All enteric coated tablets are a type of delayed
action tablet but not all delayed action tablet are
enteric
Cellulose acetate phthalate, Polyvinyl acetate
phthalate, Hydroxypropyl methyl cellulose phthate
have come into use for this .
These polymers being acid esters, are insoluble in
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gastric media that have a pH up to about 4.
Chewable tablets
Are compressed tablets which have a smooth, rapid
disintegration when chewed or allowed to dissolve in
the mouth and contains a creamy base of a specially
flavored and colored mannitol.
Two major advantages are,
a.The dose of most antacid is large so that the typical
antacid tablet would be too large to swallow
b.The activity of antacid is related to its particle size. If
the tablet is chewed prior to swallowing better acid
neutralizing may be possible from a given antacid
dose
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Xylitol may be used in the preparation of sugarfree chewable tablets. Xylitol is sweeter than
mannitol.
lubricant and binders must not affect the texture
or desired hardness of the tablet
colorant and tart or fruity flavorants are
commonly employed to enhance the appeal of
the tablets
Examples of chewable tablets:
Calcium
carbonate - antacids; Erythromycin - antibiotics;
Didanosine - anti-infectives; Carbamazepine anticonvulsants;
Isosorbide
dinitrate
vasodilator; Acetaminophen - analgesics;
various vitamins and cold-allergy combination
tablet
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Tablets used in the oral cavity
This type of tablet are placed in the mouth but not
swallowed.
*Buccal and sublingual tablets
These tablets , though not swallowed, are intended to
provide systemic drug action.
These are small, flat, usually oval dosage forms to be
inserted in the buccal , or cheek, pouch (buccal tablet) or
beneath the tongue (sublingual tablets).
The drug is absorbed directly through the oral mucosa,
thereby avoiding the acid and enzymatic environment of
the stomach and the drug metabolizing enzymes of the
liver.
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Drugs are commonly administered by the oral
mucosal route:
the vasodilator glyceryl trinitrate: Steroids, such as
methyl testosterone, testosterone propionate,
estradiol: and, possibly, some miscellaneous
hormones and drugs, such as pancreatic
lipotropic hormone factors, hesperidin, and
nicotinic acid.
Drugs that may be absorbed via the oral
mucosa have several possible advantages:
(1) Avoidance of the gastric environment and the
decomposition it may produce with some steroids and
hormone (2) a more rapid onset of drug action than
occurs with tablets which are swallowed (3) Reduction of
nausea, with drugs that produce this effect when
swallowed (4) More efficient drug utilization (lower dose),
owing to avoidance of inactivation by liver drug
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metabolising enzymes.
. Drugs absorbed from the gastrointestinal tract enter the mesenteric
circulation which feeds directly into the liver via the portal vein. Drug
absorption from the oral cavity involves drug diffusion into the blood and
lymph canals through the sublingual or oral mucosa. Blood is supplied to this
region via the external carotid artery and is returned via the jugular veins into
the general circulation rather than going directly to the portal vein. Many
steroids are either relatively or totally inert if ingested owing to inactivation by
liver enzymes. This loss of potency can be circumvented by other modes of
administration such as intramuscular injection, implantation of tablets, use of
vaginal suppositories, or absorption through the oral mucosa. The latter
method, in many instances, is preferable.
Since most drugs, including weakly acidic drug moieties, are probably
absorbed primarily in the upper small intestine. The tablet must disintegrate,
the drug dissolve, and the stomach empty at least partially before drug
absorption begin. Therefore , a time lag of 30 minutes or more (corresponding
to the time required for the drug to be dissolved and leave the stomach) is
typical before a drug effect is exerted after swallowing a tablet. on the other
hand , total drug absorption typically occurs within 30 minutes after buccal or
sublingual tablets have been administered and onset of action is common with
vasodilator drugs..
Buccal and sublingual tablets are designed not to disintegrate but to dissolve
slowly over a 15 to 30 minute period. The tablet composition should not
promote salivation, which would result in swallowing dissolved drug, thereby
circumventing the purpose of the buccal or sublingual tablets.
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Dental cones
The cones may contain an antibiotic or
antiseptic typically in a filler of Sodium
bicarbonate, sodium chloride, amino acid,
or lactose.
The cones are formulated and compression
so that a small volume of serum or fluid will
cause disintegration and dissolution in 20 to
30 minutes.
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Tablets administered by other routes
Implantation tablets
This is also known as pellets, are small sterile tablets,
cylindrical shaped and usually not over 8 mm. in length, for
subcutaneous implantation in man or animals to provide
very prolonged drug effects – for 3 to 6 months or longer.
In man, use of this dosage form is limited to very potent
drugs which are not orally absorbed, notably steroids such
as Desoxycorticosterone, testosterone, or estradiol.
The major advantage of the dosage form is to provide
continuous therapy over many months without the need for
repeated parenteral dosing. Over a long periods of time
this form of therapy can be most economical. Also, it may
provide the most even and uniform hormone therapy. 27
Implantation tablets
The immediate and potential disadvantage of
implantation therapy are:
- the surgical technique which may be required
for implantation
- the difficulty of maintaining a constant drug
release rate as the pellet changes geometry with
dissolution
- the possibility of a histopathological (tissue
toxicity) reaction against the implanted ‘foreign
body’
-the need to employ a surgical technique to
terminate the therapy should such termination
become necessary
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Vaginal tablets
Also called inserts, are generally ovoid or
pear shaped made by compression and
intended to undergo dissolution and drug
release in the vaginal cavity.
The tablets are usually used in the treatment
of trichomonas vaginitis and
contain organic iodine (iodochlor or
iodohydroxyquinoline compounds) or other
antiseptics, astringents, or steroids in a
soluble base of lactose
or sodium
biocarbonate.
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Effervescent tablets
These tablet produce effervescence when
added to cold water. Effervescence which
is usually carbon dioxide is generated due
to chemical reaction which take place
between a Bicarbonate and an acid (citric
acid and Tataric acid)
The
effervescence
causes
rapid
disintegration of the tablet and also
increases the palatability ।
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