Tablets 1 by Lc7NC17


									Pharmaceutical Technology ll

       Tablets - l
       Presented by
  Dr. Md. Harun Ar Rashid
    Department of Pharmacy
           NUB           1
“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,
 manufacturer and manufacturing pharmacist       2
    Essential qualities of a good Tablets

-They should be accurate and uniform in
-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.             3
    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
- 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     5
             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

- the easiest and the cheapest to pack and transport

- don’t require any measurement of dose

            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

  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         To the patient

                accuracy and precision, improved
                control and more reliable therapy

 To the physician
                    cheaper due to mass production
                        and easier to manufacture,
                      simplicity, economy, stability,
                                                        To the
                                    and convenience              8

 Amorphous and Low density drugs are difficult to

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
              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

         Different Types of Tablets

Classified into a number of categories, based on
  -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
                   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                            12
       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   13
(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)

            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

- Tablets break up and particle deaggregation are important

            Multiple compressed Tablet
Tablets of this category are usually prepared for one of
  the two reasons:-
a. to separate physically or chemically incompatible
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).
  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

               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

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
The enteric coated tablet is the most common
All enteric coated tablets are a type of delayed
action tablet but not all delayed action tablet are
Cellulose acetate phthalate, Polyvinyl acetate
phthalate, Hydroxypropyl methyl cellulose phthate
have come into use for this .
These polymers being acid esters, are insoluble in
gastric media that have a pH up to about 4.       20
                    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
Xylitol may be used in the preparation of sugar-
free chewable tablets. Xylitol is sweeter than
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
           Tablets used in the oral cavity
 This type of tablet are placed in the mouth but not

*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
 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
  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.
               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.
            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

  - the possibility of a histopathological (tissue
  toxicity) reaction against the implanted ‘foreign

  -the need to employ a surgical technique to
  terminate the therapy should such termination
  become necessary                              28
              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

         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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