Powder dosage forms, granules and effervescent granules

1. Powders &
Granules
Presented By
NARESH GORANTLA, M.Pharm.., (Ph.D)
Asso. Professor,
Balaji college of Pharmacy,
Ananthapuramu

2. CONTENTS
Powders and Granules
a) Introduction
b) Advantages and disadvantages
c) General Method of preparation
d) Classification
e) Method of preparation of different powders
f) Granules
g) Effervescent granules

3. Introduction:
 A Pharmaceutical powder is a mixture of
finely divided drugs or chemicals in a dry
form meant for internal or external use.
 They may be Crystalline or Amorphous
form.
 The Particle size of a Powder plays an
important role and affects dissolution,
absorption and therapeutic effectiveness
of drugs.

4. Advantages of powders :
 Can be used both internally and externally.
 More stable than other dosage forms
 flexibility of compounding and prescribing a
specific quantity.
 Less chances of incompatibility.
 Rapid onset of action
 Easy to carry.
 Large quantity also can be administered
conveniently.
 More economical because no special equipment is
required for preparation.

5. Disadvantages of powders :
 Bitter, nauseous and unpleasant taste drugs can not be
prepared in the powder form.
 Deliquescent and Hygroscopic drugs can not be dispensed
in the powder form.
 Drugs which get affected by atmosphere are not suitable.
 Dispensing is time consuming.
 Less quantity can not be weighed conveniently on
dispensing balance.

6. General method of preparation of
Pharmaceutical powders
It involves two steps:
1. The process of reducing the particle size
(Comminution)
2. The process of Blending

7. COMMINUTION OF DRUGS
 On a small scale, the pharmacist reduces
the size of chemical substances by
grinding with a mortar and pestle.
 A finer grinding action is accomplished by
using a mortar with a rough surface (as a
porcelain mortar) than one with a smooth
surface (as a glass mortar).
 Grinding a drug in a mortar to reduce its
particle size is termed trituration or
comminution.

8.  When two or more powdered substances are to be
combined to form a uniform mixture, it is best to
reduce the particle size of each powder individually
before weighing and blending.
 Depending on the nature of the ingredients, the
amount of powder, and the equipment, powders may
be blended by spatulation, trituration, sifting, and
tumbling.
BLENDING POWDERS

9. Spatulation
Spatulation is blending small amounts of
powders by movement of a spatula through
them on a sheet of paper or an ointment tile.
It is not suitable for large quantities of powders
or for powders containing potent substances,
because homogeneous blending is not as
certain as other methods.

10. Trituration
• Trituration may be employed both to
comminute and to mix powders. If simple
admixture is desired without the special
need for comminution, the glass mortar is
usually preferred.

11. What is geometrical dilution ???
 When a small amount of a potent substance is to be mixed
with a large amount of diluent, the geometric dilution method
is used to ensure the uniform distribution of the potent drug.
 By this method, the potent drug is placed with an
approximately equal volume of the diluent in a mortar and is
mixed thoroughly by trituration.
 Then, a second portion of diluent equal in volume to the
mixture is added and the trituration repeated.
 This process is continued by adding an equal volume of diluent
to the powder mixture and repeating this until all of the
diluent is incorporated.

12. • Sifting
 Powders may also be mixed by passing them
through sifters like those used in the kitchen to
sift flour.
 Sifting results in a light, fluffy product.
 This process is not acceptable for the incorporation of
potent drugs into a diluent powder.

13. Tumbling:
Another method of mixing powders is tumbling the
powder in a rotating chamber.
 Special small-scale and large-scale motorized
powder blenders mix powders by tumbling them.
 Mixing by this process is thorough but time
consuming.
 Such blenders are widely employed in industry, as
mixers that use motorized blades to blend powders in a
large vessel.

14. Classification of Powders
 Bulk Powders for internal use
 Bulk Powders for External use
 Simple and compound Powders for internal use
 Powders enclosed in cachets and capsules.
 Compressed powders (Tablets)

15. 1.Bulk powder for internal use
• They are mixture of finely divided drugs and/or
chemicals in a dry form that may be intended
for internal use (oral powders)
• Powders are dispensed in bulk when the dose
accuracy is not important.
• Contain several doses and supplied in wide
mouthed containers.
• Non potent substances like
• Antacids
• Laxatives

16. 2. Bulk powder for external use
• They are mixtures of finely divided non
potent drugs and/ or chemicals in a dry
form that may be intended for external use
available in multiple doses (dusting
powder)
• Types:
a)Dusting powders
b)Insufflations
c) Snuffs
d)Dentifrices

17. Dusting powders
• These are meant for external application on to
the skin and are applied in a very fine state of
sub division to avoid local irritation.
• Medical – for superficial skin infections
• Surgical – Body cavities and on wounds.
• The major ingredients include:
• Talc, starch and Kaolin
• Antiseptic, Astringent, Absorbent,
Antiperspirant and Antipruritics.
• Dispensed in sifter top container or aerosol
container

18. Insufflations
• These are medicated dusting powders meant for
introduction into the body cavities such as nose, throat,
ears and vagina with the help of a apparatus known as
Insufflator.
• It sprays the powder into a stream of finely divided
particles all over the site of application.
• Insufflations are used to provide local effect, as in the
treatment of ear, nose and throat infection with
antibiotics or to produce systemic effect of drugs.

19. Snuffs
• Finely divided solid dosage forms of
medicament which are inhaled into nostrils
for its
• Antiseptic,
• Bronchodilator and
• Decongestion actions.

20. Dentrifrices (Tooth powders)
• Powders which are applied with the help of a
brush for cleaning the surface of the teeth.
• They contain a suitable detergent or soap,
Abrasive and flavor.
• Abrasives – Calcium sulphate, Magnesium
carbonate, Sodium carbonate and Sodium
chloride.
• Rx,
• Hard soap – 50 g
• Calcium carbonate – 935 g
• Saccharin sodium – 2 g
• Peppermint oil – 4 ml

21. Simple and Compound powders for internal use
 Each individual dose is enclosed in paper.
 Simple powder - one ingredient
 Compound powder – more than one
 The minimum quantity of powder should be NLT 100 mg
 Simple powder – A simple powder contains only one
ingredient either in crystalline or Amorphous form.
Rx,
Aspirin – 300 mg
Make powder and send 6 doses.

22. Compound powder – A compound powder
contains two or more ingredients which are mixed
together and then divided into desired number of
individual doses which are dispensed into each
powder paper.
Rx,
Aspirin – 300 mg
Paracetamol – 150 mg
Caffeine – 50 mg
Make powder and send 8 doses.

23. Powders enclosed in cachets
 Cachets are the solid unit dosage forms of the
drug which are moulded from rice paper.
 These are made by pouring a mixture of rice
flour and water between two hot, polished,
revolving cylinders.
Cachets are used to enclose nauseous or
disagreeable powders and are available in
different sizes from 0.2 to 1.5 gm of powder.
Softened by dipping in water for a
few seconds and then placed on
the tongue and swallowed with a
draught of water.

24. Types of cachets
• Wet seal cachets:
Made up of 2 similar convex halves
having flat edges. The powder is
placed in one half, second half is
placed on it and the edges are moistened
with water and pressed to seal.
•Dry seal cachets:
Two halves, upper and lower, where the
diameter of the upper half is slightly larger
than lower half. The powder is filled in
lower half, and the upper half is placed on it
and pressed for sealing using machines.

25. 5. Tablet triturates
• Powders molded into tablets.
• Flat, circular disc shaped usually contains a
potent substance which is mixed with lactose,
dextrose or other diluents.
• The moulds consists of
• Upper perforated plate
• Lower plates having pegs
•The mould are generally available in several sizes
ranging from 30 to 250 mg.

26. • The solid medicament along with diluent are powdered
and converted into a stiff paste using 60 % alcohol.
• The paste is pressed on to the upper perforated plate
using spatula and placed on to the lower plate.
• A little pressure is applied over the top plate to move
downward, leaving the mould tablets on the projected
pegs which makes to eject the tablets.
• Tablets are kept in hot air oven for drying.
Preparation of Tablet triturates

27. Powders involving special problems
• Volatile substances
• Hygroscopic and Deliquescent powders
• Efflorescent powders
• Eutectic powders
• Liquids
• Explosive powders
• Potent drugs

28. Volatile substances
• Vegetable drugs contain volatile oils.
• To prevent the loss the vegetable drugs must be
powdered lightly.
• Volatilization of menthol, camphor and essential oils
may happen on incorporation.
Solution:
• This is prevented or minimized by double wrapping.
• The inner wrapper may be of a wax paper and the outer
wrapper may be a thick paper.

29. Hygroscopic and deliquescent substances
• Hygroscopic – absorbs moisture
• Deliquescent – absorbs moisture and becomes liquid.
Ammonium chloride, Phenobarbitone, sodium
bromide, sodium iodide, pot citrate, zinc chloride.
Solution:
• Prepare in Granular form.
• Should not be finely powdered
• Double wrapping
• Humid weather - Further wrapping in plastic paper or
aluminium foil.

30. Efflorescent powders
• Some crystalline substances liberate water of
crystallization on exposure to humid atmosphere or
during trituration and becomes wet or liquefy.
• Caffeine, Citric acid, Ferrous sulphate.
Solution:
• Using corresponding anhydrous salt.
• Use of inert substance by mixing before
incorporating with other ingredients.

31. Eutectic powders
• When two or more substances are mixed together
they liquefy due to the formation of a new compound
which has a lower melting point than RT.
• Menthol, Thymol, Camphor, Aspirin, Phenacetin.
Solution: Two methods
• Dispense as separate set of powders with directions
that one set shall be taken as a dose.
• Use of inert Absorbent like magnesium carbonate and
to be mixed gently.

32. Liquids
• Some times liquid medicaments are to be
incorporated in powders.
• Small quantity – mixed with powder ingredient
in the formula.
• Large quantity – Absorbent
• Liquid extracts and tinctures – evaporated to
concentrated mass, absorbent is added and again
subjected to evaporation.

33. Explosive powders
• When an oxidizing substance like Potassium chlorate
is mixed with reducing substance, such as Tannic acid,
there are chances of violent explosion.
Solution:
• As far a possible such prescription should not be
dispensed.
• Powder each ingredient separately in a mortar and
mix them lightly.
• Powder each ingredient separately and dispense them
in separate powder paper with suitable direction.

34. Potent drugs
• The substances having a maximum dose of less than 60
mg and poisonous substances.
• Small quantities of potent drugs should not be weighed
on dispensing balance.
Solution: Geometric dilution method
• Diluent like Lactose is added to potent drug to make a
weighable quantity.
• Drug is triturated and mixed with equal quantity of
diluent followed by trituration.
• Remaining quantity is incorporated in successive
portions with thorough trituration .

35. Granules
 Granules are aggregations of fine
particles of powders in a mass of
about spherical shape.
 Prepared for the solids which are to
be administered orally in large quantities.
 They cannot be prepared as tablets or capsules because
of large dose.
 Difficult to dispense as such in powder form because of
bitter and nauseous taste.
 Difficult to convert into liquid because of stability
problem.
 The only alternative is to prepare granules.

36. Method of preparation of granules
• Drug is mixed with sweetening agent, coloring
agent and a suitable granulating agent mixed
with suitable solvent is added to get a damp mass.
• Pass through Sieve # 10 to make granules.
• Drying at 60⁰c in Hot air oven and the dried
granules are passed through sieve # 20 and
stored in a dry well closed wide mouthed
container.
• Now a days antibiotics in granules form for
reconstitution.

37. EFFERVESCENT GRANULES
 Effervescent granules are coarse to very coarse powder
containing a medicinal agent in a dry mixture usually
composed of sodium bicarbonate, citric acid and tartaric
acid When added to water the acid and base react to liberate
carbon dioxide resulting in effervescence.
 The resulting carbonated solution mask the undesirable
taste of medicinal agent.
 Effervescent tablets and granules are intended to be
dissolved in water before use.

38. PREPARATION
Effervescent granules are prepared by two general methods.
1. The dry or fusion method
2. The wet method
 The source of binding agent is not water of crystallization
from the citric acid but the water added to the mass of powder
as moistening agent.
 In this method all of powder may be anhydrous as long as
water is added to the moistening agent.
 Just enough liquid is added to prepare a mass of proper
consistency then the granules are prepared and dried.
WET METHOD

39. Heat or fusion method
 In fusion method the one molecule of water present in
each molecule of citric acid acts as the binding agent for
the powder mixture. Before mixing the powder the citric
acid crystals are powdered and then mixed with other
powders of the same size to ensure uniformity of the
mixture.
 After mixing te powder is placed in an oven at 34- 40⁰ c.
3NaHCO3 + C6H8O7.H2O → 4 H2O + 3 CO2 + Na3C6H5O7

40. Heating causes the release of water of
crystallization from the citric acid causing
softening of powder, when it reached the proper
consistency it is removed from the oven and
rubbed through a sieve produced large granules.
Sieve 4 produce large granules, sieve 8 produce
medium size granules and sieve 10 produce small
granules
Dry at 54⁰c and transferred into Air tight
container.