POWDERS AND GRANULES INTRODUCTION

Pharmaceutical powders are solid dosage forms of medicament, in which one or more drugs are
dispensed in a finely divided state, with or without excipients, powders are available in
crystalline or amorphous form and they can be used either internally or externally.

Formulation:
The formulation of powders include
Hygroscopic substances: Ammonium citrate, sodium iodide
Effervescent substances: Caffeine, citric acid, ferrous sulphate
Eutectic substances reducing aids: Menthol, thymol camphor
Diluents: Sucrose, lactose, starch, magnesium carbonate
Processing aids: Effervescent salts, disintegrating salts
Functional aids: Glidant, granulating agents, adsorbents
Organoleptic additives liquids: Fruit juice with sugars or volatile oils
Liquids: Tinctures, volatile flavor oils
Classification:
1. Bulk powder for internal use
2. Bulk powder for external use, e .g. dusting powders and insufflations.
3. Divided powders
1. Bulk powder for internal use: Whenever several powder ingredients are present the powders
are mixed in ascending order of bulk in a mortar. At each addition, a quantity that is
approximately equal the bulk already existed in the mortar is added. Example: Compound
magnesium trisilicate powder
2. Bulk powder for external use: Classification
A. Dusting powder, (a) Medical powder (b) Surgical dusting powder
B. Insufflations
C. Dentifrices (tooth powder)

A (a) Medical dusting powder: These are used for superficial skin conditions. They are not
sterile. They are not applied on open wounds or broken skin. After mixing the powders in a
mortar it passed through a mesh no. 120 to remove gritty particles. Then it is stored in a suitable
container. Example: Starch salicylic acid dusting powder
A (b) Surgical dusting powder: These are used in body cavities and major wounds, on burns
and on the umbilical cords of newborns, hence they must be sterile. They often contain an
antibacterial agent and the diluent may be sterilized maize starch. Example: Chlorhexidine
B.P.C. surgical dusting powder.

B. Insufflations: Finely divided powders intended for application to body cavities such as tooth
socket, ears, nose and throat are known as insufflations. The apparatus is used to deliver a stream
of finely divided powder particles to the site of application is called an insufflator.

C. Dentifrices (tooth powders): Powders used to clean the teeth are called dentifrices. It is
applied with a tooth brush. They contain

x A suitable detergent – hard soap powder

x A suitable abrasive agent – calcium sulfate, magnesium carbonate, dibasic calcium
phosphate
x Sweetening agent – sodium saccharin
x Flavoring agent – peppermint oil, clove oil etc

3. Divided powders: In this form of powder, each dose is separately enclosed in a piece of
paper.
Classification:
x Simple powder: Contains only one ingredient.
x Compound powder: Contains more than one ingredient.
Packing: For wrapping the powders, white glazed paper (demy paper) is generally used. The
powder wrappers are stacked in a paper box and dispensed. Some time double wrapping is
required, especially if the powder is hygroscopic. In this case waxed paper is used as inner
wrapper, then the demy wrapper as the outer wrapper.
Advantages:
¾ Powders are generally more stable than liquid dosage forms because chemical reactions
takes place more slowly in solid form when compared to liquid form
¾ Problems of compatibility are less
 ¾ They can be easily administered to children and old persons who have difficulty in
swallowing formulations like tablets and capsules
¾ Powders are easier to carry and transport
Disadvantages:
¾ Accurate measurement of dose is difficult specially in case of powders
¾ Powders are not a suitable dosage forms for dispensing filter – taste, nauseous and
unpalatable drugs
¾ Preparation and dispensing of powders is more time consuming compared to tablets

Granules are defined as a dosage form composed of dry aggregates of powder particles that may
contain one or more APIs, with or without other ingredients. They may be swallowed as such,
dispersed in food, or dissolved in water. Granules are frequently compacted into tablets or filled
into capsules, with or without additional ingredients. Effervescent granules are popular delivery
systems for many pharmaceutical products such as antacids, analgesics, and cough/cold
formulations. They are fast dissolving, highly soluble, stable, convenient dosage forms. The
granules are added into a glass of water just before administration and the drug solution or
dispersion is to be drunk immediately. The granules are quickly dispersed by internal liberation
of Carbon dioxide in water due to interaction between acid with alkali metal carbonates or
bicarbonates in the presence of water. Due to liberation in Carbon dioxide gas, the dissolution of
the API in water as well as taste masking effect is enhanced.
Formulation: The Effervescent granules are specially prepared solid dosage form usually
contains medicament, acid and base for internal use. E.g. Citric acid, Tartaric acid and Sodium
bicarbonate.
Advantages:
x To prevent segregation of the constituents of powder Mix

x To improve the flow properties of the powder mix

x To improve the compaction characteristics of powder mix

x Granules have higher porosity than powders

x To improve the compressibility of powders

 x Good tasting, sparkling drinks containing ingredients which do not normally taste good in
liquid form.

Limitations of effervescent formulations

x It cannot be given to the children because of possibility of gas (CO2) toxicity.
x If packaging is not done properly then there are chances of degradation by environmental
moisture.
x It has shorter shelf life as compared to other solid dosage forms.
x It requires special machinery requirements for manufacturing.
x This dosage form is costly then tablets.
Preparation of effervescent granules: These granules are prepared by two methods:

A) Fusion method:

• In the 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 powders, the citric acid crystals are powdered and then mixed with the other
powders of the same sieve size to ensure uniformity of the mixture.

• The sieves and the mixing equipment should be made of stainless steel or other material
resistant to the effect of the acids.

• The mixing of the powders is performed as rapidly as is practical, preferably in an environment

of low humidity to avoid absorption of moisture and a premature chemical reaction.

• After mixing, the powder is placed on a suitable dish in an oven at 34°C to 40°C.

• During the heating process, an acid resistant spatula is used to turn the powder.

• The heat releases the water of crystallization from the citric acid, which, in turn, dissolves a
portion of the powder mixture, setting the chemical reaction and consequently releasing some
carbon dioxide.

• This causes the softened mass of powder to become somewhat spongy, and when it has reached
the proper consistency (as bread dough), it is removed from the oven and rubbed through a sieve
to produce granules of the desired size.

• No. 4 sieve produces large granules, No. 8 sieve prepares medium size granules, and No. 10
sieve prepares small granules.
• The granules are dried at a temperature not exceeding 54°C and are immediately placed in
containers and tightly sealed.

B) Wet method:
• The wet method differs from the fusion method in that the source of binding agent is not the
water of crystallization from the citric acid but the water added to alcohol as the moistening
agent, forming the pliable mass for granulation.
• In this method, all of the powders may be anhydrous as long as water is added to the
moistening liquid.
• Just enough liquid is added (in portions) to prepare a mass of proper consistency; then the
granules are prepared by passing the mass into the required sieve and dried.
Dispensing:Weigh require quantity of granules and transfer into narrow mouthed bottle tightly
closed with colored plastic screw cap.
Direction: Add two spoon full of granules, to a glass of water with stirring and drink the
solution.
Storage: Store in a dry place and protect from light.
 17. ORS POWDER
Aim: To prepare the ORS powder
Apparatus: Mortar and pestle, spatula.
Category: Rehydrating salt.
Formula:
S.No Ingredients Official Formula(WHO) for 100 ml of water
1 Sodium chloride 0.26 gm
2 Glucose 1.35 gm
3 Potassium chloride 0.15 gm

4. Tri sodium citrate dihydrate 0.29 gm

Principle: Diarrhoea in children usually gets better on its own, it causes loss of water and salts.
This may lead to dehydration, which can be dangerous, especially in very young children,
because it is difficult to see the signs of dehydration. Your child may be dehydrated if they have
any of the following symptoms fewer like child is urinating less often, they are less active than
normal, a dry mouth, crying without tears, a sunken soft spot on the top of a baby’s head. Oral
rehydration salts do not treat the diarrhoea itself, but they replace the salts and water that are lost,
and so reduce the effects of dehydration.

Procedure: Mix all the ingredients in a mortar and triturated until a fine powder is obtained.
This powder was transferred into white glazed paper (demy paper) and wrapped. Then these
wrapped sachets are kept in a paper box and dispensed. Some time double wrapping is required,
especially if the powder is hygroscopic. In this case waxed paper is used as inner wrapper, then
the demy wrapper as the outer wrapper.
Dispensing: The packed sachets are transferred into wide mouthed bottle tightly closed with
colored plastic screw cap.
Direction: Add one sachet of powder, to a glass of water with stirring and drink the solution.
Storage: Store in a cool and dry place.
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