2. Content
1) Definition of powders
2) Advantages &disadvantages of powders
3) Types of powder
4) Bulk powder for internal use
5) Bulk powder for external use
6) Powder flow properties
7) Mixing of powder
8) Problems encountered during dispensing of
powders
3. • The term ‘Powder’ may be used to describe:
The physical form of a material, that is, a dry
substance composed of finely divided particles.
• Or, it may be used to describe a type of
pharmaceutical preparation, that is, a medicated
powder intended for:
• Internal (i.e., oral powder) use.
• External (i.e., topical powder) use.
A Pharmaceutical powder is a mixture of finely
divided drugs or chemicals in a dry form that may
be intended for internal (oral powders) or external
(topical or dusting powder) use.
4. Granules are aggregated of powdered
materials to form a larger particle (2-4 mm).
Granules may be used as such (granules of
medicinal value) or in making tablets and
capsules (because of better flowability of
granules compared to powders).
(Very fine particles do not flow as freely as large
particles).
5. Advantages
1. Internal &external use.
2. More stable than liquid.
3. Convenient for the physician.
4. Chances of less incompatibility (more stable ).
5. Onset of action is rapid (Fast dispersion of ingredients).
6. Easy to carry.
7. Large quantity can be administered.
8. Convenient for small child & elderly patient.
9. More economical.
6. Disadvantages
1. Unsuitable for bitter, nauseous & unpleasant taste
drugs.
2. Can’t dispense hygroscopic & deliquescent drugs.
3. Dispensing is time consuming preparation.
4. Can’t dispense volatile drugs.
5. Inaccuracy of dose ( size of measuring spoon,
density of powder, humidity, degree of settling ,
fluffiness).
7. Types of Powders
1) Undivided (Bulk) powders
a.dusting powder
b.effervescent powder
OR
A. Bulk powders for internal use.
B. Bulk powders for external use.
C. Simple & compound powder for internal use.
D. Powder enclosed in cachets & capsule.
E. Compressed powders(tablets)
2) Divided powders
a.packets
b.cachets
c.capsules
8. Bulk Powder For External Use
• Bulk powder for external use supply non potent drug.
• The powder mixture is packed into a suitable bulk
container to facilitate dosing, such as; A wide mouth
glass jar, cardboard, plastic container. Also in sifter top
container.
Types:-.
1. dusting powder
2. Insufflations
3. Dentifrices
sifter top container
9. 1. Dusting Powder:
• These are meant for external application on to the skin and are generally applied in
a very fine state of subdivision to avoid local irritation.
• Dusting Powders are usually dispensed in sifter containers for
convenient application to the skin.
Types:
1. Medical
2. Surgical
1) Medical dusting powders: ( e.g: clortrimazole powder)
q They are used for superficial skin conditions, they should not be used for
application to open wounds or application or broken skin.
q The label should clearly specify this point.
q We do not need to sterilize the ingredients of these powders but we must be sure
that they are not containing pathogens.
2) Surgical dusting powders:
q Uses: - in body cavities, on major wounds as a result of burns and umbilical cords of
infants.
q Surgical dusting powders must be sterilized before their use.
10. Dusting powder Requirements:
1. Homogenous and very fine
2. Free from irritation.
3. Flow easily.
4. Have good covering capacity.
5. Have good adsorptive and absorptive capacity.
6. Spread uniformly over body surface.
7. Cling to skin surface after application.
8. Protect the skin from irritation caused by friction, moisture
and chemical irritants.
11. Examples for powders commonly dispensed in a bulk form
1- Powders used in a dry form
2- Powders to be dissolved in water before use
3- Powders for reconstitution
12. 1- Powders used in a dry form
A- Powders for topical application e.g. antibacterial and
antifungal powders, or non-medicated powders e.g. Talc
powder (protective action).
Dusting powders are applied to various parts of the body as
lubricants, protective, absorbents, antiseptics, antipruritic,
astringents and antiperspirants.
B- Dental cleansing powders (Dentifrices) generally
containing a soap or detergent, mild abrasive and an
anticariogenic agent.
C- Insufflations: They are medicated finely divided powders to
be applied into body cavity, e.g. ear, nose, throat or vagina, by
means of a device known as "insufflator" or a powder blower.
insufflator
13. 2- Powders to be dissolved in water before use
A- Antacids and laxatives (large dose) are used by mixing the
directed amount of powder (usually one teaspoonful) in a
portion of water before swallowing.
B- Dietary/Food supplements
C- Douche powders (e.g. vaginal douche) are dissolved in
warm water before as antiseptics or cleansing agents for a body
cavity application.
- They may be formulated for nasal (nasal wash), Otic or
ophthalmic use.
- It usually dispenses in wide-mouth glass jars or in a sachet.
14. Example on Bulk powders
Talc powder
(Perforated can)
Dental powder Nutritional supplement
15. 3- Powders for reconstitution (important)
A- Oral antibiotic; for stability problems the antibiotic is prepared in a dry form
(powder or granules) and packed in a sealed bottle, a given amount of water is
added before use Once it is reconstituted the patient should be warned of the
short shelf life (usually 1-2 weeks).
B- Powders for injection;
They may be classified as bulk or divided powders. Injections of drugs that are
unstable in solution must be made immediately prior to use and are presented as
sterile powders in ampoules. Sterile water for injection is added from a second
ampoule and the injection is used immediately.
16. 2- Divided powders
• Divided powders are similar formulations to bulk
powders but individual doses are separately wrapped.
• Powders containing potent substances or those that
should be administered in controlled dosage are
supplied to the patient in divided amounts.
• Traditionally papers are used to dispense the divided
powder.
• Hygroscopic and volatile drugs can be protected by using
a waxed paper.
17. Q/ Modern packaging materials of foil and plastic laminates
have placed paper wrapping (WHY?).
Answer/ Because they offer superior protective qualities and are
amenable to use on high speed packaging machines.
- They also may be dispensed in metal foil, small heat-sealed
plastic bags or other containers
Examples:
- Packets, Cachets, Powders for injection
18. Simple powder & compound powder for internal use
1. Simple powder: - contain only one ingredient . E.g
paracetamol powder.
2. Compound powder: - contain two or more than
two substances mix together. (Paracetamol+
Aspirin)
19. Effervescent powders
Formulation:
:
- Bulk powders or divided powders
- Packed in separate packages or dispense in
wide mouth glass jar.
- The contents are mixed in a quantity of water
at the time of dosing.
- The liquid is consumed just after the reaction
begin to subside.
20.
21.
22. Effervescent granules
• Contain sodium bicarbonate and either citric acid, tartaric
acid or sodium biphosphate in addition to the active
ingredients.
• On solution in water, carbon dioxide is released as a result
of the acid-base reaction. The effervescence from the
release of the carbon dioxide serves to mask the taste of
salty or bitter medications.
* The completed product must be dispensed in tightly
closed glass containers to protect it against the humidity
of the air.
23. Why a combination of tartaric acid and
citric acid is used as an effervescent base
rather than either acid alone?
24.
25. Powder flow properties
• Pharmaceutical powders may be classified as
free-flowing or cohesive (non-free-flowing).
Flow properties are significantly affected by changes
in :
- particle size, density, shape, electrostatic charge,
and adsorbed moisture, which may arise from
processing or formulation.
Techniques of powder flow measurements :
1. Carr`s index 2.Angle of repose 3.Hausner`s ratio
26. Factors affecting Powder Flowability:
1- Particle size: Frictional and cohesive forces
(resistance to flow) are increased as the particle
size is reduced .
27. 2- Density and porosity: - Particles with high density
and low porosity tend to posses free flowing
properties.
3- Particle shape: Rough irregular particles presents
more points of contact than smooth spherical particles
thus Spherical particles flow better than needles.
4. Particle size distribution: Larger amount of fines can
inhibit poor flowing.
5- Moisture content: Drying the powders will reduce the
cohesiveness.
28. Preparation of powders
1- Reduction of particle size of all ingredients to
the same range to prevent stratification (separation
of the large and small particles)
2- Sieving
3- Weighing each ingredient
4- Mixing
5- Packaging
29. Mixing(blending) of Powders
Importance:
1. Ensure uniform distribution of the active component(s)
2. Ensure a good appearance of the dosage form.
3. Ensure that the dosage form releases the drug at the
correct site and at the desired rate.
- Blending is used when two or more substances are to
be combined to form a uniform powder mixture.
- Depending upon the nature of the ingredients and the
amount of powder to be prepared, mixing may be by
Spatulation, trituration, Levigation, or tumbling
30. Small-Scale Mixing Equipment
1- Spatulation
The blending of powders with a spatula (movement through
the powder) on a tile or paper sheet used sometimes for
small quantities or when the mortar and pestle technique is
undesirable.
It is not suitable for large quantities of powders or for
powders containing one or more potent substance.
31. 2- Trituration
This method is used to comminute ( reduce particle size)
& to mix powders.
- A porcelain preferred than glass mortar.
- A glass mortar is preferable for chemicals that stain a
porcelain. When granular or crystalline materials are to
be incorporated into powdered product ,these materials
are comminuted individually and then blended together
in the mortar.
32.
33. 3- Levigation
In this process:
A- paste is first formed by the addition of a suitable non-
solvent to the solid material.
B-Particle-size reduction then accomplished by rubbing the
paste in a mortar with a pestle or on an ointment’ slab
using a spatula.
C- This technique is used to incorporate solids into ointment
and suspension
34. Powders may also be mixed by passing them through
sifters.
This process results in a light fluffy product.
This process is not acceptable
for the incorporation of
potent drugs into a diluent base.
4. Sifting
35. 4- Tumbling (Large-Scale Mixing Equipment)
The ideal mixer should:
1- produces a complete blend rapidly to avoid product damage.
2- It should be cleaned and discharged easily
3- be dust-tight .
4- requires low maintenance and low power consumption.
- The powder enclosed in a large container which rotates
generally by a motorized process.
- Such blenders are widely employed in industry to blend large
amounts of powders
36. Problems encountered in powder formulation
1-Hygroscopic and Deliquescent Powder
Problem:
Absorption of moisture from air leading to partial or complete liquefaction.
Solution:
1) Applied in a granular form to decrease the exposed surface to air.
2) Packed in aluminum foil or in plastic film packets
3) Addition of light magnesium oxide to reduce the tendency to damp
4) Addition of adsorbent materials such as starch
37. 2- Efflorescent powders
Problem:
Crystalline substances which during storage loose their water of crystallization and
change to powder (to be efflorescent).
The liberated water convert the powder to a paste or to a liquid.
Examples:
atropine sulfate, citric acid, codeine phosphate
Solution:
1. Using the anhydrous form,
2. Treat similar to hygroscopic powders.
38. 3- Eutectic Mixtures
Problem: mixture of substances that liquefy when mixed, rubbed or triturated
together. The melting points of many eutectic mixtures are below room
temperature.
Examples: menthol, thymol, phenol, salol, camphor
Solution:
1. Using inert adsorbent such as starch, talc, lactose to prevent
dampness of the powder.
2. Dispensing the components of the eutectic mixture separately.
39. 4- Incorporation of Liquids:
Liquids may be incorporated into divided powders.
Solution:
The liquid is triturated with an equal weight of the powder and the remaining
powder is added in several portions with trituration.
vMagnesium carbonate, starch or lactose may be added
to increase the absorbability of the powders if necessary.
vWhen the liquid is a solvent for a nonvolatile heat-stable
compound, it may be evaporated gently on a water bath.
• Lactose may be added during the evaporation to increase the
rate of solvent loss by increasing the surface area.
• Some extracts and tinctures may be treated in this manner,
although the use of an equivalent amount of a powdered extract is
a more desirable technique.
40. 5- Potent Drug
Problem:
Limited precision and accuracy of the used balances to weight small
amounts of potent drugs.
Solution:
Drug triturates:
1) Suitable diluents like lactose are mixed with the potent drug to
form 10 - 20%w/w drug triturates.
2) Geometric dilution to prepare drug triturates
41. The loss of camphor, menthol and essential
oils by volatilization when incorporated into
powders may be prevented or retarded by use
of heat-sealed plastic bags or by double
wrapping with a waxed or glassine paper
inside a bond paper.
6. Volatile Substances
42. Packaging of Powders
Depending upon their use, powders are
packaged and dispensed as follow:
ØBulk powder: Packed in to wide-mouth glass
jar , plastic container or cardboard.
ØDivided powders. Packed into sachet, cachet
and capsule.
