3. Introduction
2
Powders are the simplest dosage
forms and the basis of many other
solid dosage forms such as tablets,
capsules, etc.
Powders were originally designed as
a convenient mode of administering
hard vegetable drugs such as roots,
barks and woods.
4. 3
DEFINITION:
Powders are intimate mixtures of
dry, finely divided drugs and/or
chemicals that may be intended
for internal or external use (e.g.
external applications to the skin).
5. Advantages of powdersAdvantages of powders
4
Used both internally and externally.
Good chemical stability compared with fluids.
Rapid onset of action.
Easy to swallow even in large bulk, especially if mixed with
drink food.
Easy to carry than the liquid dosage forms.
It is suitable for small children and elderly patients.
Economical.
6. 5
Disadvantages of powdersDisadvantages of powders
Not suitable for drugs unstable in atmospheric
conditions.
Not suitable for bitter, nauseating, deliquescent and
hygroscopic drugs.
The dispensing of powder is a time consuming.
Quantity less than 100 mg or so, cannot be weighed
conveniently on dispensing balance.
7. 6
DRUG POWDER FORMULATION
To obtain powder as raw material from an original drug (animal,
vegetable drugs, or animal or synthetic chemical entities) by
different methods of division.
Mixing of various powders with or without excipients as a
function of the powders’ characteristics (e.g., flow properties).
Packaging of the finished product for an easy patient’s use.
Formulation of powders as dosage forms is performed
according to the following steps:
8. OBTENTION OF POWDERS AS RAW MATERIALS:
1.Coarse division- Reduces lump drugs into fragment of
different sizes.
2.Communition- Reduces the size, gives particle size smaller
than that coarse division.
7
9. 7
OBTENTION OF POWDERS AS RAW MATERIALS:
Coarse division- Reduces lump drugs into fragment of
different sizes.
Communition- Reduces the size, gives particle size smaller
than that coarse division.
Methods and Equipment:
1.COARSE DIVISION
8
12. 11
Powder Characterization:
Particle size:
This parameter influences the dissolution rate of the drug in-
vivo, which in turn influences absorption rate and the onset of
therapeutic activity.
Powders with different particle sizes have different flow and
packing properties, which alter the volume of powders during
each event. To avoid such problems, the particle size of drugs
should be defined during formulation and must be as uniform as
possible.
13. 12
PARTICLE SIZE ANALYSIS
Sieving.
Microscopy.
Sedimentation Rate.
Coulter Counter.
Gas Adsorption.
FLOW PROPERTIES:
Flow properties of powders are important parameters in mixing and
segregation phenomena, essentially during storage.
Flow properties depend on particle size, nature of particles, shape
and moisture content.
14. 13
Flow properties depend on particle size, nature of particles,
shape and moisture content.
It is determined by angle of repose, bulk or tapped density.
The excipients must posses the following properties:
Optimal particle size distribution,
High flowability,
High compressibility,
Optimal capacity for a drug,
15. 14
Physiologically inert,
Resistant to heat, humidity, and oxidation,
Tasteless and odourless.
Some of the excipients are
Magnesium stearate ,
PEG6000,
Calcium stearate ,
Glycerol palmito stearate ,
16. 15
MIXING OF POWDERS
The aim of mixing is to obtain a homogeneous association
of several solid products.
Factors influencing the mixing of powders- nature of surface,
density, particle size, particle shape, particle charge and proportion
of materials.
If these factors are not under control, segregation (demixing) can
occur.
Types of segregation include percolation, trajectory and
densification.
17. 16
METHODS OF POWDER MIXING
Spatulation (spatula + tile)
Trituration (mortar + pestle)
Geometric dilution:
Entire quantity of potent drug (x volume) + (x
volume) of the diluents + (2x volume) of the
diluents + (4x volume) of the diluents………
repeated until all the diluents are used.
Tumbling (wide mouth closed container)
18. 17
Packed in sifter top containers, pressurized containers, flat metal
boxes.
LABELLING:
FOR EXTERNAL USE ONLY
PACKING
19. 18
Bulk powders for external use:
Bulk powders for internal use.
Simple and compound powders for internal use.
Powders enclosed in catchets and capsules.
Compressed powders(tablets).
20. 19
Bulk powders for external use:
1.Dusting powders:
They are meant for external application to the skin and generally
applied in a very fine state of subdivision to avoid local irritation
They are of two types :
(a) Medical :
They are used for superficial skin conditions, they should
not be used for application to open wounds or application or
broken skin.
The label should clearly specify this point. We need not
sterilise the ingredients of these powders but we must be sure that
they are not containing pathogens.
21. 20
(b) Surgical:
These powders must be sterile because they are used
in body cavities and are applied on wounds. They
are sprayed on burnt areas and are placed on the
umbilical cords of infants.
These powders usually contain an antibacterial
agent. The diluent is sterilizable maize starch, which is also
called as absorbable dusting powder.
Function:
Lubricants, protective, adsorbents, antiseptic, astringents.
22. 10
2. SNUFFS:
Definition:
These are finely divided solid dosage
forms of medicaments inhaled into nostrils.
Function:
Decongestion, Antiseptic,
Bronchodilator
Packaging:
Dispensed in flat metal boxes with hinged
21
23. 22
Dental powders are applied with the help of a tooth brush for cleaning
the surface of the teeth.
Dental powders contain detergents, abrasives, antiseptics and colouring
and flavouring agents incorporated in a suitable base.
Base is calcium carbonate. The detergent is in the form of soap and the
abrasive action is provided by finely powdered pumice stone
Essential oils are added to provide flavour and freshness to the mouth as
well as antiseptic action.
3.DENTAL POWDERS:
24. 23
Insufflations are the medicated dusting powders introduced
into body cavities such as ears, nose, throat and vagina
with the help of a device called an insufflator.
It sprays the powder into a stream of finely divided
particles all over the site of application.
25. 24
Powder Dosage Forms are versatile, flexible in dosage
strengths, relatively stable, and also convenient to
manufacture, store, handle and use.
It is possible to reduce them to desired particle size and thus
facilitate rapid absorption. Thus from biopharmaceutical
considerations POWDERS are convenient and useful for
prescribing drugs.
26. 26
25
1.Jean-Mark Aiache and Erick Beyssac, Encyclopedia of Pharmaceutical
Technology, 3rd Edition, volume 5, Powders as Dosage forms, pages 2971-
2982.
2.Loyd V.Allen, Jr., Nicholas G. Popovich and Howard C. Ansel , Ansel’s
Pharmaceutical Dosage Forms & Drug Delivery Systems, Solid Dosage
Forms, pages 186-198.
3. R M Mehta, Dispensing Pharmacy, Solid Dosage Forms, pages 108-124.
C.V.S Subramanyam, J.Thimma Shetty, Sarasija Suresh and V. Kusum
devi,
4. Pharmaceutical Engineering Principles and Practices, Size Reduction,
Mixing, Pages 144-173,199-223
27. 27
26
5.Michael E. Aulton, Aulton’s Pharmaceutics The Design and
Manufacture of Medicines, 3rd edition, Powder and Granules pages
406-409.
6. C.V.S Subrahmanyam, Textbook of Physical Pharmaceutics, 2nd
edition, Micrometrics, pages 181-230.
