Powders are intimate mixtures of finely divided drugs and chemicals that can be used internally or externally. Powders have advantages like flexibility, stability, rapid action, but also have disadvantages like inaccuracy in dosage. Powders are classified based on use, dispensing method, and particle size. Manufacturing involves size reduction, mixing, packaging, and ensuring uniform particle size and distribution. Traditional Ayurvedic texts also describe powder classifications and manufacturing methods.

1. Solid dosage forms:
Powders
K.J.KARTHIKA, 2ND YEAR P.G.SCHOLAR,
DEPARTMENT OF RASASHASTRA NAD BHAISHAJYA KALPANA
GAVC,TRIPUNITHURA

2. Contents
1. Definition
2. Advantages and disadvantages of powder dosage form
3. Classification of powders
4. Pharmaceutical technology used in the manufacturing of powders.
- Size reduction
- Particle size determination
- Mixing
- Sampling
- Packing
5. Segregation
6. Granules

3. Introduction
Powders were originally designed as a convenient mode of
administering hard vegetable drugs such as roots, barks, and woods.
Powders were also found to be convenient for dispensing insoluble
chemicals such as calomel, bismuth salts, mercury, and chalk.
In Ayurveda powder dosage forms are considered as a separate
entity under the heading of churna kalpana

4. Definition
•Powders are intimate mixtures of dry, finely divided drugs and /or
chemicals that may be intended for internal or external use.
•Powder is a mixture of finely divided drugs and/or chemicals in dry
form.

5. अत्यन्तशुष्कं यद्द्रव्यं सुपिष्टं वस्त्रगालितम्।
तत्स्त्याच्चूर्णं रज: क्षोदस्त्तन्मारा कर्षसंलमता॥
(शा.म.६/१)
Classical definition

6. Advantages of powders
•Flexibility of compounding- easy to prepare.
•Good chemical stability.
•Rapid dissolution due to small particle size
•Fast action and better bio availability.
•The availability of new filler exipients that can act as ideal drug
carriers.
•Can be consumed easily by patients with swallowing difficulties.

7. Disadvantage of powders
•Time consuming.
•Inaccuracy in dosage.
•Unsuitable for many due to unpleasant taste, volatile, oxidizing,
hygroscopic and deliquescent drugs.

8. Classification of powders.
Based on
use
external
internal
Based on
dispensing
Bulk
powders
Divided
powders
Based on
particle size
Very coarse
Coarse
Moderately
coarse
Fine
Very fine

9. Powders for external use
•Dusting Powders
- Locally applied nontoxic preparations.
- No systemic effect.
- Applied as lubricants, protectives, absorbents, antiseptics,
anti pruritics, astringents and anti-perspirants).
They are of 2 types viz:-
•Medical:
for superficial skin condition and which should not be used
in open wounds or broken skin.
•Surgical:
They are sterile and used inside body cavities.

10. •Dentifrices
Agents used along with a tooth brush to clean and
polish teeth.
• Douche powders
Intended to be dissolved in water and to use as
antiseptic or cleansing agent for a body cavity.

11. Powders for internal use
•Insufflations: powders applied as a stream of finely divided particles into the body
cavities such as ear, nose, throat , vagina with the help of a device known as
insufflators.
• oral powders

12. Extending the classification to
Ayurveda
Churna for external use :
•32 churna pradeha by charaka
•Mukahalepam
•Churna anjanam
•Churna for udvartnam, utsadanam, avachurnanam, avagundanam,
mukha dharanam, pratisaranam, etc.

13. Churna for internal administration
•Churna nasyam
•Oraly administered churnam
•Churna basti prayogam
•Suchikabharana rasa prayoga

14. Bulk Powders :
•They are dispensed in bulk containers .
•A perforated or sifter can is used for external dusting and an aerosol
container is used for dusting onto skin.
•A widely mouthed Glass jars easily permit removal of a spoonful of
powder e.g, antacid, laxatives, douche powders, etc

15. •The triphala churna, jadamayadi churna, kottam chukkadi,
kolakulathadi churna, rasnadi chura etc can be considered as bulk
powders.
•Most of the Kashaya churnam and Churnas used for dhoopanam,
prakiranam, snanam, udvarthanam, utsadanam,etc can also be
included in this category.

16. Divided Powders:
•Dispensed in individual doses, usually in folded papers, metal foil;
small heat sealed or resealable plastic bags or other containers.
•After the ingredients are weighed, comminuted, and mixed, the
powders must be accurately divided into the prescribed number of
doses.

17. •Depending on the potency of the drug substance the pharmacist
decides whether to weigh each portion separately before packing or to
approximate portions by the block and divide method. (after geometric
dilution packing powder to individual unit)
•The various kupipakvarasayanas, bhasma, kshara, lavana,etc can be
included among the divided powders)

18. Based on particle size:
(Particle size are related to passing through the openings of
standard sieves)
coarse particle 10 mm
Colloidal particles 1 micro meter
Very coarse Sieve No:8
Coarse “ 20
Moderately coarse “ 40
Fine “ 60
Very fine “ 80

19. Various types of sieves were employed to prepare churnas of different
particle size.
•Stuladravya galana – chalini made of venu and shalaka
•Churna chalana – vamshaja chalani
•sukshmataram raja – chalani with frame made of karnikaram,
shalmali,etc covered with chaga charma and mesh made of vaji baala.

20. Pharmaceutical technology involved in the
manufacturing of powders.
•Size reduction(Coarse division/Comminution of Drugs)
•Sieving
•Weighing of each ingredient.
•Blending of powders.
•Packaging of finished product.

21. The definition of churna as per Sharangadhara Samhitha clearly
mention simillar aspects.
-size reduction by pounding
-Sieving by the aid of a cloth
The other 3 criteria are followed while preparation of multi drug
formulation like hinguvachadi, ashta churnam etc.

22. Step 1
Size reduction
Coarse division
Trituration
Mills and
pulverizes
Levigation
Pulverization by
intervention
Attrition
Crushing
Cutting
Comminution

23. Coarse division
reduces lumps of drugs into fragments of different sizes
•Cutting
Obtaining coarse fragments eg. Using blades.
•Crushing
Division of coarse fragments eg. Using mortar and pestle
•Attrition
Breaking down a substance by rubbing two surfaces together.

24. Comminution of drugs
•Trituration: Grinding with mortar and pestle mostly for small scale mixing.
•The efficiency of grinding or mixing operation depends on the maximum contact
between the surfaces of head of the pestle and mortar.
If Comminution is desired, a porcelain or ceramic mortar with a rough inner
surface is preferred to a glass mortar with a smooth working surface.

25. Mills and pulverizes

26. •Levigation:
- A paste is formed by combining powders and small amount of liquid (levigating
agent) in which the powder is insoluble.
- The levigated paste may be mixed well with base with the help of spatula and a
tile. Mineral oil and glycerin are generally used as levigating agent.
•Pulverizationby intervention:
- Size reduction using a solvent which is removed after size reduction. Suitable for
resins and gummy substances E.g., camphor.

27. - Ayurveda employs methods of coarse division and comminution according to the
purpose of powders.
- level of Comminution required for specific purposes are mentioned in the
following manner.
•Yavakuta churna (kwatha preparation)
•Pahala rajatulya churna ( ghreya vamana)
•Anjana sadrusha churna ( Ayaskruthi)
•Sukshma churna/Susukshmam churnam/Slakshna churna/ rekhapurna churna
(indicating fine powder for pradhamana, anjana, visha chikitsa, bhasma,etc)
The stardardization of such comparison are yet to be done.

28. 2.Particle size determination
•Sieving method:
The particles are passed on through a series of sieves, the portion of the particles
passing through or being with held on each sieve is determined.
•Microscopy:
Sample particles are sized through the use of calibrated grid background.
•Sedimentationrate:
Particle size determined by the terminal settling velocity of particles through the
liquid medium.

29. •Light energy diffraction:
By the use of laser rays the particle size is determined.
•Coulter Counter:
It determines the volume distribution of the particles suspended in an electrolyte
containing solution.
When a particle passes through a small orifice , it blocks the electric current, The
impedance is directly proportional to the particle volume .
It is used for calculating particle size assuming it a spherical shape.

30. •Gas Adsorption
-The surface area of powdered materials can be measured by adsorption of solute
from solution or of a gas.
-This method results in the specific surface area (area/unit mass).
-Usually, an inert gas, such as nitrogen, is adsorbed as a monolayer and the total
volume of gas adsorbed is used to calculate the specific surface area, which in turn
provides information on the particle size.

31. The particle size determination in Ayurveda can be seen in the following
context.
•Rekha purnata ( bhasma pariksha)
•Usage of chalani

32. Influence of Particle size on various factors
•Dissolution rateof the particles : Dissolution increase with decreased particle size.
•Suspendibility of the particles (Fine dispersion 0.5 to 10 micro meter)
•Uniformity in the distribution of drug substances so as to ensure dose to dose
content uniformity.

33. •Penetrability of drug particles.(aerosols 1-5 micro metre)
•Lack of grittiness of solid particles when used in ointments and creams.(fine
powders of 50 to 100micro meter may be used)

34. 3.Mixing of powders
•To obtain homogenous association of several solid particles

35. MIXING
MECHANISM
METHODS
DIFFUSION
CONVECTION
SHEAR
TUMBLING
SIFTING
GEOMETRICDILUTION
TRITURITION
SPATULATION

36. Mechanism
• Diffusion - redistribution of particles by random vertical or horizontal
motion
V-Blender (Twin Shell),(Tumble) Double Cone Blender, Bin Blender
• Convection- transfer from one location to another
Eg.,Ribbon Blender, planetary blender, horizontal and vertical high intensity
blender.
• Shear - formation of slip planes
– Motion imparted by high intensity mixers as in fluid beds

37. Methods for Blending or mixing of powders
•Spatulation:
- Mixing is done using a spatula and tile or sheet.
- for mixing small quantities.
- Useful for eutectic mixtures (i.e mixtures that melt at a lower temperature than
any of their ingredients when in closed prolonged contact with one another)
- It is not suitable for potent drugs.
-drawback:Lackof homogenousmixing.
•Triturition:
- It is used to comminute and to mix powders. Eg,
A glass mortar is preferable for chemicals that stain a porcelain or ceramic
surfaces as well as for simple admixture of substances without need for
Comminution.

38. •Geometricdilution:
-used when potent substances must be mixed with a large amount of diluents.
-The potent drug and an approximately equal volume of diluent are placed in a
mortar and thoroughly mixed by trituration.
A second portion of the diluent, equal in volume to the powder mixture in the
mortar is added, and trituration is repeated. The process is continued; equal
volumes of diluents are added to the powder mixture in the mortar until all the
diluents is incorporated.

39. •Sifting:
-Powders are mixed by passing them through sifters similar to those used to sift
flour.
-This process results in light fluffy product.
- not usually acceptable for incorporating potent drugs into a diluents base.
-Usually employed as a pre or post mixing method to reduce loosely held
agglomerates and to increase the overall effectiveness of blending process.
•Tumbling:
- It is the process of mixing powders in a large container rotated by a motorized
process.
- widely used in industry, as are large volume powder mixers that use motorized
blades to blend the powder in a large mixing vessel.

40. Factors influencing mixing/ Blending
•Blender Volume
•Blend times for pharmaceuticals: typically 10-20 minutes.
•Nature of material: particle size, shape, charge and proportion.

41. The ideal mixer should :-
•produce a complete blend rapidly to avoid product damage.
•Should be cleaned and discharged easily.
•Dust tight
•Low maintenance and power consumption.

43. Characteristics for an ideal bulk excipient:-
•Excellent flowability
•High physical stability
•Content uniformity.
•Specific morphology to prevent segregation.
•Chemical stability
•Low hygroscopicity
•Pleasant taste
•Suitability for all patients
•Economical to manufacture
•Directly compressible
Eg for exipients are : Magnesium stearate, PEG6000, Calcium stearate, etc

44. -The modern pharmacy has incorporated expients to increase the bulk of powders
as well as to render a target specific action for the same.
-In Ayurveda we have incorporated anupanam to render target specific drug
action.
यथा तैिं जिे क्षक्षप्तं क्षर्णेनेवप्रसिषतत।
अनुिानं बिादङ्गे तथा सिषतत भेर्जम्॥(श.म.४-५)
Just as oil spreads quickly on water so also medicines spread inside the body by
the strength of the vehicle.

45. 4,Sampling:
-To check the blend uniformity.
-Samples are collected from various portions of the blenders and then they are
analyzed to assess the uniformity of blending.
- Usually HPTLC analysis is done to screen the samples.

46. Sampling locations in blenders

47. 5. Packaging of Powders.
Papers use to pack powders
The four basic types of papers used are:-
•Vegetable parchment: a thin, semi opaque moisture resistant paper.
•White bond : opaque , no moisture resistant properties.
•Glassine: Glazed transparent and moisture resistant.
•Waxed paper: Transparent and water proof.
- e.g., The hygroscopic and volatile drugs are best protected with waxed paper
that is double wrapped with bond paper to improve the appearance.

48. GLASSINEWAX PAPERVEGETABLE PARCHMENT
BOND PAPER

49. •Glass jars are preferred for hygroscopic, deliquescent or volatile powders than
paste board containers.
•Amber or green glass for light sensitive components. They must be kept tightly
closed.
•Products for external use must be labeled indicating “external use only”.

50. Pouch packingwith machines is widely accepted in industries

51. In Classics, storage of finished products can be done in containers of:-
-Venu
-Vriksha
-Sringa
-Danta
- shankha
-,kacha
-Mrut
.

52. Segregation(Demixing of
components)
• Occurs during blending, transport, storage or discharge.
• Greater with free-flowing powders since they can separate easily (based on
size, shape, and density)
• Overcome by
– Minimizing physical differences
– Increasing cohesiveness of formulation
– Optimizing blending conditions.

53. Special problems associated with packing of powders
•Volatile substances :volatilization prevented by using heat sealed plastic bags or
double wrapping with glassine or waxed paper inside white bond.
•When liquids are incorporated into divided powder then Magnesium carbonate,
starch, or lactose can be added to increase the absorbability of the powders by
increasing the surface area.
•When the liquid is a solvent for nonvolatile heat stable compound,It is evaporated
gently in a water bath. Some fluid extracts and tinctures are treated in this way.

54. •Hygroscopicand deliquescent substances:
-They can be prepared as divided powders by adding inert diluents/ absorbents.
-Double wrapping is desirable.
- They are mostly prepared as granules to minimize the surface area.
•Eutectic mixtures:
-use of inert diluents/ absorbent like magnesium carbonate, kaolin, starch, lactose,
light magnesium oxide.
- They can be dispensed as separate sets of powders and labeled with suitable
direction.

55. •Efflorescent substances: (Crystalline substance liberates water of crystallization
due to change in humidity) caffeine, sodium carbonate, sodium phosphates etc.
They must be incorporated as anhydrous salts
•When oxidizing and reducing agents are mixed together in a mortar there are
chances of explosion.eg. Potassium chlorate and tannic acid. They must be
separately powdered and dispensed.

56. Granules
-Agglomerates of powders
-Used as such as a dosage form or to prepare tablets. Eg, effervescent granules
mask the unpleasant taste of drugs.
- They fall within 4-12 sieve size.Those passing through 12 to 20 sieve are used for
tablet making
Advantages of granules over powders.
•Free flowing
•More stable
•Better dose measurements
•Used in the manufacture of tablets and capsules.

57. Granules are prepared by
•Dry method:
Powder passed through a roller compactor and granulated in a granulator.
•Wet method:
Moisten the powder or mixture and pass through desired sieve.

58. THANKYOU