3/5 powders and granules: dalia

what is the structure of powders?

solid material in finely divided state

what is the structure of granules?

powders agglomerated to produce larger free flowing particles

what are the advantages of powdered and granulated products?

• more chemically stable than liquid ones (longer shelf life)

• faster dissolution rate than tablets or capsules as these must first disintegrate before the drug dissolves

• drugs with a large dose are dispensed in them

what are the disadvantages of powders/granules?

1. less convenient to be carried than tablets or capsules

2. masking of unpleasant tastes is difficult

3. not suitable for potent drugs with a low dose

4. not suitable for drugs which are inactivated in, or cause damage to the stomach

what is the solution to the disadvantage “less convenient to be carried than tablets or capsules”?

modern packaging methods as heat-sealable laminated sachets

what is the solution to the disadvantage “masking of unpleasant tastes is difficult”?

formulation as taste-masked effervescent product

what is the solution to the disadvantage “not suitable for potent drugs with a low dose”?

divided preparations used for more potent drugs

what is the solution to the disadvantage “not suitable for drugs which are inactivated in, or cause damage to, the stomach”?

formulation as enteric-coated tablets

what are the different powder and granule products that can be dispensed?

• insufflations for administration to ear, nose or throat

• antibiotic syrups to be reconstituted before use

• powders for reconstitution into injection

• undivided powders

• divided powders

what are the advantages to granulation?

• prevent segregation

• improve flow properties

• control the rate of the drug release

• reduce toxic dust that may arise during handling powders

• improve compaction characteristics for tablets

• improve the appearance of the tablet

what are the 3 methods of granulation?

1. wet granulation

2. dry granulation

3. melt granulation

what are the advantages of wet granulation?

• reduce air entrapment

• prevent segregation and separation of particles

• used for high dose drugs with weak compressibility

• improvement of compressibility and flowability of the powder

• used for small dose drugs to avoid non-uniformity of mixing

• uniform color distribution, but in direct compression, there is no uniform distribution of the color

what are the disadvantages of wet granulation?

• increase the incompatibility between ingredients

• time consuming especially the wetting and drying steps

• not used with heat and/or moisture - sensitive material

• high cost

• requires large area with temperature and humidity control

• material loss due to the transfer of materials from one unit operation to another

• migration of color

• decrease of dissolution of drugs

what are the advantages of dry granulation?

• used conventional excipients

• uses less equipment and space

• improves the solubility of materials

• no migration of active ingredients or colors

• used for heat sensitive and/or moisture sensitive material

• improves the disintegration of tablet

• no need for binder solution, heavy mixing equipment and time-consuming drying step

• used for preparing effervescent tablets, since the dried acid and alkali remain fully dry until the tablet is immersed in water when used

what are the disadvantages of dry granulation?

• produces softer tablets

• more dust contamination

• segregation of powder post mixing

• it does not permit uniform color distribution

• it requires a specialized heavy-duty tablet press to form slug

melt granulation is granulation by what?

fusion

what is melt granulation used in?

preparation of effervescent granules