Granulation Flashcards
What is trajectory segregation?
When larger particles travel greater horizontal distances than smaller particles
What is Elutriation segregation?
When very small particles sediment on top of the larger particles
What is percolation segregation?
Smaller particles drop to the bottom of the powder bed (as in hopper where movement of particles can take place)
Dense particles have the tendency to move to the bottom. TRUE OR FALSE?
TRUE
Dense particles have greater mass than less dense particles. TRUE OR FALSE?
TRUE
What are the reasons for granulation?
- To help improve powder flow (increase particle size)
- Help provide a uniform mix of powders
- To increase density of the powder mix
- To reduce risks of dust generation
What are the reasons for granulation?
- To help improve powder flow (increase particle size)
- Help provide a uniform mix of powders
- To increase density of the powder mix
- To reduce risks of dust generation
- Reduce risk of caking of hygroscopic powder
- As a dosage form
- As an intermediate for tableting
- Help compaction of powder mix
- Aid wetting of particles
What are the factors you need to consider with granulation?
- Mixing of powder granule formation
- Segregation of constituents after mixing
- Segregation of constituents after granule formation
- Size distribution of granules
- Tabletting and capsulation
- Accurate proportions of active ingredients and excipients
What components does a granulating fluids have?
- Solvent e.g water
- needs to compatible
- nees to be non toxic
- needs to be removable by drying
What is a binder used for?
-To help particles to adhere together after drying
What are the different states formed during wet granulation?
- Pendular state
- Funicular state
- Capillary state
- Droplet state
What occurs in Pendular state?
- Low liquid levels, discrete liquid bridges at points of contact between particles
- Assumption that there is a uniform distribution of liquid throughout powder bed
What occurs in Funicular state?
- Further liquid content, pendular bonds coalesce and liquid bridges form between non-touching points
- Dependant on degree of liquid saturation, usually 25-80%
What occurs in Capillary state?
- Liquid saturation is greater than 80%
- Granule becomes paste like and unsuitable for wet sieving
- Tensile strength of granule increases by 3 between pendular and capillary state
What is the nature and extent of liquid bridges dependant on?
-The amount of liquid added and method of wet massing
How many stages occur in bridge formation?
4
Agglomerates constantly formed and destroyed? TRUE OR FALSE?
TRUE
In dry method particle adhesion takes place due to pressure. TRUE OR FALSE?
TRUE
In wet granulation particles adhere because of liquid. TRUE OR FALSE?
TRUE
What are the three phases of agglomeration?
- Nucleation
- Transition
- Ball growth
What occurs in Nucleation?
- Partcle-particle contact and formation of liquid bridges
- Further agitation densifies pendular state which acts as a nuclei for further granule growth
What occurs in Transition?
- Nuclei can grow by single particles added via pendular bridges or wto or more nuclei can combine
- Wide size distribution exhibited
What is Ball growth?
- Further granule growth produces large spherical granules with size increasing over time
- Aggitation stopped (which would promote further coalescence making over massed particles)
Pressures used in dry granulation may cause melting of low melting point materials. TRUE OR FALSE?
TRUE
What method is used to help bond particles together when pressure is relieved?
Crystallisation
Binders used in granulating fluid hardern or crystallise on drying. TRUE OR FALSE?
TRUE
Give examples of hardening binders
synthetic polymers and pre-gelatinised starch
Slower drying times result in larger crystals. TRUR OR FALSE?
TRUE
What are the advantages of wet granulation?
- Reduced segregation of formulation components during storage/processing
- useful for formualtion of tablets with low active ingredients concentration
- uses conventional excipients
- can be post-processed (tablet coating)
What are the disadvantages of wet granulation?
- Several processing steps needed
- Solvents used in process lead to concerns e.g stability of drugs, toxicology of formulation
Dry granulation is suitable for what types of formulation?
- When product is moisture sensitive
- When drug is heat sensitive
- When there is poor compression exhibited after wet granulation
What is slugging?
-Process used to compress dry powders into a large oversized tablet
In slugging, binder can be used to improve bonding strength in compaction. TRUE OR FALSE?
TRUE
In slugging, disintergrants can be used as excipients and labricant can be added to prevent compacts sticking to the punches and die. TRUE OR FALSE?
TRUE
In slugging, disintergrants can be used as excipients and lubricant can be added to prevent compacts sticking to the punches and die. TRUE OR FALSE?
TRUE
Roller compaction requires less lubricant than for slugging. TRUR OR FALSE?
TRUE
Give examples of excipients used in roller compaction?
- Diluent - bulks up powder mix
- Disintergrant - to break up granule/tablet in solution
- Binders- binds constituents together
- Lubricant- e.g stearates
- Glidant - anti-adherent properties
What are the advantages for dry granulation?
- Both roller compaction and slugging require conventional excipients
- Methods not commonly associated with degradation/ alteration of drug method during processing
- No heat or solvents required
What are the disadvantages of dry granulation?
-Roller compaction requires specialist equipment
-segregation of components may occur post processing
may be issues regarding powder flow
-Final tablets usually softer than with wet granulation
Give example sof granulating agents
- HPMC
- MC
- ACACIA
- PVP
- PRE-GELATINISED STARCH
What is spheronisation?
-Form of granulation which forms unform sized spherical pellets
when is spheronisation used?
-when spheres required as dosage form
spheronisation is more labour intensive than other forms of granulation. TRUE OR FALSE?
TRUE
Wet massing is important to produce good quality speheres. TRUE OR FALSE?
TRUE
What are the stages of spheronisation?
Mixing - Wet massing - Extrusion - Spheronisation - Drying - Screening
Water level is not critical for optmising the spheronisation process. TRUE OR FALSE?
FALSE
