Compaction Flashcards
What are the benefits of direct compression over tableting with granulation
Less stages. Less input of energy and manual labour
What are the disadvantages of direct compression compared to tableting with granulation
Needs more excipients in mixing stage. Potentially more expensive
Components of tableting machine
upper punch, lower punch and die cavity
3 stages of tableting
filling, compressing, ejecting
Filling Stage Outline
Die cavity filled with standard powder volume by a hopper (due to gravitational forces)
Compression Stage Outline
Upper punch descends (lower punch ascends or remains stationary). Powder volume decreases when pressed between 2 punches. After compression recahes programmed force the upper punch ascends (lower descends or remains stationary).
Ejection Stages
Lower punch ascends to equal level of rest of belt. Tablet is pushed away
2 types of tablet press
Single punch and rotary
Single Tablet Press Outline
Single pair of punches and dye. Lower punch positioning dictates powder volume. Upper punch controls tableting pressure. Low volume, used in academia
Rotary Press Outline
Multiple sets of presses and dyes that rotate while the machine is in operation. Both punches move during compression. Force feeders ensure reproducible filling. Used in manufacturing. Can be automated, has high output and is easily monitored
Factors Effecting Tablet Press Compression
Tablet press speed, dwell time, tablet press maintenance and powder quality
Relationship between tablet press speed and quality of tablet
faster press = less time for cavity filling = lower tablet mass uniformity. Need to alter weight adjustment cam and feeder speed
Dwell time Def
Time that a set of punches are held under pressure by tablet rollers
Relationship between dwell time and quality of tablet
Increased dwell time = greater chance of powder reaching plastic elasticity (viscoelastic properties) = greater tablet strength
Tablet Press Maintenance Outline
Wear and tare of punches, cams, blades and other components. Regular maintenance and quality standard is important
Powder Properties Outline
Powder flowability and compressibility are important cond=siderations
Tablet Tooling Importance to Final Product
Dictates appearance: shape (oblong, circular, flat or convex), embossed/debossed and sizes
Debossed Def
Tablet contains engravings (markings are below tablet surface level). less commonly used as it has worse friability
Embossed Def
Tablet markings are above surface level. More commonly used as it has better friability
Tableting Technical Problems Outline
High weight/dose variation, low tablet mechanical strength, tablet capping/lamination, tablet adherence to machinary, mottling and tablet-machine friction
Result of high weight/dose variablility
May result in powder segragation = decraese in dose uniformity
Result of powder adhering to machine
Decrease in tablet uniformity
Mottling Def
Solid migration in drying
Powder Properties Problems Outline
Adherence properties, compaction properties, flowability and segragation tendency
Capping Outline
Partial/ complete separation of top and/or bottom of tablet on ejection
Lamination Outline
Separating of tablet into 2 or more layers
Capping and Lamination Causes
Inadequate binder, over drying of granuales, elastic deformation, air entrapment, concave tools and rapid speed of press
