(6) Pharmaceutical Engineering 1 + 2 + 3 Flashcards
(21 cards)
list methods used to reduce particle size.
- cutting methods
- compression methods
- impact methods
- combination impact and attrition
outline combination impact and attrition in size reduction
(High pressure homogeniser)
• Sample forced to pass through a very small gap at
high pressures (500-2500 bar)
• Impact and attrition lead to micro/nanonisation
• The sample can recirculate to the homogenisation
chamber
Outline combination impact and attrition method in size reduction
(Media mill)
• Small beads (0.1 – 5 mm) are the milling
media
• Impact and attrition lead to micro/nanonisation
• The sample recirculates to the milling chamber
outline cutting method of size reduction.
• Consists of a series of knives attached to a horizontal rotor
• Knives act against a series of stationary knives attached to the mill casing.
• Size reduction occurs by fracture of particles between the
two sets of knives, which have a clearance of a few millimetres.
• A screen is fitted in the base of the mill casing; thus it is self-classifying.
outline cutting methods in size reduction/
• Consists of a series of knives attached to a horizontal
rotor
• Size reduction occurs by fracture of particles between the
two sets of knives, which have a clearance of a few
millimetres.
outline direct compression.
steps involved are:
• Mixing of excipients and drug (planetary bowl/rotating drum/high- speed)
• Compression of powders into tablet
outline dry granulation.
• Involves production and subsequent compression of granules into final dosage form
• No solvent is required
• Two principle methods
1. Slugging - double compression technique, mix drugs, form large tablet, mill, compress
2. Roller Compaction - mix drugs, compress powder between two rollers, mill the ribbon produced, compress into tablets
outline wet granulation.
particles interact to form aggregates
Two primary stages involved:
- Particle-particle interactions facilitated by formation of liquid bridges
- Particle-particle interactions facilitated by formation of solid bridges.
outline why particle-particle interactions occur during drug granulation.
- Electrostatic forces - Play a role in initial cohesive
interactions but not so in granule strength. - Van der Waals interactions - major role and increase in
magnitude as particle distance decreases - Melting of components - Granules exposed to high
shear rates that may result in partial melting. Upon cooling
(solidification) increased interactions between adjacent
particles occur
what 3 factors contribute to an improved bioavailability?
- Increased dissolution rate
- Increased saturation concentration
- Enhanced bioadhesion
what are the different ways that wet granulation can be carried out?
• Blending & Oscillating Granulator
• High Speed Mixer/Granulator
• Fluidised Bed Granulatior
• Extrusion Granulator
what benefits do milling bring about?
• Improved Drug Dissolution
• Uniformity of Dosage Forms
• Enhanced Mixing and Homogenization
• Tailoring Drug Release Profiles
• Micro and Nanosizing
• Reduced Agglomeration
what do powders need to have to be mixed? How do we get this?
powders need to have the same particle size, this is done via milling
what does milling aim to do?
• It allows the manipulation of physical properties of active pharmaceutical ingredients (APIs), and excipients.
• By reducing particle size, milling enhances the dissolution rate,
bioavailability, and overall performance of drugs in various dosage forms.
• The primary objective is to reduce the size
what does the binder do?
helps the powder stick together during compression
what does the lubricant do?
ensures that when the powder is compressed into a tablet it doesn’t stick within the metal die
what does unit operations mean?
individual steps or processes involved in the manufacturing of pharmaceutical products.
What is a negative mixtures? (Complete segregation)
Negative mixing occurs in a two-phase system where the phases
differ in density and will separate unless continuously agitated.
Example: Oil and water.
what is a neutral mixture? (Random mix)
Neutral mixing occurs when neither mixing nor separation of the system occurs unless it is acted upon by a system of forces
what is a positive mixture? (Ideal/perfect mix)
Positive mixing applies to systems that given time, would spontaneously and completely mix. Example: Two gases or miscible liquids.
what is Fluidised Hot-Melt Granulation (FHMG)?
bringing particles together
- Melt agglomeration obtained through addition of a solid binder that melts during the granulation processing (50-80°C)
- Mechanism similar to granulation with liquid addition
- No need for drying
