31 Questions
Which technique is ideal for blending eutectic formers in pharmaceutical powders?
Spatulation
What is the range of particle size provided by intermediate grinders in industrial comminution?
20 to 200 mesh
Which glidant is known to possibly enhance flow in pharmaceutical powders by decreasing the repose and internal friction angles?
Magnesium stearate
Which property of powders is important for therapeutic efficacy?
Particle size
What plays a key role in the dissolution of powders?
Particle size
In what range should particle size be for powders used for inhalation?
1 - 5 µm
What is the science that deals with small particle properties such as size, shape, and density?
Micromeritics
What method can be used for particle size analysis with concerns about poor dispersion and thermal gradients?
Sedimentation method with an Andreasen pipette
How does particle shape impact behavior in biological systems?
It affects drug delivery and permeation through lipid membranes
What governs the measurement of surface area of particles?
Adsorption theory
How can pore size measurement be done?
Using isotherms
What is powder flowability defined as?
The ease with which a powder will flow under a set of conditions
What is used to measure the flow properties of powders?
Angle of repose and tapped density
What influences the flowability of powders?
Particle size and distribution
What is porosity a measure of in a powder material?
Void volume
What are the density measurements important for?
Tablet manufacture and consistent die filling
What can be used to measure the height and radius of the cone in the angle of repose measurement?
Inclinometer
What do particles produced by different processes may have different?
Porosities
What does the Hausner ratio measure in tapped density measurements?
Powder flowability
Which method for determining particle size involves a set of stacked sieves in a column, with mesh openings decreasing in size from top to bottom?
Sieving method
What does Stoke’s Law apply to in the context of particle size determination?
Velocity of sedimentation
Which method involves the tendency for particles in suspension to settle out of the fluid and come to rest against a barrier?
Sedimentation method
What is the primary purpose of using wet sieving in particle size determination?
To wash particles with water to help move them to the appropriate sieve
What factor is NOT used to decide particle size distribution?
Particle shape
What type of particle size distribution is desired in pharmaceutical preparations?
Narrow distribution
Which method is best for particles larger than 50 to 100 µm in diameter?
Sieving method
What is the primary purpose of wet sieving for fine insoluble particles?
To wash particles with water to help move them to the appropriate sieve
What is utilized in the sedimentation method for particle size determination?
All of the above
What method involves the movement through the fluid to measure particle size?
Sedimentation method
What is the primary purpose of using wet sieving in particle size determination?
To wash particles with water to help move them to the appropriate sieve
What does Stoke’s Law apply to in the context of particle size determination?
Velocity of sedimentation
Study Notes
Particle Size and Distribution in Pharmaceutical Preparations
- Particle size and distribution influence powder mixing, compression, wetability, and mechanical flow in solid dosage forms.
- Narrow particle size distribution is desired in pharmaceutical preparations, as wide size distribution leads to inaccurate dosing and inconsistent performance.
- The majority of particles in solid dosage forms are irregular in shape and size.
- Factors deciding particle size distribution include frequency, mean, and standard deviation, and the distribution curve is obtained by plotting frequency against the arithmetic mean of the particle size group.
- Pharmaceutical powders often do not possess normal particle size distribution.
- Methods for determining particle size include electron microscopy, optical microscopy, Coulter counter, and sieving method.
- The sieving method involves a set of stacked sieves in a column, with mesh openings decreasing in size from top to bottom, and the bottom pan catching particles that pass through all sieves.
- The sieving method is best for particles larger than 50 to 100 µm in diameter, and the initial sample size is important to produce consistent results.
- Wet sieving may be appropriate for fine insoluble particles, as the top sieve is washed with water to help move particles to the appropriate sieve.
- Sedimentation method involves the tendency for particles in suspension to settle out of the fluid and come to rest against a barrier, and the movement through the fluid is used to measure particle size.
- Stoke’s Law applies to the sedimentation method, with the velocity of sedimentation being used to measure particle size.
- The sedimentation method utilizes an Andreasen pipette, a graduated cylinder, and controlled temperature for particle size determination.
Test your knowledge of particle size and distribution in pharmaceutical preparations with this quiz. Explore the factors influencing particle size distribution, methods for determining particle size, and the impact of size and distribution on pharmaceutical formulations.
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