31 Questions
What does micromeritics primarily focus on?
Particle size and size distribution
In pharmaceuticals, why is particle size important?
It plays a key role in dissolution and therapeutic efficacy
What is a key property of powders in micromeritics?
Porosity
Why are micromeritics properties of powders important in pharmaceuticals?
They are used in product development and quality control to ensure batch-to-batch uniformity
Which technique is ideal for blending eutectic formers in pharmaceutical powders?
Trituration
What particle size do fine grinding mills typically provide in pharmaceutical powder formulation?
Smaller than 200 mesh
Which glidant is known to enhance flowability in pharmaceutical powders?
Magnesium stearate
Which method for particle size analysis is mentioned in the text?
Sedimentation method with an Andreasen pipette
How is powder flowability defined?
The ease with which a powder will flow under a set of conditions
What governs the measurement of particle surface area?
Adsorption theory
What is porosity a measure of in powder material?
Void volume
What impacts powder flowability?
Particle size, shape, and distribution
How are density measurements important for tablet manufacture?
They are important for consistent die filling
What is used to measure powder flow properties?
Angle of repose and tapped density
How is particle shape mentioned to impact behavior in biological systems?
Affecting drug delivery and permeation through lipid membranes
What can large increases in surface area of particles affect?
Drug delivery systems
How is pore size measurement mentioned to be done?
Using isotherms
What is powder flowability influenced by?
Particle size, shape, and distribution
What influences the flowability of powders?
Particle size and distribution
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 is the desired particle size distribution in pharmaceutical preparations?
Narrow
Which law applies to the sedimentation method for determining particle size?
Stoke’s Law
What is the main influence of particle size and distribution on in pharmaceutical preparations?
Powder mixing and compression
What does the sieving method involve for particles larger than 50 to 100 µm in diameter?
Stacked sieves in a column
What do the majority of particles in solid dosage forms tend to be in terms of shape and size?
Irregular
What is the sedimentation method for determining particle size based on?
The tendency for particles to settle out of the fluid
What is the best method for fine insoluble particles in pharmaceutical preparations?
Wet sieving
What does the sieving method involve for particles smaller than 50 to 100 µm in diameter?
Centrifugation
What is the main purpose of the sedimentation method for determining particle size?
To measure particle size
What is the primary factor deciding particle size distribution?
Particle frequency
What method involves a set of stacked sieves in a column, with mesh openings decreasing in size from top to bottom?
Sieving method
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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