Pharmaceutical biotechnology II Flashcards
What is micromeritirics?
Micromeritics is the science and technology of small
particles.
Micromeritics deals with a number of characteristics including
particle size, the size ranges of particles (size distribution), particle
shape, flowability, true volume, bulk volume.
Why is particle size important?
-Affects the drug’s release
-affects the flows and thus packing properties
-affects the rate of dissolution
What is polydisperse
particles having a range of sizes
Why is higher surface of particles important?
A higher surface area allows intimate contact of the drug with the dissolution fluids and increases the drug solubility and
dissolution.
higher the dissolution, the faster is the absorption.
* The smaller the size of the particle, the better is the physical stability of the dosage form.
Name the ‘diameters’
➢Surface diameter, which is the diameter of a sphere having the same surface
area as the asymmetric particles.
➢Volume diameter, which is the diameter of a sphere having the same volume
as the asymmetric particles.
➢Projected diameter, which is the projected diameter of a sphere having the same observed area as the particle under microscope.
➢Stokes diameter, which is the diameter describing an equivalent sphere undergoing sedimentation at the same rate as the asymmetric particle.
Why is it important to determine the flow properties of particles?
Powders with different particle sizes have different flows and packing
properties which alter the volumes of powder during each encapsulation or tablet compression.
What are the methods used for determining particle size?
- Microscopy
- Sieving
- Sedimentation technique
4.Laser light scattering techniques
What are the advantages using microscopy to determine particle size?
- Each particle is individually examined
- with visualised record
- particle shape can be observed
What are the disadvantages using microscopy to determine particle size?
- time-consuming
- Equipment cost (EM is expensive)
What types of microscopy is used to determine the size of particles and what is the range?
- Optical microscopy (0.2-100um)
- Electron microscopy (0.001-5000um)
What is the size range for sieving technique?
5um - 9mm
What are the advantages of sieving to determine particle size?
- Easy
- Wide size range
- Inexpensive
What are the disadvantages of sieving to determine particle size?
- does not provide a high resolution for a sample with narrow size range
- damage in use and cleaning
- elongated and flat particles do not yield reliable results?
Describe sedimentation technique to determine size range of particles
This method depends on the fact that
the terminal velocity of a particle in a
fluid increases with size.
What is the size range for sedimentation technique?
0.8-300um
State the advantages of using sedimentation technique to determine particle sizes
- inexpensive and simple
- accuracy and reproducibility
State the disadvantages of using sedimentation technique to determine particle sizes
- particles must be completely insoluble
- Must be carried out at low concentrations
- Particle re-aggregation
Describe the technique of laser light scattering for determining particle sizes
Particles pass through a laser beam and the light scattered by them is collected over a range of angles in the forward direction.
There must be a difference in refractive index
between particles
What is the particle size range for laser light scattering technique?
10nm - 2000um
State the advantages of using laser light scattering technique to determine particle size
- fast
- easy to use
- precise and wide range
State the disadvantages of using laser light scattering technique to determine particle size
- expensive
- Volume measurement, assuming spherical
particles - There must be a difference in refractive index
between particles
What is true density and bulk density?
True density: the density of a sample which excludes the volume of the pores and voids within the powder sample
Bulk density: the density value which includes the volume of all the pores and voids within the powder sample.
What indexes are used to measure flowability of a powder?
- Carr’s index (Carr’s compressibility index )
- Hausner ratio
- Angle of repose
The better fluidity of a product, the _______________________________________________ .
easier it is to spread smoothly and tightly, and thereby obtain a high-quality product.
What is the angle of repose dependent on?
Angle of repose is a characteristic related to inter particulate friction or resistance to movement
between particles. When the grains are smooth and rounded, the angle of repose is low. For very
fine and sticky materials the angle of repose is high. Powders with a steep angle of repose may
flow poorly, leading to problems in manufacturing processes such as blending, tablet compression,
and capsule filling.
Name the types of oral solid dosage froms
a) Powders & Granules
b) Tablets
c) Capsules
d) Lozenges
What kind of dosage forms is powder used in?
tablet, capsules, suspension, cream, ointments
What are granules?
Granules are defined as a dosage form composed of dry aggregates of powder particles that may contain one or more APIs, with or without excipients.
What methods are used to prepare granules?
- wet granulation
- dry granulation
Describe the process of wet granulation
- weighing and blending the ingredients
- add liquid binder to facilitate adhesion of powder particles
- Screen damp mass into pellets and granules
- size the granulation by dry screening.
Describe granulation
Granulation is a process by which primary powder particle adhere to form large multi particulate entities called GRANULES
What is dry granulation?
Dry granulation converts primary powder particles into granules using the application of pressure without the intermediate use of a liquid.
-avoids heat temperature
What are the 2 pieces of equipment necessary for dry granulation?
- compressing machine
- milling machine
Name the compressing methods
slugging and roller compaction
Describe disintegration and dissolution.
Disintegration: the physical process by which a tablet breaks down into fine
particles
Dissolution : the process by which the active ingredient is dissolved in a liquid
What properties should tablets possess?
*Should have elegant product identity while being free of defects like chips, cracks, discoloration, and
contamination
* Should have sufficient strength to withstand
mechanical shock during its production packaging,
shipping and dispensing
* Should have the chemical and physical stability to maintain its attributes over time
* The tablet must be able to release the medicinal agents in a predictable and reproducible manner
What are the advantages of using tablets as a form of dosage?
- Suitable for large scale production
- Large scale production at lowest cost
- Easy and cheap to package and ship
- Easy to handle
- Light and compact
- Dose precision & least content variability
- Greatest chemical and microbial stability over all oral dosage forms
- Product identification is easy and rapid
What are the disadvantages of tablets as a form of dosage?
-Drugs with poor wetting and slow dissolution properties may be difficult to formulate as a table
-Some drugs are difficult to compress
-Difficult to swallow in case of children and unconscious patients
-Drugs with bitter taste, with strong odour, or are sensitive to oxidation may require
encapsulation or coating
What are the tablets that could be used for oral cavity as opposed to oral ingestion?
- Buccal tablet
- Lozenges
- sublingual tablet
What are compressed tablets and what are the pros of it?
- standard uncoated tablets. The manufacturing process involves compression of granules or powder
- Designed to provide rapid disintegration and hence rapid drug release