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Describe the method of obtaining bulk density (as described for tapped density in Preformulation):
- 50 cc of powder is passed through sieve #20 and places in a 100cc volumetric cylinder
- The cylinder is dropped at a 2 second interval 3 times from 1inch above a wooden surface
- The weight of powder is divided by the final volume
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What does the angle of repose measure in terms of pharmaceutical properties?
Flow property
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You can measure the flow property of a drug by measuring what parameter?
The angle of repose
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A small angle of repose indicates what relative level of Flow?
Excellent
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A large angle of repose indicates what relative level of Flow?
Very poor
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What are the five advantages of powders discussed in class?
- Better stability than solutions
- Large doses can be administered
- Wide range of ingredients and doses can be used
- Rapid dispersion of the drug in the stomach (vs. compressed forms)
- Can be dispersed in liquid for administration
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Solutions or powders are more stable?
Powders
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What are the disadvantages of powders as discussed in class?
- Not good for bad tasting drugs
- Not good for drugs that deteriorate easily in the atmosphere
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What type of drugs deteriorate rapidly in the atmosphere and thus should not be used in powder formulations?
Ferrous iron salts
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Ferrous iron salts should be administered in what form?
Coated tablets because they oxidize easily
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What four ways of mixing powders were mentioned in class?
- Triturating
- Spatulation
- Sifting
- Tumbling
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Trituration, spatulation, sifting and tumbling are methods for doing what?
Mixing powders
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Describe trituration:
Mortar and pestle
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What powder mixing technique uses a mortar and pestle?
Trituration
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What is trituration used for?
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What types of mortar an pestles are commonly used?
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What is the Wedgewood mortar and Pestle commonly used for?
Pulverizing due to the rough inner surface
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What are glass mortar and pestles commonly used for?
Simple mixing
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What type of mortar and pestle would you use for simple mixing?
Glass
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What type of mortar and pestle would you use for pulverizing course material?
Wedgewood
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Describe Spatulation:
A spatula is used to mix powders on a pill tile
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What powder mixing method uses a spatula and a pill tile?
Spatulation
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What situations are ideal for spatulation:
- Small quantities of powder
- Powders being mixed have the same densities
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If you have a small amount of powder with similar densities, which powder mixing technique might you use?
Spatulation
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Relatively how much drug would you expect to loss during transfer after performing spatulation?
Minimal
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For powders that resist mixing by trituration, what other method would you use?
Sifting
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What type of drugs are ideal for sifting?
very light powders
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What mixing technique works very well for magnesium oxide and charcoal?
Sifting
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What type of sieve is used for powder sifting?
- Standard prescription sieve
- Flour sifters
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What is tumbling?
Mixing powders together by shaking or rotating them in a closed container
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What type of powder mixing process includes shaking or rotating in a closed container?
Tumbling
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When would you use tumbling to mix powders?
When two or more extremely light powders are to be combined
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What type of mixing would you choose for crystalline salts?
Trituration with a Wedgewood mortar
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If the surface of a wedgewood mortar becomes smooth, what an you do to remedy the problem?
triturate with a little pumice powder or sand
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When would you triturate with pumice powder or sand?
If you wedgewood mortar becomes too smooth
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What is electrification?
Substance repel each other due to resistance of admixture or electrical charges
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When substances repel each other due to the resistance to admixture electrical charges what do we call it?
Electrification
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How can you remedy electrification?
Moisten slightly with a few drops of alcohol or mineral oil
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In what situation would you moisten your powder mixture slightly with a few drops of alcohol or mineral oil?
When electrification occurs
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How can you avoid packing when triturating?
triturate as lightly as you can and frequently scrape the edge of the mortar with a spatula
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How can you minimize Physical Immiscibility?
- Separately, triturate two powders to a fine state
- Then, sift or tumble the two powders together
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