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1.14 Powders
powder stuff
| Question | Answer |
|---|---|
| Micrometrics | The science & technology of small particles |
| DECREASE in particle size = _____ in surface area | increase |
| INCREASE in particle size = ______ in dissolution rate | decrease |
| Communition | The mechanical process of reducing particle size |
| Mill types | Pebble or Ball, Hammer, Attrition |
| What process removes water from frozen products at low temps via sublimation? | Lyophilization (Freeze Drying, Cryodesiccation) |
| Freeze drying happens in _____ temp and _____ pressure | LOW (-40C) |
| Lyophilization | Modern method of Particle Size Reduction |
| Spray Drying | Modern method of Particle Size Reduction |
| Trituration | Modern method of Particle Size Reduction |
| What process includes rubbing particles in a pestle and mortar to reduce particle size? | Trituration |
| Which process is used to reduce particle size of gummy substances that reagglomerate? | Pulverization by intervention |
| Pulverization by intervention | Modern method of Particle Size Reduction *adding a volatile substance is done here; ex. camphor |
| Levigation | Modern method of Particle Size Reduction *Form a paste by adding an agent |
| Glycerin | Levigating agent |
| Propylene glycol | Levigating agent |
| Mineral Oil | Levigating agent |
| Improper flow = _______ tabs and caps and ________ mixtures of powder | Uneven |
| Free flowing | "Dustibility" |
| Cohesiveness | stick together; POOR flow |
| INCREASED particle size = ______ cohesion and friction | increase *POOR FLOW increases due to more contact points |
| IRREGULAR particle sizes = ______ flow | POOR |
| A mixture of small and large particle size = POOR flow due to INCREASED _______ | surface area |
| Angle of Repose | Measurement of the FLOWABILITY of powder |
| Low angle of repose = _____ Flow | Good |
| High angle of repose = _____ Flow | Bad |
| <35C = ______ Flowing | Free |
| >55C = ______ Flowing | Limited |
| Size of Free Flowing Powders | 250-1000 microns |
| Size of Poor Flowing Powders | <75 microns |
| Ways to IMPROVE Flow Properties | Spray Drying, Granulation, Use Glidants |
| Magnesium Stearate | Glidant |
| Stearic Acid | Glidant |
| Talc | Glidant |
| Starch | Glidant, Absorbent Diluent |
| >1% of Glidant = _____ flow | POOR |
| Glidants does what to the electrostatic charge on particles? | Reduces |
| Glidants does what to prevent sticking? | Absorb moisture |
| Stratification | Uneven mixture of small and large particles. Settling of large particles cause the small particles to seep in and cake |
| Particle Cohesion is caused by what? | Interlocking of irregular particles, Adsorbed moisture, van der walls, electrostatic charge |
| Adding powder in alternate layers and avoiding overblending does what to electric charge buildup? | Prevents |
| Mechanical Mixers | Power Blending Method |
| Tumbling Mixers | Power Blending Method |
| Trituration | Manual Blending Method |
| Spatulation | Manual Blending Method *Gentle Method |
| Sifting or Sieving | Manual Blending Method *Seldom used |
| Tumbling | Manual Blending Method *Rarely used by pharmacists |
| The key to Geometric Dilution is? | Mixing powders in batches |
| Metamucil Laxative | Oral Bulk Powder |
| CaCo3, MgCo3 | Abrasive Dentifrice Powder |
| SLS | Surfactant Dentifrice Powder |
| Douche Powders | Water soluble cleansing agents (eye, ear, nasal) |
| Boric Acid | Antimicrobial Douche Powder |
| Parabens | Antimicrobial Douche Powder |
| Ammonium Aluminum Sulfate | Astringent Douche Powder |
| Volatile substances (menthol, thymol, flavor oils) are lost due to what? | Vaporization |
| Hygroscopic Powders | Attracts and retains moisture; adsorbed onto powder |
| Deliquescent Powders | Extreme form of moisture absorption (turns into liquid, even) |
| Efflorescent Powders | Substances that lose water to the atmosphere upon standing or trituration |
| What powder can be overdosed due to loss of water of crystallization? | Efflorescent powder |
| Sodium Bicarbonate and Citric Acid, Tartaric Acid | Effervescent powder |
| Effervescent powders release what? | CO2 |
| Eutectic Mixtures | Two solids with relatively low MP when mixed act as impurities WRT each other; lower MP |
| Liquefaction is caused by what type of mixture? | Eutectic Mixtures |
| Mixing an equal amount of diluent with an eutectic compound before mixing with another eutect. cmpd. does what? | Prevent eutectic mixtures |
| Magnesium Carbonate | Absorbent Diluent |
| Kaolin | Absorbent Diluent |
| Amorphous solids have _______ crystallinity | Zero |
| Amorphous solids are _______ stable than crystalline forms | Less |
| Why are amorphous solids MORE reactive and MORE soluble than crystalline forms? | Enters into soln. easier than crystalline forms |
| Polymorphism | When a solid with an identical chemical formula exists in two or more different crystalline forms |
| Do amorphous solids or crystalline solids present polymorphisms? | Crystalline |
| A LESS stable polymorph will dissolve _______ and have a ________ solubility | faster; higher |
| An crystalline form with dissolve ________ than an amorphous form | slower |
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