Lecture 11 (Cut off for Exam 2) Flashcards
Blending of Powders
Two or more powdered substances are combined/blended to form a uniform mixture.
Methods of blending (4)
- Spatulation
- Titration
- Sifting
- Tumbling
Do you reduce the particle size before or after blending? Why?
Reduce particle size before blending. Creates a homogeneous mixture to work with for blending and better absorption down the road.
Spatulation
Blending small amount, especially for eutectic mictures.
Eutectic Mixtures
Two solids mixed together that become liquid when combined. Melting point for them combined is lower than each individually.
Trituration
Used to both comminute and to mix powders (mortar and pestle). Utilizes geometric dilution.
Geometric dilution
Adding a small amount of a potent drug to a portion of the base and well mixing. Continuing this pattern until the total amount is added and mixed.
Sifting
Passing powder through sifters. NOT an appropriate method for potent drug mixing.
Tumbling
Small and large scale motorized blenders (twin shell blender and ribbon blender).
Segregation
Undesirable separation of the different components of the blend. Occurs in sifting/percolation, air entrapment (fluidization), and particle entrapment (dusting).
Methods to Control Powder Segregation (6)
- Minimize transfer steps and drop heights
- Control of dust generation
- Control of fluidization
- Slow fill/transfer rate
- Appropriate venting
- Use of deflector, vane, or distributor
Granules
- Powder like product
- Prepared from powders - agglomerates of small particles
- Generally small, irregularly-shaped chunks
- Tend to fit between size 4-12 sieves (2-5 mm)
- compressed into tablets
Methods to Prepare Granules (2)
- Wet
- Dry
Choose method based on physical-chemical properties of active ingredient
Wet Method
- Moisten powder mixture
- Press “dough” through sieve
- Dry granules
- Requires “binder,” water, and heat
Dry Method
- Compress powder mixture into large cake
- Break into granules
- Use high pressure compression
Advantages to Granules v.s. Powders
- Granules flow better compared to powders
- Less surface area, more stable to atmospheric conditions
- Less likely to cake or harden upon standing
- More easily wetted by liquids
- Easily compressed into tablets
Granule Uses (2)
- Tabletting - best flow, better compression, more uniform
- Products for reconstituion - granules contain necessary excipient. Pharmacist adds water, mixes, and dispenses. EX: Antibiotic suspension (longer shelf life)
Medicated Powder Uses (5)
- Orally - systemic or local
- Inhaled - systemic or local
- Injection
- Vaginal douche
- Wounds
Can be internal or external use
Medicated Powder Advantages
- Ease of swallowing
- Some drugs are too bulky to be encapsulated/tableted
- Faster rates of dissolution and absorption
- More stable than those in liquid formations
- Easy to adjust dose with powders
Medicated Powder Disadvantages
- Undesirable taste (bitter)
- Dose titrations (potent drugs) - potential for patient to mistake correct method of use or dose
- Difficulty protecting powders from decomposition when they contain hygroscopic, deliquescent, and aromatic compounds
- Uniform individually wrapped powder doses
Powders V.S. Tablets/Capsules
Powder lacks convenience of handling, ease of product identification, and ease of administration by patient that tablets and capsules have.
Disintegration
Process tablets and capsules undergo to become granules/aggregates.
Deaggregation
Process granules and aggregates undergo to become fine particles.
Dissolution
Process tablets/capsules, granules/aggregates, or fine powders can undergo to dissolve in solution.
Hygroscopic
Substances that tend to absorb water from the air.
Deliquescent
Substances that have a tendency to become liquids.
