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powders
- chemical that is solid in its physical state or dosage that is solid in its physical state
- powder can contain the A.I. only or have additional non-medicinal ingredients or fillers (i.e., lactose)
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powder: advantages
- contain different doses of A.I. specific to patient
- can be administered easily to pediatrics who cannot swallow tabs/caps
- rapid onset of action
- more stable than in solution
- can be used to prepare other dosage forms
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powder: disadvantages
- not suitable for bitter, nauseating, or corrosive drugs
- prep is time consuming, therefore more costly
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powder properties
- partical size: influences dissolution and solubility
- partical shape: crystalline
- partical form: many types of crystal forms (polymorphic and metastable)
- flow: powder must flow easily and uniformily to aid in good production results
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comminution
reduction of partical size
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smaller partical sizes are useful to:
- increase dissolution rates of drugs
- aid in formulation process
- enhance absorption
- create uniformity of liquid mixtures
- create non-grittiness in ointments, creams
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classes of large scale mills
- 1. course crushers: jaw, roll, impact crushers
- 2. intermediate grinders: hammer, roller, rotary crushers
- 3. fine grinders: ball, hammer, colloid, fluid energy mills
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small scale reduction
- trituration: grinding using mortar and pestel
- pulverization by intervention: dissolve compound, mixed in M&P or ointment slab to enhance evap.
- levigation: trit w/ M&P or spadulating in on slab w/ lev. agent
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blending
- large scale: industrial blending equipment (Twin shell blenders, vertical impeller mixer)
- small scale: spatulation (in bag, or M&P), trituration (M&P using geometric dilution)
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types of compounded powders: Bulk powders
- oral bulk: dietary supplements, laxatives, antacids,
- effervescent granulations:
- dusting powders: dusted on skin
- douche powders: vaginal cleansing
- insufflators: into body cavities using applicator
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evidence of instability
- caking
- change in colour
- moisture (in effervescent formulas)
- swelling of mixture (excess of gas)
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