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PHRM 513 > Powders > Flashcards

Powders Flashcards

1
Q

Powder

A

A dry, solid substance composed of finely divided particles

  • made from crushing, grinding or comminuting
  • type of dosage form
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2
Q

Pharmaceutical Powder

A

dosage forms of a solid or mixture of solids reduced to a finely divided state and intended for internal or external use

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3
Q

Granules

A

prepared agglomerates of powdered materials

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4
Q

Powders have been used

A
  • Orally
  • Via the nose as snuffs
  • Insufflations- powders blown into body cavity
  • Dissolved/ solutions for topical and oral use or use as douches
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5
Q

Benefits for powders

A
  • Easy alteration of quantity of drug dose
  • Useful for children and individuals who cannot swallow tablets/ capsules
  • Provide rapid onset since absorption is not dependent upon disintegration, only dissolution of material
  • more stable than liquid dosage forms
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6
Q

Size distribution affetcs

A
  • Dissolution rate
  • Absorption
  • Stability
  • Texture and taste
  • Flow and sedimentation rates
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7
Q

Polymorphism

A

ability of a solid material to exist in more than one form or crystal structure

  • only exist in solid state and do not exist in solution
  • Can be checked by various techniques to verify and establish purity
  • Polymorphs may possess different physiochemical properties such as stabilities, solubilities, rates of dissolution and melting points
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8
Q

Dissolution

A

As a particles dissolves

  • surface molecules are the first to enter into solution
  • Saturated drug layers forms on surface known as diffusion layer
  • Drug passes diffusion layer into the dissolving fluid
  • Upon contact with membranes, absorption occurs
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9
Q

Dissolution rate

A
  • time it takes for drug to dissolve, especially at absorption site
  • controls overall bioavailability
  • rate may be increased by decreasing particle size and/ or viscosity of medium
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10
Q

Steps in preparing a powder formulation

A
  1. Obtain raw material
  2. Analyze material (characteristics): Size, chemistry. Particles of all ingredients should be similar in size
  3. Weigh
  4. Sieve
  5. Blend
  6. Package final product
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11
Q

Micrometrics

A

science of small particles

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12
Q

Examples of Micrometrics

A
  • particle size and distribution
  • angle of repose
  • porosity
  • void and bulk volume
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13
Q

Sieving

A

particles are passed by mechanical shaking through a series of sieves of known and successively smaller size

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14
Q

Other techniques for separating size

A

Microscopy- Particles measured against a grid
Light scattering/ Light diffraction
Sedimentation rate- Determined by measuring the particle settling viscosity in a liquid medium via Stokes Law

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15
Q

Powder particle size ranges from

A 
very coarse (1cm) to extremely fine (1um)
- usually can be easily characterized by the % of material retained by a series of standard sieves
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16
Q

Angle of Repose

A

simple technique estimating flow properties of a powder

  • determined by allowing a powder to flow through a funnel and fall freely upon a surface
  • Height and diameter of the resulting cone is measured
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17
Q

Angle of repose equation

A

tan(o)= height of powder cone/radius of cone = h/r

  • Powder with low angle flows freely
  • Powders with high angels flow poorly
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18
Q

Porosity

A

ratio of volume of interspaces to the volume of the mass
- Packing depends on particle shape w void spaces between particles

  • if particles are not uniform, smaller particles may fit into spaces between the large particles and decrease void spaces
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19
Q

Apparent or bulk density ( untapped density)

A
  • Density of material including pore and voids (true volume +porosity)
    pa= m/ Vbulk
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20
Q

Tapped density

A

ratio of powder bed mass to powder bed volume obtained by mechanically tapping a graduated cylinder containing sample until little to no further volume change is seen
p/ m/V

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21
Q

Particle reduction

A

increases particle number and total surface area

- Particle size and shape in a powder is irregular

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22
Q

Coarse division

A

Reducing large particle into fragments of different sizes by cutting, crushing or attrition

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23
Q

Communition

A

Process of reducing particle size

24
Q

Trituration

A

Grinding or pulverizing powders to create fine particles with a mortar and pestle

Process of reducing particle size
- Powder blending technique

25
Q

Levigation

A

commonly used in small scale preparations or ointments and suspensions
-A paste is formed with a liquid ( levigating agent) that the powder is insoluble in

Glycerin and Mineral oil are common levigating agents

26
Q

Blending powders

A

1st step for uniform mixing

- Best to reduce particle size of components to obtain a homogenous mix

27
Q

Factors that influence powder blending

A 
Amount of ingredients
Density
Surface area
Particle size
Particle changes
Powder flow
28
Q

Geometric dilution

A

Homogenous mixture of two or more substances in widely different amounts
- Smallest quantity of active ingredient is mixed thoroughly with equal amount of diluent; repeated until all material is mixed

29
Q

Spatulation

A

Combining and mixing by means of a spatula

- Generally on a piece of paper or ointment slab/tile

30
Q

Segregation

A

Demixing - components tends to separate out

-Can result in content variation and unacceptable products Usually due to particle size variation

31
Q

Approaches to minimize segregation

A
  • selection of narrow size fraction range
  • selection of excipients with density similar to active
  • granulation of powder mix to uniform distribution
32
Q

Hygroscopic powders

A

will absorb moisture from the air

33
Q

Deliquescent powder

A

powders that may absorb moisture from the air to the extent that they will partially or completely liquify

34
Q

Efflorescent powders

A

A crystalline powder that contains water of hydration or crystallization
-Powder may become sticky and pasty or even liquify

35
Q

Eutectics

A

powders that become sticky or pasty or liquefy when mixed together

  • To avoid this problem, you can mix material w a bulky absorbent powder
  • Powders should be mixed with a spatula rather than a mortar and pestle to avoid compression
36
Q

Explosive mixtures

A

Some combination of powders react when mixed

-These are most commonly oxidizing and reducing agents

37
Q

Approaches to minimize efflorescent powder problems

A

Use anhydrous form, use a bulky drying powder, avid compacting method

38
Q

Desiccant packs are used to

A

absorb moisture and keep things dry

- dispensing medications in tight containers with these packs

39
Q

Incorporation of liquids

A

Liquids can be absorbed into an inert powder that is then geometrically incorporated into the powder bulk

  • Add material in alcohol and spray it evenly on powder. This will allow the solvent to evaporate leaving the ingredient evenly dispersed
40
Q

Medicated powders

A
  1. Oral after mixing powders
  2. Aerosol Powders
  3. Topical powders
  4. Dry powder inhalers
41
Q

Oral after mixing powders

A

-Suspensions

Can be mixed with water or infant formulas or soft foods

Preferred route for people who have trouble swallowing solid dosage forms
-Ex: Laxatives, Analgesics, Antibiotics- Provided as a powder to be reconstituted with water

42
Q

Aerosol Powders

A

Insufflation is the act of “blowing” or inhaling something into a body cavity

  • Finely divided powders
  • Applied to a body cavity- Ear, nose, tooth socket, throat, lung, vagina, rectum
43
Q

Dry Powder inhalers (DPI)

A
  • Also called Metered Dose inhalers (MDIs)
  • Oral administration via inhalation
  • Micronized particles delivered in accurate metered quantities
  • Particle size range: 1-6 um in diameter
  • Drug delivered deep into lungs
  • Contains inert propellants and diluents with the API
  • Mostly for treatments of asthma
44
Q

Topical powders

A
  • Should have a uniform, small particle size
  • should not irritate the skin when applied
  • should adhere to skin
45
Q

Divided powders

A
  • After a powder has been properly blended, it may be divided into individual dosing units based on the amount to be taken or used at a single time

Ex: PEG 3350 (MiraLAX)

46
Q

Granules

A
  • dosage form compsoed of dry aggregates of powder particles
  • Usually irregular shaped, but may be prepared to be spherical
  • May be swallowed directly, dispersed in food or dissolved in water
  • May be compacted into tablets or filled into capsules with or without additional ingredients
47
Q

Granules advantageous characteristics

A
  • lower surface area for better flow
  • more stable in air
  • minimizes powder segregation
  • less likely to cake upon setting
  • more easily wetted than powders
48
Q

Wet method 1 ( granules)

A
  1. Moisten powder
  2. Resulting aggregate is passed through a screen sieve to produce desired size granules
  3. Granules are placed on drying trays and dried by air or heat in drying ovens
49
Q

Wet method 2 (granules)

A
  1. Particles in a conical tower are vigorously dispersed and suspended while a liquid excipient is sprayed on the particles
  2. Product is dried which forms granules of pellets of defined size
50
Q

Dry method 1 (granules)

A

Roll compaction

- Dry powder is passed through a roller compacter and then through a granulated machine, usually in an integrated system

51
Q

Dry method 2 (granules)

A

Slugging
Dry powder is compressed into large tablets or slugs under 8-12,000 lbs. The pressure comes from using a compression machine (tablet press)
2. Slugs are then into the desired size

52
Q

Effervescent granulated salts

A
  • tablet or granule dry mixtures containing a medicinal agent, citric acid, tartaric acid, and sodium bicarbonate
  • It rapidly release CO2 when in contact with water
53
Q

Advantages of effervescent formulations

A
  • resulting carbonated solution can mask flavors
  • protects low pH sensitive materials in stomach
  • Assists in delivering large doses
  • No need to swallow tablets
  • Enhanced absorption of some active drugs
54
Q

Effervescent tablets and granules must be

A

dissolved in water, not swallowed directly

55
Q

Dry/fusion method (effervescent)

A

One molecule of water acts as the binding agent for the powder mixture

  • All preparations are done in low humidity environment and in stainless steel vessels
  • Powders are sized and blended and sieved to ensure uniformity
  • Mixture is then moved to drying ovens at 34-40˚C which releases water which dissolves some material and binds mixture
  • Mixture is then sieved to produce granules of desired size and then dried at a temp kept less than 54˚C before packaged in tightly sealed containers
56
Q

Wet method (effervescent)

A

Binding water is from a moistening agent

Manufacture can be done is reaction vessels like V-blenders

  • Once enough moistening agent is added, the procedure is the same as dry method
  • The granules are prepared and dried and either packaged as product or further processed into tablets
  • Lastly, the material is then packaged appropriately protected from moisture
57
Q

Patient needs to be instructed to allow

A

for the reconstitution of granules to ensure complete wetting of all ingredients with sufficient time and agitation to allow the soluble components to dissolve

PHRM 513 (13 decks)

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