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Pharm 125 > solid dosage forms: powders and granules > Flashcards

solid dosage forms: powders and granules Flashcards

1
Q

powder properties: (powder technology) (3)

A

particle form

particle shape

particle size
-particle size analysis, reductions and separation methds

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2
Q

bulk powder properties (3)

A

density
-particle density
pwder density or bulk density

porosity

specific SA

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3
Q

other properties? (3)

A

powder flow

mixing and segregation

powder and granules as dosage forms

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4
Q

griseofulvin particle size (2 kinds)

A

microsize

  • 4 micrometer particle size
  • dose 500mg to 1g/day

ultramicrosize

  • 1 micrometer PS
  • 375 to 750mg/day
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5
Q

relative absorption of griseofulvin particle sizes

A

ultramicrosize griseofulvin absorption is almost complete

microsize griseofulvin is variable
-27-72% of an oral dose

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6
Q

powder defn

-size

A

single solid or mix of solids in a finely divided state

sizes smaller than 1000micrometers

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7
Q

granule def’n

-sizes

A

solid dosage form composed of agglomerations of smaller particles

sizes 0.2mm to 4mm

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8
Q

what has better flow granules or particles

A

granules usually used to inc particle size to flow better

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9
Q

powders and granules can be used as (2)

A

solid dosage forms

intermediates in the production of other dosage forms (tablets or capsules)

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10
Q

solids can have 3 forms

A

crystalline

amorphus

polymeric

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11
Q

crystalline solids

  • defn
  • 3 subtypes
A

regular geometric arrangement or lattice repeated in all 3 dimensions (unit cell)

polymorphs, hydrates/solvates, salts/cocrystals

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12
Q

amorphous solids

  • defn
  • subtypes
A

irregular geometric arrangement

amophous
amorphous dispersions

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13
Q

polymeric solid

-def’n

A

large molecule made up of many small repeating units (monomers)

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14
Q

particle form: polymorphism

A

different packing pattern of the same molecule, giving different crystal forms

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15
Q

metastable polymorphism

A

metastable (thermodynamically unstable) fomr s will convert to ONE truly stable form over time (monotropic polymorphism

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16
Q

particle form: polymorphism

-if more stable forms exist

A

if more stable forms exist, and reversible transformation is called enantiotropic polymorphism

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17
Q

particle form: polymorphism

-how characterize

A

x-ray diffraction

thermal analysis (differential scanning calorimetry or DSC; thermogravimetric analysis or TGA_, spectroscopy

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18
Q

particle form: polymorphism

- what changes between polymorphs

A

changes in pysiochemical properties

-MP, dissolution rate, bioavailability, stability

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19
Q

what packing arrangement has more energy to dissolve

A

tighter packing arrangement requires more E to dissolve

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20
Q

why use a metastable form with lower MP

risk?

A

-lower MP = weak lattice = more soluble = faster dissolution rate

RISK
-may revert to stable form

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21
Q

particle form: hydrates/solvates

A

entrapment of solvent molecules within crystal lattice

anhydrous crystals are more soluble than the hydrates

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22
Q

particle form: salts

A

two ionized molecules within the crystal lattice (drug + counterion)

increased solubility, dissolution rate and bioavailability for poorly soluble drugs

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23
Q

particle form: co-crystals

A

crystal that contains more than one component within the crystal lattice (drug + co-former)

netrual cpds with non-ionic interactions (H+ bonds, VDW, etc)

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24
Q

particle form: amorphous solids

-order

A

not packed in a defined order

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25
Q

particle form: amorphous solids

-glass transition

A

have glass transition T (Tg)

  • at low T (below Tg): material is brittle or glassy
  • at higher T (above Tg): material is rubbery
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26
Q

particle form: amorphous solids

-how produce

A

produced by fast solidification process or by breakage of crystals
ex. milling

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27
Q

particle form: amorphous solids

-used in what preparations

A

solid amorphous dispersions and co-amorphous

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28
Q

particle shapes (6)

A

acicular

columnar

flake

plate

lath

equant

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29
Q

what is crystal habit

A

external shape of a crystal

-refer to particle shape

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30
Q

particle size: micrometrics

A

science and tech of small particles

-particle size measurements, size distribution and packing arrangements

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31
Q

particle size: effect on dissolution rate

A

micronized drugs can inc rate and bioavailability

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32
Q

particle size: dose uniformity

A

uniform distribution of API in powder miz to ensure dose to dose content uniformity

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33
Q

particle size: control of particle suspension

A

control the suspension of particles dispersed in a vehicle

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34
Q

particle size: physical stability

A

improve physical stability, smoothness and appearance of semisolids
ex. creams, oints etc

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35
Q

particle size: MOST IMPORTANT for powders and granules (3)

A

affect flow and packing properties

facilitate drying

improve pen (in lungs) of particles used in inhalation products

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36
Q

particle size: dimensions

A

particles are 3D objects

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37
Q

particle size: what do MOST measurements assume wrt particles shape

A

most measurements assume that the material is sphericle

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38
Q

it is impossible to describe a particle using a single number (t/f)

A

true

-SO use particle size distribtions

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39
Q

howparticle size: how may they be dispersed

A

particle size of a sample is heterogenous or polydispersed

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40
Q

look at ferets diameter and martins diameter and projected area diameter and length and width

A

asldkjfasl;kdjfuhireruhieerhiulerhiueihur

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41
Q

particle size distributions

  • cumulative distribution curve
  • expressions for mean diameter based on what
A

cumulative distribution curve
- plot frequency vs particle size

expressions for mean diameter based on what
-diameter
Dd is mean diameter based on particle diameter

-surface area
Ds is mean diameter based on particle surface

-volume
Dv is mean diameter based on particle volume

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42
Q

broad cumulative distribution curve

A

lots different particle sizes

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43
Q

what shape cumulative distribution curve do you want

A

sharp curve, less diffs in particle size

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44
Q

look at graphs page 18

A

asdjfh

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45
Q

particle size: coarse

A

mesh opening size (microns)
- >355

mesh size number
20-40

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46
Q

particle size: moderately fine

A

mesh opening size (microns)
- 180-355

mesh size number
- 40-80

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47
Q

particle size: fine

A

mesh opening size (microns)
- 125-180

mesh size number
80-120

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48
Q

particle size: very fine

A

mesh opening size (microns)
- greater than or equal to 125

mesh size number
- 120-200

49
Q

how do you determine particle size distribution (5)

A

1) microscopy
2) sieving
3) laser light scattering
4) sedimentation
5) electrical zone sensing (coulter counter)

50
Q

Microscopy

A

optical microscope

scanning electrom microscope (SEM)

transmission electron microscopy (TEM)

dynamic image analyses

DEFINITIONS ON PP

51
Q

mean particle diameter (dave)

A

(sum of midsize*number of particles in ea size group) / (sum of number particles in ea size group)

52
Q

sieving method (2)

  • def’n
  • range
A

predetermined weight of dry powder passed through wire mesh screens

  • ea screen has openings of different sizes
  • weight of powder retained on each sieve is measured

range: ~40 micrometers to 5mm (dpnding on sieve sizes

53
Q

mesh sizes (sieving)

A

mesh number is the number of openings per linear inch

54
Q

large sieve number separates

A

small particles

55
Q

small sieve number

A

separates large/coarse particles

56
Q

sieving method: calculate diameter ave

A

diameter ave = [(%retained)(ave size)] / 100

57
Q

sieving method advantages (2)

A

simple cheap easy to interpret

technique is well adapted for bulk materials
-large amount of material can be loaded into sieve trays

58
Q

sieving method disadvantages (2)

A

-smallest particle sieve size (400 mesh) is 38 micrometers

amount of E used to sieve the sample is empirically determined

  • over-energetic sieving causes attrition of the particles
  • insufficient E fails to break down loose agglomerates
59
Q

light scattering (2)

A

includes: laser diffraction and dynamic light scattering

particle size is determined by the angle and intensity of scattered light reaching the sensor

60
Q

light scattering can be used to determine what

A

determine much smaller particle sizes

61
Q

sedimentation method (3)

  • def’n
  • assumption/parameters
A

refer to the settling of a single particle in a liquid medium under the influence of gravitational and centrifugal forces

assumes particles are spherical, the particle [ ] is dilute (max2%) and their sedimentation is unaffected by interaction between particles

diameters determined from stokes law

62
Q

pp slide 28 stokes law

A

asdfasdfasdf

63
Q

sedimentation method example: andreasen pipette (4)

A

samples are mized with liquid to form a suspension and placed into the andreasen pipette

mixture is stirred by shaking pipette and left to rest for certain period of time

10mL of sus is collected from a position 200mm below surface of sus

weight of solid obtained after drying sample,
-used to calc the diameter according to the stokes equation

64
Q

what particle size sediments faster

A

larger

65
Q

electrical sensing zone method (coulter counter) (2)

A

particle suspended in conducting liquid that passes through small orifice surrounded by electrodes and measures a change in the electrical signal proportional to the volume of the particle

measure volume of particles

66
Q

powder production (3)

A

pptation and crystallization
- can lead to diff polymorphs depending on conditions

spray drying and freeze drying
-allows for control over size, shape, composition, of particles

communition
-(particle size reduction)
+often start with large particle size and break down by milling

67
Q

Mechanism of size reduction: powder comminution

A

-aplication of external forces (mechanical) as a way of decreasing cohesion between powder particles

based on crack propagation
-material breaks along cracks so most effective size reduction would be to focus force on cracks

only 2% of force fractures the material
-remaining E is distributed in other processes (shit ton listed in lecture)

68
Q

comminution equipmetn (3)

A

coarse crushers

  • jaw, gyratory, roll and impact crushers
  • not used in pharmaceutical industry

intermediate grinders

  • rotary cutters, disk, hammer, roller, chaser mills
  • produces particles between 20 and 200 mesh

fine grinding mills
-ball, pin, hammer, colloid, fluid-E mills (or air-jet mill)

69
Q

what generates more heat during comminution

A

smaller particle size product

70
Q

Fine grinding mills

A

ball mill

  • as rotates, balls rotate and fall break down particles
  • ball type det particle size
  • contamination probs bc need clean ea ball

fluid energy mill or air jet mills

  • mostly used for ground powder inhalers
  • produces v fine powders
  • air jets, as spin air collides with particles and breaks down
  • good for heat labile bc air is cooling
71
Q

comminution equipment small scale (3)

A

trituration

pulverization by intervention

levigation (use liquid to triturate)

72
Q

bulk density properties: density

4 types

A

true density
- ratio of mass of particle to its actual volume (excludes pores and gaps

particle density
-ratio of mass of particle to volume of particle including intraparticulate pores, excluding gaps

bulk density
-ratio of powder bed mass to volume of loose powder bed, includes pore and gap volume

tapped density
-ratio of powder bed mass to volume of tapped (or compacted) powder bed, includes pore and gap volumes

73
Q

bulk density properties: density, what is void

A

void
-pores (intraparticulate air volume)

-gaps (interparticulate air volume

74
Q

bulk density properties: porosity (% of void space)

3

A

volume of the pore interor and gap space in a powder

indicate the packing efficiency of a powder

measured by gas absoption method or mercury porosimetry

ON PP IS CALC

75
Q

bulk density properties: specific SA

A

determined by particle size and porosity. provides info on void space on particle surface (pores) or within an agglomerate

measured by gas absorption or gas permeability procedures

76
Q

powder flowability definition (2)

A

ease with which a powder will flow under a specified set of conditions

complex phenomenon, referring to both physical properties affecting powder flow and the equipment required for handling, storage, and processing

77
Q

importance of powder flow (4)

A

uniform feed from storage containers or hoppers into the feed mechs of tableting or capsule-filling equipment

reproducible filling of tablet dies and capsule dosetors

uneven powder flow can result in excess entrapped air within powders affecting compression

cause lubrication problems and increase dust contamination risks during powder transfer

78
Q

factors affecting powder flow

A

adhesion/cohesion

size, shape, density

79
Q

adhesion

A

tendency of dissimilar particles or surfaces to cling to one another

mechanical, chemical, dispersive, electrostatic, diffusive etc

80
Q

cohesion

A

tendency of similar or identical particles/surfaces to cling to one another

intrinsic property of a substance that is caused by the shape and structure of its molecule

81
Q

alteration of particle size

-ranges and flow

A

250-2000 micrometers (flow freely

75-250micrometers (may cause flow problems

<50micrometers (irregular flow or no flow (mainly due to VDW florces))

82
Q

alteration of particle shape

-what shapes flow better

A

spheres flow better than needles

83
Q

Bulk density

A

flowability can be estimated from bulk density of powder using a tapped density device

84
Q

bulk density: hausner ratio

A

hausener ratio = ptapped/pbulk

85
Q

bulk density: carr’s index

A

CI = [ptapped-pbulk]/ptapped * 100

86
Q

slide 45 table of flow character and carr index/ hausner ratio

A
87
Q

high carr index

A

poor flow

88
Q

low carr index

A

good flow

89
Q

hausner ratio low

A

good flow

90
Q

hausner ratio high

A

poor flow

91
Q

angle of repose (2)

A

angle between the free surface of the powder body and the horizontal plane when poured from a funnel

simple method, poor reproducibility

92
Q

angle of repose

-flow indicators

A

flatter cone = better flow

sharp peak = poorer flow

93
Q

flow through an orifice (2)

A

direct method
-measure rate of powder discharging from the hopper or a funnel

flow rate calculated by dividing mass of powder by total time taken for powder to flow out from funnel

94
Q

shear cell (2)

A

more reproducible results, time consuming

bulk solid sample loaded in container or “cell”, load is applied and the powder bed is sheared until a uniform consolidation (constant shear stress value)

95
Q

powder mixing

A

operation that serves to make two or more components uniformly distributed in the powder bed

96
Q

mechanisms of powder mixing

A

diffusion

convection

shear

97
Q

mechanisms of powder mixing: diffusion

A

when powder bed is forced move/flow, it dilates

increase air space btwn particles

98
Q

mechanisms of powder mixing: convection

A

transfer of large groups of particle from one part of powder bed to another
ex. mizer blade moves through mix, tumbling mizers

99
Q

mechanisms of powder mixing: shear

A

layer of material moves/flows over another layer

ex. tumbling mixers

100
Q

generally diffusion convection and shear are used in a mixing process of powders (t/f)

A

true

101
Q

powder demixing (segregation)

A

separation of drug from other powder components

102
Q

factors affecting segregation: particle size

A

particle size = main cause of segregation
-smaller particles fall into spaces btwn larger (percolation segregation)

-larger particles move greater distances then smaller particles (trajectory segregation)

during mixing dust is blown upwards, when mixing stops, dust sediments on top of caorser particles (elutriation segregation or “dusting out”)

103
Q

factors affecting segregation: particle density and particle shape

A

denser particles move down

spherical particles easier to mix, but tend to segregate more

104
Q

how to minimize segregation (6)

A

1) select similar particle size range for drugs and excipients
2) control crystallization of drugs and excipients to give same particle shape
3) choose excipients with same density as APIs
4) granulation of powder mix
5) reduce vibration after mixing
6) production of an ordered mix

105
Q

ordered mix

A

micronized powders absorbed on surface of larger carrier particle
-used in antibiotic formulations and dry powder inhalers

micronized powders dont flow well by themselves so absorbed to surface of larger carrier

106
Q

mixing equipment (3)

A

mortar and pestle

  • most common, small scale
  • important to mix by geometric dilution steps
  • combines comminution and mixing (shear)

tumbling mixers/blenders

  • V-mixers, rotating cube, cone, etc
  • mixes powders or granules with good flowability

shear and forced-circulation mixer

  • blade mixers, planetary mizers, high-speed mizers, ribbon agitator mizer, nauta mizer
  • high speed mizer can be used easily break up agglomerates, not suitable for materials that fracture easily
  • provides more complete mizing
107
Q

powders/granules as a dosage form: advantages (5)

A
  • more chemically stable than liquids
  • easier to swallow than capsules and tablets
  • larger doses can be dispensed
  • faster dissolution and absorption rates (higher SA)
  • can be applied to many body cavities such as ears, nose, throat
108
Q

powders/granules as a dosage form: disadvantages

A

-less conventient to carry

hard to mask unpleasant tastes

not suitable for potent drug with low dose

not suitable for drugs that are inactivated or cause dmg to stomach

109
Q

types of powders and granules (5)

A
  • bulk powders
  • divided powders
  • powders and granules for oral solution or suspension and for injection
  • dusting powders
  • inhalation powders and nasal powders
110
Q

Bulk powders

A

packed in bulk containers

-nonpotent substances with large doses

111
Q

problem with bulk powders

A

inaccuracy of dosing

112
Q

bulk powders: effervescent powders/granules

A
  • special class of bulk powders
  • consist of API in combo with effervescent salt pairs
  • help cover unpleasant or bitter taste
113
Q

effervescent granule ratio

A

1 (citric acid) : 2 (tartaric acid) : 3.4 (sodium bicarbonate)

114
Q

divided powders or granules: bulk powders where individual doses are packaged separately

A

traditionally packed in paper, now replaced foil and plastic laminats

115
Q

divided powders or granules: powders and granules for oral solution or suspension and for injections (2)

A

reconstituted just prior to administration by adding water or sterile water for injections

drugs with physical and chemical stability problems that need to be dispensed in the dry state
ex. antibiotics

116
Q

dusting powders: use

A

designed for external use

-act as therapeutic, lubricant, or protective

117
Q

dusting powders: how dispensed

A

usually dispensed in relatively fine state (micronized) to increase efficacy and decrease irritation
-should be passed through 100-200 mesch sieve and should have excellent flowability

118
Q

dusting powders: how packed

A

packed in with perforated lid to allow powders to be dusted to the effective area

119
Q

Inhalation powders and nasal powders (3)

1) insufflator
2) why insufflator use decline
3) DPI

A

1) insufflations are fine powders of drugs dosed into the nose, ear, or throat by the use of an insufflator
2) use of conventional insufflators has declined due to poor patient complianse and dose non-uniformity
3) dry powder inhalers (DPIs) have replaced most traditional insufflation dosage forms

Pharm 125 (5 decks)

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