Powders and granules

Question 1

Dusting powder

Answer 1

Dusted on skin with sifter top container, may contain active ingredient, base helps deliver active agent and protects skin from irritation and friction, powder absorbs secretions- drying

Question 2

When should dusting powder not be applied

Answer 2

To broken skin

Question 3

Insufflations

Answer 3

Extremely fine powder introduced into body cavities

Question 4

What size sieve do extemporaneous insufflations pass through

Answer 4

100 mesh sieve

Question 5

Aerosol powders

Answer 5

Powders dispensed under pressure, powder of definite size to prevent clogging of valve and provide uniform application

Question 6

Why is particle size important in accuhalers and turbuhalers

Answer 6

Too large = particles get deposited on back of throat and don’t make it to the lung
Too small = particles make it to the lung but then get exhaled

Question 7

Benefits of bulk powder

Answer 7

Non potent, can be dosed with acceptable accuracy and safety using measuring devices

Question 8

Divided powders

Answer 8

Single doses individually wrapped in cellophane, metallic foil or paper

Question 9

What is better, bulk or divided powders

Answer 9

Divided powders as they are more accurate then bulk powders because the dose does not need to be measured

Question 10

Granules

Answer 10

Agglomerates of powders to make larger more free flowing particles

Question 11

Oral powders/granules vs tablets/capsules

Answer 11

Oral powders and granules have a faster dissolution rate, tablets and capsules require disintegration before dissolution

Question 12

Chemical nature of effervescent granules

Answer 12

Contain acid and alkali that react with water to make CO2

Question 13

Ratio of ingredients in effervescent granules

Answer 13

Citric acid and tartaric acid in 1:2 ratio

Question 14

Dry/fusion method for creating effervescent granules

Answer 14

Citric monohydrate contains a water molecule, heat releases water molecule, provides moisture, released water creates moist mass/clumps to form granules

Question 15

Wet method for creating effervescent granules

Answer 15

Add alcohol/water mix to make dough, use sieve to put wet mass through, place wet granules in oven to dry

Question 16

What is micrometrics

Answer 16

Science of small particles and particle size distribution

Question 17

What properties of powders does micrometrics cover

Answer 17

Shape, bulk/true volume, apparent density, porosity, flowability

Question 18

What is the importance of particle size

Answer 18

Affects drug release rate (smaller particle = faster dissolution), affect sedimentation rate, aerosol pulmonary drug delivery, mixing of powders, flow properties of powders, chemical stability of powder

Question 19

How do we define particle size

Answer 19

The equivalent sphere

Question 20

Methods of particle size analysis

Answer 20

Sieve methods, microscope methods, electrical stream sensing zone method, laser light scattering methods, sedimentation methods

Question 21

Sieve method

Answer 21

Stack of sieves, each lower sieve has lower aperture size than the one above it

Question 22

Advantages and disadvantages of sieve analysis

Answer 22

Easy, inexpensive, can get reduction in particle size if prolonged agitation, irregular shaped particles will eventually orient to pass through, shift in apparent size to lower values, need reproducible shaking technique

Question 23

Advantages and disadvantages of microscopy

Answer 23

Can view particles directly, only 2D view, don’t know particle depth, have to count 500-1000 for statistical validity, time consuming, labour intensive, subject to error

Question 24

Ferets diameter

Answer 24

Distance between 2 futhermost points on particle

Question 25

Martins diameter

Answer 25

Line that divides particle into 2 equal parts

Question 26

Projected area diameter

Answer 26

Diameter of a circle that has the same projected area as the particle

Question 27

Stokes law

Answer 27

Sedimentation rate of a particle in a fluid increases with size

Question 28

Do larger or smaller particles settle the quickest

Answer 28

Larger

Question 29

How does a Coulter counter work

Answer 29

Particles suspended in dilute electrolyte, flow individually through aperture, volume displaced changes resistance, number of changes = number of particles

Question 30

What does a Coulter counter measure

Answer 30

Particle size

Question 31

How does laser light scattering work

Answer 31

Shine a laser beam into suspension, measure scatter of light, angle and intensity correlate with particle size

Question 32

What types of formulations can laser light scattering be used for

Answer 32

Emulsions, suspensions, dry powders and aerosols