Lecture 2: Powder Dosage Form

Question 1

What are powders?

Answer 1

Intimate mixtures of finely divided drug or drug and excipient for internal or external use

Question 2

What is 1 advantage and 1 disadvantage to powder?

Answer 2

1) Advantage – used to prepare many other dose forms

2) Disadvantage – as a dose form has limited use

Question 3

What is micromeritics?

Answer 3

The science of small particles; includes particle size, distribution and shape, angle of repose, porosity, true and bulk volume, and tapped and apparent density

Question 4

What 4 factors do particle size and shape influence?

Answer 4

1) Dissolution rate
2) Suspendability
3) Uniformity
4) Grittiness

Question 5

What 3 properties is small particle size associated with?

Answer 5

1) Larger surface area
2) Faster dissolution
3) Better suspendability

Question 6

What is needed for a truly homogenous mixture?

Answer 6

Particles of similar shape and size

Question 7

How is particle shape seen and inferred?

Answer 7

Seen by microscopy; inferred through angle of repose

Question 8

Describe angle of repose

Answer 8

A powder is allowed to flow through a funnel and fall freely onto a surface. The height and diameter of the resulting cone are measured and the angle of repose is calculated by tan (theta) = h (height)/r (radius)

Question 9

What can be determined about powders with a low angle of repose?

Answer 9

They flow freely

Question 10

What is needed for a particle to have better flow?

Answer 10

More spherical and smooth

Question 11

What does poor flow lead to?

Answer 11

Poor mixing of tablet components

Question 12

What is true density?

Answer 12

The weight per unit volume

Question 13

What affects apparent and tapped density for solids?

Answer 13

Particle size and shape

Question 14

What happens to apparent density with larger, rougher particles?

Answer 14

They have more space between them, causing an apparent larger volume per unit of mass

Question 15

What is levigation with a mortar and pestle useful for?

Answer 15

Suspensions

Question 16

With respect to suspensions, what is small particle size useful for?

Answer 16

Dispersion and suspendability

Question 17

What happens to powders with different particle sizes?

Answer 17

They segregate and don’t remain homogeneous

Question 18

What should be done to a powder with different particle sizes?

Answer 18

Trituration

Question 19

When does a eutectic mixture occur?

Answer 19

When the melting point of the mixed materials is depressed to the point they liquefy

Question 20

What does the occurrence of a eutectic mixture depend on?

Answer 20

Proportions of materials, use of trituration, and presence of adsorbent material

Question 21

What are 5 examples of materials that form eutectic mixtures?

Answer 21

1) Acetaminophen
2) Aspirin
3) Camphor
4) Salicylic acid
5) Urea

Question 22

What are 2 strategies for dealing with eutectic mixtures?

Answer 22

1) Allow eutectic mixture to form while triturating and add an adsorbing inert material until mix is powder-like
2) Mix the components separately with adsorbent

Question 23

What are 2 types of powders that are designed for external use?

Answer 23

1) Dusting powder

2) Powder for dissolution followed by soaking or application

Question 24

What are 4 types of powders that are designed for internal use?

Answer 24

1) Tablets
2) Capsules
3) Powder papers
4) Powders in bulk (ex: Metamucil)

Question 25

What are 3 advantages to solid-state products?

Answer 25

1) Increased stability
2) Flexible release or contents
3) Convenient administration and packaging

Question 26

What are bulk powders?

Answer 26

Non-potent medications which can be dosed with acceptable accuracy using teaspoons or tablespoons

Question 27

What are 3 common bulk powders?

Answer 27

1) Dietary supplements
2) Antacids
3) Laxatives

Question 28

What must be considered when choosing a diluent for an external bulk powder?

Answer 28

Must be inert, free of grittiness, protects skin, and absorbs secretions

Question 29

What are 3 common diluents used for external bulk powders?

Answer 29

1) Bentonite
2) Talc
3) Kaolin

Question 30

What are divided powders useful for?

Answer 30

Young children or the elderly

Question 31

What are divided powders?

Answer 31

Single dose of powdered medication wrapped in paper or foil-plastic laminates

Question 32

Why are divided powders useful?

Answer 32

Delivers an accurate quantity of medication and can be used for potent drugs; also useful when medication is only available as a solid oral dose form and patient cannot take it

Question 33

What are granulations?

Answer 33

Coarse particles made by blending powders then moistening to form a pasty mass; the mass is then passed through a sieve and formed granules are allowed to air-dry

Question 34

What are granulations used for?

Answer 34

Preparation of tablets and sometimes capsules

Question 35

When should granulations be used?

Answer 35

For non-potent drugs as a bulk preparation where a teaspoon/tablespoon is used to measure and the product is dissolved in water

Question 36

How can effervescent granules be made?

Answer 36

By mixing granules made with citric and tartaric acids with granules made with sodium bicarbonate

Question 37

What is the equation for surface area?

Answer 37

square root of (height x weight in kg)/3600