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The Medicine 2 - Sem 2 > Comminution > Flashcards

Comminution Flashcards

1
Q

Particle size influences bioavailability - a smaller particle size results in faster dissolution. True or false?

A

True

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2
Q

What is meant by comminution?

A

The reduction of solid materials from a bigger mean particle size to a smaller mean particle size

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3
Q

The efficiency of a conventional ball mill is greater than that of a vibratory mill. True or false?

A

false, vibratory mill more efficient

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4
Q

Dry sieving is usually more efficient than wet sieving. True or false?

A

False

Wet sieving more efficient

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5
Q

Which milling method is defined as self-classifying?

A

Cutter mill

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6
Q

Separation efficiency is the effectiveness of a given process in separating particles into oversized and undersized fractions. True or false?

A

True

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7
Q

How many micrometres is a coarse powder?

A

> 350

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8
Q

How many micrometres is a medium/fine powder?

A

100-350

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9
Q

How many micrometres is a fine powder?

A

50-100

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10
Q

How many micrometres is a very fine powder?

A

10-50

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11
Q

How many micrometres is a micronised powder?

A

<10

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12
Q

The sieve method is simpler and more cost effective than microscopy. True or false?

A

True

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13
Q

The sieve method provides particle shape information. True or false?

A

False

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14
Q

Which particle size analysis method sorts a large quantity of particles into different size ranges and determines the particle size distribution based on the mass collected in each range?

A

Sieve method

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15
Q

Mohs’ scale is a quantitative measure of hardness. True or false?

A

False

Qualitative

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16
Q

Brinell or vickers is a quantitative measure of hardness true or false?

A

True

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17
Q

Which milling method achieves a particles size of 1-300 micrometres?

A

Attrition

18
Q

Which milling method achieves a particles size of 100-100,000 micrometres?

A

Cutting

19
Q

What particle size can a ball mill achieve?

A

1 to 200 micrometres

20
Q

Which milling method achieves a particles size of 20-100,000 micrometres?

A

End runner

21
Q

Which milling method achieves a particle size of 1-1000 micrometres?

A

Vibration

22
Q

Which milling method achieves a particle size of 600-200,000 micrometres?

A

Roller

23
Q
  1. Which milling method achieves a particle size of 30 -10,000 micrometres?
A

Hammer

24
Q

What particle size can a fluid energy mill achieve?

A

1-100,000 micrometres

25
Q

Which milling method achieves a particle size of 10-9,000 micrometres?

A

Pin mill

26
Q

What are larger particle sizes usually used for?

A

granules used in capsules or for suspensions

27
Q

What type of particles are used in dry powder inhalers?

A

Small solid particles

28
Q

How can milling change the characteristics of poorly soluble drugs?

A

can modify their wetting and dissolution, solubility also directly linked to particle size so important that all particles have similar size, shape and surface characteristics

29
Q

Why is particle size important in parenteral administration?

A

influences accumulation of micro-particulates after admin

30
Q

Size of particle affects manufacturing processes such as mixing but what other characteristics of powders?

A

flowability and packing properties, quality control to guarantee uniformity, prediction of pharmaceutical effect and efficacy

31
Q

To adequately describe a particle what do you need?

A

Precise measurements of at least 3 dimensions

32
Q

What is the equivalent sphere method?

A

consider a particle to be a sphere and reduce the 3 dimensions to a single number

33
Q

What are some shape descriptors used to classify particle shape?

A

spherical smooth, rounded, acicular, spherical rough, angular, spherical irregular, elongated irregular, dendritic

34
Q

What is the ideal particle size range?

A

25-50 micrometres

35
Q

Why can particle sizes smaller than 15 micrometres be problematic?

A

they tend to aggregate, affecting quality of the mix and can cause an uneven distribution of the powder

36
Q

When designing comminution processes what is important to consider?

A

the toughness, hardness, additional energy requirements and particle shape

37
Q

The extent of size reduction is always related to what?

A

Milling time

38
Q

What is size reduction mainly driven by?

A

crack propagation, localized stress produces strain in the particles which essentially ruptures the bonds and the crack spreads

39
Q

Which processes can be used to separate different particle sizes?

A

agitation methods, brushing methods, centrifugal methods

40
Q

What are the most common milling methods and how do they work?

A

Cutter mill (series of knives and blades on a rotor, blades fracture the particles, screen to retain larger material), Roller mill (two rollers, one mechanically driven, second rotated by friction as particles pass through), Ball/vibration mill (filled with porcelain or stainless-steel balls, in ball milling impact causes reduction but in vibrational, reduction occurs because of constant impact and vibration of balls)

The Medicine 2 - Sem 2 (14 decks)

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