L5: Creams/ Ointments/ Pastes

Question 0

What is a cream always miscible with?

Answer 0

It’s continuous phase

Question 1

What is a cream?

Answer 1

Two phase semisolid emulsion.

Question 2

What type of cream is an ‘oily cream’ and what is its continuos phase?

Answer 2

Continuous phase = oil.

–> w/o cream.

Question 3

What can oily creams be used as?

Answer 3

Bases.

–> and have good emollient properties.

Question 4

Describe oily creams.

Answer 4

They are:
Creamy
White or translucent
Rather stiff

Question 5

What type of cream is an ‘aqueous cream’ and what is its continuos phase?

Answer 5

Oil in water.

Continuous phase = water.

Question 6

What can aqueous creams be used as?

Answer 6

As a base for RAPID ABSORPTION, and penetration of drugs.

Question 7

Why are creams more acceptable than ointments? (4)

Answer 7

1) Less greasy
2) Easier to spread
3) Easier to wash away
4) Water evaporating from w/o cream has cooling and soothing effect.

Question 8

How are drugs incorporated into a cream?

Soluble solids

Answer 8

Added into the molten base, at the LOWEST possible temperature, and stirred until cold.

Question 9

How are drugs incorporated into a cream?

Insoluble solids

Answer 9

Incorporated using a tile and spatula.

More than one –> doubling up technique.

Question 10

How are drugs incorporated into a cream?

Non volatile miscible liquids

Answer 10

Mixed with the molten base in an evaporating basin.

Question 11

How are drugs incorporated into a cream?

Volatile or immiscible liquid

Answer 11

Triturate with the base in ointment tile.

Small amount of liquid can be folded into the base.

Question 12

What type of surfactant can be used for o/w creams?

Answer 12

Ionic AND non ionic

Question 13

What type of surfactant can be used for w/o creams?

Answer 13

Non ionic

Question 14

What are ointments?

Answer 14

Semisolid preparations with greasy bases.

Question 15

Ointment bases consist of a mixture of….. (3)

Answer 15

Waxes

Fats

Oils

Question 16

What are 4 types of ointment bases?

Answer 16

1) Hydrocarbon bases
2) Absorption bases
3) Water-miscible/emulsifying bases
4) Hydrophilic (water soluble) bases

Question 17

Describe hydrocarbon bases (3)

Answer 17

Water free mainly

Not absorbed by the skin

Usually consist of soft paraffin/ mixture of soft and liquid paraffin.

Question 18

Hydrocarbon bases are used mainly for their emollient effect… Describe how?

Answer 18

Form a greasy waterproof film on the skin,
to prevent water loss from skin,
and therefore improve hydration of the skin.

Question 19

Describe absorption bases?

Answer 19

Already w/o emulsion that permits the incorporation of small, additional quantities of aqueous solution.

Question 20

Describe water-miscible emulsifying bases

Answer 20

Anhydrous bases,
Containing o/w emulsifying agents,
Making them miscible with water.

Question 21

Describe hydrophilic bases

Answer 21

Contain both water soluble and insoluble components.

Incompatible with many chemicals, e.g. Phenol, iodine,potassium iodide.

Reduce anti microbial properties of quaternary ammonium compounds

Question 22

Name advantages of hydrophilic bases (3)

Answer 22

Non irritant to skin
Easily washed off
Allows medications to mix with skin secretions

Question 23

General considerations of selecting a base (5)

Answer 23

1) desired release rate of particular drug from ointment base
2) enhancing drug absorption
3) short/long term stability of the drug in base
4) influence of the drug on the features of the base
5) patient factors

Question 24

How are semisolid products packed?

Answer 24

Always packed in jars or in tubes

Question 25

Factors needed to consider during packaging and storage (5)

Answer 25

1) air
2) light
3) moisture
4) heat
5) possible chemical reactions between preparation and the container

Question 26

What are pastes?

Answer 26

Semisolid preparations for external use.

Very stiff.