4. Ointments

Question 1

What are ointments?

Answer 1

Ointments are semisolid preparations intended for external application to the skin or mucous membranes

Question 2

What are the types of ointments?

Answer 2

Ointments may be Medicated or Un-medicated.

Question 3

What are the uses of non-medicated ointments?

Answer 3

Un-medicated ointments are used for the physical effects they provide as protectants. emollients, or lubricants.

Question 4

What are ointment bases?

Answer 4

Ointment bases, may by used for their physical effects or as vehicles for medicated ointments.

Question 5

What is the classification of ointment bases?

Answer 5

Ointment bases are generally classified by the USP into four groups:
(a) Oleaginous bases,
(b) Absorption bases,
(c) Water-removable bases,
(d) Water-soluble bases.

Question 6

What are oleaginous bases?

Answer 6

Oleaginous bases are also termed Hydrocarbon bases.
Water and aqueous preparations may be incorporated, but only in small amounts and with some difficulty.

Question 7

What are the characteristics of oleaginous bases?

Answer 7

On application to the skin, they have an emollient effect, protect against the escape of moisture, are effective as occlusive dressings, can remain on the skin for long periods without drying out and because of their immiscibility with water, are difficult to wash off.

Question 8

What are the examples of oleaginous bases?

Answer 8

Petrolatum, white petrolatum, white ointment, and yellow ointment.

Question 9

What are the types of absorption bases?

Answer 9

Absorption bases are of two types:
(a) those that permit the incorporation of aqueous solutions resulting in the formation of water-in-oil (W/O) emulsions (e.g., Hydrophilic Petrolatum), and
(b) those that are W/O emulsions (syn: emulsion bases) that permit the incorporation of additional quantities of aqueous solutions (e.g., Lanolin).

Question 10

What are the features of absorption bases?

Answer 10

1. These bases may be used as emollients, although they do not provide the degree of occlusion afforded by the oleaginous bases.
2. Absorption bases are not easily removed from the skin with water washing, because the external phase of the emulsion is oleaginous.
3. Absorption bases are useful as pharmaceutical adjuncts to incorporate small volumes of aqueous solutions into hydrocarbon bases.

Question 11

What are water-removable bases?

Answer 11

Water-removable bases are oil-in-water emulsions resembling creams.

Question 12

What are the characteristics of water-removable bases?

Answer 12

1. Because the external phase of the emulsion is aqueous, they are easily washed from skin and are often called water washable bases.
2. They may be diluted with water or aqueous solutions.
3. They can absorb serous discharges.

Question 13

What are examples of water-removable bases?

Answer 13

Hydrophilic ointment USP

Question 14

What are water-soluble bases?

Answer 14

Water-soluble bases do not contain oleaginous components.
They are completely water washable and often referred to as greaseless.

Question 15

What are characteristics of water-soluble bases?

Answer 15

1. Because they soften greatly with the addition of water, large amounts of aqueous solutions are not effectively incorporated into these bases.
2. They mostly are used for incorporation of solid substances.

Question 16

What are examples of water-soluble bases?

Answer 16

Polyethylene glycol (PEG) ointment, NF, is the prototype example of a water-soluble base.

Question 17

Which factors affect the selection of an ointment base?

Answer 17

Selection of the base to use in the formulation of an ointment depends on following factors:
1. Desired release rate of the drug substance from the ointment base
2. Desirability of topical or percutaneous drug absorption
3. Desirability of occlusion of moisture from the skin
4. Stability of the drug in the ointment base
5. Effect, if any, of the drug on the consistency or other features of the ointment base
6. Desire for a base easily removed by washing with water
7. Characteristics of the surface to which it is applied

Question 18

How are ointments prepared?

Answer 18

Ointments are prepared by two general methods,
(a) incorporation and
(b) fusion,
depending primarily on the nature of the ingredients.

Question 19

Give details of incorporation and fusion method.

Answer 19

From slides

Question 20

Give the packaging of ointments?

Answer 20

As all pharmaceutical ointments are intended for external use, a suitable container would be either an amber wide-necked ointment jar or metal collapsible tube.

Amber glass jars are preferable to clear glass jars as they protect the preparation from degradation by light.

More recently, plastic ointment jars have become available and although cheaper than glass jars, are less preferable because of an increased likelihood of the products reacting with the container (e.g. as can occur in preparations containing coal tar).

Question 21

What are the discard dates for ointments?

Answer 21

It is suggested that ointments are given a three-month discard date. This is significantly longer than the suggested discard date for extemporaneously prepared creams (which is four weeks) owing to the fact that ointments are less susceptible to microbial contamination.

Diluted ointments would normally be given a two-week discard.

Question 22

How are ointments labelled?

Answer 22

‘For external use only’ – This warning must be added to the label of all extemporaneously prepared ointments as all are for external use only.

‘Store below 15 C’ – Depending on the temperature of the environment, it may be advisable to place a storage temperature warning on the label.

Question 23

Give formula of simple ointment BP

Answer 23

Wool fat - 50g
Hard paraffin - 50g
Cetostearyl alcohol - 50g
Yellow or white soft paraffin -850g

Question 24

Give formula of suphur ointment BP

Answer 24

Precipitated sulfur, finely sifted- 100g
Simple ointment- 900g