Page 64 - Practical DF2 Corrected (2)

Pharm D Clinical Pharmacy program 2024-2025 Level 2, Semester 2 Pharmaceutical Dosage Forms II (PT 405)

Ointments

• Definition:
They are semisolid preparations intended for external application to the skin.

• There are two methods of preparations:

A. Trituration method
- When the base is soft.
- Finely divided insoluble powders are first levigated by levigating agent
(mineral oil or small quantity of the base) to form a smooth nucleus
which is then incorporated to the base.

B. Fusion Method:
- When the ingredients have high melting point. The ingredients are
melted together at the lowest temperature and stirred gently until cool.

Notes:

1. Melting time can be shortened by

1.1. Grating the high melting point ingredients (such as hard paraffin and the
emulsifying wax) and heated until other ingredients are being weighed.

1.2. Melting all ingredients together.
1.3. Stirring during melting.
1.4. Lowering the dish as far as possible into the water bath so that the maximum

surface is exposed to heat.

2. Vigorous stirring causes excessive aeration which should be avoided

2.1. Makes colored preparation pale in appearance.
2.2. Increase the risk of oxidation of the base or oxygen sensitive medicaments.
2.3. May lead to contraction after packing which may cause partial collapse of

the tubes which used as containers.

3. Localizing cooling may result in separation of hard lumps of higher
melting point ingredients and rises from:

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