Topical Semi-solid Preparations of the British Pharmacopoeia

Question 1

What is the purpose of a cream?

Answer 1

Creams are formulated to provide preparations that are essentially miscible with the skin secretion. They are intended to be applied to the skin or certain mucous membranes for protective, therapeutic or prophylactic purposes especially where an occlusive effect is not necessary.
Creams should not normally be diluted. However, should dilution be necessary care should be taken, in particular, to prevent microbial contamination. The appropriate diluent should be used and heating should be avoided during mixing. Excessive dilution may affect the stability of some creams. If diluted, creams should normally be used within two weeks of their preparation.

Question 2

What is the purpose of an ointment

Answer 2

Ointments are formulated to provide preparations that are immiscible, miscible or emulsifiable with the skin secretion. Hydrophobic ointments and water-emulsifying ointments are intended to be applied to the skin or certain mucous membranes for emollient, protective, therapeutic or prophylactic purposes where a degree of occlusion is desired. Hydrophilic ointments are miscible with the skin secretion and are less emollient as a consequence.