The vehicle of an ointment is known as ointment base. The choice of a base depends upon the clinical indication for the ointment, and the different types of ointment bases are:
Hydrocarbon bases e.g. hard paraffin, soft paraffin
Absorption bases e.g. wool fat, beeswax
Water soluble bases e.g. macrogols 200, 300, 400
Emulsifying bases e.g. emulsifying wax, cetrimide
Vegetable oils e.g. olive oil, arachis oil, coconut oil
The medicaments are dispersed in the base and later they get divided after the drug penetration into the living cells of skin.
Ointments are homogeneous, semi-solid preparations intended for external application to the skin or mucous membranes. They are used as emollients or for the application of active ingredients to the skin for protective, therapeutic, or prophylactic purposes and where a degree of occlusion is desired.
Ointments are formulated using hydrophobic, hydrophilic, or water-emulsifying bases to provide preparations that are immiscible, miscible, or emulsifiable with skin secretions. They can also be derived from hydrocarbon (fatty), absorption, water-removable, or water-soluble bases.