physical effects: protectants, emollients, or lubricants

can also be vehicles for medicated ointments 

1. hydrocarbon bases
2. absorption bases
3. water removable bases
4. water soluble bases 

• provide emollient effect
• protect against the escape of moisture
• occlusive dressing
• remain on skin for long periods without drying out 
• contain oleaginous ingredients 
• water - immiscible , difficult to wash off

• water absorbing or emulsifying property
• can absorb reasonable amounts of water or aqueous solutions without losing consistency
• AKA emulsifiable ointment bases
• dont provide occlusion provided by hydrocarbon bases
• not easily water washable, external phase is oleaginous 
• useful when small volumes of aqueous solutions need to be incorporated into hydrocarbon bases 

• contain water
• water in oil emulsion. also called emulsion bases. permit incorporation of additional quantities of water but only accept limited amounts of water because they already contain it. 

oil in water emulsions 

water washable: can be readily washed from skin or clothing with water. 

water is external phase so these bases may be diluted with water 

ex: hydrophilic ointment 

hydrophilic ointment 

"greaseless ointment bases" 

contain water soluble constituents only. 

ex: polyethylene glycol ointment 

technique used if the substance to be incorporated into a vehicle is a powder. 

the technique uses an intervening liquid in which the powder is insoluble. 

the process of grinding a solid between hard surfaces in the presence of a liquid in which the solid is not soluble until it has been reduced to a fine almost impalpable material.