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II. Water soluble (Hydrophilic) Bases :
▪ They do not contain any oleaginous components, completely water washable, non staining
and non occlusive
▪ They are often referred to as greaseless bases
▪ Polyethylene Glycol Ointment, NF, is the prototype example of a water-soluble base.
▪ The general formula for preparation of 1000 g of polyethylene glycol ointment is
Polyethylene glycol 3350 (solid) 400 g
Polyethylene glycol 400 (liquid) 600g
▪ Disadvantages:
1. Because they soften greatly with the addition of water, large amounts of aqueous
solutions are not effectively incorporated into these bases
2. Very irritant to mucous membrane (absorb water from surrounding tissues)
3. Cause skin dehydration (thus hinders percutaneous absorption)
4. May contain peroxide impurities

III. Absorption Bases:
▪ They are characterized by:
1. May be used as emollients, although they do not provide the degree of occlusion
afforded by the oleaginous bases
2. The spreading properties of these formulations are more favorable than for
hydrocarbon bases
3. Not easily removed from the skin with water washing, since the external phase of
the emulsion is oleaginous
4. Incorporation of small volumes of aqueous solution is possible
▪ Absorption bases are useful as pharmaceutical adjuncts to incorporate small volumes of
aqueous solutions into hydrocarbon bases by incorporating the aqueous solution into the
absorption base, and then incorporating this mixture into the HC base
▪ Uses: Protectants, emollient, and vehicle for aqueous solutions and solid drugs
▪ Examples of absorption bases:
1. Hydrophilic Petrolatum, USP (Aquaphor)
2. Anhydrous Lanolin, USP
3. Lanolin, USP

IV. Water miscible/Removable Bases:
▪ These are water-miscible bases that are used to form O/W emulsions for topical applications.
The use of these bases offers a number of advantages, including:
1. They are able to accommodate large volumes of water, e.g. excess moisture at the
site of application, exudates from abrasions and wounds
2. They are not occlusive
3. They may be easily washed from the skin and from clothing
4. Furthermore, they may be readily applied to hair
5. Can absorb serious discharges

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