Cream's vs Ointments

Many different galenical forms are needed in the topical treatment of skin conditions. They range from liquids to powders including the most frequently used forms, the semi-solid creams and ointments. The latter galenical preparations are emulsions. An emulsion is a preparation of two immiscible liquids, one of which is dispersed in the other with the help of emulsifiers.

The Choice of a Galenic form depends:

• On intensity of skin dryness: Water in Oil (e.g. Ointment) are more effective for severe situation
• On body location: for hands, face ointments are too greasy
• On surface to be treated: lotion for large areas

On the other hand 0/W emulsions provide less lipids on the surface of the horny layer. Their hydrating effect is faster but of shorter duration. Due the evaporation of water from the formula they provide a cooling and soothing effect as it is desired in case of sunburn or inflammation.

As a general rule W/0 formulas are to be used for conditions with very dry skin when the horny layer is defective in its capacity to retain water (like in neurodermatitis).

However there are other considerations that have an impact in the choice of a galenical form:

• Location where the product is to be applied: for application on the face, creams are preferred over ointments as they do not leave a shiny glance on the skin.
• On hairy areas non-sticky 0/W formulas are more convenient to use
• When large skin surfaces have to be treated, lotions (W/0 or 0/W) are much more convenient to use, as they represent a more liquid form of the ointment and the cream.
• When direct contact can be painful, as for instance in desinfecting a fresh wound, a spray is the most appropriate.

Galenic forms which are particularly important in the field of Nappy Rash are pastes. A paste is a cream or an ointment to which a powder is added at high concentration (at least 10%). The powder is usually zinc oxide, but it can be titanium dioxide, talc etc. There are two types of pastes: lipophilic pastes and hydrophilic pastes. Hydrophilic pastes are powder into a cream (O/W) and lipophilic pastes are powder into an ointment (W/O).

Pastes have been used for years due to their supposed properties which are: "cooling, drying, exudate absorbing, and protecting" as often presented in textbooks. But, in fact, the true properties of pastes have only recently been analyzed and documented scientifically. Recent research has shown that the two types of pastes have very different properties regarding absorption of water and protection:

• hydrophilic pastes absorb water and dries the skin, something which is sought in case of oozing nappy rash. Further they adhere well to wet, oozing skin. On the other hand hydrophilic pastes are less protective, not making a continuous lipidic film on skin surface.
• lipophilic pastes, like ointments, are protective and also can be applied on skin which is not oozing. But they do not absorb water and do not dry the skin.

This means that the general properties cited above in brackets do not apply to all pastes, but must be declined according to paste type. Pastes are either absorbing but less protecting (hydrophilic pastes) or protecting but not absorbing (lipophilic pastes).