Formulation

Topical corticosteroids are available in various formulations—creams, ointments, solutions, lotions, gels, sprays, shampoos—to suit the type of skin lesion, severity of condition, site of application and patient preference.

The formulation of a topical corticosteroid affects absorption and potency. Absorption-enhancing ingredients (eg propylene glycol in the optimised-vehicle formulation) and occlusion can increase relative potency. A corticosteroid in an ointment is generally more potent than the same concentration of corticosteroid in a cream.

Creams are mixes of water suspended in oil. They are moisturising and can vanish into the skin, which may be more cosmetically appealing. However, they often contain preservatives, which can increase the risk of irritation, stinging and contact allergy. They are not occlusive.

Ointments are usually semi-solid, water-free or nearly water-free, greasy, sticky and protective. Ointments are less likely to cause irritation and contact allergy because they do not require preservatives for stability. However, they can cause folliculitis and miliaria because they are occlusive.

Lotions, gels and solutions can contain alcohol, which has a drying effect and can sting inflamed skin. They are useful in treating hairy areas because lotions penetrate the skin easily and leave little residue, and gels dry quickly and do not cause matting.

In addition, choice of topical formulation can depend on the:

• nature of the skin condition
  • wet or oozy skin conditions—creams and lotions are appropriate
  • dry scaly skin conditions—ointments are appropriate
  • inflamed skin—wet compresses and soaks, followed by creams or ointments, are appropriate
• site of application
  • palms or soles—ointments or creams may be preferred depending on level of greasiness desired or tolerated
  • skin folds—creams or lotions are usually preferred because ointments may be too occlusive for these areas
• patient preference.