Skin diseases: Topical methods of administration for local action

With skin conditions or skin infections, a patient is able to apply a medicine to the body itself, as opposed to an organ. This topical / local skin treatment also prevents a number of side effects that may occur when the patient is taking systemic medication. Topical therapy consists of an active ingredient, a suitable medium or base to deliver it, and often a preservative or a stabilizer to maintain the shelf life of the product. A cosmetically acceptable product is necessary. In addition, a user manual is required. Furthermore, topical medicines often do not contain odors or perfumes. The most commonly used topical methods of administration for local action in skin diseases include creams, gels, lotions, pastes and ointments.
  • Creams
  • Gels
  • Lotions
  • Pastas
  • Ointments
  • Safety of local steroids in skin diseases
  • Problems with the topical application to the skin
  • Contact allergy
  • Folliculitis
  • Systemic absorption

Creams

A cream is a semi-solid mixture of oil and water that is held together by an emulsifier. This is a somewhat more aqueous ointment and is also more fluid. It is easier to remove cream from the skin. The cream contains preservatives such as parabens. They are 'lighter' and rub easier than ointments. They have a high cosmetic acceptability and are useful for topical treatment of the face and hands. An aqueous cream is particularly useful as a replacement for soap.

Gels

Gels are semi-solid, syrupy preparations that mainly consist of water and alcohol (glycerol & ethanol). They are non-greasy and easily spreadable when they come into contact with the skin, making them easy to wash off. They are useful for treating hairy skin (such as the scalp).

Lotions

These are based on a liquid carrier such as water or alcohol (ethanol & isopropanol). They are usually thin and liquid and evaporate quickly which gives a cooling effect on the skin. They are useful for burning or fiery skin diseases and are ideal for use on hairy skin (such as the scalp). The cooling effect is also useful against the itch. Lotions may not contain alcohol in case of skin disorders, because if the patient uses this, he will get a very stinging skin. Furthermore, depending on the purpose, the lotion contains protective, healing, cleansing or caring substances.

Pastas

Pastes contain a high percentage (> 40%) of powder in an ointment base. This fairly solid is thick and stiff and difficult to remove from the skin. They are useful when the treatment has to take place precisely on the skin injury without smearing it on the surrounding normal skin. For example, zinc paste can be used in the treatment of skin diseases in which eczema (chronic skin disease with dry skin and itchy skin) occurs.

Ointments

These are semi-solid preparations that do not contain water. Ointments are usually based on oils or fats, such as polyethylene glycol (water-soluble) or paraffin (fat). The ointment producer mixes these fatty substances with one or more medicines. They feel greasy or sticky. They are the best treatment for skin conditions where a dry, flaky skin is created because they hydrate (moisturize) the stratum corneum well. In addition, an ointment results in a more efficient functioning of an active ingredient (for example, a steroid). If patients do not like the oily nature of ointments, the use of a cream is better than no treatment, but creams are less effective and the patient should use it more often. It is then sometimes a good compromise to apply a cream to the face and use an ointment elsewhere on the body.

Safety of local steroids in skin diseases

Since the patient with a skin disease uses preparations with a suitable concentration in a place on the body, these drugs can be used safely in the intermittent long term without problems. If the patient abuses powerful steroids, they do lead to skin atrophy and symptoms such as stretch marks (red and white stripes on the skin), wrinkles, fragile skin and dilated blood vessels on the skin (telangiectasia).

Problems with the topical application to the skin

Contact allergy

Contact allergy is not uncommon with topical preparations and occurs with unusually resistant diseases or with an apparent deterioration of a skin disease after the application of a substance. This is more common with creams and is often the result of allergies to the preservative or emulsifier. An allergy is also possible from the active ingredient itself (for example, neomycin or hydrocortisone).

Folliculitis

Folliculitis (inflammation of the hair follicles with pain and itching of the skin) occurs as a result of a blockage of the hair follicles. The patient should apply creams and ointments to the skin in the same direction as hair growth to prevent blockage. Folliculitis occurs more frequently when using ointments in warm weather, especially if the skin injury is covered with a dressing. A lighter cream is a better option with folliculitis.

Systemic absorption

Systemic absorption only occurs when very large inflamed skin areas receive topical treatment, and especially when the skin lesions are covered with a closed dressing or polyurethane films after treatment (wound film that protects the skin). Newborns are particularly sensitive to this because of the relative increase in body surface volume.

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