Shampoos and other prepara- tions for scalp and hair condi-

13.9 Shampoos and other prepara- tions for scalp and hair condi-

Skin tions

13.1.1 Vehicles

13.10 Anti-infective skin prepara- tions

647 Both vehicle and active ingredients are important in the

13.10.1 Antibacterial preparations

treatment of skin conditions; the vehicle alone may have

13.10.1.1 more than a mere placebo effect. The vehicle affects the

Antibacterial preparations only degree of hydration of the skin, has a mild anti-inflamm- used topically

atory effect, and aids the penetration of active drug.

13.10.1.2 Antibacterial preparations also Applications are usually viscous solutions, emulsions, used systemically

or suspensions for application to the skin (including the

13.10.2 Antifungal preparations

scalp) or nails.

13.10.3 Antiviral preparations

Collodions are painted on the skin and allowed to dry to leave a flexible film over the site of application.

13.10.4 Parasiticidal preparations

Creams are emulsions of oil and water and are generally

13.10.5 Preparations for minor cuts and well absorbed into the skin. They may contain an anti- abrasions

microbial preservative unless the active ingredient or

13.11 basis is intrinsically bactericidal and fungicidal. Gener- Skin cleansers and antiseptics 656

ally, creams are cosmetically more acceptable than

13.11.1 Alcohols and saline

ointments because they are less greasy and easier to apply.

13.1.2 Suitable quantities for prescribing BNF 57 Gels consist of active ingredients in suitable hydrophilic

not apply to corticosteroid preparations—for suitable or hydrophobic bases; they generally have a high water

quantities of corticosteroid preparations see section content. Gels are particularly suitable for application to

the face and scalp. Lotions have a cooling effect and may be preferred to

ointments or creams for application over a hairy area. Lotions in alcoholic basis can sting if used on broken

13.1.3 Excipients and

skin. Shake lotions (such as calamine lotion) contain

sensitisation

insoluble powders which leave a deposit on the skin surface.

Excipients in topical products rarely cause problems. If a Ointments are greasy preparations which are normally

patch test indicates allergy to an excipient, products anhydrous and insoluble in water, and are more occlu-

containing the substance should be avoided (see also sive than creams. They are particularly suitable for

Anaphylaxis, p. 173). The following excipients in topical chronic, dry lesions. The most commonly used ointment

preparations are rarely associated with sensitisation; the bases consist of soft paraffin or a combination of soft,

presence of these excipients is indicated in the entries liquid and hard paraffin. Some ointment bases have both

for topical products. See also Excipients under General hydrophilic and lipophilic properties; they may have

Guidance, p. 2.

occlusive properties on the skin surface, encourage hydration, and also be miscible with water; they often have a mild anti-inflammatory effect. Water-soluble oint-

Imidurea ments contain macrogols which are freely soluble in

Beeswax

Isopropyl palmitate water and are therefore readily washed off; they have

Benzyl alcohol

Butylated hydroxyanisole N-(3-Chloroallyl)hexami-

a limited but useful role where ready removal is desir- Butylated hydroxytoluene nium chloride (quater- able.

Cetostearyl alcohol (includ- nium 15) ing cetyl and stearyl

Polysorbates Pastes are stiff preparations containing a high propor-

Propylene glycol tion of finely powdered solids such as zinc oxide and

alcohol)

Sodium metabisulphite starch suspended in an ointment. They are used for

Chlorocresol

Edetic acid (EDTA) Sorbic acid circumscribed lesions such as those which occur in

Wool fat and related sub- lichen simplex, chronic eczema, or psoriasis. They are

Ethylenediamine

stances including less occlusive than ointments and can be used to protect

Fragrances

Hydroxybenzoates (para-

lanolin 1

inflamed, lichenified, or excoriated skin.

bens)

Dusting powders are used only rarely. They reduce friction between opposing skin surfaces. Dusting pow- ders should not be applied to moist areas because they can cake and abrade the skin. Talc is a lubricant but it does not absorb moisture; it can cause respiratory irritation. Starch is less lubricant but absorbs water.