SWEAT GLANDS

Millions of tiny sweat glands are located in the dermis all over the body. There are two types of sweat gland.

Exocrine glands are the commoner type and are mostly concentrated in the palms, soles and forehead. They become active when the body temperature rises through exercise, a hot environment or emotional stress. They promote cooling by evaporation of their secretion on the skin’s surface.

Apocrine glands are found in the axillary, anal, genital and mammary areas of the body. Sweat is produced by these glands under the influence of the sympathetic nervous system when emotionally stressed.

SEBACEOUS GLANDS

Sebaceous glands are situated in the dermis. Their function is to produce sebum, an oil containing fatty acids, cholesterol and substances toxic to bacteria. Sebum is discharged through the sebaceous duct into the hair follicle, moving along the shaft of the hair to the skin surface, keeping both the skin and the hair soft. The glands are located all over the body, except the palms and soles, in close association with body hair.

NAILS

The nails are keratinised epidermal cells that have a horny texture and serve to protect the fingers and toes. A nail consists of:

HAIR

A hair behaves in a similar way to a nail, in that it is formed by a group of cells at its base that multiply and push forwards to the surface of the skin, where it is ultimately shed or removed. The base of each hair, referred to as the bulb, is situated in the dermis. A pointed projection of the dermis protruding into the hair bulb is known as the papilla. The papilla nourishes the cells of the hair follicle housing the hair root. The root is the part beneath the surface of the skin; the shaft is the visible part. By the time the hair follicle reaches the surface, its cells have become hard and keratinised.

ENDOGENOUS ECZEMA

EXOGENOUS ECZEMA

TREATMENT

Eczema and dermatitis are treated similarly, but it is especially important in cases of dermatitis to avoid or remove the causative agent (e.g. cosmetic, household cleaner). Treatment with bland emollients is often helpful (allowing patient choice). Creams for direct application are easy to use and provide welcome relief from itching. Emollient bath additives are useful in many cases of dry skin. The use of topical corticosteroids, starting with a mild product then moving to a moderate product depending on response, provides symptom control. Overuse of corticosteroids must be avoided due to the dangers of absorption leading to systemic side effects (see p. 341). Alternating emollients with corticosteroids may be a useful strategy.

Coal tar preparations have a limited place in the treatment of chronic atopic eczema. Poor acceptance by the patient and possible long-term side effects have curtailed their use. Ichthammol has properties similar to those of coal tar but is milder in action. Ichthammol has antipruritic properties that may be useful in chronic eczema.

In situations in which allergy and/or infection are present, oral antihistamines or antibiotics will be required. The use of gamolenic acid in atopic eczema is not based on firm evidence of therapeutic benefit. Seborrhoeic eczema of the scalp is treated by shampoos containing coal tar or selenium, or a specially formulated corticosteroid scalp preparation in the form of a mousse. The preferred treatment is a shampoo containing ketoconazole, an antifungal agent. Figure 25.2 shows the sites of action of various treatments. Table 25.1 outlines the use of immunosuppressant drugs in both eczema and psoriasis.

Fig. 25.2 Sites of drug action in eczema.

(From Page CP, Hoffman BF, Curtis M et al. 2006 Integrated pharmacology. Mosby, Edinburgh. With permission of Mosby.)

Table 25.1 Immunosuppressant drugs used in the treatment of skin diseases

TREATMENT

Topical and oral therapies are available, many of which require specialist advice. For mild conditions, an emollient may be useful to minimise scaling. This will seldom provide adequate relief but can be helpful when plaque thickness has been reduced by other therapies. Salicylic acid (2% ointment) has keratolytic properties. Care should be taken with products containing high concentrations of salicylic acid to control the amounts applied in order to avoid absorption leading to systemic toxicity.

Coal tar preparations have anti-inflammatory and antiscaling properties. Choice of product will depend on the site of the plaques and the preference of the patient. Dithranol is a more potent agent than coal tar. The use of dithranol requires expert management by prescriber, nurse and patient. Dithranol acts by combining with deoxyribonucleic acid, resulting in the inhibition of nucleoprotein synthesis and so diminishing cellular proliferation. Short-contact appli-cations of 1 h are effective, the strength of dithranol depending on the patient’s condition within a range of 0.15–2%, often incorporated in Lassar’s paste. Dithranol can cause severe skin irritation and, for this reason, it must be used strictly in accordance with the prescription. It must be applied only to psoriatic plaques (protecting surrounding skin), commencing with a low concentration and gradually increasing this to an optimum concentration that produces a therapeutic effect without irritation. Dithranol stains skin purple-brown, but this fades in 2–3 weeks. It is essential for nurses to wear gloves and avoid all contact, especially with the eyes, when applying dithranol preparations. Hands should be thoroughly washed after use.

A range of strengths of dithranol is available in cream formulations, which are easier to apply than stiff pastes. Contact time will depend on the strength of active ingredient (e.g. 0.1% overnight contact, 1–2% maximum of 1 h). A novel dermal delivery system for dithranol presents dithranol (1 or 3%) in a special cream. The dithranol is incorporated in a protective ‘sandwich’ that maintains the chemical stability of dithranol. Contact time is 30 min for the 3% cream when used on the scalp under medical supervision.

Topical corticosteroid creams have a limited place in the treatment of plaque psoriasis. Skin atrophy can result and render the condition intractable to treatment. A mild or moderate corticosteroid may be used in the flexures. Potent corticosteroids may be used on the scalp in the short term.

Calcipotriol (a derivative of vitamin D) is used topically for mild to moderate plaque psoriasis. A scalp preparation is available. Unlike dithranol, it is easy to use and is non-staining (van der Vleuten 2001). Calcitriol and tacalcitol are used for similar conditions. These products should be used only in accordance with clearly defined ‘dosage’ regimens, i.e. quantity and frequency of application.

For more severe psoriasis not responding to topical treatments, oral treatments may be required. Acitretin (a vitamin A derivative) is an oral retinoid. This should be prescribed only by or under the supervision of a consultant dermatologist; 25–30 mg is administered daily for 2–4 weeks, then adjusted according to response. This will usually be in the range of 25–50 mg daily for a further 6–8 weeks; however, a higher dose and longer treatment time may be needed. Side effects include dryness and cracking of the lips, pruritus and nosebleeds. Acitretin is teratogenic, and contraceptive measures in women who may become pregnant should be commenced at least 1 month before treatment initiation and continued for at least 2 years following cessation of the drug. Tazarotene is a retinoid available as a gel formulation for the treat-ment of mild to moderate plaque psoriasis affecting up to 10% of skin area.

TREATMENT

Treatments available include topical and systemic (oral) preparations. Topical products are intended to remove follicular plugs and reduce skin bacterial flora. Benzoyl peroxide alone or in combination with an antimicrobial agent is widely used. Such products have both a keratolytic and an antimicrobial action. Irritation of the skin commonly occurs but will normally subside. Azelaic acid (25% cream) has similar actions to benzoyl peroxide. Gels containing nicotinamide (4%) have an anti-inflammatory effect that may be valuable in mild to moderate inflammatory acne.

Tretinoin reduces sebum production. When applied to the skin, it produces an erythematous reaction, and skin peeling may occur after application for several days. Topical preparations of erythromycin, tetracycline or clindamycin are useful in patients with mild to moderately severe acne. A combination product of an antibiotic and a retinoid is available for topical use. Topical corticosteroids should not be used for acne.

Topical retinoids (forms of vitamin A) have anti-comedogenic properties, both locally and systemically. Creams and gels of both tretinoin and isotretinoin are available. Redness of the skin and peeling may occur, which should settle in time. Contact with mucous membranes and eyes must be avoided. Both topical and oral retinoids are contraindicated in pregnancy and eczema. Adalpene is a retinoid-like drug used topically.

If acne is severe, a course of oral tetracycline or erythromycin may be prescribed: 250 mg three times daily before meals for 1–4 weeks then reduced to twice daily until improvement occurs. Several months’ treatment or even longer may be required. If resistance to tetracycline antibiotics or erythromycin occurs, trimethoprim (see p. 303) may be useful but should be initiated only by a specialist. Female patients must stop tetracycline if they become pregnant, because this drug is deposited in developing teeth and bones of the fetus. If the treatments described above are unsuccessful, isotretinoin, an oral drug, may be prescribed. This has an action that is similar, but more powerful, to that of tretinoin. It is a hospital-only preparation and should be prescribed only by or under the supervision of a hospital consultant. Side effects include dry lips, nosebleeds and some loss of hair. Isotretinoin is teratogenic and must not be given to pregnant women. Contraceptive measures in women who may become pregnant must be effective and must last for 1 month after completion of treatment. Broad-spectrum antibiotic treatment can compromise the effectiveness of combined oral contraceptives. This is thought to be due to the effect of the antibiotic on the gut flora, which is responsible for recycling ethinylestradiol from the large bowel. Suitable guidance must be given to patients using oral contraception.

Hormone therapy (co-cyprindiol) has an anti-androgenic effect. The drug reduces sebum secretion when given daily (one tablet) starting on Day 1 of the menstrual cycle. Figure 25.4 shows the sites of action of the drugs used. The side-effects are as for COCs.

Fig. 25.4 Sites of action of drugs used to treat acne.

(From Page CP, Hoffman BF, Curtis M et al. 2006 Integrated pharmacology. Mosby, Edinburgh. With permission of Mosby.)

TREATMENT

Antibiotic treatment is used to reduce inflammation. In mild cases, topical metronidazole (cream) is commonly used. For more severe rosacea, an oral antibiotic such as oxytetracycline (500 mg twice daily) or tetracycline (500 mg twice daily) may be added. When these drugs are contraindicated, as in renal impairment, doxycycline (100 mg daily) may be used instead. In severe cases, minocycline (100 mg daily) may be further added. When there is resistance to antibiotics or there are persistent clinical features, oral tretinoin may be prescribed. Laser therapy may be required for the treatment of telangiectasia.

As well as complying with the prescribed treatment, patients can assist by avoiding or reducing their intake of spicy foods, chocolate, hot drinks, alcohol, etc. A non-irritant sunscreen should be used to prevent a worsening of the condition. Redness may be effectively disguised with the assistance of a camouflage cream.

TREATMENT

It is essential that the correct diagnosis is reached by a healthcare professional before treatment is begun. A living, moving louse must be found to confirm the diagnosis. Detection of live lice is by wet combing, which involves intensive combing for at least 30 min over the whole scalp at 4-day intervals for a minimum of 2 weeks using a plastic detection comb and hair conditioner. The most successful formulations for treating lice are lotions and liquids that stay on the head long enough to kill eggs as well as lice. Lotions, being of an alcohol base, are unsuitable for young children or those with asthma or eczema, in which case liquids must suffice. Shampoos are too diluted to be effective.

In order to prevent resistance developing, a mosaic approach is currently recommended whereby if, out of three possible treatment options, the first one fails, treatment moves to the second option and so on to the third (Aston et al. 1998). The insecticides available are malathion (liquid and lotion), permethrin (cream), phenothrin (liquid, alcoholic lotion and mousse), and carbaryl (liquid and lotion). Malathion is an organophosphate that should not be used more than once a week and for not more than 3 consecutive weeks. Carbaryl is considered a potential human carcinogen and is therefore a prescription-only medicine. Whichever course of treatment is selected, two applications of insecticide should be made 7 days apart. The head should be thoroughly checked 2–3 days after the final application, using a plastic detection comb.

When applying a lotion or liquid to the head, it is important to use enough of it (at least 50 mL per application; more if the hair is thick). It should also be remembered that it is the scalp that has to be treated rather than the hair. The hair should be parted while it is still dry and the lotion sprinkled into the parting until the whole scalp has been moistened, taking care to avoid contact with the eyes. The scalp is massaged gently, paying particular attention to the back of the head and to the areas behind the ears. The hair may then be combed and should be allowed to dry naturally. The application is removed 12 h later using ordinary shampoo.

If one member of a family is affected, the whole family must be treated to make certain that they are all free from infestation. Classmates should be treated similarly. Mothers should be advised to make a regular check on their children’s heads and to encourage combing of the hair, especially at bedtime.

Nurses in the community, at school and in hospital should exercise diplomacy when dealing with affected patients or explaining the condition to a child’s parents. While not wanting to create offence or embarrassment, the nurse, as a health educator, must ensure that this particular problem is not allowed to go unchecked.