Atopic Dermatitis (eczema)

Atopic Dermatitis (Eczema) 15/04/09 KIUNG HSIA LING

Eczema

Introduction “Atopic” refers to a group of often inherited IgE-

mediated diseases, such as allergic rhinitis, asthma, and AD Atopic diseases are noted by their tendency to produce IgE antibodies to harmless inhalants, & dust mites Pervasive inflammatory skin condition, vicious cycle of itching and scratching Hallmark symptoms: chronic, relapsing, itchy and inflamed skin

Etiology Hereditary component: strong One affected parent: 60% Both parents are affected: 80% Children with AD more frequently develop severe

asthma than asthmatic children without AD

Clinical Presentation Acute

- intensely pruritic, erythematous papules and vesicles scratching that results in excoriations and exudates Subacute - thicker, paler, scaly, erythematous, and excoriated plaques Chronic - thickened plaques, lichenification and fibrotic papules

Clinical Features Often starts in the first few months of life Initially appears of infant’s cheeks, which continue

to affect the face, neck & trunk Later manifestations typically present on flexor surfaces Lesions are typically symmetric

Exacerbating Factors Soaps, detergents, chemicals, mold, dust, pollens,

emotional stress, changes in temperature or humidity, bacterial skin infections, contact with irritating clothing (especially cially wool) In some infants, food allergies may provoke AD

Atopic Dermatitis - Distribution Characteristically involves different parts of the body

at different ages At 2-3 months, it usually involves the face, sternal area, nappy area, extensor surfaces of elbow and knees For toddlers, it involves the neck, flexural surface of elbow, knee and ankle joints For older children, it usually involves the palm, foot, flexural surfaces of limbs

Diagnosis Several visit to a doctor may be needed to establish

the diagnosis No specific test for AD exists A doctor makes the diagnosis based on the typical pattern of the rash & often on whether other family members have allergies

Treatment Goals Maintain skin hydration Relieve or minimize symptoms of itching and

weeping Avoid or minimize factors that triggers of aggravate the disorders

No cure exists, but certain measures can help

Nonpharmacological Therapy  Identify & eliminate potential allergens  Reduce frequency of bathing; bathe every other day  Use of tepid water in baths  Avoidance of irritating soaps (dyes, fragrances, &

preservatives can all contribute to further exacerbations)  Avoid washcloths or irritating scrubs  Air dry skin and gentle pat dry  Application of emollient within 3 minutes after bathing  Keep fingernails short and clean to prevent scratching  Consider cotton gloves to prevent scratching at night  Use of cotton sheets and pajamas  Avoid harsh laundry detergents  Moisturize as often as necessary to keep skin soft and pliable (at least twice a day)

Topical Corticosteroids  Potency of the steroid depends upon the vasoconstrictive properties

- typically, use high-potency steroids: use no longer than 3 weeks use on thickened lesions not for use on face, skinfolds, or mucous membranes, eyelids  The vehicle is as important as the steroid concentration - occlusives can increase percutaneous absorption - ointments are stronger than creams, which are stronger than lotions - gels may be beneficial for hairy or oily areas  Use with moisturizers - apply corticosteroid first - the goal is to increase moisturizers while decreasing corticosteroid use

Topical Corticosteroids Potency Potency

Drugs

Low

Hydrocortisone 1%

Moderate

Betamethasone valerate 0.01-0.05% Clobetasone butyrate 0.05%

High

Betamethasone valerate 0.1% Mometasone furoate 0.05%

Very high

Clobetasol propionate 0.05%

Topical Corticosteroids Choosing a topical steroid Area

Steroid potency

Base/carrier

Open, dry

Moderate

Ointment/cream

Plantar surface of foor, thick skin, hard

Moderate

Ointment

Forehead, underarm

Low

Gel, lotion

Face

Low

Cream

Groin

Low

Lotion, cream

Eyes

Low

Opthalmic preparation

Topical Immunomodulators E.g. tacrolimus 0.1%, pimecrolimus 1% MOA: anti-inflammatory, inhibits calcineurin thus

blocking T cell proliferation and preventing release of inflammatory cytokines Offer more long-term options, can be used on all parts of the body for prolonged periods Common ADRs: transient itching & burning at the site of application

Antihistamines Used to attempt to break the itch-scratch cycle Although commonly believed to have antipruritic

effects, their therapeutic value is primarily due to their sedative properties Newer, less sedating antihistamines are of little value, unless allergies triggers are involved, e.g. house dust mite Sedating antihistamines are useful at night in patients having trouble getting to sleep or waking regularly because of excessive itching

Tar preparations Coal tar – reduce itching and inflammation Used in conjunction with topical corticosteroids, as

adjuncts to lower strengths of corticosteroid E.g. coal tar (1, 3, 6%) Should not be used on acute oozing lesions as would result in stinging and irritation Limiting factors: strong odor, staining of clothing Counseling: avoid contact with eyes, may stain skin, hair and clothes, apply enough to cover affected area and rub in gently, use at bedtime and wash it off in the morning

Systemic Immunosuppressants Systemic corticosteroids

- e.g. prednisolone - short course to control severe flare Cyclosporine - severe, recalcitrant - adults: 5mg/kg - childrens: 3mg/kg

References Adams VR, Yee GC. Lymphoma. In: Dipiro JT, Talbert RL, Yee

GC, et al. Pharmacotherapy: a pathophysiologic approach. 6th edition. New York: McGraw-Hill; 2006. Chapter 97 pg 1785-91 Koda-Kimble MA. Applied therapeutics: the clinical use of drugs. 8thedition. USA: Lippincott Williams &Wilkins; 2005. Chapter 38: pg 1-18 Austrlian Medicines Handbook, 2009 Guidelines for the management of atopic eczema. Primary Care Dermatology Society & British Association of Dermatologist. 28, 2006