|Year : 2013 | Volume
| Issue : 1 | Page : 4-8
Topical therapy of atopic dermatitis
Department of Paediatric Dermatology, Institute of Child Health, Kolkata, West Bengal, India
|Date of Web Publication||23-Aug-2013|
Flat 9 C, Palazzo, 35, Panditia Road, Kolkata - 700 029, West Bengal
Source of Support: None, Conflict of Interest: None
Topical therapy is first line of treatment for mild to moderate atopic dermatitis (AD) which is the commonest form of the disease in India. Avoidance of overbathing, use of a synthetic detergent preferably with a slight acidic pH is recommended. Regular use of a moisturiser preferably containing an occlusive and a humectant which perfume free is to used liberally. Topical corticosteroids are the most important pillars of topical treatment of AD. Understanding the proper and judicious use of topical corticosteroids is of prime importance. The choice of the molecule, frequency and amount and method of application and whether or not to use combination and the proper monitoring will decide the optimum outcome to the treatment. Concomittant long term use with gradual tapering of corticosteriod is recommended. Mild recurrences can be controlled by monotherapy. Proper and judicious use of all the elements of topical therapy is needed for successful treatment outcome.
Keywords: Atopic Dermatitis, topical therapy, corticosteroid
|How to cite this article:|
Dhar S. Topical therapy of atopic dermatitis. Indian J Paediatr Dermatol 2013;14:4-8
| Introduction|| |
Topical treatment is the "first line of therapy" of atopic dermatitis (AD). In India, where we mostly come across mild to moderate cases of AD, , topical treatment forms the sheet anchor of its management.
| Bath and Cleansing Agents|| |
Topical treatment of AD starts with proper cleaning of the skin. Soaps and detergents used in bathing remove lipid and oil from the skin surface and have a drying effect  that may exacerbate eczema. However, there are a few advantages of bathing in AD. Bathing allows removal of dirt and debris from the skin and thereby reduces the chance of infection. This has a special connotation in hot and humid climate of India. For atopic skin, a mild, less alkaline (pH 5.5) soap should be chosen. Addition of moisturizer to the soap is useful. 
The water for bathing should be lukewarm, neither too hot nor too cold. Addition of antiseptics to bath water may reduce the commensal bacteria on the surface of the skin and make the atopic skin more prone to infection by virulent bacteriae from the environment as well as increases the chances of developing contact dermatitis. Hence, their routine use in not warranted.
Oil or moisturizers should be used immediately after bath which only helps reducing dryness of atopic skin, but also reduces the post bath tightness and itching.
| Compresses|| |
Compresses are wet dressings used effectively in the management of acute eczema. There are different types of compresses such as saline compresses, medicated compresses wherein potassium permanganate, silver nitrate or hydrogen peroxide is used as an additive. The compresses act as a smoothening agent, it reduces vasodilatation and thereby inflammation; it also reduces the quantum of surface bacteria and remove the dirt and debris so that the eczematous lesions remain clean.
This plays an important role in the management of AD. Atopics generally have dry skin. The more dry skin is, more is the itching. Softness and suppleness of the skin is not dependent on the oil content of the skin but on the water content. So better the cutaneous hydration is maintained, better is the outcome. Two types of products can be used (i) humectants and (ii) occlussives.
Humectants are the compounds that are hygroscopic in nature, i.e., they draw moisture into the skin. Examples are glycerin, propylene glycol etc. The main disadvantage of this agent is that in a dry atmosphere, it draws water from the skin. So in winter, it makes the skin dry from inside.
Occlusive are agents that make the skin soft and pliable by increasing the hydration of the stratum corneum, e.g., white soft paraffin. These are the agents that are used in the management of AD. 
After a short bath (maximum 5 min) in tepid water, the skin is patted with a soft towel in such a way that a thin film of water remains on the skin. Immediately a moisturizer is applied over the wet skin. The idea is to trap the water in the skin to maintain hydration. At 2-3 times, daily moisturizer application will keep the skin soft and supple. In India, however, moisturizer all over the body is required for atopics only in winter. During the summer and rainy season (which together constitutes 80% of the year in more than 80% of the geographic area of the country), moisturizer is required only over the dry patches of eczema. As the atopics sweat a lot in hot and humid season, application of moisturizer all over the body may lead to more sweating leading to uneasy sticky feeling of the skin and miliaria formation.
Some authors advocate bath oils sprinkled onto the bucket or bath tub. Theoretically, it is good and the child shows a good response while the grandfather gets a fracture neck femur in the bathroom.
In a country like India, where cost of treatment is a major concern, use of coconut oil, which is rich in unsaturated fatty acids, can be advocated as an effective alternative to costly bath oils.
Ichthymol and Tar
Tar preparations have been used successfully for many years in the treatment of eczema and were the most important modality before the advent of corticosteroids. Tars are divided into shale, wood and coal tar depending on the source. Ichthymol is a derivative of shale, less irritant than coal tar. Preparations of coal tar and ichthymol may be useful as maintenance therapy for chronic lichenified eczema. Coal tar in strength of 1-10% may be added to a variety of creams, ointments and paste bases. 
| Topical Corticosteroid|| |
TC(s) still remain the treatment of choice for treating the majority of the cases of AD.  However, AD is a chronic disease frequented by relapses; hence TCs need to be prescribed from time to time to control the inflammation of eczema. Key issues in the judicious use of TCs are (1) Which molecule to choose? (2) In what form (ointment, cream, gel, lotion)? (3) How much to apply? (4) What will be the frequency of application? What brand to select? (5) How to monitor the therapy? All these queries are to be addressed before starting TC therapy.
Choosing a TC Preparation
Priority should be given to the desired potency. The decision is based on the patient's age and the type, severity, extent, location and expected duration of eczema. [Table 1]  gives a guideline of this and [Table 2] highlights some commonly used TCs in AD.
|Table 2: Some commonly used corticosteroid preparations according to their potency|
Click here to view
Among these, mometasone and alcomethasone are potent but have less potential for adrenal suppression. Fluticasone propionate is also potent; its atrophogenic potential and adrenal suppression power is less than its congeners and it is the molecule approved by US Food and Drug Administration for use in infants above 3 months of age.
Whether to Choose Ointment, Cream, Gel or Lotion?
Vehicle is an important consideration while opting for TC therapy. Ointments have an oily base, hence gives an occlusion effect (just like occlussives) after application. Hence, the penetration of the drug is better and potency increases. Thick lichenified areas are the best target sites for ointments. Creams have watery base, best applied on non lichenified mild eczematous areas. Lotions and gels are best for intertriginous and hairy areas. Lotions are also used over oozing areas. Gels can give rise to stinging sensation and better avoided in small children.
How Much to Apply?
This is determined by the concept of fingertip unit (FTU). A FTU is the amount of ointment expressed from a tube with a 5 mm diameter nozzle, applied from the distal skin crease to the tip of the palmar aspect of the index finger. One FTU weighs 0.49 g and covers 312 cm2 in adult males and weighs 0.43 g and covers 257 cm2 in adult females. 
A general principle is to choose a topical steroid strong enough to control the severity of AD by twice daily application for 3-7 days; then either to reduce the frequency of application or the potency of topical steroid for maintenance therapy.
We prefer a potent steroid for 5-10 days followed by a moderately potent steroid for maximum 10-14 days in adults. In children, a moderately potent steroid is chosen first followed by a mildly potent steroid for more less the same durations.
Selection of a Brand
In an interesting study by Stoughton, it was found that identical steroids produced by various pharmaceutical companies had different therapeutic effects.  Therefore, only after long-term trials, which substantiate the improvement brought about a new preparation, should the switch from well-known preparations be considered.
Wet Wrap Treatment
This method involves the use of open-weave cotton tubular dressings (tubifast) impregnated with 10% dilution of betamethasone valerate (0.01%) cream.  After a bath, patients are advised to apply medicated ointment to the affected areas and petrolatum to the unaffected areas. The tubifast dressings soaked in warm water are then placed over the affected areas of the body. A second layer of dry tubifast is placed over the wet layer. This is done at bedtime and the dressings are kept overnight and removed the next morning. The contact period with the ointment is approximately 8 h.
These types of dressings for moderate to severe AD are quite effective in the west. However, in Indian hot and humid climate, these dressings can produce adverse effects of occlusions for such a prolonged period e.g., aggravation of itching at the local sites, folliculitis, furunculosis, absorption leading to growth retardation and hypothalamic-pituitary-adrenal (HPA) axis suppression in children. Such adverse effects have been noted even in the western set-up. 
The increased incidence of carriage state of Staphylococcus aureus has been a subject of interest in patients with AD.  Several studies , including one by the author  also demonstrated increased carriage state of S. aureus in both involved and uninvolved skin of patients with AD. Exacerbation of AD is reported to be induced when the density of S. aureus is greater than 106 CFU/cm2. It has been shown that topical and/or systemic antibiotics reduce the quantity of S. aureus colonizing the skin and nasal mucosa and thus eczema. The combined force of TC and antibiotic tackles S. aureus superantigens better than only topical steroid. Betamethasone in combination with topical gentamicin has been successfully used to treat AD for the past two decades. Topical mupirocin is effective in clearing S. aureus carriage from skin and nasal mucosa.  Hence a combination of fluticasone, a moderately potent corticosteroid and mupriocin effectively controls ecze ma and its perpetuation by S. aureus.
Monitoring of Topical Steroid
Topical steroids can have both local and systemic side-effects. Various topical side-effects are atrophy, striae, telangiectasia, hypertrichosis, petechiae formation, folliculitis (under occlusion), steroid induced rosacea, delayed wound healing, glaucoma (when applied near eyes) etc. Systemic adverse effects are suppression of HPA axis, growth retardation in children and iatrogenic Cushing's syndrome (when a potent steroid applied over large areas of skin). To avoid these, proper pre-treatment counseling of the patients/parents of children with AD is a "must." Guidance regarding the quantity of steroid to be applied, frequency of application and duration of treatment are to be clearly given to the patients/parents.
Failure to Respond to TCs
Various causes are faulty selection of the molecule, early termination of treatment, poor compliance of the patients, contact sensitization and onset of infection. Of these, the commonest cause is poor compliance of the patients.
| Tacrolimus|| |
Topical tacrolimus, a calcineurin inhibitor, has been the molecule of recent interest in the treatment of AD.  The long-term efficacy of tacrolimus (0.1%) ointment has been investigated in large multicentric, Phase III trials in adults (aged more than 18 years)  or pediatric (age 2-15 years) patients with moderate to severe AD. Tacrolimus (0.1%) ointment was applied twice daily to all affected areas for up to 12 months in children  and up to 6-12 months in adults.  Both strengths (0.30% and 0.1%) were found to be significantly more effective than placebo in the treatment of moderate to severe AD in patients aged 16 years and older in large Phase III clinical trials.  The adverse effects of topical tacrolimus are usually mild and transient. On continuation of treatment beyond first few days, majority of the adverse effects disappear.  Various adverse effects are burning and erythema at the site of application, pruritus and stinging sensation, allergic reaction at a distant site, flu-like symptoms, herpes simplex infection at the site of application as well as non-application sites, folliculitis, headache , etc. Indian experiences with topical tacrolimus have also been quite encouraging. ,
The ointment should be applied over the affected areas twice daily. Both 0.03% and 0.1% formulations are recommended for use in adults, whereas only 0.03% formulation is recommended for use in children aged 2-15 years.  Treatment should be continued for 1 week after the subsidence of eczema.  Tacrolimus ointment should not be used under occlusion, in children younger than 2 years, in pregnant ladies and nursing mothers. The drug is not recommended for treating AD like dermtitis of Netherton's syndrome. During treatment, it is better to avoid direct sunlight exposure as far as possible. ,
| Pimecrolimus|| |
Is an ascomycin derivative  and has been found effective in controlling eczematous reactions of AD when applied topically. 
Topical pimecrolimus is applied as 1.0% cream twice daily over the eczematous lesions of AD. It reduces pruritus and controls flare and inflammation. It has been evaluated in randomized double blind vehicle controlled clinical trials in infants (aged 3-23 months), children (aged 2-17 years) and adults with mild to severe AD. 
Adverse effects are usually mild and transient e.g., burning, pruritus at the local site, herpes simplex or herpes zoster virus infections. ,
| Conclusions|| |
Topical steroid is the mainstay of topical therapy in most of the cases of AD. Tacrolimus is a promising topical molecule. However, as of now, it appears to be a supplement rather than substitute of topical steroid. Moisturizers and cleansers also play significant roles in the topical management of AD. Selection of a topical agent has to be tailored according to the type, extent and severity of eczema as well as associated risk factors.
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[Table 1], [Table 2]