PRINCIPLES OF DERMATOLOGIC THERAPY
Dermatologic diseases are diagnosed by the types of lesions they cause. To make a diagnosis: identify the type of lesions and obtain the elements of history, physical examination and appropriate laboratory tests to confirm the diagnosis.
Tabel. 1 Morphologic categorization of skin lesions and diseases
| Pigmented | Freckle, lentigo, seborrheic keratosis, nevus, blue nevus, halo nevus, atypical nevus, melanoma |
| Scaly | Psoriasis, dermatitis (atopic, statis, seborrhoic, chronic alerglly contact or irritant contact), xerosis (dry skin), lochen simplex chronicus, tinea, tinea versicolor, secondary syphilis, pityriasis rosae, discoid lupus erytematosus, exfoliative dermatitis, actinic keratoes, Bowen disease, Paget disease, intertrigo |
| Vesicular | Herpes simplex, varicella, herpes zoster, dyshidrosis (vesicular dermatitis of palms and soles), vesicular tinea, dermatophytid, dermatitis herpetiformis, miliaria, scabies, photosensitivity |
| Weepy or encrusted | Impetigo, acute contact allergic dermatitis, any vesicular dermatitis |
| Pustular | Acne vulgaris, acne rosacea, folliculitis, candidiasis, miliaria, any vesicular dermatitis |
| Figurate (shaped) erythema | Urticaria, erythema multiforme, erythema migrans, cellulitis, erysipelas, erysipeloid, arthropod bites |
| Bullous | Impetigo, blistering dactylitis, pemphigus, pemphigoid, porphyria cutanea tarda, drug eruptions, erythema multiforme, toxic epidermal necrolysis |
| Papular | Hyperkeratosis: warts, corns, seborrheic keratoses Purple-violet: lichen planus, drug eruptions, Kaposi sarcoma Flesh-colored,umbilicated: molluscum contagiosum Pearly: basal cell carcinoma, intradermal nevi Small, red,inflammatory: acne,miliaria,candidiasis,scabies,folliculitis |
| Pruritus1 | Xerosis, scabies, pediculosis,bites,systemic causes, anogenital pruritus |
| Nodular, cystic | Erythema nodosum, furuncle, cystic acne, follicular (epidermal) inclusion cyst |
| Photodermatitis (photodistributed rashes) | Drug, polymorphic light eruption, lupus erythematosus |
| Morbiliform | Drug, viral infection, secondary sypilis |
| Erosive | Any vesicular dermatitis, impetigo, aphthae, lichen planus, erythema multiforme |
| Ulcerated | Decubiti, herpes simplex, skin cancer, parasitic infection, syphilis (chancre), cancroids, vasculitis, statis, arterial disease |
1 Not a morphologic class but included because it is one of the most common dermatplogic problem
Principles of Dermatologic Therapy
Frequently Used Treatment Measures
A.Bathing
Soap should be used only in the axillae and groin and on the feet by persons with dry or inflamed skin. Soaking in water for 10-15 minutes before applying topical corticosteroids enhanced their efficacy.
B. Topical Therapy
1. Corticosteroid-Topical corticosteroids are divided into classes based on potency. There is little except price to recommend one agent over another within the same class. An ointment is more potent than a cream. The potency of corticosteroid may be dramatically increased by applying an occlusive dressing over the corticosteroid. At least 4 hours of occlusion is required to enhanced penetration. Such dressing may include gloves, plastic wrap or plastic occlusive suits for patients with generalized erythroderma or atopy. Caution should be used in applying topical corticosteroids to areas of thin skin (face, scrotum, vulva, skin folds). Topical corticosteroid used on eyelids may results in glaucoma or cataracts. One may estimate the amount of topical corticosteroid needed by using the “rule of nines”. In general, it takes an average os 20-30 g to cover the body surface of an adult once. Systemic absorption does occur, but adrenal suppression, diabetes, hypertension osteoporosis and other complications of systemic corticosteroid are very rare.
2. Emollients for dry skin (moisturizers)-Dry skin is not related to water intake but to abnormal function of the epidermis. Many type of emollients are available. Petroleum, mineral oil, Aquaphor, Vanicream and Eucerin cream are the heaviest and best. Emollients are more effective when applied to wet skin. If the skin is too greasy after application, pat dry with a damp towel. Vanicream is relatively allergen-free and can be used if allergic contact dermatitis to topical products is suspected. The scaly appearance of dry skin may be improved by urea, lactic acid, or glycolic acid-containing products provided no inflammation (erythema or pruritus) is present
3. Drying agents for weepy dermatoses- If the skin is weepy from infection or inflammation, drying agents maybe beneficial . The best dry agent is water, applied as repeated compresses for 15-30 minutes, alone or with aluminum salts or colloidal oatmeal.
4. Topical antipruritics-Lotions tha contain 0.5% each of camphor and menthol or pramoxine hydrochloride 1% are effective antipruritic agents. Hydrocortisone, 1% or 2.5%, may be incorporated for its anti-inflammatory effect. Doxepin cream 5% may reduce pruritus but may cause drowsiness. Pramoxine and doxepin are most effective when applied with topical corticosteroids.
5. Systemic antipruritic drugs
A. Antihistamines- H1 blockers are the agents of choice for pruritus when due to histamine such as in urticaria. Otherwise, they appear to relieve pruritus only by their sedating effects. Except in the case of urticaria, nonsedating antihistamines are of limited value in inflammatory skin diseases.
Hydroxyzine 25-50 mg nightly is typically used for its sedative effect in pruritic diseases. Sedation can limit daytime use. The least sedating antihistamines are loratadine and fexofenadin. Cetirizine causes drowsiness in about 15% of patients. Some antidepressants such as doxepine, mirtazapine, sertraline and paroxetine can be effective antipruritics.
B. Systemic corticosteroids
Mechanism of Action
Cortisol is a steroid hormone that is normally secreted by the adrenal cortex in response to ACTH. It exerts its action by binding to nuclear receptors, which then act upon chromatin to regulate gene expression, producing effects throughout the body.
Relative Potencies
Hydrocortisone and cortisone acetate, like cortisol, have mineralocorticoid effects that become excessive at higher doses. Other synthetic corticosteroids such as prednisone, dexamethasone, and deflazacort have minimal mineralocorticoid activity.
Tabel 2. Systemic versus topical activity of corticosteroids 1
| Corticosteroids | Systemic Activity | Topical Activity |
| Prednisone | 4-5 | 1-2 |
| Fluprednisolone | 8-10 | 10 |
| Triamcinolone | 5 | 1 |
| Triamcinolone Acetonide | 5 | 40 |
| Dexamethasone | 30-120 | 10 |
| Batamethasone | 30 | 5-10 |
| Batamethasone valerate | - | 50-150 |
| Methylprednisolone | 5 | 5 |
| Fluocinolone acetonide | - | 40-100 |
| Flurandrenolone acetonide | - | 20-50 |
| Fluorometholone | 1-2 | 40 |
| Deflazacort | 3-4 | - |
| | | |
1 Hydrocortisone = 1 in potency
Sunscreens
Protection from ultraviolet light should begin at birth and will reduce the incidence of actinic keratoses and some nonmelanoma skin cancers when initiated at any age. The best protection is shade, but protective clothing, avoidance of direct sun exposure during the peak hours of the day, and daily use of chemical sunscreens are important.
Fair-complexioned persons should use a sunscreen with an SPF (Sun Protective Factor) of at least 15 and preferably 30-40 everyday. Sunscreens with high SPF values (>30) afford some protection against UVA as well as UVB and may be helpful in managing photosensitivity disorders. Physical blockers (titanium dioxide and zinc dioxide) are available in vanishing formulations. Aggressive sunscreen use should be accompanied by vitamin D supplementation in persons at risk for osteopenia (eg organ transplant recipients).
Complications of Topical Dermatologic Therapy:
1. Allergy. Of the topical antibiotics, neomycin and bacitrasin have the greatest potential for sensitization. Diphenhydramine, benzocaine, Vitamine E, aromatic essential oils, and bee pollen are potential sensitizers in topical medications. Preservatives and even the topical corticosteroids themselves can cause allergic contact dermatitis.
2. Irritation. Preparations of tretinoin, benzoyl peroxide, and other acne medications should be applied sparingly to the skin
3. Overuse. Topical corticosteroids may induce acne-like lesions on the face (steroid rosacea) and atrophic striae in body folds.
