DERMATOLOGIC THERAPY Dr.MOHAMED NASR Lecturer Of Dermatology & Venereology

I. Topical therapy In medicine, a '''topical''' medication is applied to body surface such as the skin or mucous membranes.

CLASSES OF TOPICAL PREPARATIONS Solutions These are a powder dissolved in a base of water or alcohol.

Lotions Lotions are similar to solutions but thicker and more emollient. They are usually oil mixed with water.

Shake lotions These are suspensions of fine powders in oil mixed with a water-based solution. The mixture separates with time so it needs to be shaken well into suspension before usage.

Emulsions These are oil in water emulsions, they are more stable than shake lotions and less drying than lotions

Cream (hydrophilic ointment) A Cream is a semisolid compound of oil (or petrolatum) and water in approximately equal proportions stabilized with a detergent such as sodium lauryl sulphate. Cream is thicker than lotion. It has a good penetration power of the stratum corneum.

Ointment An '''ointment''' is a homogeneous, viscous, semi- solid preparation of the active ingredient in a greasy, thick oil or white soft paraffin (petrolatum) with a concentration of oil 80% and water 20%.

Gel Gels are thickened aqueous lotions. They are often a semisolid emulsion of high molecular weight polymers in an alcohol base. Gels and lotions are especially suitable for treatment of the scalp and other hairy areas as well as body folds.

Collodions They are liquid preparations consisting of cellulose nitrate in an organic solvent. They evaporate rapidly to leave a flexible film holding the medicaments in contact with skin.

Transdermal patch A method of delivering a drug by diffusion to the skin.

Powder Powder is either the pure drug by itself or the drug is mixed in a carrier such as corn starch.

Solid Some medications are placed in a solid form such as deodorants, antiperspirants and astringents. Some solids melt when they reach body temperature e.g. rectal suppositories.

Tape Topical applications may be used under occlusion by a tape. This greatly increases the potency and absorption of the topical agents.

Paste Paste is a semisolid preparation, thicker and drier than an ointment. Protective fatty paste is a suspension of a powder such as zinc oxide or starch in a greasy ointment base. It is greasy and water insoluble. It acts as occlusive, protective and hydrating agent. Drying paste (cooling paste) is a mixture of powder with liquid so it is non greasy and water miscible and easy to apply and remove. It acts as a drying and soothing agent.

1-Topical steroids: Indications: Dermatitis Lichen planus Alopecia areata DLE Psoriasis

Side effects: Epidermal atrophy. Impaired wound healing. Persistent vasodilatation and telangiectasia. Hypopigmentation (melanocyte inhibition). Striae due to collagen synthesis inhibition. Acneiform eruption. Suppression of inflammatory signs of infectious cases as impetigo contagiosa followed by marked exacerbation of the condition after stoppage of steroids. Scabies and fungus infection clinical pictures may be modified by the use of steroids leading to scabies incognito and tinea incognito.

Indications for intralesional steroid injection 1. Keloid 2. Hypertrophic lichen planus 3. Alopecia areata 4. Nodulocystic acne 5. DLE 6. Post scabietic nodules

2-Topical retinoids: Tretinoin 0.1% and isotretinoin 0.05% cream and gel are used for acne, melasma and solar lentigenes. They may cause dermatitits and irritation. Adapalene 0.1% gel is less irritant and better tolerated.

II.Systemic therapy

Antihistamines Indications: itchy skin diseases as: Generalized pruritus Atopic dermatitis and other types of eczema Urticaria and angioedema Scabies Lichen planus

Types of antihistamines : 1- H1 receptor antagonists First generation (sedation & atropine like effect). Second generation (do not cross the blood brain barrier, so do not cause drowsiness, they also have longer action).

2-H2 receptor antagonists They are antagonists for H2 histamine receptors, found principally in the parietal cells of the stomach. They can be combined with H1 antihistamines in chronic urticaria

Systemic steroids Indications: Acute anaphylactic reactions. Autoimmune diseases: pemphigus, pemphigoid, Behcet's. Connective tissue diseases: SLE, Dermatomyositis, systemic sclerosis. Lichen planus: oral ulcerative lichen planus, destructive nail involvement and generalized lichen planus. Disseminated or extensive cases of eczema.

Antimalarials They are indicated in: lupus erythematosus especially DLE and solar urticaria.

Dapsone It is indicated in leprosy and acne conglobata.

Ivermectin It is effective against Sarcopts scabiei. Dose in scabies is 200 μg / kg repeated in 7 to 14 days. Side effects: (rare and usually minor) Transient tachycardia Flushing Nausea Diarrhea Skin rash

Oral retinoids Oral retinoids are synthetic derivatives of Vitamin A (retinol). They have a role in normalization of skin differentiation and keratinization.

Etretinate: It is the parent of retinoids. Acitretin: It results from hydrolysis of etretinate and is now superior to it. It is used in extensive forms of psoriasis especially erythrodermic and pustular forms. It is also used in disorders of keratinization as icthyoses, palmoplanter keratoderma, PRP and lichen planus. The dose ranges from 0.25: 1 mg/ kg per day. It is best taken after a meal because it needs fat to be absorbed through the gut wall.

Isotretinoin: it is effective in severe and resistent forms of acne as nodulocystic acne and cases not responding to ordinary treatments. Bexarotene: for cutaneous T cell lymphoma.

Side effects of retinoids: The most serious is teratogenecity, so pregnancy should be absolutely prevented for at least 2-6 months after stoppage of the drug. Headache,lethargy, anorexia, nausea and vomiting. Benign intracranial hypertension (with isotretinoin). Dryness of lips, nose and eyes. Skeletal hyperostosis in prolonged therapy. Elevation of liver enzymes. Changes in serum lipids and elevation of triglycerides and cholesterol.