Drugs Used for Skin Disorders



Drugs Used for Skin Disorders



Overview


Many drugs that are used to treat skin disorders are also administered for systemic disorders, but for skin disorders, the drug formulation is usually designed in a way that limits their absorption and distribution to the skin surface. Systemic distribution in these cases is generally not desirable and can lead to an increased number or severity of adverse effects. In severe skin disease, however, systemic administration is appropriate, and oral preparations are available for such treatment.


Glucocorticoids are a commonly used drug class for treating skin disorders such as dermatoses because of their antiinflammatory, immunosuppressive, and other effects. Glucocorticoids alter gene expression in cells located in the dermis and epidermis by binding to glucocorticoid response elements on DNA. These drugs are transported to the cell nucleus after forming complexes with cytoplasmic receptors. Glucocorticoids include hydrocortisone, beta-methasone, and clobetasol (for psoriasis).


Retinoids, a family of naturally occurring and synthetic vitamin A analogs, affect cell differentiation and proliferation by regulating transcriptional activity mediated by nuclear retinoic acid receptor subtypes. Commonly used retinoids include adapalene, isotretinoin, and tretinoin (for severe acne); acitretin (for severe psoriasis); bexarotene (for early-stage cutaneous T-cell lymphoma); alitretinoin (for cutaneous lesions of Kaposi sarcoma); and naturally occurring β-carotene (for reducing skin photosensitivity).


Other dermatologic agents include antimicrobial, antimalarial, antifungal, and antiviral drugs; drugs (primarily pyrethrins and pyrethroids) used to treat scabies and lice; cytotoxic and immune-modulating drugs; systemic antihistamines (to treat, for example, urticaria, angioedema, and cutaneous mastocytosis); drugs to treat pigmentation disorders; keratolytic agents, such as salicylic acid, urea, lactic acid, and colloidal or precipitated sulfur (to treat excess thickening of the outermost layer of the skin); selenium sulfide (to treat dandruff); and psoralens (eg, 8-methoxypsoralen) and porphyrins (used as photosensitizers to enhance phototherapy).


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Figure 12-1 Anatomy of the Skin
The skin is a complex, multicomponent organ. It is commonly classified into 3 anatomical regions and multiple subregions: the epidermis, which includes the strata corneum, lucidum, granulosum, spinosum, and basale; the dermis, which includes the papillary and reticular layers; and the subcutaneous tissue, which includes sweat glands. All layers are extensively supplied by blood vessels and innervated by motor and sensory neurons. Disorders of the skin can develop either as primary disease (localized to 1 or more layers of the skin) or as a secondary result of a systemic disease. Drugs for management of these disorders involve topical or systemic administration of medications to treat the dermal or systemic source of the problem. Major classes of drugs used in dermatologic pharmacology include glucocorticoids, antibacterials, antifungals, antivirals, antiparasitics, and retinoids.

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Figure 12-2 Alopecia
Alopecia—the loss or absence of hair, especially of the head—can be caused by illness, drugs, endocrine disorders, some types of dermatitis, hereditary factors, radiation, and physiologic processes such as aging. Drug therapy, when appropriate, involves topical steroids (eg, clobetasol) or intradermal injections of triamcinolone for alopecia areata (defined patches, usually on the scalp or beard; occurs most often in children and in autoimmune diseases); minoxidil for androgenic alopecia (affects androgen-sensitive follicles on the scalp of men and women); and griseofulvin, itraconazole, or terbinafine for tinea capitis (fungal infection). Scarring (cicatricial) and permanent alopecias are treated with potent corticosteroids used topically or intralesionally on active inflammatory borders. Systemic drugs (eg, acitretin, chloroquine, doxycycline, low-dose methotrexate, minocycline, prednisone, quinacrine, tetracyclines) may also be used if the disease type and extent warrant them.
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Jun 21, 2016 | Posted by in PHARMACY | Comments Off on Drugs Used for Skin Disorders

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