Drugs for Dermatologic Disorders
Dermatologic disorders (Skin disorders)
- Skin disorders, such as acne and dermatitis, are among the top reasons that patients seek medical attention.
- Pharmacological approaches to correct skin abnormalities, including infections, can be administered topically or systemically, depending on the nature and extent of the disorder.
Drugs for various skin disorders are as following :
1. Drugs for Acne vulgaris
- Acne vulgaris (common acne) is a common skin disorder that is characterized by pimples, comedones, pustules, and sometimes nodules and scarring. Comedones are clogged hair follicles (pores) in the skin, which can be open (blackhead) or closed (whitehead).
- Acne occurs due to alterations in pilosebaceous units—skin structures that contain a hair follicle and a sebaceous (oil) gland. Androgens stimulate sebaceous glands, thereby producing sebum that leads to follicular keratinization and obstruction. Under androgenic stimulation the sebaceous follicles of face and neck produce excess of sebum and get colonized by bacteria and yeast (Propionibacterium acnes, S taph. epidermidis, Pityrosporum ovale).
- Treatments for acne help to reduce sebum production or control.
- Drugs used to cure Acne vulgaris are following :
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2. Topical Anti-bacterial agents
- Organisms such as staphylococci and streptococci can cause folliculitis, abscesses, fasciitis, cellulitis, impetigo, and many pus-forming infections.
- Several gram-positive and gram-negative bacteria cause infections that are not limited to the skin and may cause serious diseases, since they can spread and become systemic infections.
- To treat bacterial infection of skin, following agents can be used topically.
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- Ectoparasites are parasites that live on the skin of animals from which they derive nutrition.
- Pediculosis (infestation with lice) and scabies (caused by Sarcoptes scabiei, human mite are common ectoparasitic infections.
- Ectoparasites growing on skin can be killed or retarded by following agents :
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4. Agents for Pigmentation disorders
- Pigmentation disorders like hyperpigmented skin conditions, vitiligo can be managed with following drugs :
Melanizing agents : Melanizing agents are drugs that increase sensitivity to solar radiation and promote repigmentation of vitiliginous areas of skin.
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Demelanizing agents : They lighten hyperpigmented patches on skin.
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5. Agents for Psoriasis
- Psoriasis is an immunological skin disorder manifesting as localized or widespread erythematous scaling lesions or plaques.
- Psoriasis appears to have both genetic factors and T-cell–mediated immune components.
- Drugs can diminish the lesions, but cannot cure the disease.
- Topically applied emollients, keratolytics, antifungals afford variable symptomatic relief, but topical corticosteroids are the primary drugs used.
- The majority of patients have mild to moderate psoriasis, and this can be managed with topical treatments including retinoids, vitamin D analogues, keratolytic agents, and corticosteroids. More severe cases require systemic therapy with phototherapy (methoxsalen followed by UVA or UVB alone), methotrexate, cyclosporine, or biologic response modifiers (for example, etanercept, adalimumab).
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6. Trichogenic agents
- Trichogenic agents are indicated for the treatment of androgenic alopecia (“male pattern baldness”).
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7. Topical corticosteroids
- Corticosteroids (glucocorticoids) have immunosuppressive and antiinflammatory properties. They benefit by virtue of their antiinflammatory, immunosuppressive, vasoconstrictor and antiproliferative (for scaling lesions) actions.
- The intensity of action depends on the extent of absorption to the deeper layers, thus lipophilicity of the compound determines potency to a great extent.
- Topical corticosteroids are used for the treatment of variety of dermatological conditions like – psoriasis, eczema, contact dermatitis, and other skin conditions manifested by itching and inflammation.
- They are administered locally and via topical and intralesional routes.
- Topically used corticosteroids are as following :
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c = cream, g = gel, l= lotion, o= ointment, s=solution
- Demulcents are inert substances which sooth inflamed/ denuded mucosa or skin by preventing contact with air/ irritants in the surroundings.
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- Emollients are bland oily substances which sooth and soften skin.
- They form an occlusive film over the skin, preventing evaporation, thus restoring elasticity of cracked and dry skin. Olive oil, arachis oil, sesame oil, cocoa butter, hard and soft paraffin, liquid paraffin, wool fat, bees wax and spermaceti are the commonly employed emollients.
- They are also used as vehicles for topically applied medicaments and as ointment bases.
- E.g. Olive oil, arachis oil, sesame oil, cocoa butter, hard & soft paraffin, liquid paraffin, wool fat, bees wax & spermaceti
- Adsorbants are finely powdered, inert and insoluble solids capable of binding to their surface (adsorbing) noxious and irritant substances.
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- Adsorbants, Demulcents, emollients are also called protectives because they afford physical protection to the skin or mucosa
- Astringents are substances that pree1p1tate proteins, but do not penetrate cells, thus affecting the superficial layer only.
- They toughen the surface making it mechanically stronger and decrease exudation.
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- These are drugs effective in seborrheic dermatitis which affects areas rich in sebaceous glands (scalp, face, trunk) and is characterized by erythematous, scaling lesions.
- Dandruff is the commonest complaint.
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- Sunscreens are substances that protect the skin from harmful effects of exposure to sunlight.
Chemical sunscreens : They absorb and scatter UV rays that are responsible for sunburn and phototoxicity, but allow longer wave lengths to penetrate, so that tanning occurs. Efficacy of a sunscreen formulation is quantified by its ‘Sun protection factor’ (SPF) which is the ratio of the dose of UVB radiation that will produce minimal erythema on protected skin to the dose required for the same on unprotected skin.
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Physical sunscreens (sun shades): These are opaque substances that stop and scatter not only UV but also visible light. They have to be applied as a thick lotion/ cream which may be cosmetically disagreeable. They withhold longer wave lengths also, which are mostly involved in photoallergy. Not only sunburn, but tanning as well is prevented.
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