General Dermatologic Therapy

From WiserWiki

[edit] General Dermatologic Therapy

James C. Shaw

[edit] WOUND HEALING

The most important principle of wound healing is adequate hydration. Migration of keratinocytes and the making of collagen by fibroblasts are both dependent on a moist environment. Wet-to-dry dressings for wounds have been replaced by dressings that simulate a biologic environment. Bioocclusive dressings can be designed at home or in the office with the use of antibacterial ointments covered with an occlusive film or gauze dressing (petrolatum-impregnated gauze), or they can be purchased as prepackaged dressings (e.g., DuoDerm, Vigilon, OpSite). Although these products are expensive, they can be helpful in the healing of large ulcers, abrasions, and burns.

[edit] TOPICAL CORTICOSTEROIDS

[edit] The Vehicle: Cream vs. Ointment

The vehicle containing a corticosteroid can be as important as the steroid itself. Creams and lotions are composed of a combination of oil and water. The higher the ratio of oil to water, the thicker the preparation. The presence of water in the vehicle may contribute to skin drying through evaporation. Vehicles containing water also must contain preservatives to prevent contamination with bacteria and fungi. Preservatives such as quaternium 15 and imidazolidinyl urea can occasionally cause allergic contact dermatitis. In general, patients tolerate creams and lotions better than ointments, but ointments have some inherent occlusive properties that enhance the penetration of steroids. Creams and lotions tend to be more effective in intertriginous or moist areas because of their drying properties. Ointments are used preferably on dry skin because their occlusive properties retard drying. Solutions usually contain alcohol and are best used on the scalp.

[edit] Side Effects

Corticosteroids are graded from class I (most potent) to class VII (least potent). Corticosteroids applied topically are generally safe when used for a short time. Chronic use can result in side effects if the steroid is stronger than class VII. The main side effect seen with chronic use of potent steroids is skin atrophy with thinned dermis with prevalent telangiectasis and increased friability. These changes can lead to the development of striae. When potent steroids are used on the face, a rosacea-like papular and pustular dermatitis, referred to as steroid-induced rosacea, can occur.

[edit] Use of Potent Steroids

In general, potency correlates with fluorinated or chlorinated steroids (Table 83-1). Class I (most potent) steroids should be considered in the most recalcitrant dermatoses as short-term treatment only. These steroids, in general, should never be used on the face. Class II through V levels of potency can be used on open areas of the skin for up to several months without concern but should be avoided in intertriginous areas. The weakest, Class VI and VII, are generally safe on the face and in intertriginous areas.

Table 83-1 Selected Topical Corticosteroids

[edit] Occlusion

Steroids have increased effectiveness when they are occluded. The use of an ointment provides some natural occlusion, but additional occlusion can be provided with the use of a plastic or other synthetic dressing such as DuoDerm. Even simple tape increases the penetration of the steroid. Although occlusion increases effectiveness, it also increases the chances of side effects.

[edit] Intralesional Steroids

On occasion, when a recalcitrant dermatosis is of limited size, the use of intralesional steroids can be helpful. Either intralesional betamethasone valerate (Celestone) 6 mg/ml or triamcinolone acetonide (Kenalog) 5 mg/ml can be used judiciously in plaques of psoriasis, prurigo nodules, inflamed cysts, and in localized patches of alopecia areata. Skin atrophy is a risk whenever intralesional steroids are used.

[edit] COMPRESSES, SOAKS, AND WRAPS

[edit] Indications

Wet compresses are helpful in reducing itching and in drying areas of inflamed skin with serous oozing. The main goals of wet dressings are to cool the skin temperature, debride necrotic tissue, and dry out the skin through evaporation. Soaks are used to hydrate dry skin. A 10 to 15 minute soak in warm plain water hydrates dry skin before application of emollients.

[edit] Procedure

Generally, plain water can be used for wet dressings, but occasionally aluminum acetate (Burow's solution and others) aids in the drying of the skin. The compresses should not be occlusive and should allow for evaporation. A thin fabric is wetted and applied to the affected skin for 5 to 10 minutes and repeated for 30 minutes. This protocol can be followed two or three times a day until the skin has achieved the desired dryness.

Wraps can be beneficial, short-term treatment in any severe dermatitis. Petrolatum or a paste or ointment containing zinc oxide is applied to the skin and wrapped by a thin cotton or linen sheeting. Topical steroids may be added to the base ointment.

[edit] EMOLLIENTS

Emollients provide a barrier to evaporation and deliver some oil content to the skin. Emollients can be pure ointments (Vaseline), which deliver an oil product to the stratum corneum and which provide the greatest protection against evaporation (Table 83-2). Creams represent a combination of oil product plus water and are thinner and therefore easier to apply. Because of the water content, some evaporation takes place. In the most severe cases of dry skin, creams may not provide an adequate protective barrier. Lotions are the thinnest of the emollients because of a higher water content and a lower oil content. These preparations are effective in the mildest forms of dryness, but tend to be ineffective in severe xerosis.

Table 83-2 Selected Emollients

Emollients contain petrolatum, mineral oil, or glycerin. The addition of urea or lactic acid promotes hydration and removal of excess keratin in the skin and can be helpful in the treatment of dry skin (see Table 83-2).

Emollients are best applied after the skin has been exposed to water through a shower, bath, or soak. Even dry skin absorbs some moisture through gentle bathing, especially if soap is avoided. Emollients can then be applied immediately after the bath or shower to protect the hydrated skin from evaporation.

[edit] ANTIHISTAMINES

Antihistamines are valuable in the treatment of numerous skin problems. The main use is for the treatment of histamine-mediated dermatosis, such as urticaria, as well as for the general treatment of pruritus (Table 83-3). For urticaria, any of the antihistamines can be used, and frequently a combination of antihistamines are effective, such as a nonsedating product during the day and a sedating one at night. For other pruritic dermatoses, only the sedating brands are beneficial.

Table 83-3 Selected Antihistamines Used in Dermatology

[edit] ANTIBIOTICS

[edit] Topical Antibiotics

Numerous topical antibiotics are available for the treatment of acne and minor bacterial skin problems (Table 83-4).

Table 83-4 Topical Antibiotics✢

✢Application: Infections: multiple times daily. Acne: once or twice daily.

†Best for acne vulgaris.

‡Best for acne rosacea.

[edit] Topical Antibiotic Ointments.

Several topical antibiotic ointment preparations are available for use in minor wounds (see Table 83-4). Patients can develop allergic contact dermatitis to topical application of neomycin and bacitracin. A newer topical antibiotic, mupirocin (Bactroban ointment), is effective against infections with gram-positive cocci. This antibiotic is especially useful in patients who are carriers of Staphylococcus aureus in the nares. Topical clindamycin phosphate and metronidazole have become standards of care in the treatment of acne and rosacea, respectively.

[edit] Antiseptic Cleansers.

The main antiseptic cleansers include povidone iodine (Betadine), hexachlorophene (pHisoHex), and chlorhexadine gluconate (Hibiclens). These effective antibacterial cleaners are useful as adjunctive therapy in superficial skin infections.

[edit] Oral Antibiotics.

Dermatologic uses of systemic antibiotics include bacterial infections, acne, rosacea, hidradenitis suppurativa, and folliculitis. The antiinflammatory effects of the tetracycline and erythromycin families of drugs may be of equal importance as the antibacterial effects in the treatment of inflammatory skin disorders.

[edit] ANTIFUNGAL THERAPY

Topical antifungal therapy is effective in tinea pedis (excluding onychomycosis), tinea crurus, tinea versicolor, and seborrheic dermatitis (Table 83-5).

Table 83-5 Selected Topical Antifungal Agents

✢Terbinafine effective in candida skin infections in some studies.

[edit] SYSTEMIC ANTIFUNGAL THERAPY

Systemic use of antifungal drugs is indicated in the treatment of tinea corporis, tinea capitis, onychomycosis, all deep fungal infections, and most fungal infections that occur in the setting of human immunodeficiency virus (HIV) infection.

Griseofulvin, the first systemic antifungal for use in dermatology, is now limited in use. Its main use is in tinea capitis in children. Recent research, however, suggests that terbinafine and itraconazole may be as effective and will likely replace griseofulvin.

Ketoconazole, the first oral imidazole antifungal, is no longer used routinely because of potential liver toxicity and the advent of newer, less toxic, and more effective antifungals.

Fluconazole is effective against dermatophytes, Candida species, and Malassezia furfur. Its concentration in skin tissue lends to its use in skin infections. It is used commonly in the treatment of oral thrush (200 mg as the first dose, then 100 mg/day) and vaginal candidiasis (150 mg single dose). It has also been found to be effective as a single-dose therapy for tinea versicolor and as a weekly 200-mg dose for onychomycosis. Liver toxicity is a rare complication, and drug interactions can be significant.

Itraconazole, another imidazole antifungal, is approved for treating onychomycosis in a pulse regimen of 200 mg twice daily for 1 week per month, for a total of 3 months. Drug interactions and potential liver toxicity require monitoring.

Terbinafine is an allylamine derivative effective against most superficial skin fungal infections. Risks of liver toxicity and drug interactions are less than with imidazole antifungals. It is approved for the treatment of onychomycosis (250 mg/day for 3 months).

[edit] ANTIVIRAL THERAPY

Acyclovir is effective against herpesvirus infections, including herpes simplex virus (HSV) and herpes zoster. The antiviral activity of acyclovir requires activation by the viral enzyme thymidine kinase. Because of this requirement, acyclovir has little toxicity to human cells and therefore has relatively few systemic side effects. The specific treatment recommendations for HSV and herpes zoster are discussed in Chapter 91 .

Valacyclovir is used for the same indications as acyclovir. It achieves higher blood levels than acyclovir with oral dosing. After absorption, valacyclovir is metabolized to acyclovir.

Famciclovir is indicated for the treatment of acute herpes zoster and recurrent HSV. Its pharmacologic action is similar to acyclovir and valacyclovir.

Topical antivirals include penciclovir and acyclovir, both indicated in the treatment of recurrent HSV infections. Both drugs have demonstrated reduced healing time and viral shedding.

[edit] PROCEDURAL DERMATOLOGY

[edit] Skin Biopsy

Skin biopsy can be essential to making a correct dermatologic diagnosis, and all clinicians should know how to perform this procedure. See Chapter 82 for a detailed description of the skin biopsy.

[edit] Liquid Nitrogen Cryosurgery

[edit] Indications.

The correct use of cryosurgery requires confidence in the diagnosis. This treatment should be avoided if the diagnosis is questionable. Liquid nitrogen is effective in treating small, superficial lesions of epidermal origin such as verruca, seborrheic keratoses, or actinic keratoses. Small lesions with a dermal component, such as acrochordons, also may respond to this treatment. Larger dermal lesions and skin malignancies can be treated with liquid nitrogen but require special temperature monitoring techniques to maximize the response and minimize complications. Liquid nitrogen should never be used to treat melanocytic nevi because of the possibility of misdiagnosing what is actually a malignant melanoma (Box 83-1).

[edit] Procedure.

Liquid nitrogen (boiling point: 196° C) is commercially available and requires storage in an industrial container. It may be applied by cotton applicator or spray. Cotton applicators generally need to be tailored to a size slightly smaller than the lesion.

[edit] Warts.

The amount of freezing required to adequately treat the lesion depends on the size and location. Flat warts and small warts on thin skin require the least amount of freezing. Large and deep warts, such as plantar/palmar warts, require a relatively more aggressive treatment. Repeated freezing-thawing produces more tissue damage. Although the treatment is painful, local anesthetic is usually not required except in large lesions on the palms, soles, and fingers.

[edit] Seborrheic Keratoses.

Seborrheic keratoses, which are epidermal growths, tend to be more superficial than warts and therefore require less freeze time than large warts.

[edit] Actinic Keratoses.

The time required to treat actinic keratoses with liquid nitrogen depends on the amount of keratinized surface and on the depth of involvement. These lesions generally require less freeze time than warts. If there is uncertainty about the diagnosis, cryosurgery should be avoided.

[edit] Complications.

Blister formation is common after cryosurgery. Pain may be severe in the 48 hours after treatment. The use of cryosurgery is limited in dark-skinned people because of the high frequency of healing with hypopigmentation. Infection rarely occurs after cryosurgery, and dressing changes are not required. In general, scarring is usually minimal but is more common on the face.

Cryotherapy in children and elderly patients should be performed with caution because of these patients' increased susceptibility to blister formation and scarring.

[edit] Skin Tag Removal

Acrochordons are treated by a variety of methods depending on the size of the lesions. The smallest lesions can be treated with liquid nitrogen. Larger lesions are best treated by removal with a scalpel or scissors. The need for local anesthesia depends on the size of the lesion, but most can be removed without anesthesia as long as the cutting of each lesion is swift.

[edit] Cyst Removal

Surgical excision of small cysts can be uncomplicated. Large lesions on the face or scalp require the same surgical precautions as larger excisions. In a noninflamed cyst, failure to remove the entire cyst wall can result in its recurrence. Small cysts are best excised after local anesthesia by means of an elliptical or punch incision to gain access to the cyst, and removal of the entire cyst wall is achieved with blunt and sharp dissection. Closure can require both dermal and surface suturing.

[edit] ADDITIONAL READINGS

• KA Arndt: Manual of dermatologic therapeutics ed 5. Boston: Little, Brown; 1995:
• TP Habif: Clinical dermatology ed 3. St Louis: Mosby; 1996: