Skin Disorder Topical Drugs

DRUG CLASSES


Antibiotic topicals


Antifungal topicals


Antiviral topicals


Antiseptics and germicides


Corticosteroids


Antipsoriatic topicals


Enzymes and Keratolytics


Local anesthetics



This chapter discusses the following types of topical drugs: anti-infectives, corticosteroids, antipsoriatics, enzymes, keratolytics, and anesthetics. Each of the following sections discusses only select topical drugs. See the Summary Drug Table: Topical Drugs for a more complete listing of the drugs and additional information.



PHARMACOLOGY IN PRACTICE



The medication nurse in the long-term care facility caring for Mr. Park asks you about his shingles outbreak. Her cousin has cold sores and uses an acyclovir ointment when they first appear. She questions why Mr. Park was not prescribed a topical drug to ease the pain and irritation from the shingles lesions. Would not the same help Mr. Park? As you read about topical preparations, consider her question.


TOPICAL ANTI-INFECTIVES


Localized skin infections may require the use of a topical anti-infective. The topical anti-infectives include antibiotic, antifungal, and antiviral drugs.


Actions and Uses


Topical Antibiotic Drugs


Topical antibiotics exert a direct local effect on specific microorganisms and may be bactericidal (i.e., lethal to bacteria) or bacteriostatic (i.e., inhibit bacterial growth). Bacitracin inhibits cell wall synthesis and is an example of a topical antibiotic.


These drugs are used to:


•  Treat primary and secondary skin infections


•  Prevent infection in minor cuts, wounds, scrapes, and minor burns


•  Treat acne vulgaris


Topical Antifungal Drugs


Superficial mycotic infections occur on the surface of, or just below, the skin or nails. Superficial infections include athlete’s foot (tinea pedis), jock itch (tinea cruris), ringworm (tinea corporis), and nail fungus (onychomycosis). In hot and humid climates a generalized fungal infection (tinea versicolor) is bothersome. Antifungal drugs exert a local effect by inhibiting growth of fungi. Antifungal drugs are used for treating:


•  Athlete’s foot, jock itch, ringworm


•  Cutaneous candidiasis


•  Other superficial fungal infections of the skin


Topical Antiviral Drugs


Acyclovir and penciclovir are topical forms of antiviral drugs used to treat oral herpes simplex virus (HSV). These drugs are used to inhibit viral activity:


•  During initial episodes of HSV (prodrome phase)


•  Directly on lesions to speed up recovery


Docosanol is a cream sold over the counter (OTC) and speeds healing as well.


Adverse Reactions


Adverse reactions to topical anti-infectives are usually mild. Occasionally, the patient may experience a rash, itching, urticaria (hives), dermatitis, irritation, or redness, which may indicate a hypersensitivity (allergic) reaction to the drug. Prolonged use of topical antibiotic preparations may result in a superficial superinfection (an overgrowth of bacterial or fungal microorganisms not affected by the antibiotic being administered).


Contraindications, Precautions, and Interactions


These drugs are contraindicated in patients with known hypersensitivity to the drugs or any components of the drug.


The topical antibiotics are pregnancy category C drugs and are used cautiously during pregnancy and lactation. Acyclovir and penciclovir are pregnancy category B drugs and are used cautiously during pregnancy and lactation. The pregnancy categories of the antifungals are unknown except for econazole, which is in pregnancy category C, and ciclopirox, which is in pregnancy category B; both are used with caution during pregnancy and lactation. There are no significant interactions for the topical anti-infectives.



  HERBAL CONSIDERATIONS


Aloe vera is used to prevent infection and promote healing of minor burns (e.g., sunburn) and wounds. When used externally, aloe helps to repair skin tissue and reduce inflammation. Aloe gel is naturally thick when taken from the leaf but quickly becomes watery because of the action of enzymes in the plant. Commercially available preparations have additive thickeners to make the aloe appear like the fresh gel. The agent can be applied directly from the fresh leaf by cutting the leaf in half lengthwise and gently rubbing the inner gel directly onto the skin. Commercially prepared products are applied externally as needed. Rare reports of allergy have been reported with the external use of aloe (DerMarderosian, 2003).


TOPICAL ANTISEPTICS AND GERMICIDES


An antiseptic is a drug that stops, slows, or prevents the growth of microorganisms. A germicide is a drug that kills bacteria.


Actions


The exact mechanism of action of topical antiseptics and germicides is not well understood. These drugs affect a variety of microorganisms. Some of these drugs have a short duration of action, whereas others have a long duration of action. The action of these drugs may depend on the strength used and the time the drug is in contact with the skin or mucous membrane.


Chlorhexidine


Chlorhexidine affects a wide range of microorganisms, including gram-positive and gram-negative bacteria.


Hexachlorophene


Hexachlorophene (pHisoHex) is a bacteriostatic drug that acts against staphylococci and other gram-positive bacteria. Cumulative antibacterial action develops with repeated use.


Iodine


Iodine has anti-infective action against many bacteria, fungi, viruses, yeasts, and protozoa. Povidone–iodine (Betadine) is a combination of iodine and povidone that liberates free iodine. Povidone–iodine is often preferred over iodine solution or tincture, because it is less irritating to the skin and treated areas may be bandaged or taped.


Uses


Topical antiseptics and germicides are used for the following:


•  To reduce the number of bacteria on skin surfaces


•  As a surgical scrub and preoperative skin cleanser


•  For performing hand hygiene before and after caring for patients


•  In the home to cleanse the skin


•  On minor cuts and abrasions to prevent infection


Adverse Reactions


Topical antiseptics and germicides provoke few adverse reactions. Occasionally, an individual may be allergic to the drug, and a skin rash or itching may occur. If an allergic reaction is noted, use of the topical drug is discontinued.


Contraindications, Precautions, and Interactions


These drugs are contraindicated in patients with known hypersensitivity to the individual drug or any component of the preparation. There are no significant precautions or interactions when the drugs are used as directed.


TOPICAL CORTICOSTEROIDS


Topical corticosteroids vary in potency, depending on the concentration (percentage) of the drug, the vehicle (lotion, cream, aerosol spray) in which the drug is suspended, and the area (open or denuded skin, unbroken skin, thickness of the skin over the treated area) to which the drug is applied.


Actions and Uses


Topical corticosteroids exert localized anti-inflammatory activity. When applied to inflamed skin, they reduce itching, redness, and swelling. These drugs are used in treating skin disorders such as:


•  Psoriasis


•  Dermatitis


•  Rashes


•  Eczema


•  Insect bites


•  First- and second-degree burns, including sunburn


Adverse Reactions


Localized reactions may include burning, itching, irritation, redness, dryness of the skin, allergic contact dermatitis, and secondary infection. These reactions are more likely to occur if occlusive dressings are used. Systemic reactions may also occur with hypothalamic-pituitary-adrenal axis suppression, Cushing’s syndrome, hyperglycemia, and glycosuria.


Contraindications, Precautions, and Interactions


Topical corticosteroids are contraindicated in patients with known hypersensitivity to the drug or any component of the drug; as monotherapy for bacterial skin infections; for use on the face, groin, or axilla (only the high-potency corticosteroids); and for ophthalmic use (may cause steroid-induced glaucoma or cataracts). The topical corticosteroids are not used as sole therapy in widespread plaque psoriasis. The topical corticosteroids are pregnancy category C drugs and are used cautiously during pregnancy and lactation. There are no significant interactions when these drugs are administered as directed.


TOPICAL ANTIPSORIATICS


Action and Uses


Topical antipsoriatic drugs are drugs used to treat psoriasis (a chronic skin disease manifested by bright red patches covered with silvery scales or plaques) by helping to remove the plaques associated with the disorder.


Adverse Reactions


These drugs may cause burning, itching, and skin irritation. Anthralin may cause skin irritation, as well as temporary discoloration of the hair and fingernails.


Contraindications, Precautions, and Interactions


Topical antipsoriatics are contraindicated in patients with known hypersensitivity to the drugs. Anthralin and calcipotriene, pregnancy category C drugs, are used cautiously during pregnancy and lactation.


TOPICAL ENZYMES


Actions and Uses


A topical enzyme is used to help remove necrotic (dead) tissue from:


•  Chronic dermal ulcers


•  Severely burned areas


These enzymes aid in the removal of dead soft tissues by hastening the reduction of proteins into simpler substances. The process is called proteolysis or a proteolytic action. The components of certain types of wounds, namely, necrotic tissues and purulent exudates (pus-containing fluid), prevent proper wound healing. Removal of this type of debris by application of a topical enzyme aids in healing. Examples of conditions that may respond to application of a topical enzyme include second- and third-degree burns, pressure ulcers, and ulcers caused by peripheral vascular disease. An example of a topical enzyme is collagenase.


Adverse Reactions


The application of collagenase may cause mild, transient pain and possibly numbness and dermatitis. There is a low incidence of adverse reactions to collagenase.


Contraindications, Precautions, and Interactions


Topical enzyme preparations are contraindicated in patients with known hypersensitivity to the drugs, in wounds in contact with major body cavities or where nerves are exposed, and in fungating neoplastic ulcers. These drugs are pregnancy category B drugs and are used cautiously during pregnancy and lactation. Enzymatic activity may be impaired by certain detergents and heavy metal ions, such as mercury and silver, which are used in some antiseptics. The optimal pH for collagenase is 6 to 8. Higher or lower pH conditions decrease the enzyme’s activity.


KERATOLYTICS


Actions and Uses


A keratolytic is a drug that removes excess growth of the epidermis (top layer of skin) in disorders such as warts. These drugs are used to remove:


•  Warts


•  Calluses


•  Corns


•  Seborrheic keratoses (benign, variously colored skin growths arising from oil glands of the skin)


Examples of keratolytics include salicylic acid and masoprocol. Some strengths of salicylic acid are available as nonprescription products for the removal of warts on the hands and feet.


Adverse Reactions


These drugs are usually well tolerated. Occasionally a transient burning sensation, rash, dry skin, scaling, or flu-like syndrome may occur.


Contraindications, Precautions, and Interactions


Keratolytics are contraindicated in patients with known hypersensitivity to the drugs and for use on moles, birthmarks, or warts with hair growing from them, on genital or facial warts, on warts on mucous membranes, or on infected skin. Prolonged use of the keratolytics in infants and in patients with diabetes or impaired circulation is contraindicated. Salicylic acid may cause salicylate toxicity with prolonged use. These drugs are pregnancy category C drugs and are used cautiously during pregnancy and lactation.


TOPICAL LOCAL ANESTHETICS


A topical anesthetic may be applied to the skin or mucous membranes.


Actions and Uses


Topical anesthetics temporarily inhibit the conduction of impulses from sensory nerve fibers. These drugs may be used to relieve itching and pain due to skin conditions, such as minor burns, fungal infections, insect bites, rashes, sunburn, and plant poisoning (e.g., poison ivy). Some are applied to mucous membranes as local anesthetics.


Adverse Reactions


Occasionally, local irritation, dermatitis, rash, burning, stinging, and tenderness may be noted.


Contraindications, Precautions, and Interactions


These drugs are contraindicated in those with a known hypersensitivity to any component of the preparation. Topical anesthetics are used cautiously in patients receiving class I antiarrhythmic drugs such as tocainide and mexiletine, because the toxic effects are additive and potentially synergistic.



NURSING PROCESS


PATIENT TEACHING FOR MEDICATION INFORMATION


ASSESSMENT


Preadministration Assessment


The preadministration assessment involves a visual inspection and palpation of the involved area(s). Carefully measure and document the areas of involvement, including the size, color, and appearance. The appearance of the skin lesions, such as rough, itchy patches; cracks between the toes; and sore and reddened areas, is noted so treatment can begin with an accurate database. A specific description is important so that changes indicating worsening or improvement of the lesions can be readily identified. Figure 52.1 illustrates common types of lesions found on the skin. Note any subjective reports, such as pain, burning, or any complaint of itching. Some agencies may provide a figure on which the lesions can be drawn, indicating the shape and distribution of the involved areas. Other agencies may document the appearance of the lesions using photography.


Ongoing Assessment


At the time of each application, inspect the affected area for changes (e.g., signs of improvement or worsening of the infection) and for adverse reactions, such as redness or rash. Contact the primary health care provider, and do not apply the drug if these or other changes are noted or if the patient reports new problems, such as itching, pain, or soreness at the site. You may be responsible for checking the treatment sites 1 day or more after application and should inform the primary health care provider of any signs of extreme redness or infection at the application site.



Figure 52.1 Types of skin lesions. (From Cohen, B. J. [2003]. Medical terminology [4th ed.]. Philadelphia: Lippincott Williams & Wilkins.)



  LIFESPAN CONSIDERATIONS


Pediatric


Because infants and children have a high ratio of skin surface area to body mass, they are at greater risk than adults for systemic adverse effects when treated with topical medication.

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Aug 14, 2016 | Posted by in PHARMACY | Comments Off on Skin Disorder Topical Drugs
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