Corticosteroids
Class Summary
Corticosteroids have anti-inflammatory properties and cause profound and varied metabolic effects. These agents modify the body's immune response to diverse stimuli.
Triamcinolone topical (Kenalog, Triderm, Zytopic)
Topical triamcinolone (0.1% cream) is an anti-inflammatory that is administered for intense, localized allergic reactions. This agent can be used to treat inflammatory dermatosis that is responsive to steroids.
Topical triamcinolone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and reversing capillary permeability.
Hydrocortisone (Cortizone, Ala-Cort, Westcort)
Hydrocortisone is an adrenocorticosteroid derivative suitable for application to the skin or external mucous membranes. It decreases inflammation by suppression of the migration of polymorphonuclear leukocytes and reversal of increased capillary permeability.
Clobetasol (Temovate, Clobex)
Clobetasol is a class I superpotent topical steroid; it suppresses mitosis and increases the synthesis of proteins that decrease inflammation and cause vasoconstriction. Clobetasol decreases inflammation by stabilization of lysosomal membranes, inhibition of polymorphonuclear leukocytes, and deregulation of mast cells.
Antihistamines
Class Summary
Antihistamines are used to treat minor allergic reactions and anaphylaxis. These agents act by competitive inhibition of histamine at H1 receptor.
Chlorpheniramine (Chlor-Trimeton, Teldrin, Aller-Chlor, Chlor-Hist)
Chlorpheniramine is used to treat intense, localized allergic reactions. This agent competes with histamine or H1-receptor sites on effector cells in blood vessels and the respiratory tract.
Diphenhydramine (Anti-Hist, Allerdryl, Benadryl)
This is a first-generation antihistamine with anticholinergic effects that binds to H1 receptors in the CNS and the body. It competitively blocks histamine from binding to H1 receptors. It is used for symptomatic relief of symptoms caused by the release of histamine in allergic reactions.
Loratadine (Claritin, Alavert)
Loratadine selectively inhibits peripheral histamine H1 receptors. It is tolerated well, with rate of sedation not significantly different from placebo.
Desloratadine (Clarinex)
Desloratadine is a long-acting tricyclic histamine antagonist selective for the H1-receptor. It is a major metabolite of loratadine, which, after ingestion, is extensively metabolized to the active metabolite 3-hydroxydesloratadine.
Cetirizine (Zyrtec)
Cetirizine selectively inhibits histamine H1 receptor sites in blood vessels, the GI tract, and the respiratory tract, which, in turn, inhibits the physiologic effects that histamine normally induces at H1 receptor sites. Once-daily dosing is convenient. Bedtime dosing may be useful if sedation is a problem.
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The bedbug is a flat, oval, reddish brown insect that turns violaceous after feeding. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000).
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Bedbugs feeding on a human host. Courtesy of Colonel Dirk M. Elston, MD (from Elston, 2000).
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Human infestation with bedbugs, lice, and mites are common causes of dermatologic symptoms. Although these organisms thrive in conditions of overcrowding and decreased sanitation, Americans of all socioeconomic backgrounds may be at risk for infestation. Clinicians must maintain high suspicion in the appropriate set of clinical circumstances to identify and treat infestations, as they can cause substantial dermatologic and psychological discomfort for patients. Images courtesy of the US Centers for Disease Control and Prevention.
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Bedbugs are parasitic arthropods from the family Cimicidae. They are typically less than 1 cm in length and reddish brown in color. Bedbugs can be found in furniture, floorboards, peeling paint, or other small spaces, most commonly in areas of clutter. These insects come out at night in search of prey upon which to feed, with peak feeding times just before dawn. Bedbugs are typically attracted to body heat, carbon dioxide, vibration, sweat, and odor. The image of a Cimex lectularius is shown courtesy of the US Centers for Disease Control and Prevention (CDC).
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After bedbugs find a food source, they bite down with their mouths and inject anticoagulant and anesthetic compounds into the skin. Depending on the species, these parasites feed on the host blood via 1 of 2 mechanisms. Vessel feeders directly insert their mouthparts into superficial capillaries, whereas pool feeders damage the superficial tissue and feed on the accumulated blood. As bedbugs feed, their color may change as they swell with the host blood, as shown in this picture of a larval bedbug feeding on a volunteer host. Image courtesy of the US Centers for Disease Control and Prevention (CDC).
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Bedbug bites themselves are typically painless. However, the subsequent allergic reaction that may develop can cause intense pruritus. While feeding, bedbugs may inject one of several pharmacologically active substances, including hyaluronidase, proteases, and kinins. These compounds may induce different skin reactions, such as erythema, wheals, vesicles, or hemorrhagic nodules. Repeated bites may sensitize individuals, leading to more pronounced cutaneous manifestations or systemic hypersensitivity reactions. The local trauma from bedbug bites can lead to secondary bacterial infection, causing ecthyma, cellulitis, or lymphangitis. There is some evidence that bedbugs may also be a vector for hepatitis B and Chagas disease. Histologic findings from bite-site biopsy specimens typically show eosinophilic infiltrates, which are indicative of the allergic nature of the reaction. The image shown is papular urticaria, which may develop from bedbug bites.
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Treatment for bedbug bites is typically supportive. Local antiseptic lotions or antibiotic creams can be applied for secondary infections, whereas corticosteroid creams and oral antihistamines can be used for allergic reactions. Bedbugs can be eliminated through the use of permethrin insecticides, baited traps, special bedbug-free beds, and bed nets. Homemade methods, such as wrapping duct tape around bed legs as shown, may be effective, but bedbugs have been known to climb other objects and then fall down onto a bed. Image courtesy of Wikimedia Commons.
