DRUG-INDUCED ERUPTIONS
Posted by recep on April 20th, 2009The most common drug-induced skin eruption is a fairly symmetric maculopapular, pruritic rash. Eruptions typically appear 1 to 10 days after the patient starts taking the drug and last until about 14 days after the patient stops taking it.
The drugs that most commonly cause skin eruptions include penicillins, sulfonamides, gold, phenylbutazone, and gentamicin. However, any oral medication, including OTC preparations and sporadically used drugs, can cause eruptions.
Erythema Multiforme
An inflammatory eruption characterized by symmetric erythematous, edematous, or bullous lesions of the skin or mucous membranes. In about 50% of cases, the cause is unknown. In the others, the disorder appears to be a hypersensitivity reaction that can be triggered by almost any drug and many infections, particularly herpes simplex.
The severity varies from characteristic target lesions with a red periphery and cyanotic center appearing in groups on the limbs to extensive erosion of the skin with bullae on the mucous membranes in the mouth, pharynx, anogenital region, and conjunctiva (Stevens-Johnson syndrome). Corneal ulceration is common in those with severe conditions.
Treatment: All suspected causative agents should be removed, when possible. Localized eruptions should be treated symptomatically. Patients with severe conditions require hospitalization so fluid balance and ophthalmologic, renal, and pulmonary statuses can be monitored. The use of systemic corticosteroids is controversial and should not be a routine practice. If herpes simplex precedes recurrent severe erythema multiforme, a regimen of acyclovir 200 mg orally 5 times/day beginning with the herpetic prodrome may prevent attacks.
Toxic Epidermal Necrolysis
(Lyell’s Syndrome)
A severe condition that begins with general malaise, skin tenderness, and erythema and rapidly progresses to skin blistering and erosion. Applying a lateral force to the skin causes the overlying epidermis to shear off (Nikolsky’s sign). The cause in about 33% of cases is a drug most commonly a sulfonamide, barbiturate, NSAID, penicillin, or hy-dantoin. Toxic epidermal necrolysis is a life-threatening condition with a high mortality rate.
Treatment: The patient should be managed in a burn unit, and possible causative agents should be removed. All denuded areas of the dermis should be covered with an antibacterial agent, such as silver sulfadiazine cream. When possible, the area should be covered with a biologic dressing, such as a pigskin xenograft. Meticulous eye care with close supervision by an ophthalmologist is necessary. Use of systemic corticosteroids is common, but it has not been proved to influence the course of the disease and does increase the risk of sepsis.
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