Eczematous drug eruption

Usually, but not invariably, dermatologic lesions are restricted to light-exposed areas. Changes may vary from urticaria to papular and eczematous eruptions with subsequent exfoliation and lichenification. Microscopically, it is very difficult to distinguish photoallergic reactions from nummular eczema, atop dermatitis, eczematous drug eruptions, and, especially, allergic contact dermatitis. 

A retrospective review of 462,969 adult patients was carried out to assess the risk and pattern of cutaneous adverse reactions associated with the use of PPIs. Sixty-four patients with cutaneous adverse reactions were identified within the study population, and matched with 65 subjects, who did not experience adverse events while on therapy with PPIs. The overall prevalence of cutaneous reactions was 22.6 per 100,000 treated subjects, with specific values of 20, 16,15,10 and 3 per 100,000 for lansoprazole, pantoprazole, omeprazole, rabeprazole and esomeprazole, respectively. Most cutaneous reactions were attributed to omeprazole (n = 50 78.1%). The most frequent reaction was maculo-papular rash (43.8%), but other adverse events included cases of angioedema and/or urticaria, Stevens-Johnson syndrome and toxic epidermal necrolysis, erytiiema multiforme, eczematous drug eruption, urticarial vasculitis and fixed drug eruption. None of the patients experienced cross-reactions among individual PPIs [34 ]. 

The most frequent manifestations of drug allergy involve the skin. Urticaria, angioedema, exanthematous skin rashes, allergic eczematous contact dermatitis, photodermatitis, fixed drug eruptions, erythema multiforme, and the Stevens-Johnson and Lyell syndromes are the best characterized clinical manifestations. Their clinical aspects, evolution, and pathophysiological mechanisms are described in detail in the following chapter. 

A 22-year-old man with a history of fixed drug eruptions, seasonal rhinitis, and mild atopic dermatitis took one tablet of desloratadine and on the next day developed generalized eczema. Patch tests performed 2 months later were strongly positive and were followed during the next 24 hours by a relapse of the pruriginous eczematous lesions spreading on the trunk. 

Hypersensitivity Anaphylaxis angioedema arthralgia chills drug fever eczematous, erythematous, or maculopapular eruptions lupus-like syndrome associated with pulmonary reactions myalgia pruritus urticaria. 

Adverse drug reactions can be classified simply according to their onset or severity. ADRs are occasionally classified as acute/ subacute/ or latent. Acute events are those observed within 60 minutes after the administration of a medication and include anaphylactic shock/ severe bronchoconstrictioii/ and nausea or vomiting (17). Subacute reactions occur within 1 to 24 hours and include maculopapular rasly serum sicknesS/ allergic vasculitiS/ and antibiotic-associated diarrhea or colitis. Latent reactions require 2 or more days to become apparent and include eczematous eruptions/ organ toxicity/ and tardive dyskinesia. 

All the cobalamins have the same pattern of adverse reactions. The adverse effects of high doses of cobalamins include urticaria, eczematous and exanthematous skin lesions, and anaphylactic reactions (SEDA-4, 265), but it is not clear whether the reactions are caused by the drug itself, a preservative, or possibly by contaminants. High oral or parenteral doses of vitamin Be and especially hydroxocobalamin are also on rare occasions suspected to induce acne which is, however, always benign (SEDA-5, 347) (1). Several cases of vitamin Bi2-induced folliculitis and acneiform eruptions have been described, in one case in connection with a patient receiving total parenteral nutrition (2). 

Photoallergic reactions are far less common. They occur after external application or internal administration of photosensitizing drugs, combined with exposure to sunlight. In such circumstances internal administration tends to produce a more exanthematous type of eruption, while external application leads to eczematous manifestations. Transitional cases between the two forms may be encountered. 

Positive patch tests to phenolphthalein have been reported in some eczematous lesions (Bernstein 1931 Wise and Sulzberger 1933). False positive patch tests, reflecting epidermal hysteresis, have also been demonstrated after phenolphthalein administration (Shelley et al. 1972). Wyatt et al. (1972) found that serum taken during exacerbations produced a local inflammation when injected intradermally. Possible cross-reaction with erythrosin which is used as a food and drug colorant has been reported (Wile 1936). Other rare allergic manifestations after phenolphthalein administration are urticaria, Stevens-Johnson syndrome, lupus erythe-matosus-like eruptions, and encephalitis (Lindemayr 1959 Kendall 1954). 

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