subject: Investigation and treatment of drug reaction [print this page] Investigation and treatment of drug reaction
The evaluation of a possible drug reaction should includethe following: A careful assessment of the risk to the patient, from therash itself and from the involvement of other organs, e.g.kidneys and brain in a vasculitis; an assessment of theairway and maintenance of adequate circulation inurticaria/anaphylaxis. A full drug history, including all current and recentlycompleted treatments (tablets, mixtures, injections, suppositoriesetc.) and their timing in relation to the onsetof the rash. Some drugs can cause a rash several daysafter they were last given, e.g. ampicillin, gold and depotpreparations. Past drug history and associated rashes. Other possible explanations for the rash, e.g. a virusinfection. Consideration of which drugs can be stopped. Nonessentialdrugs should be stopped and essential drugschanged to structurally different ones if possible. Laboratory investigations. Except for the investigationof drug-induced blood dyscrasias, these are disappointing.Blood eosinophilia, if present, is supportive of drugeruption. A skin biopsy may help in some cases. Treatment. The most immediately serious drug reactionis anaphylaxis. Emergency treatment is with 1:1000adrenaline, 1 mL i.m., or slowly i.v. if the patient is moribund.Parenteral antihistamine and hydrocortisone arealso given, and if necessary the patient is intubated andmanaged on ICU.Depending on severity, some patients with erythroderma,bullous erythema multiforme, toxic epidermal necrolysis.
Skin manifestations of malignancy Direct involvemente.g. Direct spread from breast carcinoma; plaques and nodules from lymphomaGenetic predispositione.g. Multiple cysts and benign skin tumours occurring with colonic carcinomawith autosomal dominant inheritance (Gardner's syndrome) Carcinogen (also causing skin disease)e.g. Vinyl chloride skin eruption and angiosarcoma of the liver followingexposure to vinyl chloride monomer (used in plastic manufacture) Metabolic products of tumoure.g. Flushing due to malignant carcinoid; migratory necrolytic erythema withglucagonoma - partly due to essential amino acid deficiencies induced by metabolic abnormality and vasculitis will require treatment with systemic corticosteroids.
