Contact dermatitis to topical medicaments: a retrospective chart review from the Ottawa Hospital Patch Test Clinic.

BACKGROUND: Topical medicaments are a common cause of allergic contact dermatitis. This study will evaluate the prevalence of contact allergy to a wide array of topical medicaments at the Ottawa Patch Test Clinic. OBJECTIVES: The objectives of this study are to report the results of positive patch testing to topical medicaments at the Ottawa Patch Test Clinic and identify common sensitizers in topical medicaments. METHODS: Patients were tested with the standard North American Contact Dermatitis screening series of 70 allergens plus supplementary allergens when indicated. A retrospective chart review of patients positive to topical medicaments between January 1, 2000, and September 30, 2010, was undertaken. RESULTS: The average age of patients was 49.5 years. Thirty-four percent were atopic. Common sensitizers included topical antibiotics (58%), steroids (30%), anesthetics (6%), and antifungals (6%). Patch testing showed that 61% of patients tested positive to antibiotics, 21% to topical steroids, 17% tested positive to topical anesthetics, and 1% tested positive to topical antifungals. The most common reactions were to bacitracin (44%) and neomycin (29%). The most common steroid screener was tixocortol-17-pivalate (group A) (19%), and the most common local anesthetic was lidocaine (12%). CONCLUSIONS: Topical medicaments of all kinds are common causes of allergic contact dermatitis. Those that are more readily available, in over-the-counter preparations, are the most frequent culprits.

Sensitivity to local anaesthetics among asthmatic children.

OBJECTIVES: Although true allergic reactions to local anaesthetics are rare in the general population, the importance of the problem among asthmatic children has yet to be documented. SAMPLE AND METHODS: Skin prick, intradermal and incremental challenge tests with lidocain were performed in 157 asthmatic children aged 8-15 years and compared with 72 nonasthmatic children of a similar age. All of the asthmatic subjects were allergic to at least one allergen, most frequently pollens and house dust mites. Prick testing began with an undiluted solution in patients without a history of allergy and with 1:100 dilution in those with a reaction history. Following negative prick testing, intradermal or incremental challenge tests were performed. RESULTS: A total of 125 patients (80%) had been given local anaesthetics in the past, only three children gave history of an adverse local reaction. At the end of the tests, none of the subjects including controls, were found to have immediate or delayed-type allergy to lidocain. CONCLUSIONS: Local anaesthetic allergy does not seem to be a serious problem among asthmatic children and testing in all asthmatic children is not warranted. Those with an adverse reaction history to local anaesthetics should be tested with these drugs.

Studies on platelets: XXVIII: acute thrombocytopenic purpura due to lidocaine (Xylocaine)-mediated antibody. Report of a case.

A patient developed severe thrombocytopenia three days after the administration of lidocaine (Xylocaine) for dental extractions. Petechial bleeding and thrombocytopenia regressed promptly, probably aided by treatment with adrenocorticotropic hormone (ACTH) and prednisone. The patient is well one year after her experience and has received other drugs with impunity. The thrombocytopenia appeared related to the presence of a specific antibody, predominantly immunoglobulin M (IgM), heat labile, in the patient's plasma and serum. The antibody was lytic in action and needed complement. It probably coupled to the drug, forming an antigen-antibody complex able to fix itself to and cause the lysis of platelets. Thrombocytopenia was induced with the parenteral administration of a small dose of lidocaine to the patient. This case may represent the first recorded example of hematologic complication related to the use of lidocaine.

[Does local regional anesthesia exert an immunosuppressive effect?]. / L'Anesthésie loco-régionale peut-elle exercer une action immuno-dépressive

Lignocaine in very high doses exhibits immunodepressant properties in vitro. In vivo, in surgical patients submitted to spinal anaesthesia, lymphocyte transformation is diminished for one week. This inhibition is, however, less marked than after general anaesthesia.