Usefulness of patch tests in drug adverse reaction induced by tetrazepam and anti-inflammatory drugs

Skin testing with the suspected drugs may be helpful in determining the cause of a cutaneous adverse reaction (CADR). Tetrazepam (T) is a muscle relaxant of the benzodiazepine group frequently used in rheumatology in association with anti-inflammatory drugs (AIDs). We propose to determine the usefulness of patch testing in this context. Patients and methods A retrospective study was conducted including all patients referred between 2000 and 2010 for patch testing after a CADR occurring after concomitant administration of T and AIDs. Patch test were performed at least 6 weeks after healing with T and AIDs diluted at 10 % in petrolatum in a commercial form (Chemotechnique Laboratory Diagnostics, Malmö, Sweden) or crushed and diluted in petroleum. All patients were contacted by letter in 2010 and data concerning T or AID rechallenge, after the patch testing, were collected. T patch testing was also performed on 10 controls, ie individuals who already took T but did not present any CADR.