Patch testing with budesonide in serial dilutions: the significance of dose, occlusion time and reading time.

Budesonide is advocated as a marker molecule for corticosteroid contact allergy. When patch testing corticosteroids, one must consider their sensitizing potential but also their anti-inflammatory properties, as well as the possibility of different time courses for such properties. The dose-response relationship for budesonide was therefore investigated with regard to dose, occlusion time, and reading time. 10 patients were patch tested with budesonide in ethanol in serial dilutions from 2.0% down to 0.0002% with occlusion times of 48, 24, and 5 h. Readings were on D2, D4, and D7. The 48-h occlusion picked up most positive reactors, 8/10. The D4 reading (48-h occlusion) detected most positive reactors, 8/10, and here 0.002% picked up most contact allergies. Late readings favoured high concentrations. The "edge effect" was noted for several concentrations at early readings. Due to the individual corticosteroid reactivity, the dose-response relationship and the time courses of the elicitation and the anti-inflammatory capacity, several features may be explained, i.e., that lower concentrations may detect budesonide allergy better at early readings, that patients with an "edge reaction" can have positive reactions to lower concentrations.