Tixocortol pivalate contact allergy in the GPMT: frequency and cross-reactivity

In spite of their intrinsic anti-inflammatory properties, corticosteroids can induce contact allergy. When studying the allergenic properties of corticosteroids it has to be considered that both the allergenic and anti-inflammatory effect may influence the induction phase as well as the elicitation phase and that such effects may be dose-dependent. A multiple dose guinea pig maximization test (GPMT) was therefore used to study the dose-response relationship of tixocortol pivalate. The GPMT was conducted according to OECD guideline #406, using a multiple-dose design and test results were analysed with logistic regression analysis. There was a significant tixocortol pivalate sensitization of the test animals compared to the control group (p < 0.05), after both challenge and re-challenge. The challenge with 1% tixocortol pivalate gave more positive reactions than the challenge with 3%. The highest frequency of positive animals was observed when the animals were treated with low to intermediate induction concentrations and intermediate to high challenge concentrations with tixocortol pivalate in the TRUE Test(TM) Cross-reactivity was found between tixocortol pivalate and hydrocortisone, which was expected from their close molecular resemblance, whereas no cross-reactivity was seen between tixocortol pivalate and the 3 other corticosteroids: amcinonide, budesonide, and hydrocortisone-17-butyrate.