DISCRIMINATION OF THE TOXIC POTENTIAL OF CHEMICALLY DIFFERING TOPICALGLUCOCORTICOIDS USING A NEUTRAL RED RELEASE ASSAY WITH HUMAN KERATINOCYTES AND FIBROBLASTS

In inflammatory skin disease, hydrocortisone and prednisolone double e sters are about equipotent to conventional medium potency topical gluc ocorticoids, such as betamethasone valerate. Local adverse effects, in particular skin atrophy, are a potential problem with topical glucoco rticoids. Recently, cell cultures have shown promise as a means of ass essing local tolerance. To investigate the toxic potential of hydrocor tisone, hgdrocortisone-17-butyrate, hydrocortisone aceponate, prednica rbate, triamcinolone acetonide, betamethasone valerate and desoximetha sone, human keratinocytes and fibroblasts were exposed to these agents in vitro, using a modified neutral red release assay. In addition, th e morphology of these cells was assessed by light microscopy. Although all the topical glucocorticoids tested proved toxic to both cell type s, there were major differences between gIucocorticoids in their effec t on fibroblasts. Hydrocortisone and the non-halogenated double-ester- type glucocorticoids were less toxic than the conventional medium pote ncy topical glucocorticoids tested (betamethasone valerate and desoxim ethasone). In particular, hydrocortisone aceponate was less toxic than betamethasone valerate (P less than or equal to 0.05). In general, th e effect of topical glucocorticoids on the cells, based on neutral red release, was more marked with keratinocytes than with fibroblasts. Al though the ranking order with respect to the toxic potential was simil ar, a clear-cut difference was not observed between non-halogenated do uble-ester-type gIucocorticoids and betamethasone valerate. Morphologi cal changes due to glucocorticoid exposure followed the same pattern w ith both keratinocytes and fibroblasts. The neutral red release assay is able to discriminate between the cytotoxic effects of chemically di ffering topical gIucocorticoids on human keratinocytes and fibroblasts . The present data support the hypothesis of an increase in benefit/ri sk ratio with the new double esters of hydrocortisone and prednisolone .