Percutaneous absorption of hydrocortisone was studied in 18 children (aged from 6 weeks to 14 1/2 years) with atopic or seborrhoeic dermatitis, by measuring their serum cortisol before and after application of 1% hydrocortisone cream. Endogenous secretion of cortisol was suppressed with dexamethasone. A 24 h absorption test was performed on nine children. In six, percutaneous absorption was detected. The highest serum cortisol level was reached within the first 6 h. A 4 h absorption test was developed on the basis of the 24 h test. This short absorption test was performed on nine children, and in eight of them absorption of hydrocortisone was detected. The rise of serum cortisol ranged from 98 to 2669 nmol/l. The 2 h ACTH test was performed to evaluate the effect of previous treatment with topical glucocorticoids. Suppressed adrenocortical function was found in five of 13 children, and was associated significantly with high post-application serum cortisol levels. This occurred more often in infants with a severe skin disorder than in older children or in those with mild or moderate skin disease.

Percutaneous absorption of hydrocortisone was measured by a fourhour absorption test in !6 children duting and after the acute phase of dermatitis. In the acute phase, after the application of 1% hydrocortisone cream the increment in plasma cortisol ranged from 47 to 961 nmol per liter (median 248 nmol/L), After the acute phase the increment was significantly (P < 0,0!) lower: range 18 to 241 nmol per liter (median 95 nmol/L), In addition to local effect, topical hydrocortisone therapy of childhood dermatitis is accompanied by a systetnic effect that may be pronounced in the acute phase of disease. Convalescence is connected with a diminished systemic efFect due to the restoration of the skin barrier to hydrocortisone.Percutaneous absorption of drugs is influenced by the physical and chemical characteristics of the drugs, the vehicle, and the barrier properties of the skin. Clinically important is the question of how the skin barrier to glucocorticoids is influenced by dermatitis. Feinblatt et al (1) suggested that the percutaneous absorption of labeled hydrocortisone, measured by excretion in urine, was higher in children with atopic dermatitis than in those with normal skin, Bronaugh et al (2) showed that absorption of hydrocortisone through eczematous monkey skin in vitro is double that through normal skin, A study using direct measurement of plasma cortisol revealed that absorption was higher in children with severe skin disorder than in those with mild or moderate skin disease (3).The present study evaluated the effect of dermatitis on the percutaneous absorption of hydrocorti-

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