Clobetasone butyrate is a new corticosteroid, selected for study because of its combitation of good activity in the vasoconstriction test and low systemic activity in animals. Formulated as an 005o% ointment and cream (MolivateN it was clinically effective in patients with eczema, its activity being significantly greater than that of hydrocortisone 1% or fluocortolone 020°, (Ultradil). Under conditions that predispose to maximal percutaneous absorption clobetasone butyrate ointment had minimal effect on hypothalamic-pituitary-adrenal function. In an animal model of cutaneous atrophy it caused less thinning of the epidermis than steroids other than hydrocortisone. ClobetasonebutyrateO.05% ointment and cream gave every indication of offering clinically effective topical anti-inflammatory activity with a wide margin of safety.

SUMMARY A new topically active corticosteroid, clobetasol propionate, has been investigated in the laboratory and in dermatological clinics to determine the best formulation for clinical use. Clinical trials involving 1150 patients were undertaken. In patients with bilateral psoriasis or eczema, clobetasol propionate, at a strength of 0.05%, was compared with betamethasone 17‐valerate ointment and cream, fluclorolone acewnidc ointment and cream and fluocinonide (FAPG). The new steroid was shown to be effective therapeutically, especially in psoriasis. Each comparison in the trial was analysed independently and the following statistically significant differences were demonstrated.

Clobetasone butyrate ointment has been shown to be more effective in treating psoriasis and eczema than flurandrenolone ointment yet to cause less epidermal thinning in a human experimental model. This is an indication that the clinical activity of topical glucocorticoids may not necessarily be inseparable from their propensity to cause atrophy of the skin.

Plasma corticosteroid levels in 295 out-patients using halogenated topical steroids were compared with levels in 158 controls. The mean level of the treated patients was 12-5 /(g/ioo ml compared with 14 /ig, 100 ml in the controls; 96'',, of the patients who used topical steroids and 99",) of the controls had levels of 6 /fg/ioo ml or more. Five of the six patients whose plasma corticosteroid levels were less than 5 /jg/ioo ml on first sampling had normal values on retesting after an interval of 2 weeks or more.

A new glucocorticoid, clobetasone butyrate, has been shown in patients to have good topical anti-inflammatory activity and a minimal effect on hypothalamic-pituitary-adrenal function. Among a group of topically active corticosteroids, compared in a controlled study in the domestic pig, clobetasone butyrate is shown to cause less epidermal thinning than any of the others except only 1% hydrocortisone. This evidence of a lesser atrophogenic effect may indicate further dissociation of unwanted from wanted properties in clobetasone butyrate.