The effect of systemic prednisolone on arachidonic acid, and prostaglandin E2 and F2 alpha levels in human cutaneous inflammation.

1 In order to test the proposal that the anti-inflammatory effect of corticosteroids is attributable to inhibition of release of the prostaglandin precursor, arachidonic acid, the effect of systemic prednisolone on arachidonic acid and prostaglandin levels in abdominal skin of six patients receiving this treatment for alopecia totalis, was studied. 2 Inflammation was produced in an area of abdominal skin by topical application of 5% w/w tetrahydrofurfuryl nicotinate (THFN) cream. 3 The erythema produced was assessed visually, and exudate recovered from normal and inflamed skin, by a suction bulla technique. 4 Arachidonic acid and PGE2 and PGF2 alpha levels, as measured by gas chromatograph-mass spectrometry (GC-MS) were significantly elevated in the reddened (THFN) treated skin, compared with control areas. 5 After prednisolone treatment both arachidonic acid and prostaglandin levels in THFN-treated areas were suppressed near to values obtained from untreated skin, before prednisolone therapy. There was partial reduction of THFN induced erythema in three out of six subjects. Levels of arachidonic acid on control skin were not affected by the steroid. 6 These results provide direct evidence that steroids inhibit prostaglandin formation by blocking evoked rise in the concentration of free arachidonic acid. The relationship of this effect, in human skin, to the anti-inflammatory action of systemic steroids is uncertain.