Studies of Blood Histamine Levels during Topical Corticosteroid Therapy Compared with Those during Systemically Administered Corticosteroids

Abstract Blood histamine levels during topical corticosteroid therapy have not been reported, although decreased blood histamine levels are known to occur after the systemic administration of corticosteroid. Blood histamine levels and serum 11‐hydroxycorticosteroids (11‐OHCS) after systemic corticosteroid were compared with those after topical corticosteroid. Both blood histamine and serum 11‐OHCS levels decreased in a parallel and dose‐dependent manner during systemic administration of 0.5‐1.0 mg/day of betamethasone. Blood histamine levels increased and serum 11‐OHCS levels decreased during systemic administration of 0.25 mg/day to the betamethasone and topical corticosteroid group. Changes in blood histamine levels in the topical corticosteroid group appeared between 0.25 and 0.5 mg/day of systemically administered betamethasone. Fifteen cases of dermatological inpatients suffering from wide‐spread eczema or exfoliative dermatitis were treated with the topical corticosteroids betamethasone 17‐valerate, budesonide and diflorasone diacetate. In each case, blood histamine levels were examined and an equipotent dose of oral administeration of betamethasone was calculated. Thirteen cases in whom blood histamine levels were measured fell into the dosage range from 0.1 to 0.5 mg/day. In each case, serum 11‐OHCS levels were also examined and an equipotent dose of oral administration of betamethasone was calculated by the same method. Fourteen cases in whom serum 11‐OHCS levels were measured compared to a dose of less than 1.0 mg/day of betamethasone. Blood histamine levels in rats treated with 20 or 50 mg/kg/day of prednisolone were decreased significantly, and peripheral total leukocytes, lymphocytes, neutrophils and basophils were also decreased significantly.