[Study on suppression of the pituitary-adrenocortical function by the therapeutic use of corticosteroids and its spontaneous recovery (author's transl)].

The present study was undertaken to investigate suppression of the pituitary-adrenocortical function by long-term corticosteroid therapy and spontaneous recovery from such a suppressant drug effect. Sixty patients who were on corticosteroids (hereinafter their dosage is expressed as the equivalent of prednisolone) given at 10 to 40 mg initially and then on a gradually decreasing basis down to below 10 mg currently or who had already been withdrawn from such a drug regimen were involved in the study and analysed for baseline values for plasma cortisol. These patients were evaluated for the functional status of the pituitary-adrenocortical system in relation to varying combinations of such factors as the total dose of corticosteroids, the duration in days of medication, the duration in days of mecication at reduced dosage levels, and time in days elapsed from cessation of medication. The results led to the following conclusions: (1) In patients receiving corticosteroids at such daily dosage levels as are reduced gradually to 7.5 mg or below within the duration in days as defined by the inequality Y greater than or equal to 8.4X + 222 (where Y stands for total dose given and X stands for the duration in days of administration), the pituitary-adrenocortical function is assumed to be in a state of being suppressed. When corticosteroids have been given at daily dosages reduced gradually to 7.5 mg or below within the duration in days as determined by the inequality Y less than or equal to 6.8X + 140 (where Y and X, respectively, stand as mentioned above), the pituitary-adrenocortical function of the recipient patient is considered to be in a state either of being not suppressed or of being recovered from suppressant drug effect. (2) In cases where corticosteroid therapy is started with a moderate dosage, then reduced to a low dosage level or stopped within relatively short period of time, the recipient patient can be safely withdrawn from the drug therapy without suppression of the pituitary-adrenocortical function if the dosage schedule is in line with the inequality Y less than or equal to 5.9X + 331 (where X denotes the duration in days of medication and Y, total dose). These results led the author to formulate a model of a corticosteroid dosage schedule which is reasonable free from the risk of causing pituitary-adrenocortical insufficiency. More particularly, the dosage of corticosteroids is reduced by a 5 mg decrement at regular intervals of 5, 8, 13, 27 and 103 days, respectively, when the initial daily dose is 30, 25, 20, 15 and 10 mg. By following this dosage regimen one might expect safe withdrawal from corticosteroid therapy without risking suppression of the pituitary-adrenocortical function. (3) Corticosteroid therapy, when given at a dosage of 7.5 mg or less daily, is considered to have little suppressant effect on the pituitary-adrenocortical function...