The effect of corticosteroids on theophylline metabolism.

Because of recent reports linking elevations of serum theophylline levels to toxic ranges with the administration of large doses of hydrocortisone we undertook a study of the effect of high-dose corticosteroids on theophylline blood levels in normal volunteers. Seven volunteers received a sustained-release theophylline preparation every 12 hours until stable blood levels were achieved. Each subject then received during three separate eight-hour testing sessions intravenous boluses of either methyl prednisolone, hydrocortisone or saline. Theophylline levels were obtained hourly. Corticosteroids did not increase serum theophylline levels significantly. In fact, theophylline clearance rates on corticosteroids were 21% higher than on saline, p less than .02.