Two pretreatment regimens for high-risk patients receiving radiographic contrast media.

The risk of anaphylactoid reaction (AR) developing from radiographic contrast media in patients who previously have had an AR to radiographic contrast media ranges from 17% to 60%. Pretreatment with prednisone plus diphenhydramine or prednisone and diphenhydramine plus ephedrine decreased the reaction rate to 9.0% and 3.1%, respectively, during 657 procedures in 563 patients. No deaths occurred, and only three episodes of transient hypotension developed, one of which was treated with epinephrine. Pretreatment consisted of prednisone, 50 mg, 13 hr, 7 hr, and 1 hr before the procedure and diphenhydramine, 50 mg, 1 hr and or ephedrine, 25 mg, 1 hr before the procedure. The addition of ephedrine provided a statistically significant reduction in reaction in 192 procedures (chi 2 = 5.4996, p = 0.019). In 138 procedures in patients whose initial AR was considered serious, pretreatment was as effective as for patients with histories of mild to moderate reactions. Emergency equipment should be available for all procedures.