Dr. Steven Sireci (Director, Medical and Professional Services/Bracco Diagnostics) reponds:

In the Isovue package inserts, under the heading "Drug Incompatibilities", there is stated the following:

"Many radiopaque contrast agents are oncompatible in vitro with some antihistamines and many other drugs; therefore, no other pharmaceuticals should be admixed with contrast agents."

Many other contrast media package inserts have similar wording. Therefore, no official recommendation can be made concerning dilution. However, federal law permits physicians to make use of approved drugs as they see fit. Each physician, when considering each patient, must balance the potential for contrast media-related adverse reactions with the need for effective diagnosis.

The ACR Manual on Contrast Media, 4th Edition, does state that chemotoxic reactions are related to ionicity and osmolarity. Therefore, a careful evaluation of the ionicity and osmolarity of any admixture would seem to be appropriate.

Anaphylactoid reactions are not related to concentration. Dilution will have no effect on them.

Any information supplied by Dr. Sireci through RadiologyWeb is not to be considered as professional advice being offered by Dr. Sireci, either on behalf of Bracco Diagnostics or on behalf of himself individually. The viewer should use any such information and/or opinions for general reference only. The information is not intended to provide definitive or complete medical, instructional, or treatment information.