We appreciate the remarks made by Cantilena and Honig in reference to our comments on antipyrine metabolism.1 In the "Comment" section, we were only speculative in stating that antipyrine metabolism may predict warfarin metabolism. Cantilena and Honig referred to one study that demonstrated little relationship between antipyrine and tolbutamide disposition when effected by known inhibitors of drug metabolism.2 We are unaware of other studies showing a similar relationship (or lack thereof) between antipyrine and warfarin. Clearly, more investigation is needed in this area before firm conclusions can be made.
Rindone J. Antipyrine as a Model Drug Substance to Assess Oxidative Metabolism-Reply. Arch Intern Med. 1994;154(5):590. doi:10.1001/archinte.1994.00420050162016