Abstract: To the Editor: Litin and Gastineau state in their excellent review, which was published in the March 1995 issue of the Mayo Clinic Proceedings (pages 266 to 272), that concurrent use of certain drugs can predispose to hemorrhagic complications of anticoagulant therapy. In that article, one table (Table 3) listed some serious interactions between warfarin and other drugs. Lovastatin1Ahmad S Lovastatin: warfarin interaction.Arch Intern Med. 1990; 150: 2407Crossref PubMed Google Scholar and gemfibrozil,2Ahmad S Gemfibrozil interaction with warfarin sodium (coumadin) [letter].Chest. 1990; 98: 1041-1042Crossref PubMed Scopus (24) Google Scholar two important and widely used hypolipidemic agents, should be added to that list. Gemfibrozil may inhibit the parahydroxylation of warfarin in the liver and, thereby, increase the serum levels of warfarin to a point at which signs of warfarin intoxication (bleeding) occur. Because lovastatin is strongly protein bound, it may displace warfarin from its binding sites and, thereby, potentiate its hypoprothrombinemic action. Lovastatin, like gemfibrozil, also probably inhibits the parahydroxylation of warfarin in the liver and, thus, augments the effect of warfarin. Because lovastatin, gem and warfarin, and warfarin are widely used, heightened clinical awareness of these poten tially dangerous interactions between drugs is warranted and should be publicized. Therefore, the prothrombin time should be monitored diligently when warfarin therapy is prescribed to patients who are receiving these hypolipidemic agents. Warfarin Therapy: In responseMayo Clinic ProceedingsVol. 70Issue 5PreviewDr. Ahmad raises some important points about two potentially serious drug interactions with warfarin that were not included in our table that listed drugs that commonly augment or interfere with the effects of warfarin. That table was not intended to be all-inclusive. As referenced in our article, it was modified from a recent, wellwritten review on warfarin interactions by Wells and colleagues,1 who who analyzed all articles that reported original data on drug and food interactions with warfarin from 1966 to 1993. Full-Text PDF