The influence of fibrate initiation on INR and warfarin dose in patients receiving chronic warfarin therapy

Investigation of the separate and simultaneous bindings of warfarin and fenofibrate to bovine serum albumin

Lipid-lowering drugs are often taken with anticoagulant drugs in hyperlipidemia patients. Fenofibrate (FNBT) and warfarin (WAR) are common clinical lipid-lowering drugs and anticoagulant drugs, respectively. A study of binding affinity, binding force, binding distance, and binding sites was performed to determine the interaction mechanism between drugs and carrier proteins (bovine serum albumin, BSA), as well as their effects on BSA conformation. Both FNBT and WAR can form complexes with BSA by van der Waals force and hydrogen bonds. WAR had a stronger fluorescence quenching effect on BSA, a stronger binding affinity, and greater effects on BSA conformation than FNBT. According to fluorescence spectroscopy and cyclic voltammetry, co-administration of drugs decreased one drug's binding constant to BSA and increased its binding distance. This suggested that each drug's binding to BSA was disturbed by each other, as well as each drug's binding ability to BSA was altered by the other. It was demonstrated that co-administration of drugs had greater effects on the secondary structure of BSA and microenvironment polarity surrounding amino acid residues, using multiple spectroscopy techniques, such as ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and synchronous fluorescence spectroscopy.

Drug Interactions Affecting Oral Anticoagulant Use

Oral anticoagulants (OACs) are medications commonly used in patients with atrial fibrillation and other cardiovascular conditions. Both warfarin and direct oral anticoagulants are susceptible to drug-drug interactions (DDIs). DDIs are an important cause of adverse drug reactions and exact a large toll on the health care system. DDI for warfarin mainly involve moderate to strong inhibitors/inducers of cytochrome P450 (CYP) 2C9, which is responsible for the elimination of the more potent S-isomer of warfarin. However, inhibitor/inducers of CYP3A4 and CYP1A2 may also cause DDI with warfarin. Recognition of these precipitating agents along with increased frequency of monitoring when these agents are initiated or discontinued will minimize the impact of warfarin DDI. Direct oral anticoagulants are mainly affected by medications strongly affecting the permeability glycoprotein (P-gp), and to a lesser extent, strong CYP3A4 inhibitors/inducers. Dabigatran and edoxaban are affected by P-gp modulation. Strong inducers of CYP3A4 or P-gp should be avoided in all patients taking direct oral anticoagulant unless previously proven to be otherwise safe. Simultaneous strong CYP3A4 and P-gp inhibitors should be avoided in patients taking apixaban and rivaroxaban. Concomitant antiplatelet/anticoagulant use confers additive risk for bleeding, but their combination is unavoidable in many cases. Minimizing duration of concomitant anticoagulant/antiplatelet therapy as indicated by evidence-based clinical guidelines is the best way to reduce the risk of bleeding.