Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Pharmacogenetics‐Guided Warfarin Dosing: 2017 Update
Warfarin is a widely used anticoagulant with a narrow therapeutic index and large interpatient variability in the dose required to achieve target anticoagulation. Common genetic variants in CYP2C9, VKORC1, CYP4F2, and the CYP2C cluster (e.g., rs12777823), plus known nongenetic factors, account for ∼50% of warfarin dose variability. This document is an update to the 2011 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2C9 and VKORC1 genotypes and warfarin dosing and aims to assist in the interpretation and use of CYP2C9, VKORC1, CYP4F2, and rs12777823 genotypes to estimate therapeutic warfarin dose among patients with a target international normalized ratio (INR) of 2–3, should clinical genotype results be available to the clinician. The CPIC of the National Institutes of Health's Pharmacogenomics Research Network develops peer‐reviewed gene/drug guidelines that are published and updated periodically on https://cpicpgx.org/guidelines/ and http://www.pharmgkb.org based upon new developments in the field.1 These guidelines were written with a global audience in mind, although the majority of the data that underpin these guidelines arise from people of European ancestry, East Asia, and African Americans.