Comprehensive review of genotoxicity data for diclofenac

Diclofenac is a non-steroidal anti-inflammatory drug discovered several decades ago, which has since been used by an estimated one billion patients and has demonstrated an acceptable safety profile. In support of its marketing approval, a comprehensive set of genotoxicity studies were conducted in vitro and in vivo. Despite the fact that these studies preceded both Good Laboratory Practice (GLP) requirements and International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines on genotoxicity testing, they were conducted using the best scientific principles and are considered appropriate by contemporary standards. In addition to bacterial mutagenicity and mammalian in vitro assays, repeat-dose somatic, germ cell and dominant lethal assays were conducted. These data are made available for the first time to offer researchers an opportunity to review the existing data set that unequivocally demonstrates that diclofenac sodium is not genotoxic. This is further substantiated by long-term bioassay data demonstrating that diclofenac sodium has no carcinogenic potential in rodents. However, more recently, new studies have been published showing a genotoxic potential for diclofenac in novel or modified in vitro test systems. These new publications are discussed in the context of the existing comprehensive data package.