Purpose In this fourth paper in a series on emergent drug trends in the UK (2006 ketamine, 2009 MDMA powder/crystal, 2010 mephedrone), the authors consider how the pharmacological landscape has changed since substituted cathinones (including mephedrone) were controlled in April 2010 and in particular assess the prevalence of mephedrone in the general night time economy (NTE) and its...