How ketamine could help treat severe depression

Ketamine – used as an anaesthetic since the 1970s and abused as a party drug for almost as long – could be used to treat people suffering with severe depression. With some patients not responding to traditional treatments (therapy, antidepressants, exercise), some experts think it’s time for ketamine and its derivatives to be used. One clinic in the US has been doing so since 2011 and in 2014 an Oxford psychiatrist reported positive findings from study using ketamine intravenously. Which ketamine-like drug candidate will be the first to clinic?