This article misses the second part of the study, as elucidated by Derek Lowe here <a href="http:&#x2F;&#x2F;blogs.sciencemag.org&#x2F;pipeline&#x2F;archives&#x2F;2016&#x2F;05&#x2F;06&#x2F;it-isnt-ketamine" rel="nofollow">http:&#x2F;&#x2F;blogs.sciencemag.org&#x2F;pipeline&#x2F;archives&#x2F;2016&#x2F;05&#x2F;06&#x2F;it-...</a>:<p><i>In a rather elegant experiment, the authors deuterated ketamine at the methylene next to its carbonyl group, and showed that this compound (as expected) displayed the same NMDA activity as the parent compound – but that it was far slower at producing the metabolite, and had no activity in the antidepressant screens.</i>