feeling of depression really go away. >> reporter: two years ago she heard about a clinical trial for a drug that's the chemical cousin of ketamine, perhaps best known as a club drug. over the last few years some doctors have been using it off label to treat the most stubborn cases of depression. now they have an fda approved drug to do the same. >> it's for about one third of people who don't seem to respond to the existing treatments. >> dr. manji is the head of neuroscience at janssen pharmaceuticals. >> all our previous anti-depressants work by serotonin or norepinephrine. this is completely novel. it works on the nmda receptor and turns on what we think are long-term synaptic changes. >> reporter: esketamine is a