Ketamine

There's no quick fix for severe depression.

Although antidepressants like Prozac have been around since the 1970s, they usually take weeks to make a difference. And for up to 40 percent of patients, they simply don't work.

As a result, there are limited options when patients show up in an emergency room with suicidal depression.

The doctors and nurses at Ben Taub General Hospital in Houston say they see this problem every day.