Ketamine has gained attention as an effective and fast-acting treatment for patients with major depressive disorder who have suicidal ideation as well as for patients with treatment-resistant depression. Traditional antidepressants take at least four to six weeks to produce an antidepressant effect. However, research has shown that ketamine produces this effect within hours of administration. The study showed that esketamine (S-ketamine or SPRAVATO®) produces an effect two hours after intravenous administration. Intranasal esketamine is approved by the US Food and Drug Administration for the treatment of treatment-resistant depression when used in combination with oral antidepressants. For the treatment of depressive disorders, a racemic mixture of ketamine is used off-label.