Repeated doses of intranasal ketamine produce a fast-acting antidepressant effect in people with major depressive disorder, including those with treatment-resistant depression. In a meta-analysis of six randomized controlled trials totaling 858 participants, depression scores on the Montgomery–Asberg Depression Rating Scale dropped by an average of 6 points at 2–4 hours, 10 points at 24 hours, and 4 points at 28 days. The likelihood of achieving remission was about 3.5 times higher at 24 hours and 1.7 times higher at 28 days compared with placebo. Transient dissociative symptoms and other mild side effects occurred, but no persistent psychosis or mood switches were reported.
In patients undergoing bronchoscopy, combining esketamine with propofol reduced the risk of dangerously low oxygen levels during the procedure compared with the standard combination of sufentanil and propofol. In a randomized trial, 27.2% of patients given esketamine experienced hypoxemia versus 66.7% given sufentanil. The esketamine group also had shorter episodes of low oxygen, higher minimum oxygen saturation, and faster recovery from anesthesia, though they required more propofol. Adverse reactions did not differ between groups. The authors suggest esketamine plus propofol may be a better option for preventing hypoxemia during bronchoscopy, but note that optimal dosing needs further study.