The US drugs regulator has approved the sale of a new nasal spray to treat depression.
The manufacturer, Janssen says Esketamine can lift a patient’s mood within 24 hours of use.
The drug is intended for patients who have not responded to two other, conventional anti-depressants which can take weeks to have an effect.
However, critics argue that the spray – sold as Spravato – may have been approved without adequate testing.
The spray was first approved by the Food and Drug Administration (FDA)’s advisory panel in February, and can cost up to $885 (£673) per treatment.
In a statement, Janssen said it offers “a potential therapy for adults living with treatment-resistant depression,” including help with tackling suicidal thoughts.
Traditional anti-depressants like Prozac try to ease depression by making more serotonin available in the brain to pass messages between nerve cells.
Serotonin is thought to have a good influence on mood, emotion and sleep.
In contrast, esketamine targets glutamate, a chemical linked with learning and memory, and generally considered the most essential for normal brain function.
The spray is absorbed through the nose into the blood stream and must be taken along with another, oral, anti-depressant.
About 300 million people suffer from depression worldwide, according to the World Health Organization.
The UN body said depression-related suicide was the second-leading cause of death among people aged 15-29 around the world.