Ketamine was first used in a medical context as a surgical anesthetic over 50 years ago. Since then, its applications for treating mental health and chronic pain have become evident. Traditional antidepressants target the serotonin and noradrenaline systems of the brain. In contrast, ketamine blocks N-myethyl-D-aspartate (NDMA), a receptor in the brain activated by a neurotransmitter called glutamate. In the process, it repairs damage in the brain’s synapses.