What is the role of the NMDA receptor? Which opioids block the NMDA receptors?
Methadone, levorphanol, and ketamine are three opioids that block the NMDA receptor. The role of the NMDA receptor is to cause sensitization of the neuron and heightened responses following glutamate activation. This sensitization is what can lead to spontaneous pain and allodynia long term. When the NMDA receptor is blocked from the glutamate receptor over time, the process of prolonged glutamate activation is stopped causing less neuronal sensitization.