EDDP, may prolong the cardiac QTc interval and result in the serious arrhythmia torsade de pointes. I further know that methadone binds to the glutamatergic NMDA (N-methyl-D-aspartate) receptor, thus modulating glutamate , a primary excitatory neurotransmitter in the central nervous system. As such, methadone mediates, among other things, peripheral pain sensitization