Glutamatergic drugs for schizophrenia treatment

It is accepted that both positive and negative symptoms of schizophrenia may be due to hypofunction of glutamatergic pathways leading to altered dopaminergic neurotransmission activity. Specifically, there may be diminished glutamatergic signaling at the level of the NMDA receptors, but direct receptor agonists have no clinical utility due to their nonspecific actions and undesirable side effects. Given the problems of ineffectiveness or side effects of drugs that act directly on ionotropic and metabotropic mGlu2-3 receptors, clinical trials have been conducted with other drugs that have other mechanisms of action, especially indirect mechanisms, such as the co-administration of NMDA agonists (glycine or D-serine), glycine transporter inhibitors (sarcosine bitopertin), ampakines (CX-516), and mGlu5 receptor agonists. However, despite repeated failures, the glutamatergic approach to the treatment of schizophrenia has not been exhausted and all theoretical aspects that relate these complex neurochemical mechanisms with symptoms of schizophrenia should be reviewed until we find truly effective molecules with an acceptable side effect profile.