The dominant focus on dopamine D2 receptor antagonists as the main target of drug development led to market approvals of several antipsychotic drugs that generally improved the pos. symptoms of schizophrenia but had little impact on the rate-limiting steps of functional recovery, i.e., neg. symptoms and cognitive impairment.An excitation/ inhibition imbalance in the cortex is opined to be brought about by lower GABAergic activity, which leads to disinhibition of glutamatergic neurons.In turn, disinhibited glutamatergic neuronal projections to the midbrain activate dopaminergic projections to the striatum, leading to excessive striatal dopamine release and inducing psychoses and other psychopathologies noted in schizophrenia.Therefore, inhibitors of GlyT1 (glycine transporter 1) or DAAO (D-amino acid oxidase) were developed to potentially improve neg. and cognitive symptoms.After initial excitement, bitopertin, a GlyT1 inhibitor, has not shown any benefit as an adjunctive treatment for suboptimally responsive pos. or neg. symptoms in large, controlled trials.Iclepertin, a selective GlyT1 inhibitor, showed pos. results in a phase 2 study for cognitive impairments in schizophrenia, and large multinational trials are underway to confirm the initial findings he mechanistic shift away from dopaminergic D2 receptor antagonists to a broader circuit-level dysfunction in schizophrenia involving GABAergic-glutamatergic projections has opened the door to newer therapeutic opportunities with improved safety profiles and that target symptoms more allied to recovery, i.e., neg. symptoms and cognitive impairments.