iclepertin iclepertin iclepertin (developmental code name bi 425809) is an investigational nootropic to enhance the cognition and functional capacity in schizophrenia developed by boehringer ingelheim. as of may 2020, it is in phase iii of clinical trial under the code name connex-3. bi 425809 is an inhibitor of glycine transporter 1 (gly-t1) that in phase ii improved cognition after 12 weeks in patients with schizophrenia. doses of 10 mg and 25 mg showed the largest separation from placebo. if these encouraging results are confirmed in phase 3 trials, bi 425809 could provide an effective treatment for cognitive impairment associated with schizophrenia. schizophrenia is characterized by abnormalities in glutamatergic pathways related to nmda receptor hypofunction. inhibition of glyt1 on the presynaptic membrane or astrocytes is hypothesized to increase glycine levels within the synapse. the nmda receptor function may be enhanced by increasing levels of its co-agonist, glycine, within the synaptic cleft, which may lead to improvements in cognitive function. iclepertinclinical dataother namesbi 425809legal statuslegal status investigational identifierscas number1421936-85-7pubchem cid155259577uniim43zdu10ddchemical and physical dataformulac20h18f6n2o5smolar mass512.42 g·mol−1