Combination of an inhibitor of the glycine transporter (GlyT1) and an antipsychotic for the treatment of symptoms of schizophrenia as well as preparation and use thereof.

A medical product, comprising (a) an antipsychotic selected from the group consisting of risperidone, paliperidone, and pharmaceutically acceptable salts thereof, pharmaceutically acceptable esters thereof and enantiomeric forms thereof and (b) a GlyT1 inhibitor selected from the group consisting of Compound No. 1 ** (See formula) Compound No. 2 ** ** (See formula) ** and pharmaceutically acceptable salts thereof, pharmaceutically acceptable esters thereof and enantiomeric forms thereof; as a combined preparation for simultaneous, separate or sequential use in treating or preventing symptoms of schizophrenia associated with disorders such as schizophrenia, dementia, depression, Alzheimer's, ADHD, substance abuse and anxiety.