sodium benzoate + clozapine

**Sodium benzoate + clozapine** is an investigational combination therapy in which sodium benzoate, a D-amino acid oxidase (DAAO) inhibitor traditionally used as a food preservative, is added to clozapine, an atypical antipsychotic, for the treatment of refractory (clozapine-resistant) schizophrenia. Clozapine is the standard last-line treatment for schizophrenia unresponsive to other antipsychotics, acting primarily as a dopamine D2 and serotonin 5-HT2A receptor antagonist. Sodium benzoate, by inhibiting DAAO, increases the availability of D-serine, which acts as a co-agonist at the glycine site of the N-methyl-D-aspartate (NMDA) receptor. This mechanism is hypothesized to improve glutamatergic neurotransmission, which is often disrupted in schizophrenia. Clinical trials have shown that adding sodium benzoate to clozapine can improve negative symptoms and overall symptomatology in clozapine-resistant schizophrenia with a favorable safety profile. The combination has not yet received regulatory approval for this indication, but is being studied further for optimal dosing and long-term effects[1][2][3].