Dr. Itokawa, a researcher in the Schizophrenia Research Project, conducted an investigator-initiated clinical trial of K-163-SZ (pyridoxamine) on 10 patients with schizophrenia from 2011 through 2012. Subsequently, a sponsor-initiated clinical trial was conducted on 97 schizophrenia patients exhibiting negative symptoms (K-163 group: n=45, placebo group: n=52) from 2017 to 2019 to evaluate the efficacy of K-163 in improvement of negative symptoms.
We analyzed changes from baseline of the negative symptom subscale of the PANSS (Positive and Negative Syndrome Scale) and found no significant differences between the K-163 and placebo groups.
In the original investigator-initiated trial, two patients had developed Wernicke encephalitis, so in the sponsor-initiated Phase2 trial, Vitamin B1 was planned to be administered to patients who showed signs of low vitamin B1 in the blood. However, since the first patient in the Phase2 trial developed Wernicke encephalitis, the protocol was modified so that all patients took vitamin B1 throughout the trial.
Details are available in the Japanese registry of clinical trials (jRCT) linked below.
Pyridoxamine was not shown to improve negative symptoms of schizophrenia in the phase 2 clinical trial and the trial has been suspended. However, we will continue our research to elucidate the causes of schizophrenia and develop treatments.
