Safety, tolerability and pharmacokinetics of open label sarcosine added on to anti-psychotic treatment in schizophrenia - preliminary study.

Background: Hypofunction of NMDA receptor-mediated neurotransmission might play a critical role in schizophrenia. Sarcosine, N- methylglycine and inhibitor of the glycine transporter-1 (Gly-T1), has been suggested as a novel treatment for schizophrenia.

Methods: Open label sarcosine was added to 22 stabilized patients: 5 patients received 2 gm/d, and 17 received 4gm/d. Pharmacokinetics samples, clinical and cognitive parameters using PANSS, CGI and MCCB were collected for all patients.

Results: Significant improvement was observed after one week of treatment on PANSS sub-scale of 'positive symptoms' (Z= -2.68; P=0.007) and 'general psychopathology' (Z= -3.02; P=0.003), an improvement in PANSS total score and CGI-S showed a trend (Z= -2.72; P=0.06; Z=-2.69; P=0.08). Speed of processing (MCCB subscale) improved significantly (Z=-2.13; P=0.03). Sarcosine exhibited linear kinetics, with a Tmax and t½ of ~1½- 2½ hr and ~1hr, respectively.

Limitations: This was a short period, open label pilot study with small sample size per dosage group.

Conclusions: Sarcosine is a safe compound and might be efficacious in the treatment of schizophrenia.