According to a new study, rapastinel, an experimental drug currently being evaluated for the treatment for major depression, may relieve the symptoms of obsessive compulsive disorder (OCD) rapidly and with few side effects.

Results of the small proof-of-concept study, led by NARSAD 2009 and 2014 Young Investigator Carolyn I. Rodriguez, M.D., Ph.D., at Stanford University School of Medicine, were reported December 1, 2016 in The American Journal of Psychiatry. Helen Blair Simpson, M.D., Ph.D., a 2005 Young Investigator and 2010 Independent Investigator at Columbia University College of Physicians and Surgeons, was also a member of the research team.

Rodriguez and her colleagues are investigating rapastinel because they previously found that some OCD patients receive rapid relief from their symptoms when treated with ketamine. Ketamine has long been used as an anesthetic, and in recent years researchers have found that it can also rapidly relieve symptoms of depression. However, the drug’s side effects, which include a feeling of dissociation—a sense of detachment from one’s self, or an “out-of-body” experience—are a challenge for broad clinical use in treating psychiatric disorders.

Hoping to find a treatment that reduces patients’ obsessions and compulsions quickly without dissociative side effects, Rodriguez and her colleagues have turned to rapastinel. It, like ketamine, is a drug that modulates the action of NMDA receptors in the brain – docking ports for the neurotransmitter glutamate and important in learning, memory and synaptic plasticity and thought to play a role in OCD. But rapastinel works differently than ketamine and has a lower risk of causing dissociative side effects, the researchers say.

Seven people with OCD participated in the team’s initial clinical study. Each was given a single dose of rapastinel. The drug was well tolerated—no patient reported dissociative side effects—and within hours of treatment, the severity of patients’ symptoms had declined significantly. The drug reduced the severity of patients’ obsessions and compulsions, as well as symptoms of anxiety and depression, the researchers report.

While rapastinel’s effects on OCD symptoms were rapid, they were not long-lasting. When the research team evaluated patients one week after treatment, symptoms were about as severe as they had been prior to treatment. The scientists say important next steps will be testing the effects of repeated dosing and working to develop related drugs that reduce OCD symptoms over a sustained period.