Common Cat Anesthetic Used To Treat Depressed Patients
May 31, 2012

Common Cat Anesthetic Used To Treat Depressed Patients

Ketamine, an anesthetic commonly used in veterinary practice for feline surgical procedures, has been found to help bipolar patients suffering from depression.

Researchers at the National Institute of Mental Health had previously found that a single dose of ketamine produced rapid antidepressant effects in depressed patients with bipolar disorder.

The team has now replicated that finding in an independent group of depressed patients, who also had bipolar disorder.

During the new study, the researchers administered a single dose of ketamine and a single dose of placebo to a group of patients on two different days, two weeks apart.

The patients in the study were then monitored, and were asked to "score" their depressive symptoms and suicidal thoughts.

Patients who received ketamine found that their depression symptoms significantly improved within 40 minutes, and remained improved over 3 days.

Seventy-nine percent of the patients improved with ketamine, while no patients reported they improved while on the placebo.

The researchers found that ketamine significantly reduced suicidal thoughts among the patients, a feat that occurred within one hour of the initial dose.

"Our finding that a single infusion of ketamine produces rapid antidepressant and antisuicidal effects within one hour and that is fairly sustained is truly exciting," Dr. Carlos Zarate, who led the study, said in a press release.

"We think that these findings are of true importance given that we only have a few treatments approved for acute bipolar depression, and none of them have this rapid onset of action; they usually take weeks or longer to have comparable antidepressant effects as ketamine does."

Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that works by blocking the actions of NMDA.  It is commonly used in veterinary practice, and has also been a drug sold on the streets as "Special K."

Antidepressants are commonly prescribed to treat or prevent depressive episodes, but they are not universally effective.

Patients who are on antidepressants can still continue to have periods of depression even while being treated.  For some, it may take several weeks of treatment before a patient begins to feel relief from the drug's effects.

Zarate said this research could see that ketamine is used as the next-generation of drugs used to treat those who are diagnosed with depression.

"Importantly, confirmation that blocking the NMDA receptor complex is involved in generating rapid antidepressant and antisuicidal effects offers an avenue for developing the next generation of treatments for depression that are radically different than existing ones," Zarate said in a press release.

The research was reported in the journal Biological Psychiatry this week.