Deplin, a prescription form of the B-vitamin folate, is developing buzz for its ability to increase the effect of antidepressants.

Folate is important for cell growth and brain function; it has recently been found to play a role in the production of serotonin, dopamine, and norephinephrine – neurotransmitters that help regulate mood.

Deplin helps the body to create sufficient levels of these neurotransmitters, the drug’s maker says. And it can do so more efficiently than taking folic acid, which still needs to be converted in the body.

Two studies, both supported by the drugmaker, have evaluated Deplin. The first found no difference between subjects on low levels of Deplin and those on a placebo. In the second study, involving 75 depressed patients, 32 percent of those on Deplin responded, compared to 15 percent on a placebo.

“Many of the patients I put on Deplin come back and say, ‘Wow, my medication is working again’ or ‘Hey, doc, this medicine never worked this well before,’” says psychiatrist Thor Bergersen, who practices in Needham, Mass. and New York City.

The cost of the drug may be prohibitive, however. A one-month supply costs an estimated $98 and not all insurers cover it.