The antidepressant bupropion may hold promise for improving symptoms in younger women diagnosed with so-called hypoactive sexual desire disorder, a small study suggests.

The disorder, called HSDD for short, is diagnosed when a person has a persistently low interest in sex, and that disinterest is causing personal distress or relationship problems.

In the new study, Iranian researchers found that bupropion sustained-release (Wellbutrin SR) generally boosted sex drive among 116 women with HSDD who took the drug for 12 weeks. Compared with 116 women given an inactive placebo, their scores on a standard measure of sexual function were twice as high, according to findings published in the medical journal BJU International.

In some cases, low sex drive is related to underlying health conditions, like depression, or to side effects from some medications, like high blood pressure drugs or some antidepressants.

HSDD, however, refers to low sex drive that is not better accounted for by depression or other mental health disorders, and not caused by a medical condition or drug side effect.

As it stands, there is no treatment for HSDD that is widely accepted by women, according to the researchers on the new study, led by Dr. Mohammad Reza Safarinejad of Shahid Beheshti University in Tehran.

In Europe, a testosterone patch called Intrinsa is approved for treating HSDD in postmenopausal women. It is not approved in the U.S.

In an email, Safarinejad noted that studies have shown bupropion SR to improve sexual function in women who are having sexual side effects from using other antidepressants known as selective serotonin reuptake inhibitors (SSRIs).

Decreased libido is a potential side effect of SSRIs, which include drugs like sertraline (Zoloft), paroxetine (Paxil) and fluoxetine (Prozac). Bupropion has a different mechanism of action from SSRIs, targeting the nervous system chemicals dopamine and norepinephrine rather than serotonin.

For the current study, Safarinejad and colleagues randomly assigned 232 women between the ages of 20 and 40 to take either bupropion SR or a placebo every day for 12 weeks. All of the women had been diagnosed with HSDD and were free of depression or other major health problems.

The study received no drug industry funding, Safarinejad said.

At the outset, both groups of women had similar scores on a standard questionnaire gauging sexual function — just under 16, on average. The average score for healthy women with a regular partner is 33.6, Safarinejad said.

After 12 weeks, that score improved to 33.9 among women in the antidepressant group, versus 16.9 in the placebo group.

The most common side effects linked to bupropion included headache (affecting 9 percent of the group), insomnia and dry mouth (each affecting 7 percent), and nausea and muscle aches (each affecting 6 percent).

While the findings suggest that bupropion improves low sex drive, this is the first study to test the antidepressant in premenopausal women with HSDD.

"Further studies are needed to better elucidate the role of bupropion in HSDD," Safarinejad noted.

Exactly why bupropion might improve sexual function is unclear. One theory attributes the effects to enhanced dopamine and norepinephrine activity; research suggests that dopamine is a key player in the brain's "pleasure center," being released in response to "rewards" like food and sex.