BOSTON -- There could be new hope for women who suffer from low libido in the form of an antidepressant being hailed by some as Viagra for women.

The antidepressant flibanserin can be used to treat a condition known as hypoactive sexual desire disorder, or lack of libido, researchers at the University of Ottawa said.

"Over 60 to 75 percent of women actually felt the drug did something for them," said Dr. Andre Guay, the director for the Center for Sexual Function at Lahey Clinic.

Unlike male Viagra, which increases blood flow to the genitals to treat erectile dysfunction, flibanserin affects women's brains to enhance mood, and, in turn, can increase sexual desire and satisfaction, researchers said.

"Viagra increases blood flow. This doesn't do that. It affects the brain. (Flibanserin) affects the neurotransmitters in the brain that affects sex," Guay said.

Hypoactive sexual desire disorder affects about 20 percent of women in the U.S., according to HSDD Online.

The multi-nation study tested the drug's effects in 1,378 women between the ages of 18 and 50 who were in stable, communicative, monogamous, heterosexual relationships.

Women who took the medicine reported 22 percent more "satisfying sexual events" than those given a placebo in two clinical tests, according to abstracts released at the European Society for Sexual Medicine.

The study also found that premenopausal women who took the drug for 24 weeks showed significant improvements in sexual desire and functioning compared with those given the placebo.

"We've known for years that other anti-depressant molecules, like Zoloft or Prozac or Lexipro, have a negative impact on female sexuality. We don't know specifically why this one has a positive impact," said Dr. John Thorpe, a researcher with UNC Chapel Hill.

But there was also a strong placebo effect among the study's participants, and not all researchers are sold on its findings.

Problems with sexual desire are "a big deal," for women, according to Dr. Marie Savard, a medical consultant to ABC News.

"We know the role of sex is so important to relationships," she said. "But for women it's unrealistic to think a pill is going to fix the impact of so many issues that women face."

Savard said women have many reasons for a lack of libido, including stress, caregiving roles and lack of self-esteem, and added it's difficult to label women with a simple diagnosis like HSSD. But she said since the brain is a woman's "biggest sex organ," it might make sense that they would benefit from a drug like flibanserin.

If approved by U.S. regulators, the drug, which is being developed by German drug maker Boehringer Ingelheim, could be the first treatment for women who suffer from hypoactive sexual desire disorder.

The randomized, double-blind study was conducted at Canada's Women's Health Center of the Ottawa Hospital, as well as at the University of Virginia, University of North Carolina Chapel Hill and Italy's University of Pavia.