FDA signs off on Zoloft for extreme PMS

ROCKVILLE, Maryland (CNN) -- For a week or two each month, some women have premenstrual syndrome that's so severe, they can barely function.

The condition is called Premenstrual Dysphoric Disorder, and it affects about 4 percent of all women. The good news: the FDA has given the drug Zoloft approval for treating PMDD.

"You don't have to take the drug all month," said Dr. Kimberly Yonkers of Yale University who's done studies of Zoloft in women with PMDD. "You can take it intermittently, so during the two weeks from ovulation to the beginning of menses. Even women who take at symptom onset can get some benefit."

Studies of Zoloft in more than 500 women with PMDD show about 60 percent of patients have an improvement in their symptoms. The women who experienced the most benefit suffered predominantly from emotional symptoms.

The diagnosis of PMDD can be made if women suffer from at least five symptoms characterized by changes in mood such as irritability, anxiety, tension, difficulty concentrating, persistant anger and physical symptoms such as weight gain and bloating.

"Women with PMDD have significant impairment," said Yonkers. "They snap at their children, their spouse, they can't do everything they need to do at home, they pass on social engagements, sometimes miss work."

Zoloft is in a class of anti-depressants known as SSRIs that increase the level of a brain chemical, serotonin. The drug Prozac, also a SSRI, was approved by the FDA in 2000 for the treatment of PMDD.

"One would assume all SSRI's would work for PMDD, but we don't know for certain," Yonkers said. "There may be nuances. A woman may respond to one but not another. The side effects are different for the drugs and people respond differently. It's nice to know there are other options."

Some people taking Zoloft may experience side effects such upset stomach, insomnia, abdominal pain, tremor, sweating and dry mouth. Zoloft has been on the market for more than a decade and is approved to treat depression, post-traumatic stress disorder, panic disorder and obsessive-compulsive disorder.

While it may take 4 to 6 weeks of treatment with an SSRI for people with depression to feel benefit, women with PMDD can get results almost immediately.

"We don't know why we get the effect right away," Yonkers said. "With depression, it's an entrenched biological process and it may take longer to reverse changes. With PMDD you do have a period of wellness, so the biology is different. There's also some evidence that in PMDD that the SSRI's are working on progesterone metabolism."