Can Prozac Put An End To PMS?

By Pat Rich
The Medical Post, June 20, 1995

BOSTON - Premenstrual symptoms that are serious enough to interfere with daily activities can be significantly relieved by fluoxetine (Prozac), new Canadian research has shown.

Research by the Canadian Fluoxetine/Premenstrual Dysphoria Collaborative Study group headed by Dr. Meir Steiner, chief of psychiatry at St. Joseph's Hospital at McMaster University in Hamilton, Ont., was published recently in The New England Journal of Medicine.

They report premenstrual dysphoria, as it is officially known, can affect between 3% and 8% of women of reproductive age and to date "no treatments have proved consistently effective."

Because premenstrual syndrome shares many features of depression and anxiety, they speculated fluoxetine could be effective as a treatment and small preliminary trials of the drug have yielded promising results.

To test this premise, women were recruited from seven university-affiliated women's health clinics who met the diagnostic criteria for premenstrual dysphoria. This included at least a one-year history of at least five symptoms attributable to premenstrual syndrome which were serious enough to interfere with daily living. Women who had other major psychiatric disorders were excluded.

In the two-phase study, women first received placebo for two menstrual cycles, followed by a randomized, double-blind, placebo-controlled trial for six menstrual cycles. Women in the treatment group received 20 mg/day or 60 mg/day of fluoxetine.

Symptoms were assessed during clinic visits which took place twice during each menstrual cycle throughout the study period. Primary outcome measures consisted of visual analogue scales for tension, irritability and dysphoria.

A total of 180 completed the study out of 313 who entered the randomization process with a number of dropouts occurring in the placebo group because of lack of efficacy.

Women receiving fluoxetine had significantly fewer symptoms of tension, irritability and dysphoria when compared to the placebo group. Half of the women receiving any dose of fluoxetine had at least moderate improvement in symptoms which began within the first cycle of treatment, compared with 22% on placebo.

Those on the higher dose of the drug reported significantly more side effects. Thirty-five of the 106 women initially entered into this group dropped out because of side effects, the most common of which were insomnia, nausea, tremor and fatigue.

The researchers said the mechanism of action for fluoxetine in this condition "remains uncertain" but is probably unrelated to the way in which serotonin reuptake inhibitors such as fluoxetine act on depressive symptoms.

They concluded, "Fluoxetine in doses of 20 mg/day or lower may be effective in decreasing the psychological symptoms of tension, irritability and dysphoria in women who have premenstrual dysphoric disorder."

In addition to St. Joseph's, centres involved in the study were St. Mary's Hospital and Montreal General Hospital, Montreal, St. Michael's Hospital, Toronto, University Hospital, Vancouver, Queen's University, Kingston, University of Alberta, Edmonton.

In an accompanying editorial, Drs. David Rubinow and Peter Schmidt from the U.S. National Institute of Mental Health at Bethesda, Md., said the data are consistent with descriptions of PMS as a form of atpical depression, but raise questions about why 40% of women with PMS have no response to fluoxetine or other serotonin reuptake inhibitors.

They concluded "there are now treatments for PMS that have stood the test of rigorous trials and enable use to reduce the considerable suffering of women with this disorder."

Copyright 1995 Maclean Hunter Publishing Limited
Reprinted with permission.

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