Menopause affects every woman, and with the large baby boomer generation reaching midlife and beyond, an unprecedented number of women are now postmenopausal. Approximately 6,000 women in the United States alone reach menopause every day — more than 2 million per year.

For most women, menopause occurs between the ages of 45 and 55, although perimenopause, the prolonged stage of gradually falling and fluctuating hormone levels, can begin several years earlier when levels of estrogen and progesterone first begin to fluctuate.

Hot flashes (or hot flushes), which occur due to changes in the thermoregulatory system, are the number one complaint of women in the perimenopausal and post-menopausal period. But a new experimental drug class has shown promise in dramatically reducing the impact of hot flashes.

The transition to menopause is an important time a woman's lifespan that may be associated with varied physical and psychological symptoms, such as erratic fluctuations in reproductive hormone levels, often leading to irregular menstrual cycles, vasomotor symptoms, changes in mood or cognition, and sexual dysfunction. Low-dose oral contraceptives and other hormonal therapies are often effective in managing perimenopausal symptoms.

Treating menopause symptoms can be grouped into three tiers:

• lifestyle changes, such as stress reduction, regular exercise and improved diet
• alternative medicine, such as phytoestrogenic supplements, hormone-regulating supplements or a combination of the two
• medications, such as hormone replacement therapy (HRT) and antidepressants; and surgery, such as removal of uterine fibroids that may cause irregular bleeding

Typically, physicians recommend that women begin with the first tier and move on to the others only if necessary.

Up to 70 percent of women who undergo natural menopause — and almost all women whose menopause is induced by surgery — experience hot flashes. The specific causes of hot flashes are complex and not well understood, although there is some evidence that women who have a narrower thermoregulatory zone compared to other women are more likely to experience hot flashes because their bodies are more sensitive to temperature change.

Hot flashes may be a mild nuisance for some women. Others experience frequent severe episodes that lead to clothes and bed sheets drenched in sweat and relentless waking from sleep that ultimately impacts their working, social and home lives. To address this particular symptom, a new class of experimental drugs, tested by scientists at Imperial College London, reduced hot flashes in menopausal women by almost three-quarters in three days.

The scientists conducted a randomized, double-blind, placebo-controlled trial, involving 37 menopausal women between ages 40 and 62 years who experienced seven or more hot flashes a day. Participants were randomly chosen to first receive either an 80 mg daily dose of the drug, called MLE4901, or a placebo over the course of four weeks. They then switched to receive the other tablet for an additional four weeks, which assured that the women acted as their own controls during the study and that the effects of the drug were clear.

The scientists found that MLE4901 significantly reduced the average total number of flashes and their severity during the four-week treatment period compared to when the women received the placebo for four weeks. Furthermore, the women reported an 82 percent decrease in the amount their hot flashes interrupted their sleep and a 77 percent reduction in problems with concentration.

The new experimental compound is thought to work by blocking the action of a brain chemical called neurokinin B (NKB). Previous animal and human trials have shown increased levels of NKB may trigger hot flashes.

Although the efficacy of this drug is encouraging for those who suffer with relentless hot flashes, side effects affecting liver function prohibit this compound from advancing through further clinical trials. However, two similar drugs that also block NKB but do not appear to carry these side effects have entered larger patient trials, with one such trial launched in the United States last year.

Scientists hope these types of compounds may provide women with an alternative to HRT, the current treatment for symptoms of menopause.