The scourge of premenstrual tension, which affects more than half of women and causes physical as well as emotional trauma, could soon be eradicated by a safe, low-dose pill, scientists said yesterday.
A laboratory-based study has found that very low doses of the anti-depression drug Prozac can eliminate the symptoms of premenstrual syndrome, which include mood swings, tiredness, irritability, headaches and joint pains.
The scientist leading the research said the findings, which have so far been observed in laboratory rats, are strong enough to warrant a full-scale clinical trial with Prozac given that the drug has already undergone the necessary safety tests at the higher doses needed to treat depression. A clinical trial could begin within six months, and if the results are favourable, women could be taking the drug to treat premenstrual syndrome within two years, said Thelma Lovick, a neuroscientist at the University of Birmingham, who led the study.
Not all women have the monthly symptoms associated with their menstrual cycle, but it is estimated that 75 per cent have experienced them at some time and that between 30 and 40 per cent have more severe symptoms that badly affect their work and family lives.
The three-year study, funded by the Medical Research Council, has shown that Prozac taken in doses of about a tenth of that needed to treat depression can stop premenstrual symptoms in rats, animals which show physical and emotional changes, such as increased anxiety and sensitivity to pain, similar to those seen in women. Higher doses of Prozac have been prescribed to women suffering from premenstrual syndrome in the past, especially by doctors in the US, but usually for the treatment of more severe symptoms such as depression.
Dr Lovick told the British Science Festival in Birmingham that Prozac in low doses can affect levels of natural chemicals in the brain that are associated with changes in the female hormone progesterone, which rises and falls during each menstrual cycle.
Although rats have an oestrus cycle rather than a menstrual cycle, they are considered to be a useful model of what happens in humans, Dr Lovick said. "The tests we've used on rats, to our amazement, completely eliminated the symptoms. It was quite dramatic, it was not a one-off, we can repeat it," she said.
"We don't expect to see this in women. I wouldn't say it's going to cure everyone, but taken with other things, such as lifestyle changes, we may be getting there," she added.
Dr Lovick said that Prozac, also known as fluoxetine, probably reduces the premenstrual symptoms by stopping the sudden decline of a steroid substance in the brain called allopregnanolone, or "allo" for short.
"Allo can alter the activity of nerve cells, so it is described as a neuroactive steroid. It enhances the activity of GABA, one of the brain's inhibitory neurotransmitter chemicals, and in those parts of the brain that process emotional responses, allo normally produces calming effects," she said.
"However, when brain levels of progesterone, and hence allo, fall sharply during the late premenstrual period, the natural inhibition is effectively turned off," she said.
"As a consequence, these brain circuits become more excitable, leaving the individual more responsive to stress, which is often manifested behaviourally as anxiety and aggressive behaviour," she added.
The full study will be submitted to a scientific journal for peer review, Dr Lovick said.
Treating a 'severe' condition
Prozac does not have a pharmaceutical licence for treating PMS in Britain, but some doctors are already prescribing the drug.
"I've used it on patients for about 15 years," says Shaughn O'Brien, a professor of obstetrics and gynaecology at Keele University and North Staffordshire Hospital.
"It doesn't have a licence, not because it isn't effective but because for too long PMS hasn't been considered to be significant enough. But it can be severe, causing some women to suffer pain or become physically violent towards relatives.
"I prescribe doses of 20mg or occasionally 40mg, and would like to see the rationale for giving much lower doses. It is an effective treatment for a condition that deserves much more attention."
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