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Last Updated: Wednesday, 3 December, 2003, 02:06 GMT
Antidepressant blocks cancer drug
Woman holding head
Women taking tamoxifen can experience menopausal symptoms
Antidepressants, which can reduce the hot flushes linked to a cancer drug, may also reduce its effectiveness, researchers have warned.

Women taking tamoxifen sometimes experience menopausal symptoms such as flushes.

Previous research found antidepressants could reduce the symptoms.

But scientists at the Indiana University School of Medicine found they may stop tamoxifen being broken down properly in the body.

Antidepressant drugs, such as the selective serotonin reuptake inhibitors (SSRIs) paroxetine and fluoxetine, are usually used to treat anxiety and depression.

Treatment

Researchers at Johns Hopkins looked at the effect of paroxetine on tamoxifen.

The study of paroxetine raises some concerns in terms of treatment of breast cancer patients
Stephen Duffy, Cancer Research UK
They tested the blood of 12 women with breast cancer who were being treated with tamoxifen and who had taken paroxetine for around four weeks during their treatment.

They then looked at levels of active chemicals, created in the body after tamoxifen had been metabolised.

It was found levels of one metabolite, named endoxifen, halved after the women took paroxetine.

Dr Vered Stearns, who led the research said: "Larger trials are required to evaluate the clinical implications of low circulating endoxifen concentrations.

"Until further data becomes available, the results of this small study should not alter treatment recommendations."

Drug interactions

Stephen Duffy, Professor of Cancer Screening at Cancer Research UK's Department of Epidemiology, Mathematics and Statistics, told BBC News Online: "The study of paroxetine raises some concerns in terms of treatment of breast cancer patients.

"Since the study is relatively small and uncontrolled, there remains considerable uncertainty and larger definitive studies are necessary."

He added: "Also, there is some variation in the activity of SSRI's, so the interaction of other SSRI's with tamoxifen should also be researched.

"In the interim, it is reassuring that the drug does not appear to be licensed for use for hot flushes in the UK.

"While it is by no means established from this study that use of SSRI's will definitely impair the effect of tamoxifen, treatment decisions for depression or hot flushes in breast cancer patients currently taking tamoxifen should at least take into account the possibility that it may."

The research is published in the Journal of the National Cancer Institute.


SEE ALSO:
Test 'helps tailor cancer care'
30 Oct 03  |  Health
Clue to cancer drug success
05 Mar 03  |  Health


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