Sunday, May 31, 2009

Antidepressants Cut Effectiveness of Tamoxifen in Breast Cancer

Tamoxifen, a breast cancer medicine used by millions of women, doesn’t work when taken with antidepressants like Eli Lilly & Co.’s Prozac, Pfizer Inc.’s Zoloft and GlaxoSmithKline Plc’s Paxil, a study says.

Tumors were more than twice as likely to return after two years in women taking the antidepressants while on the cancer drug, compared with those taking tamoxifen alone, the study showed. The research, by Medco Health Solutions Inc., was presented today at a meeting of the American Society of Clinical Oncology in Orlando.

Doctors began treating hot flashes with antidepressants, an unapproved use, after a U.S. study seven years ago linked the former standard remedy, hormone replacement therapy, to an increased risk of breast cancer and heart attacks. Other types of antidepressants, such as Wyeth’s Effexor, may be safer for women on tamoxifen than Paxil or Prozac, said Powel Brown, director of cancer prevention at the Lester and Sue Smith Breast Cancer Center at Baylor College of Medicine in Houston.

“Effexor doesn’t interfere with tamoxifen so that is the preferred drug for oncologists to treat hot flashes,” said Brown, who wasn’t involved in the study. “We need to get that message out to primary care doctors and psychiatrists and gynecologists so they will be aware that antidepressants like Paxil have a risk of inhibiting tamoxifen.”


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