Study Shows Common Antidepressant Lowers Effectiveness of Breast Cancer Drug

By February 10, 2010Dangerous Drugs

As a dangerous drug attorney, I was interested to see a recent study adding information to the debate about antidepressants and breast cancer. A Feb. 9 article from HealthDay reports that researchers have found an increased risk of dying for breast cancer patients taking both the cancer drug tamoxifen and the antidepressant Paxil (paroxetine). The study is important because antidepressants are frequently prescribed to tamoxifen-taking patients to help reduce the menopause-like hot flashes that are a side effect of the drug. It also helps to clarify previous studies that have found mixed and uncertain results when examining the relationship between tamoxifen and antidepressants.
The study, conducted at Sunnybrook Health Sciences Center in Toronto and published in the Feb. 8 issue of the British Medical Journal, looked at the medical records of 2,430 women taking tamoxifen for breast cancer between 1993 and 2005. About thirty percent of the patients were also taking an antidepressant, with Paxil the most common antidepressant. The risk of dying from breast cancer went up significantly for the patients taking Paxil, the study found, and the risk was greater the longer patients took both drugs. Paxil, a selective serotonin reuptake inhibitor, inhibits a bodily enzyme needed to process tamoxifen, the researchers said. This was not seen with other SSRIs, like Effexor or Celexa. Lead researcher Dr. David Juurlink suggested that patients and doctors discuss transitioning to an antidepressant other than Paxil, but warned that quitting the SSRI cold turkey can cause withdrawal.
This study interests me as a defective prescription drug lawyer because it may help settle a debate in the medical community. Scientists already knew that SSRIs can interfere with the enzyme described above, but two 2009 studies conflicted about whether this lead to an increased risk of death. This study provides strong evidence that Paxil, at least, may interfere with the effectiveness of the breast cancer drug. And that means that thousands of patients may have been put at an unnecessary risk of dying. It also means that breast cancer patients may have been unnecessarily exposed to the numerous serious side effects of Paxil. Paxil already carries a warning about increased risk of suicidal thoughts and can cause reproductive and sexual problems in both men and women. As the article mentioned, it can also cause severe withdrawal symptoms.


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