SSRI-Crusaders : Message: avoid Prozac & Seroxat with Tamoxifen NHS warn in 2005 !!!

SSRI-Crusaders : Message: avoid Prozac & Seroxat with Tamoxifen NHS warn in 2005 !!!

avoid Prozac & Seroxat with Tamoxifen NHS warn in 2005 !!!



http://www.ukmicentral.nhs.uk/



Medicines Information Web Site

Trent and West Midlands regional Medicines Information services

http://www.ukmicentral.nhs.uk/headline/database/printstory.asp?NewsID=3854


News Story 05 January 2005

Adverse SSRI - tamoxifen interaction?

Tamoxifen is metabolised to a potent active metabolite (endoxifen) by cytochrome P450 2D6, which is subject to genetic variation. Plasma levels have been shown to depend on CYP2D6 genotype, and this study showed that drugs that inhibit this enzyme accentuate the variation. In an open-label, prospective, observational study, 80 women taking tamoxifen for breast cancer were followed. For those women with the most common genotype (homozygous wild-type), administration of an SSRI reduced endoxifen levels by a mean of 58%; in heterozygotes the mean reduction was 38%. Paroxetine was the most potent CYP2D6 inhibitor, followed by fluoxetine. The authors suggest that according to their data, women taking tamoxifen should avoid paroxetine and fluoxetine, and other potent inhibitors of CYP2D6.



J Natl Cancer Inst 2005; 97: 30-9 - JNCI website; from Reuters Health for 4th January 2005, via Medscape (free registration required)