Starting tomoxifan and wandering ?

[linn65]

I was taking lexapro and Dr. Switched me to Effexor for the hot flashes. I thought lexapro worked better for mood swings. But was told by my sister that lexapro might interfere with tamoxifen's strength. I think maybe I should stick with Effexor if that's the case?.

[tricia keegan]

My Onc said the only safe one for hormone positive patients was Effexor so I took that for a short time but didn't need it after a while.

[linn65]

Thank you! I am ER+ 30% and I have seen people ER+ 90% taking tamoxifan. I really do not understand....If you are ER+ no matter what percentage you take it???

[karen z]

Someone else will jump in but, from what I can tell, yes.........to be safe.

[rhondalea]

Let me say first that I don't know a lot about Effexor or Lexapro (or any of the other antidepressants, for that matter), but I've spent a lot of time reading about Cytochrome P450 substrates, inhibitors and inducers.

Tamoxifen requires several different liver enzymes to be metabolized. There has been a disagreement (conflicting studies) over the need to test individuals taking tamoxifen for their ability to produce these enzymes. My own oncologist tried to patronize me out of my (well-founded) concern, even though I told her I am an intermediate metabolizer for CYP2D6 (the main enzyme for tamoxifen). A very recent study has now made her look like a...well, never mind. My gripes about my onc are legend.

So, it is an issue. Effexor apparently does not interfere. See here:

http://www.ncbi.nlm.nih.gov/pubmed/9597349

"In vitro, venlafaxine [Effexor] is a weaker CYP2D6 inhibitor than most of the selective serotonin reuptake inhibitors (SSRIs) by a factor of 1-3 orders of magnitude."

The above conclusion is echoed by nearly every article, study, opinion I've read.

Further poking reveals that Lexapro is *slightly* more risky, but "slightly" is the key word. This chart I found at breastcancer.about.com seems to concur with most of what I've read:

http://breastcancer.about.com/od/hormonetherapydrugs/a/Antidepressants-And-How-They-Interact-With-Tamoxifen.htm

I'm hesitant to ask, but I'll do it anyway: are you using antidepressants for a pre-existing condition or is this all cancer/cancer drug-related? If so, you might want to consider alternative treatments for the side effects you're experiencing. There are several that are safe. For example, pine bark (pycnogenol) is exceptional for hot flashes. (I have almost none, and those I do have are very, very mild--in fact, they're so mild that my genius of an oncologist feels that I'm not having hot flashes at all.) There are other supplements that will also help, depending on your specifc symptoms. If you're taking an antidepressant for a different reason, just ignore this bit of advice.

Another thing you can do is be genotyped to determine whether you are a poor metabolizer, intermediate metabolizer or extensive metabolizer. You can ask your doctor to order these tests or you can do it yourself at 23andMe.com for $99. (You'll also get a lot of additional genetic information.) If you are an extensive metabolizer, then your risk when using Lexapro will be significantly less than someone who is either a PM or IM.

[tricia keegan]

linn I was told you don't have to take it at all but if you want help with anxiety or hot flashes this is the only safe one to take, I note Rhonda in the above post has far more detailed info and hope this helps you. In my case I chose to not to take anything and was fine thankfully.