Posted by medlib on April 11, 2000, at 19:08:12
In reply to Effexor vs. Effexor XR dosage, posted by LD on April 11, 2000, at 9:16:35
> I'm planning on changing from Effexor to the XR version, and I was wondering if anyone could help me with some dosage guidelines. My doc wanted me to go up to 375mg of the regular, but when I told her I wanted to go on the XR, she said the max I could go was 225mg. I am on 225mg of the regular right now. Is this an equivalent dose of the XR? Is the XR stronger? ALso, how do I go about the transition? Just take 3, 75mg XR all at once? I'm in the middle of having to change doctors because of insurance and I'm not going back for a month, so I'm kinda on my own in this. Thank you so much.
LD-- Many of us on this board are on Effexor XR up to 375mg/day. I take 300mg. Effexor XR (in two l50mg. capsules) in the morning. Keep in mind that Effexor acts on different neurotransmitters at different dose levels. I believe that it acts exclusively on serotonin receptors up to 150mg/day. Above that, it acts on norepinephrine NTs as well. I believe that it also acts on dopamine NTs at the highest levels.
You don't mention what you're taking the Effexor for. If it is GAD, there might be a reason to keep the dose lower; recruiting the NE NTs could increase anxiety. Higher doses are often prescribed for depression, as needed.
According to the drug monograph, Effexor XR has the same total absorption (and conversion to its active metabolite) as Effexor tablets; E XR just has a slower absorption rate. Therefore, it should not be necessary to taper off. If you were on Effexor tabs 75mg/3x/day, take Effexor XR 225mg in the morning. I would wait to increase the dosage until you check in with your new pdoc. It's likely you'll experience fewer side effects with the XR version--most do.
Hopefully, Cam (our highly-valued resident pharmacist) will be logging in soon and can check my data and maybe add more specifics.
Good luck! -medlib
poster:medlib
thread:29623
URL: http://www.dr-bob.org/babble/20000411/msgs/29660.html