Posted by King Vultan on July 8, 2004, at 12:34:48
In reply to Re: Effexor vs. Effexor XR, posted by roobie on July 8, 2004, at 9:58:12
> Todd - I have another question (or 2)...
>
> can you explain 1/2 life to me? I think it has to do with the lenght of time the meds are in your system...
>
> Also, I now have FUNKY dreams... did you experience this?
>
> Sharon
The half life is a measure of how quickly the drug is metabolized and removed from your system. For instance, if a drug has a half life of five hours, that means that five hours after taking it, half of the drug will have been metabolized and removed from your system. After 10 hours, another half will have been metabolized and removed (you now only have one quarter of what you started with, as half of a half is a quarter). After 15 hours, you will only have 1/8 of what you started with, 20 hours, 1/16, and 25 hours 1/32.You can see that with a half life that is this short, after 24 hours, you have virtually none of the drug left in your blood. It has mostly all been metabolized and eliminated, which is the situation with the standard Effexor, as it has a half life in this area. This is why it has to be taken twice a day in order to keep up the level in your blood, as well as avoid withdrawal symptoms.
The XR version is designed to absorb more slowly into the blood, which in effect, creates a longer half life--perhaps double--that keeps the level in the blood from falling as quickly and avoids the withdrawal symptoms you might experience taking the standard formula once a day. As I indicated in my previous post, I found that the drowsiness I experience after taking Effexor is more drawn out in time on the XR version, which makes sense because the XR is being more slowly absorbed--and is thus in action in the blood for a longer period of time.
As for the dreams, sorry, I tend not to dream very much when on ADs, at least not that I can remember. The only exception was when I first started Wellbutrin SR and had some interesting erotic dreams. Unfortunately, these went away after a week or two.
Todd
poster:King Vultan
thread:363658
URL: http://www.dr-bob.org/babble/20040704/msgs/364065.html