Posted by SLS on December 2, 2005, at 17:21:26
In reply to Blood levels testing for TCAs?, posted by Racer on December 2, 2005, at 14:53:57
Hi Racer.
> Years ago, when I was on nortiptyline, I was told that the TCAs ALL had therapeutic windows associated with them.
What was meant by the term "therapeutic windows" as used by these people?
> That blood tests were done, routinely, to see when you hit that level.
15 years ago, this was true. The range of blood levels considered therapeutic was very wide however, and really served as a rough guideline.
Nortriptyline is a strange beast. Unlike the other TCAs, it has demonstrated a true window of efficacy (as opposed to a therapeutic window). If you take the right amount of it, you can respond wonderfully. However, you can actually bring the dosage up too high so that it stops working. This is not true of the other TCAs. Bringing one of these up too high simply exagerates the side effects, but leaves the positive response intact. Nortriptyline is the best-studied of the antidepressants for therapeutic blood levels. A daily dosage of 75mg seems to be right for most people. This will usually place them in a range of 50-150ng/ml as a blood level. For these people, the response is lost at 100mg. Testing for blood levels can help identify the point at which someone is beyond the window of efficacy so that further increases are not made in error.
> Dr EyeCandy, though, said that nortriptyline was just about the only TCA with blood levels that could be checked.You can see why he made this comment. However, it is still useful to check the levels of other TCAs in circumstances where the dosage is high and there is still no response or even a lack of side effects. Some people metabolize TCAs much more rapidly than others. It is sometimes necessary to check for rapid-metabolizers that they are taking enough. Some people do well at 75mg of imipramine while others need 450mg.
- Scott
poster:SLS
thread:584634
URL: http://www.dr-bob.org/babble/20051126/msgs/584706.html