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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 5 of 5. This is the beginning of the thread.
Posted by Racer on December 2, 2005, at 14:53:57
This has been on my mind, on and off, for a long time now -- more Dr EyeCandy stuff, but it still bugs me.
Years ago, when I was on nortiptyline, I was told that the TCAs ALL had therapeutic windows associated with them. That blood tests were done, routinely, to see when you hit that level.
Dr EyeCandy, though, said that nortriptyline was just about the only TCA with blood levels that could be checked.
So, uh, anyone know the real story?
Thanks.
Posted by med_empowered on December 2, 2005, at 15:22:54
In reply to Blood levels testing for TCAs?, posted by Racer on December 2, 2005, at 14:53:57
hi! I dig your nickname for your doc. Mine used to be..."The Ice Queen/Pill Queen" and "Malibu Ken".
Anyway, TCA blood testing isn't the most helpful blood test...by this I mean its not very helpful at all. If there's a concern about toxicity (ex: high-dose outpatient treatment for resistant-depression, or combos with MAOIs, SSRIs, etc. that could prove harmful) blood tests can help detect potentially harmful drug levels. Other than that...TCA blood level testing isn't very helpful, although some docs do order the tests now and then. This is similar to the situation with neuroleptics...there isn't a very strong correllation between blood levels and therapeutic effects (although there is something of one with blood levels and side effects.)
Good luck!
Posted by jamestheyonger on December 2, 2005, at 16:46:08
In reply to Blood levels testing for TCAs?, posted by Racer on December 2, 2005, at 14:53:57
"Years ago, when I was on nortiptyline, I was told that the TCAs ALL had therapeutic windows associated with them. That blood tests were done, routinely, to see when you hit that level."
Blood level does not correlate to levels in the nervous system or at least we do not yet know how to correlate them. I have heard of them used to identify rapid/slow metabolizers or in polydrug situations to detect toxic levels. Sometimes the latter is post mortum.
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
Posted by Racer on December 2, 2005, at 18:49:08
In reply to Re: Blood levels testing for TCAs?, posted by SLS on December 2, 2005, at 17:21:26
Thanks Scott. I appreciate your explanation, and it does make sense.
I can't remembr what dose I needed of N, but I was told that it was quite high. I also remember taking, as I recall, 12 pills per day? It also didn't work all that effectively until the doctor had me add L-tryptophan. {shrug} Still, it saved my life back then.
Take good care of yourself, and you can answer my short email, rather than the long one ;=D
This is the end of the thread.
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