Posted by Larry Hoover on February 23, 2003, at 8:03:46
In reply to Question for the med heads, posted by Jackster on February 22, 2003, at 23:37:42
> I'm not expecting anyone to be able to answer this question (unless some neurologists regularly read this!) but I'm hoping someone might be able to point me in the way of a website that might offer a solution. I'm on Paxil (40mg) and nortriptyline (10mg) - and I know the Paxil inhibits the metabolism of the TCA. I'm about to up the nortriptyline to 20mg. My PDoc assures me this will be OK - but I just want to know roughly what the drug interaction increases the effective dosage of the nortriptyline to. (i.e. is it twice the dosage? three times?). I will be having a blood test - but my PDoc wants me at 20mg before I take it. I'm just a bit paranoid after my previous PDoc had a habit of prescribing dodgy drug combos. (I now like to do my own research as a double check).
>
> Thanks for any advice
> JackieJackie, the enzyme that both drugs depend on for clearance is known as CYP2D6. This enzyme is almost non-existent in some people, whereas others have quite large amounts of it; there is more than 100-fold variation in 2D6 concentration in different people. Those with low levels are called "poor metabolizers".
Unless you know whether you're a poor metabolizer or not (generally determined by experience), it's impossible to predict the outcome with any certainty. However, the simple fact that you can take 10 mg nortriptyline with the paroxetine is a good sign in itself. Cautiously raising the dose of the TCA is quite an appropriate process. What you should do is familiarize yourself with the signs and symptoms of TCA overdose, so that you can self-assess with some certainty. If those signs appear, you just quit taking the TCA.
The info you'll need is at www.rxlist.com
Just enter "nortriptyline" in the search box, and select the generic name from the list presented to you. For some reason, brand name information is not as complete. Anyway, once you've selected the generic name, you'll see a variety of headings. Select the one that mentions overdose, and look at the heading "other signs". You won't be experiencing acute overdose, in any case, but if adverse effects like those listed begin to occur, you'll know how to interpret them.
Good luck,
Lar
poster:Larry Hoover
thread:202967
URL: http://www.dr-bob.org/babble/20030219/msgs/203025.html