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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 6 of 6. This is the beginning of the thread.
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
Jackie
Posted by Thomas123 on February 23, 2003, at 1:17:53
In reply to Question for the med heads, posted by Jackster on February 22, 2003, at 23:37:42
I think no one on earth could answer this question before the fact. There is a lot of variation in drug metabolizing enzymes from person to person. Too the knowledge is usually fairly worseless as there is often no correltion between blood level and efficacy, though this may be untrue for nortryptykine which is admittedly one of the drugs you are taking. That is a very modest dosage of nortryptline. Your doctor seems to be conservative.
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
Posted by Ritch on February 23, 2003, at 10:26:57
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
> Jackie
Jackie, you could ask your doctor about taking the extra 10mg just every other day for a week before you go to 20mg every day. That's what I did when I was titrating it upwards. It is a little less jarring on side effects that way whatever your blood level of NT happens to be. You could also ask your pdoc to do an extra blood draw after a week of that just to settle your mind-if you don't mind the expense.
Posted by Shawn. T. on February 23, 2003, at 22:47:38
In reply to Question for the med heads, posted by Jackster on February 22, 2003, at 23:37:42
Taking Paxil with amitriptyline doubles the serum level of nortriptyline (a metabolite of amitriptyline). I doubt that it's reasonable to extrapolate that data onto your own situation; your body doesn't have to metabolize amitriptyline, and everyone is obviously different. If you have low P4502D6 (an enzyme that Paxil affects) activity, that could affect the situation as well. Based on the fact that people show on average a doubling of nortriptyline concentrations even while having to metabolize amitriptyline as well, you should have no reason to worry while waiting for your test.
Shawn
Posted by Jackster on February 24, 2003, at 0:32:03
In reply to Re: Question for the med heads, posted by Shawn. T. on February 23, 2003, at 22:47:38
This is the end of the thread.
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