Posted by Cam W. on February 6, 2000, at 22:46:59
In reply to Re: cigarette and paxil, posted by Joanne on February 6, 2000, at 17:13:55
> Ok, my answer doesn't answer the question, only offers my own opinion.
> When I was first diagnosed with clinical depression, I had quit smoking for the
> second time in 4 months... The first person I talked to was a great counselor
> who taught me a lot in a short time... the first thing she told me was this:
> When you are first trying to deal with depression, don't take on extra things... Her
> exact words: "Don't quit smoking right now". So, I didn't.
> Like I said, I know I didn't answer the question, but I felt that in this, my
> opinion meant something...
> Anyway, I've quit smoking one more time since then, made it for 6 weeks...
> I'll let you know what happens next time!Brian - The answer to your question is maybe. Cigarette smoke induces, or causes the production of more of, a certain type of liver enzyme. The cytochrome P450 (CYP) system is involved in the metabolism of many psychiatric, as well as non-psychiatric, drugs. Cigarette smoke induces one of the families of enzymes in this system (CYP-1A2) and Paxil is metabolized by CYP-1A2, but only in a minor way. Cigareette smoke will increase the metabolism of Paxil, but probably not in a clinically significant way. Paxil is mostly metabolized by the family called CYP-2D6 and also to a lesser extent by CYP-3A3/4. Some people have what is called polymorphism of CYP-2D6, in which their CYP-2D6 enzyme system either works very well or not so well. People who are ultrapoor metabolizers at CYP-2D6 will have Paxil metabolism switched to CYP-1A2 and CYP-3A3/4. In this case, the Paxil metabolism may be increased causing lower blood levels of the drug, but the decreased metabolism by CYP-2D6 would probably offset this. Basically, the chance that cigarette smoking would affect Paxil blood levels is very remote. Hope this helps. (P.S. Some other drugs - eg some protease inhibitors - can have there blood levels altered significantly by cigarette smoke and make a clinical difference, but only if you change your smoking habits after being stabilized on the drug)
- Cam W.
poster:Cam W.
thread:20558
URL: http://www.dr-bob.org/babble/20000128/msgs/20670.html