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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 4 of 4. This is the beginning of the thread.
Posted by brian on February 5, 2000, at 11:54:39
Is it true that cigarettes have maois in them? If that is true would smoking increase the effects of ssri's like paroxetine? Sort of wondering whether smoking would effect someone on antidepressants differantly than someone not taking them. Thanks
-Brian
Posted by Brandon on February 5, 2000, at 12:56:00
In reply to cigarette and paxil, posted by brian on February 5, 2000, at 11:54:39
Brian,
Nicotine does contain a MAOI but only in the B type. Their are two types of MAOI type A and type B. Type A inhibitors such as Parnate, and Nardil mainly prevent the breakdown of serotonin and norepenephrine that is where the chance of interaction would be greatest. Type B however primarily inhibits the breakdown of dopamine and to some extent norepenephrine. And nicotine does this weakly compared to its other pharmacologic effects. That is why people who smoke on prozac and such dont keel over:) Hope this helps.
Brandon
Posted by Joanne on February 6, 2000, at 17:13:55
In reply to Re: cigarette and paxil, posted by Brandon on February 5, 2000, at 12:56:00
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!
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.
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