Posted by Sunnely on November 2, 2000, at 1:16:12
In reply to Remeron and Wellbutrin interaction, posted by ChrisW on November 1, 2000, at 1:51:03
> Had an interesting experience that I thought I'd share.
> I've been taking Remeron 45 mg for several months and p-doc added Wellbutrin 300 mg about 10 days ago. I noticed an increase in the effects (and side effects) of the Remeron which I thought was odd until I discovered a useful web site. http://www.rxlist.com
> Basically in the information on Wellbutrin pharmacokinetics it mentions "Many drugs, including most antidepressants (SSRIs, many tricyclics), beta-blockers, antiarrhythmics, and antipsychotics are metabolized by the CYP2D6 isoenzyme. Although bupropion is not metabolized by this isoenzyme, bupropion and hydroxybupropion are inhibitors of the CYP2D6 isoenzyme in vitro". It goes on to talk about a study involving concomitant administratiopn of Wellbutrin and desipramine (a tri-cyclic) in which it was found that desipramine levels were higher and that the desipramine took longer to be metabolized. And then when I went to look up Remeron on the same website, it turns out that Remeron is metabolized by the CYP2D6 isoenzyme. Meaning that the increase in effects that I experienced was not my imagination but a result of the inhibition of this enzyme by bupropion (wellbutrin). Perhaps this is another way in which someone taking a drug with a short half life like Effexor and Paxil can alleviate some of the withdrawal symptoms. If they have some Wellbutrin lying around I'll bet that one Wellbutrin would increase PBCs and T 1/2 s in much the same manner as Prozac seems to work for Effexor withdrawals. Am I way off base here or has anyone tried this?++++++++++
Hi ChrisW,
Actually, mirtazapine (Remeron) is metabolized by 3 different isoenzymes: CYP1A2, CYP2D6, and CYP3A4, with each isoenzyme appearing to contribute approximately equally to its clearance. Drugs that inhibit CYP2D6 (for example, bupropion or Wellbutrin) when combined with Remeron will probably not result in clinically significant pharmacokinetic drug-drug interactions, as there will be 2 other isoenzymes to serve as alternative pathways in the metabolism of Remeron. Remeron, on the other hand weakly interferes with the action of the cytochrome isoenzymes action causing no clinically significant pharmacokinetic drug-drug interactions with the other drugs including Wellbutrin. Incidentally, Wellbutrin (parent compound, bupropion) is mainly metabolized by CYP2B6 and CYP3A4, while its active metabolite is metabolized by CYP2D6.
poster:Sunnely
thread:47895
URL: http://www.dr-bob.org/babble/20001022/msgs/47985.html