Posted by Crotale on June 17, 2008, at 23:26:29
In reply to Re: Considering an MAOI, posted by undopaminergic on June 3, 2008, at 12:50:11
> Chlorpheniramine (CPI) was an extremely bad example, because it is one of only two antihistamines that are known to be unsafe with MAOIs (the other one is brompheniramine, BPI). The reason is that CPI and BPI are serotonin reuptake inhibitors, and their use under MAO inhibition poses the risk of serotonin syndrome.
That's interesting; I had never heard that. I suspect they are not very strong SRIs, as I have used ChlorTrimeton (chlorpheniramine) a number of times (for allergies and the like) and never had any problem.
> > It's decongestants (pseudoephedrine, ephedrine, phenylpropanolamine, etc.) that you need to watch out for.
>
> This is true, but they can sometimes be useful against MAOI-induced hypotension. Amphetamines are similar to the anticongestants mentioned above, and cause a dose-dependent elevation of blood pressure, and hypertensive crisis if the dose is high enough. Nevertheless, when used with caution, amphetamines can be used not only to treat hypotension, but also to augment an unsatisfactory response to MAOIs.I recommend against using these drugs in this manner except under a doctor's supervision. I once had a hypertensive crisis due to accidental ingestion of something that apparently had ephedrine in it. (Some kind of over-the-counter herbal "food supplement," IIRC.)
When I had orthostatic hypotension (don't get this any more) I used to use salt tablets to balance out my BP. Much less risky than decongestants or other vasoconstrictors.
Cocaine has the potential to cause either serotonin syndrome or hypertensive crisis (the latter owing to its catecholaminergic activity). Amphetamine likewise has the potential to cause a hypertensive reaction, although it has been used safely with MAOIs in many cases.
> Most tricyclic antidepressants, except clomipramine and imipramine, can be used with MAOIs.
In general, secondary amine tricyclics (e.g., desipramine, nortriptyline, amoxapine, maprotiline (this last is sometimes called a "tetracyclic": in reality it has an ethylene bridge on the centre ring)) are safest to use with MAOIs because they tend to have relatively little activity at the serotonin transporter. Clomipramine is probably the most dangerous of the TCAs, but imipramine and amitriptyline are also tertiary amine tricyclics and have significant effect on serotonin reuptake.
> On the other hand, all SSRIs and SNRIs have the capacity to precipitate serotonin syndrome in combination with MAOIs.
If by SNRIs you mean drugs like Effexor (venlafaxine) (serotonin-norepinephrine reuptake inhibitors?) then yes, they are just as contraindicated with MAOIs as are SSRIs. OTOH the other ones you mentioned, atomoxetine and reboxetine, could be called "selective norepinephrine reuptake inhibitors," with hardly any effect on serotonin reuptake. These are safe with MAOIs just as the secondary-amine tricyclics are, and for similar reasons.
> Alpha2-adrenergic antagonists, such as yohimbine, idazoxan, and mirazapine, should be used with caution due to their noradrenaline-releasing properties, which may give rise to hypertensive reactions.
I actually don't know of any cases of hypertensive crisis attributed to this combination. Mirtazapine I think is considered a bad risk because of the potential for serotonin syndrome.
> Yohimbine may furthermore have MAOI-inhibitory features, opening the possibility for a MAOI overdose.
It's true that MAOIs should not be combined with other MAOIs, but I have never heard of an interaction happening between yohimbine and MAOI, nor do I believe there have been any reports of such interaction (in humans or rats).
> Most antipsychotics, with the possible exception of ziprasidone - due to its monoamine reuptake inhibiting features - pose no notable risks in combination with MAOIs.
This is interesting. I did not know this about ziprasidone. Which monoamine transporters does it block?
> Chlorpromazine is in fact an effective antidote to serotonin toxicity.
Yes, I've heard of Thorazine (chlorpromazine) and other neuroleptics being used in this way.
> Of the narcotic analgesics, pethidine (meperidine) and tramadol pose definite risks of serotonin toxicity, although they have sometimes been combined with MAOIs without problems.
Not Demerol (meperidine/pethidine), I don't think. The risk of an interaction with that one is quite well-documented.
> The case of fentanyl and methadone is more uncertain, but theoretical serotonergic properties have been reported, so caution is warranted. Other opiates, such as codeine, oxycodone, morphine, and buprenorphine, are very safe to use with MAOIs.
I have actually taken all of these, with the exception of codeine, while taking MAOIs (mainly Parnate) and none of them has caused any ill effects. In fact, I have been taking buprenorphine on a more or less daily basis for several years in combination with Parnate, so I can certainly vouch for that one! Most of the others I've taken at least a fair number of times (while under a doctor's care, of course). I never had any problems with hypertension, hyperpyrexia, etc. with any of them.
poster:Crotale
thread:826622
URL: http://www.dr-bob.org/babble/neuro/20080418/msgs/835190.html