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Memantine as a mood stabilizer in bipolar disorder 
(written 5/2012) 

Summary:  Too early to say (see writing date above) what the role for this stuff is, but recent studies certainly make one think about it.  

If the trend these in studies is maintained, I'll be back to write more (I hope). Right now, this is mostly just a page to hold some references. 


Memantine as a mood stabilizer

After a couple of single-case reports, the first big suggestion we should pay attention to this medication as an option in bipolar disorder came from "naturalistic" study -- which means they just gave memantine to a bunch of people (40, in this case). and watched what happened. No control group, so no way to tell how much is a placebo response. But they watched in a systematic way, measuring outcomes, and they watched a good long while (12 months).Koukopoulos

Results?  Wait a minute. May I remind you:  when a new medication or a new use for an old one first appears, there is a tendency for the early studies to look really good. Thus the joke among doctors: "Use it quick before it stops working." So one should not get too excited by these early studies. See if the trend holds up. And compare the side effects/risks, we can do that already based on the medication's use in other conditions (mainly Alzheimer's). 

Results: two thirds of the patients with rapid cycling stopped having any more cycles, over the year of follow-up. That's huge (remember, don't get too excited). By the end of the study, 3/4 of the patients were much better and only a little over 10% dropped out (in a year, that's pretty impressive). 

An earlier, shorter study found similar degrees of improvement, within three weeks.Keck  But a more recent study found memantine no better than a placebo when added to lamotrigine.Anand

Side effects

One study suggests that in some people, memantine could cause psychotic symptomsCanan (careful, we have no idea yet how common this might be. It could be rare, or it could be a significant risk).

Typical side effects from previous studies in Alzheimer's (where you might expect these older folks to have more problems with medications):

(these data are from the "prescribing information"; numbers submitted to the FDA)

But in one study, nearly 50% of patients experienced some side effect. They kept going, though: The most common side effects in that study were constipation, nausea, and headache. As you can see from the table above, these side effects were not major problems in a different set of patients.

What dose?

A study designed to find the best dose found the best outcome -- surprisingly -- at the lowest dose, 20 mg per day. Keck