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Dr. Bob is Robert Hsiung, MD,
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Posted by desolationrower on May 29, 2009, at 0:18:20
saw someone post this study, and it might be relevant for why you found a lower dose better than higher:
Biol Pharm Bull. 2009 May;32(5):850-5.
Influence of memantine on brain monoaminergic neurotransmission parameters in mice: neurochemical and behavioral study.
Onogi H, Ishigaki S, Nakagawasai O, Arai-Kato Y, Arai Y, Watanabe H, Miyamoto A, Tan-no K, Tadano T.Department of Pharmacology, Tohoku Pharmaceutical University, Sendai, Japan.
Memantine, a non-competitive antagonist of NMDA receptors, has recently been used in Alzheimer's disease. The influences of memantine on behavioral changes, monoamine oxidase (MAO) activity and reuptake of both serotonin (5-HT) and dopamine in mice were examined in the present study. Memantine dose-dependently increased locomotor activity. This effect was inhibited by intraperitoneal (i.p.) administration of haloperidol. Furthermore, administration [intracerebroventricular (i.c.v.)] of memantine did not induce the head-twitch response (HTR). However, the 5-HT-induced HTR was potentiated by the combined administration of memantine. The enhanced HTR was inhibited by i.p. administration of haloperidol or 5-HT(2A) antagonist ketanserin. Memantine at 1 mM inhibited both MAO-A and MAO-B activities in mouse forebrain homogenates to 37% and 64% of controls, respectively. Lineweaver-Burk plots analysis revealed competitive inhibition with both MAO-A and MAO-B. The inhibitions were also reversible. Memantine inhibited the reuptake of both 5-HT and dopamine into mouse forebrain synaptosomes. 5-HT and dopamine reuptakes were inhibited to 2% and 16% of controls, respectively, with 1 mM memantine. These findings suggest that the increased locomotor activity and enhanced 5-HT-induced HTR by memantine may result from the reuptake and turnover inhibitions of 5-HT and dopamine.
PMID: 19420753
-d/r
Posted by SLS on May 29, 2009, at 4:59:20
In reply to hey scott - namenda/MAOI, posted by desolationrower on May 29, 2009, at 0:18:20
Thanks d/r.
> saw someone post this study, and it might be relevant for why you found a lower dose better than higher:
I'll remember to retry a low dose. I am starting Topamax. It might take a few weeks to reach a therapeutic dosage of 100mg. The gradual titration is to reduce the appearance of cognitive side effects. I heard this a long time ago, and I don't know how true it is, but I remember hearing that if you can prevent the cognitive side effects from evolving, you can remain free of them at higher dosages. However, if you titrate too rapidly, the cognitive side effects that appear linger indefinitely.I plan to restart memantine, but I might decide to wait a week or two just to establish some sort of equilibrium that produces a stable improvement. That way, I'll know if the memantine is helping or hurting. I had planned to restart it right at 20mg, but I guess it makes sense to invesitgate lower dosages.
- Scott
**************************************************
> Biol Pharm Bull. 2009 May;32(5):850-5.
> Influence of memantine on brain monoaminergic neurotransmission parameters in mice: neurochemical and behavioral study.
> Onogi H, Ishigaki S, Nakagawasai O, Arai-Kato Y, Arai Y, Watanabe H, Miyamoto A, Tan-no K, Tadano T.
>
> Department of Pharmacology, Tohoku Pharmaceutical University, Sendai, Japan.
>
> Memantine, a non-competitive antagonist of NMDA receptors, has recently been used in Alzheimer's disease. The influences of memantine on behavioral changes, monoamine oxidase (MAO) activity and reuptake of both serotonin (5-HT) and dopamine in mice were examined in the present study. Memantine dose-dependently increased locomotor activity. This effect was inhibited by intraperitoneal (i.p.) administration of haloperidol. Furthermore, administration [intracerebroventricular (i.c.v.)] of memantine did not induce the head-twitch response (HTR). However, the 5-HT-induced HTR was potentiated by the combined administration of memantine. The enhanced HTR was inhibited by i.p. administration of haloperidol or 5-HT(2A) antagonist ketanserin. Memantine at 1 mM inhibited both MAO-A and MAO-B activities in mouse forebrain homogenates to 37% and 64% of controls, respectively. Lineweaver-Burk plots analysis revealed competitive inhibition with both MAO-A and MAO-B. The inhibitions were also reversible. Memantine inhibited the reuptake of both 5-HT and dopamine into mouse forebrain synaptosomes. 5-HT and dopamine reuptakes were inhibited to 2% and 16% of controls, respectively, with 1 mM memantine. These findings suggest that the increased locomotor activity and enhanced 5-HT-induced HTR by memantine may result from the reuptake and turnover inhibitions of 5-HT and dopamine.
>
> PMID: 19420753
>
> -d/r
Posted by greywolf on May 29, 2009, at 17:50:08
In reply to Re: hey scott - namenda/MAOI » desolationrower, posted by SLS on May 29, 2009, at 4:59:20
Scott:
My psychiatrist suggested starting Namenda at 10mg for a week or two, then going to 20mg.
Greywolf
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