Posted by AndrewB on June 25, 2000, at 12:32:25
In reply to Re: Pramipexole (Mirapex) For Depression » AndrewB, posted by SLS on June 24, 2000, at 15:02:51
> Dear Andrew,
>
> Mirapex and amisulpride are more like opposites at the level of receptor function. I don't think it serves well to consider them as being similar in action. Mirapex stimulates while amisulpride inhibits DA receptors. The reason amisulpride may exert an antidepressant effect at low dosages is that it prefers to bind to presynaptic DA autoreceptors as compared to postsynaptic receptors.
>
You and I have gone over this before. Both amisulpride's and Mirapex's antidepressant effects are thought to be due to their ability to increase firing of the D2/D3 (postsynaptic) receptors though they accomplish this by different actions. Call them opposties if you wish.> I want to learn more about the relative affinities of Mirapex for different DA receptors, particularly D3.
Mirapex has a ten times greater affinity for D3 receptors than D2 and a preference for receptors in the striatum over the limbic system.
>
> A few questions for Andrew:
>
> 1. Does Mirapex antagonize the antidepressant effects of amisulpride or sulpiride. Have you ever taken amisulpride and Mirapex in combination?
>
I had taken Mirapex and amisulpirde together for over 2 months. They do not antagonize each other or, in my experience, enhance one another. The only changes I noticed with the addition of Mirapex was a lot of crying during tear jerker movies and a greatly improved jump shot!> 2. How does Mirapex compare to the other DA agonist Parkinson's drugs for treating depression?
>
No comparison studies have been made.> 3. What information have you run across regarding efficacy of Requip in treating depression?
>
None, I’ve only read of speculation that Requip would have similar antidepressant action to Mirapex. Requip has a 10 fold selectivity for the D3 recpetor over the D2 recpetor. It is a D2/D3/D4 agonist.> 4. Do DA D3 receptors appear as presynaptic autoreceptors?
Yes. I researched this since it was my impression that every D2 and D3 postsynaptic receptor was matched (across the synapse) with an (presynaptic) autoreceptor. This may or may not be true. D3 autoreceptors do exist however.
>
> 3. At what dosage of amisulpride did you first begin to respond? What dosage did you end up with?I started with 50mg./day and I am currently at 50mg/day. 100mg has slightly less effect for me.
>
Scott, I will be gone for a week.AndrewB
poster:AndrewB
thread:11831
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