Posted by Shawn. T. on January 1, 2004, at 22:11:06
In reply to Re: Stimulants with Dopamine Noradrenaline effect, posted by scott-d-o on January 1, 2004, at 20:17:17
A drug can be "stimulating" in a number of ways; the stimulation mediated by epinephrine in the heart is sympathetic stimulation rather than psychomotor stimulation or some other type of stimulation. The word "psychostimulant" seems to have become associated with drugs that increase dopamine concentrations in the striatum. For example, the norepinephrine reuptake inhibitor atomoxetine (Strattera) isn't considered a stimulant even though it can induce stimulating effects in some people. Atomoxetine can inhibit dopamine reuptake in the prefrontal cortex because the dopamine in this region is transported primarily by the norepinephrine transporter; therefore, psychostimulants are linked to increased dopamine levels in a specific region of the brain (regions of the striatum like the nucleus accumbens).
I think that it is important to note that Ritalin (methylphenidate) inhibits dopamine reuptake transporters more potently than it inhibits norepinephrine transporters (it is roughly 5 times more potent ... see http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7851480&dopt=Abstract ). It's important to consider this fact when comparing Ritalin with Strattera; do not assume that the two affect norepinephrine reuptake equally.
Another well-known psychostimulant that blocks dopamine and norepinephrine reuptake is cocaine; it also inhibits the serotonin transporter to a lesser degree.
Drugs in clinical trials that inhibit the reuptake of dopamine, norepinephrine, and serotonin include Sepracor's (R)-sibutramine metabolite (phase II; see http://www.sepracor.com/science/index.cfm?s=2B ), DOV's DOV 216,303 (phase II; see http://www.dovpharm.com/sub_page/product_dov216303.html ), and DOV's DOV 21,947 (phase I).
GSK's GW353162 is a dopamine and norepinephrine reuptake inhibitor in phase I clinical trials. I believe that Pfizer has a dopamine, norepinephrine, and serotonin reuptake inhibitor in phase II, but I don't know the name of the drug. There are likely several others being investigated.
Shawn
poster:Shawn. T.
thread:295460
URL: http://www.dr-bob.org/babble/20031231/msgs/295572.html