Posted by yxibow on March 24, 2006, at 1:09:33
In reply to Re: what is buspar's affinity for d2 ? » Meri-Tuuli, posted by Phillipa on March 23, 2006, at 21:53:25
> Merri do you understand what link is talking about? I'm really starting to feel stupid. Love Phillipa
Don't feel stupid -- I only learn by discovery... to fully describe affinity, here's a graduate level example:http://www.mc.uky.edu/Pharmacology/instruction/pha824mp/PHA824mp.html
A particular compound or drug has an affinity for (usually more than one) receptor in the brain. Affinity means how strongly the medication occupies the receptor. These are usually measured in Ki values, the dissociation constant, Kd, the equilibrium constant, and nM, the nanomolar (one mole of molecules has a mass equal to the molecular weight of the compound in grams) and the lower the value, the stronger the drug will occupy a receptor.There is a chart, but it can only be accessed from academic institutions that subscribe to it:
http://www.cpa-apc.org/Publications/Archives/CJP/2002/february/inReviewSeemanPhilipTable1.asp
I'm sure there are others out on the web -- in fact I know there are several powerpoint presentations I forget seeing, I just happened upon this one at the moment.
This study notes that besides Perphenazine (very strong) and Fluphenazine (Prolixin), Haloperidol (Haldol) has among the lowest K (which I believe are averages of Ki and Kd) values (inverse is stronger) -- less than 1.0, which means that they grab onto your D2 receptors like a powerful magnet whereas Quietapine (Seroquel) has a K value of 122 which means it grabs it lightly and lets go.
Then there are values also mentioned in IC50 -- "inhibitory concentration" -- "The molar concentration of an antagonist, which produces 50% of the maximum possible inhibitory response for that antagonist."
(http://www.everythingbio.com/glos/definition.php?word=IC50)It gets quite complicated after here, and goes over my head although I get the general gist of it, having never taken a pharmacology course.
I'm sure someone else can jump in.
Tidings
- J
poster:yxibow
thread:623699
URL: http://www.dr-bob.org/babble/20060322/msgs/624059.html