Posted by hawkeye on December 14, 2003, at 16:52:29
In reply to Zyprexa Abilify cancel each other?, posted by Sebastian on December 14, 2003, at 14:39:01
I'm no psychopharmacologist, BUT it seems to me that in using the two together, the Zyprexa would defeat the unique "partial agonist" mechanism of Abilify.
Abilify acts as a weak stimulator (so-called "partial" agonist) at dopamine D2 receptors, with the potential for exerting either antagonistic (inhibitory) or agonistic (stimulating) effects, depending on the sensitivity of the receptors and availability of dopamine, its natural agonist in the brain. [Abilify also has similar actions at serotonin 5-HT1A receptors, as well as acting as an antagonist at serotonin 5-HT2A receptors, and having a number of other lesser actions.]
In other words, partial agonism refers to the ability of a drug to block a receptor if it is overstimulated or in competition with a natural agonist, such as dopamine and serotonin themselves, but also to stimulate a receptor when the natural agonist is unavailable. These are unprecedented properties in a clinically effective antipsychotic agent.
Zyprexa acts as a full agonist at the D2 recptor. Therefore, it would seem that any advantages offered by Abilify's partial agonist mechanism would be drowned by Zyprexa's full agonist mechanism.
poster:hawkeye
thread:289704
URL: http://www.dr-bob.org/babble/20031213/msgs/289770.html