Posted by cumulative on January 12, 2008, at 22:40:14 [reposted on January 16, 2008, at 22:15:10 | original URL]
In reply to Re: Do stimulants induce mania? » qbsbrown, posted by ShawnThomas on January 12, 2008, at 21:34:33
The HVA test measures dopamine metabolite. However, this isn't a reliable test of overall dopaminergic function, especially in the presence of a general (as you note) dopamine receptor antagonist like Zyprexa. Methylphenidate doesn't significantly increase the rate of dopamine release except at very very high doses -- the primary effect in increasing dopaminergic transmission is inhibition of the reuptake pumps.
The PFC/striatum DA release increase from olanzapine is very interesting, as is the fact that it's a stronger antagonist at serotonin receptors than dopamine, but note that the classic side effects that remain associated with olanzapine (particularly olanzapine, in fact) include apathy, sedation, weight gain, loss of motor skills, loss of volition, etc. ... these symptoms are certainly associated with impaired dopaminergic function, and are to some extent the sort of symptoms that typical therapeutic application of methylphenidate seeks to repair.
While I never wrote that the two are opposites (that's not really a meaningful statement in this complex, complex system), I am adamant that Zyprexa can easily diminish the positive therapeutic effects of stimulants.
poster:cumulative
thread:807107
URL: http://www.dr-bob.org/babble/neuro/20080114/msgs/807114.html