Posted by jrbecker on August 29, 2003, at 9:31:26
http://www.medwire.md/News_single.aspx?newstype=3&date=20030829&story_id=18862
Pindolol's SSRI boost specific to paroxetine
J Affect Disord 2003; 75: 285–289
Accelerating the response to antidepressant by co-administering pindolol with selective serotonin reuptake inhibitors (SSRIs) appears to only be successful with paroxetine, study findings reveal.
Treatment with SSRIs in combination with pindolol, a partial agonist at the serotonin (5-HT)1A receptor, has been proposed to produce a fast antidepressant response because, by blocking this receptor, the compound prevents the initial decrease in the firing of serotonergic neurons seen with SSRIs.
To investigate, Per Plenge and Erling Mellerup, from the Laboratory of Neuropsychiatry in Copenhagen, Denmark, used pharmacokinetic data to estimate the free SSRI concentration in patients either receiving the first dose, or in steady state treatment with five different SSRIs – citalopram, fluoxetine, paroxetine, and sertraline.
Results showed that 5-HT uptake inhibition obtained with clinically relevant doses differed markedly among the SSRIs due to differences between the drugs regarding protein binding, distribution volume, and affinity for the 5-HT transporter (5-HTT).
Specifically, with paroxetine, a substantial 5-HTT blockade was reached after just the first dose, and further increased in the steady state situation.
"This is due to a combination of the very high affinity of paroxetine for the 5-HTT, a moderate distribution volume, and a medium protein binding, resulting in a relatively high free concentration," the team reports in the Journal of Affective Disorders.
In contrast, a much lower level of 5-HTT blockade was obtained with citalopram fluvoxamine and sertraline after the first dose, while fluoxetine resulted in the lowest level of blockade.
The findings explain why previous studies have found a preferential effect of pindolol on paroxetine and suggest that "pindolol together with paroxetine may be advantageous at least in the beginning of an antidepressant treatment," Plenge and Mellerup conclude.
poster:jrbecker
thread:255281
URL: http://www.dr-bob.org/babble/20030828/msgs/255281.html