Pretreatment platelet 5-HT concentration predicts the short-term response to paroxetine in major depression. Grupo de Trastornos Afectivos.
BACKGROUND
A previous retrospective study revealed that a high pretreatment platelet serotonin (5-HT) concentration was associated with a low response to serotonergic antidepressants in drug-free major depressives. We have examined such a relationship in depressive patients treated with paroxetine.


METHODS
Seventy-four drug-free major depressives (DSM-IV) were admitted to the study. Clinical ratings were performed and blood was drawn prior to the initiation of treatment and after 4 weeks of paroxetine (20 mg/day). The concentrations of 5-HT, 5-hydroxyindoleacetic acid, and tryptophan were determined in plasma and blood.


RESULTS
Paroxetine treatment reduced platelet 5-HT to 17% of baseline after 4 weeks of treatment. Responder patients had a pretreatment platelet 5-HT concentration 22% lower than nonresponders (p < .035). Admission HAMD scores, plasma paroxetine concentration, or platelet 5-HT concentration at endpoint did not differ between responders and nonresponders. Yet, the response rate was 11% in patients with high pretreatment platelet 5-HT (> 900 ng/10(9) platelets) and 50% in those below that value (p < .004).


CONCLUSIONS
These findings support that depressed patients with a high pretreatment platelet 5-HT concentration have a poor therapeutic outcome after treatment with a standard paroxetine dose. These differences may be related to the existence of molecular differences in the 5-HT transporter.
Figueras
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Department of Neurochemistry, Instituto de Investigaciones Biomédicas de Barcelona, CSIC (IDIBAPS), Spain.
Pérez
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V
San Martino
O
O
Alvarez
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E
Artigas
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F
D000293:Adolescent; D000368:Aged; D018687:Antidepressive Agents, Second-Generation / Q000627:therapeutic use*; D001792:Blood Platelets / Q000378:metabolism*; D003865:Major Depressive Disorder / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D017374:Paroxetine / Q000627:therapeutic use*; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012074:Remission Induction; D012701:Serotonin / Q000097:blood*; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use*; D013030:Spain; D013997:Time Factors
D018687:Antidepressive Agents, Second-Generation; D017374:Paroxetine; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors