Rationale: Alterations in 5-HT2A receptor binding are implicated in suicidality and depression. 5-HT2A receptors may also be involved in the therapeutic effects of antidepressants.
Objectives: The purpose of this study was to assess the effect of paroxetine and nefazodone on 5-HT2A receptors after a single dose.
Methods: Seven subjects received a single dose of nefazodone 200 mg and five subjects received a single dose of paroxetine 20 mg. Before and after the dose, 5-HT2A binding potentials (Bmax/Kd) were determined in each subject using [18F]-setoperone PET.
Results: Nefazodone induced a significant change in 5-HT2A binding potential (-39+/-17%,, P = 0.003) while paroxetine showed no significant alteration of 5-HT2A binding potential (+3+/-13%, P = 0.73).
Conclusions: The change in 5-HT2A binding potential seen with nefazodone represents blockade of 5-HT2A receptors by the drug. We do not find evidence for acute downregulation of 5-HT2A receptors with paroxetine within 9 h.