Pharmacological characterization of the serotonin transporter in young andelderly subjects

The potency of some tricyclics (imipramine and clomipramine) and selective 5-HT reuptake inhibitors (fluoxetine, paroxetine, and citalopram) in displa cing the [H-3]paroxetine binding to platelet membranes was measured in youn g and elderly subjects of both sexes. The results showed that the most pote nt compound in all subjects was paroxetine, followed by clomipramine, cital opram, fluoxetine, and imipramine, with no differences between male and fem ale subjects. All drugs, except paroxetine and clomipramine, showed signifi cantly lower pKi values in the elderly subjects of both sexes. These findin gs would suggest that although the pharmacological profile of the 5-HT tran sporter is not modified qualitatively by age, quantitative changes in its a ffinity do perhaps occur which would justify more careful studies on this t opic in order to get optimal dosages of drugs acting at this level.