Selective Inhibition of the Serotonin Transporter in the Treatment of Depression: Sertraline, Fluoxetine and Citalopram.

Discovery and development of the selective serotonin reuptake inhibitors mark a milestone in neuropharmacology. Drugs from this class alter the functioning of the serotonin system by the potentiation of serotonin through the negative allosteric modulation of its neuronal uptake by the human serotonin transporter. Selective serotonin reuptake inhibitors show few side effects compared to those caused by traditional antidepressants and they vary in the binding interactions formed during binding. Generally, their binding involves three specific regions of the drug structures, each participating in vital interactions, such as salt bridge formation and additional hydrophobic interactions with conserved residues in the central binding site of the target protein. Side effects, however, such as the initial lack of response to treatment, or drowsiness, nausea, and sexual dysfunction occasionally may arise. Additional binding studies, furthermore, highlighted the importance of enantioselectivity in the binding of these compounds, raising concerns about the beneficial application of racemate mixtures of some of these compounds. Therefore, additional characterisation of binding and further structural improvement of this class of drugs is necessary. The recently synthesized sertraline salts, and functional derivatives of fluoxetine and citalopram show promising results in delivering antidepressant activity as well as in effectively overcoming anorexigenic side-effects in rodent models. Hence, despite certain non-desired effects associated with selective serotonin reuptake inhibitor applications, this class of drugs is considered as first-line medication in the management of major depression, and is carrying an excellent potential for the development and refinement of the currently available and novel antidepressant therapies.