What is the difference between SNRI's and SARI's (serotonin antagonist and reuptake inhibitors)?

How Do Serotonin Antagonist and Reuptake Inhibitors Work?
Neurotransmitters are chemicals that pass messages in your brain, telling you to feel certain ways. A specific neurotransmitter, serotonin, is thought to be responsible for feelings of well-being and happiness. When an individual suffers from major depressive disorder, their brain experiences decreased serotonin activity, resulting in low self-esteem, low energy and loss of interest in daily activities. Neurotransmitter receptors receive the messages from the neurotransmitters resulting in your brain processing these signals. Serotonin antagonist and reuptake inhibitors work by antagonizing, or blocking, the serotonin receptors from their usual reuptake process, where the neurotransmitters would generally process and then be removed. Instead, the SARIs allow serotonin to remain in the neurotransmitter system for longer periods of time, thus resulting in an elevated mood and an increased pleasure in activities. Used in combination with therapy, SARIs allow individuals struggling with major depressive disorder to develop the coping skills necessary to manage their depression. Therapy provides a safe place for people to process their feelings and learn how to handle them in the future. Aided by the increased sense of well-being provided by the serotonin antagonist and reuptake inhibitors, individuals with major depressive disorder are better able to combat their depression and live a happy, healthy life.

Resources “Rediscovering trazodone for the treatment of major depressive disorder” – Fagiolini A, Comandini A, Catena Dell’Osso M, Kasper S

Trazodone is a triazolopyridine derivative that belongs to the class of serotonin receptor antagonists and reuptake inhibitors (SARIs). The drug is approved and marketed in several countries worldwide for the treatment of major depressive disorder (MDD) in adult patients. In clinical studies, trazodone has demonstrated comparable antidepressant activity to other drug classes, including tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs) and serotonin-noradrenaline (norepinephrine) reuptake inhibitors (SNRIs). Moreover, the SARI action of trazodone may overcome the tolerability issues that are often associated with second-generation antidepressants such as SSRIs (i.e. insomnia, anxiety and sexual dysfunction). Recent focus has been placed on the development of a new prolonged-release once-a-day formulation of trazodone (TzCOAD), which may provide improved tolerability over the conventional immediate-release formulation of trazodone. Clinical studies have led to the recent approval in the USA of TzCOAD (as Oleptro™; Angelini Labopharm LLC, Princeton, NJ, USA), which may see resurgence of interest in the drug for the management of patients with MDD. Although trazodone is approved for the treatment of depression, evidence supports the use of low-dose trazodone as an off-label hypnotic for the treatment of sleep disorders in patients with MDD. The most common adverse effects reported with trazodone are drowsiness (somnolence/sedation), headache, dizziness and dry mouth. Other events reported, albeit with low incidence, include orthostatic hypotension (particularly in elderly patients or those with heart disease), minimal anticholinergic activity, corrected QT interval prolongation and torsade de pointes, cardiac arrhythmias, and rare occurrences of priapism and suicidal ideation. Overall, trazodone is an effective and well tolerated antidepressant (SARI) with an important role in the current treatment of MDD both as monotherapy and as part of a combination strategy. Trazodone is effective in controlling a wide range of symptoms of depression, while avoiding the negative effects on sleep seen with SSRI antidepressants. The recently approved prolonged-release formulation should provide further optimization of this antidepressant and may be useful for enabling an appropriate therapeutic dose to be administered with improved patient compliance.

Resource: National Library of Medicine
National Center for Biotechnology Information