How do antidepressants work?
In this article, we will describe how do antidepressants work.
Different kinds of antidepressants target different neurotransmitters.
Common antidepressant groups
Selective serotonin reuptake inhibitors (SSRIs) – are the most commonly prescribed antidepressants available. They include citalopram and sertraline. Both drugs affect a serotonin transporter but also affect other serotonin receptors to relieve major depression.
Serotonin and norepinephrine reuptake inhibitors (SNRIs) – are among the newer types of antidepressant. As the name implies, they block the reuptake of both serotonin and norepinephrine. They include duloxetine and venlafaxine.
Norepinephrine and dopamine reuptake inhibitors (NDRIs) – are another class of reuptake inhibitors, but they’re represented by only one drug: bupropion. It affects the reuptake of norepinephrine and dopamine.
Mechanism of action of antidepressants
Other antidepressants: tetracyclics and SARIs
Tetracyclics – are another class of antidepressant drugs, including mirtazapine. Although it affects neurotransmitters, it does not prevent reuptake in the same way. Instead, it seems to stop neurotransmitters from binding with specific receptors on the nerves. Because the norepinephrine and serotonin don’t bind to the receptors, they seem to build up in the areas between the nerve cells. As a result, the neurotransmitter levels rise.
Serotonin antagonist and reuptake inhibitor (SARIs) – appear to act in two ways. They prevent the reuptake of serotonin. But they also prevent serotonin particles that are released in a synapse from binding at certain undesired receptors and redirect them instead to other receptors that can help nerve cells within mood circuits function better. An example is trazodone.
Older antidepressants: tricyclics and MAOIs
These drugs were among the first to be used for depression. Although they are effective, they can have serious side effects and can be especially dangerous in overdose. Nowadays, many doctors only turn to these drugs when newer – and better tolerated – medicines have not helped.
Tricyclics and MAOIs might not be the best approach for someone who was just diagnosed. But they can sometimes be very helpful for people with treatment-resistant depression, or certain forms of depression (such as depression with anxiety).
Tricyclic antidepressants (TCAs) – include amitriptyline and imipramine. Like reuptake inhibitors, tricyclics seem to block the reabsorption of serotonin and epinephrine back into nerve cells after these chemicals are released into a synapse.
Because of the potential side effects, your doctor might periodically check your blood pressure, request an ECG, or recommend occasional blood tests to monitor the level of tricyclics in your system. These medicines might not be safe for people with certain heart rhythm problems.
Monoamine oxidase inhibitors (MAOIs) – include selegiline. These drugs seem to work a little differently. Monoamine oxidase is a natural enzyme that breaks down serotonin, epinephrine, and dopamine. MAOIs block the effects of this enzyme. As a result, the levels of those neurotransmitters might get a boost.
A downside is that MAOIs also prevent the body’s ability to break down other medicines metabolised by this enzyme (such as Sudafed, or stimulants) – raising the risk for high blood pressure – as well as an amino acid called tyrosine, which is found in certain foods like aged meats and cheeses.
MAOIs also should not be combined with other medicines that can raise serotonin (such as certain migraine medicines, or other antidepressants), because that can cause a buildup of excessive serotonin (called “serotonin syndrome”), which can be life threatening.
Summary
We have described how do antidepressants work. We hope it has been helpful.
Last Reviewed on 7 March 2024