Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) are a class of antidepressants used in psychiatric treatment. They are primarily used to treat clinical depression, but also have a use in the treatment of obsessive-compulsive disorders, anxiety disorders, attention deficit hyperactivity disorder (ADHD) and other mental health disorders. SNRIs are different from other classes of antidepressant drugs, such as Selective Serotonin Reuptake Inhibitors (SSRIs), because they work specifically with the neurotransmitters serotonin and norepinephrine.
Neurotransmitters are chemicals that act as messengers in the brain. It is important for these ‘messengers’ to function properly. A mood disorder, such as an anxiety disorder or depression, can sometimes be explained by abnormalities in neurotransmitter activity. Research suggests that the neurotransmitters serotonin and norepinephrine play an important role in the regulation of mood.
SNRI Medications Include:
SNRIs are used to correct imbalances of serotonin and norepinephrine levels in the brain. SNRIs achieve this by blocking the ‘reuptake’ of serotonin and norepinephrine. Reuptake is the absorption of neurotransmitters back into the part of the brain that released them. By blocking the reuptake process, SNRIs allow more serotonin and norepinephrine to be available in the brain. Although the precise mechanism of action is not clear, it is thought that this increases the effect of these neurotransmitters. Serotonin can elevate mood and cause a calming effect. Norepinephrine can increase alertness, concentration and motivation. SNRIs are believed to relieve depression and other mood disorders by increasing the effect of norepinephrine and serotonin in the brain. Because of their unique effect, SNRIs are often prescribed for depression that does not respond to SSRIs.
SNRIs have a similar mechanism of action as SSRIs and therefore can share similar side effects.
Common Side Effects Include:
- Changes in appetite
- Vivid dreams
- Sexual dysfunction
SNRIs work with norepinephrine as well as serotonin and SNRI specific side effects can occur. Medications that inhibit the re-uptake of norepinephrine can sometimes cause anxiety and elevated blood pressure. Individuals who are susceptible to hypertension, heart disease, or stroke should consult a doctor before taking an SNRI. If SNRIs are abruptly discontinued it can cause a period of discomfort that is called a ‘discontinuation syndrome’. Symptoms of discontinuation syndrome include nausea, headache, dizziness, lethargy and flu-symptoms. If a person wants to stop taking an SNRI, it is important to consult a doctor and taper off of the medication under medical supervision. If a person who is taking an SNRI experiences suicidal thoughts, they should consult a doctor immediately. In rare cases, SNRIs may increase suicidal feelings.
SNRI’s are related to SSRI’s and other reuptake inhibitors as they specifically target the reuptake of certain molecules in presynaptic neuron.
Like SSRI’s dependence can develop with most serious symptoms relating to withdrawal syndrome. These symptoms include:
- Unpleasant Sensations (Tingling/Burning/Shocks)
- Lack of Coordination
- Worse Depression/Suicidal Thoughts
- Balance Problems/Vertigo