SNRI stands for serotonin-norepinephrine reuptake Inhibitor. These may also be called selective serotonin-norepinephrine reuptake Inhibitors (SSNRIs). SNRIs increase levels of serotonin and norepinephrine in the brain by blocking or delaying their reuptake by nerves.
Serotonin is a neurotransmitter that is often referred to as the “feel good hormone”. It carries messages between brain cells and contributes to well-being, good mood, appetite, social behavior, as well as helping to regulate the body’s sleep-wake cycle and internal clock.
Norepinephrine is another neurotransmitter that is also thought to be important in the regulation of emotions and thought processes. It works closely with dopamine and serotonin systems and is thought to help mobilize the brain for action, increasing alertness, focus and the retrieval of memory.
Having more serotonin and norepinephrine available in the nerve synapse means that information can be transmitted easier from one nerve to another. All SNRIs are thought to work in this way.
SNRIs help to relieve the symptoms of depression in major depressive disorder (MDD) such as low mood, irritability, feelings of worthlessness, restlessness, anxiety, and difficulty in sleeping.
In addition to depression, some SNRIs may be used to treat other conditions, such as:
Some reduction in symptoms may be noticed within one to two weeks; however, it may take six to eight weeks of treatment before the full effects are seen.
Although all SNRI antidepressants are thought to act in the same way, each has a different effect on reuptake inhibition. Venlafaxine inhibits serotonin reuptake more than norepinephrine reuptake. Although the difference is less with duloxetine and desvenlafaxine, the effect on serotonin remains greater with these two SNRIs. Milnacipran exerts a relatively equal influence on serotonin and norepinephrine whereas levomilnacipran affects norepinephrine more than serotonin. Depending on the SNRI, serotonin side effects may be seen before norepinephrine side effects.
Venlafaxine was the first SNRI marketed in the United States. Only venlafaxine immediate release and milnacipran are dosed twice a day, all the rest are dose once a day. Both venlafaxine and duloxetine are available in generic formulations.
Duloxetine has the most approved indications followed by venlafaxine. Desvenlafaxine (depression), levomilnacipran (depression) and milnacipran (fibromyalgia) have only one indication each.
Compared to other antidepressants, such as SSRIs or TCADs the SNRIs have relatively short half-lives and only venlafaxine has an active metabolite (desvenlafaxine).
Venlafaxine and duloxetine are more likely than other SNRIs to interact.
| Generic name | Brand name examples |
|---|---|
| desvenlafaxine | Khedezla, Pristiq |
| duloxetine | Cymbalta, Irenka |
| levomilnacipran | Fetzima |
| milnacipran | Savella |
| venlafaxine | Effexor, Effexor XR |
When taken at the recommended dosage, SNRI antidepressants are considered safe. However, they have been associated with a few serious, potentially fatal, severe side effects such as:
Some of the more commonly reported side effects of SNRIs include:
Some SNRIs have been associated with a discontinuation syndrome when they have been stopped suddenly. For this reason, it is best to withdraw all antidepressants slowly.
For a complete list of side effects, please refer to the individual drug monographs.
Additional references:
Sansone RA, Sansone LA. Serotonin Norepinephrine Reuptake Inhibitors: A Pharmacological Comparison. Innovations in Clinical Neuroscience. 2014;11(3-4):37-42.
Data Source:drugs.com
Cymbalta is a prescription medication used to treat depression, anxiety, and certain types of chronic pain. It belongs to a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs) and works by increasing the levels of certain chemicals in the brain that help improve mood and relieve pain. Cymbalta is typically taken orally in capsule form and is available in various strengths. It is important to follow the dosage instructions provided by a healthcare professional and to discuss any potential side effects or interactions with other medications before starting treatment with Cymbalta.
Data Source:medlineplus.gov
Desvenlafaxine ER is a medication used to treat depression and anxiety disorders. It belongs to a class of drugs called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). This extended-release formulation allows for once-daily dosing, providing a steady release of the medication throughout the day. Desvenlafaxine ER works by increasing the levels of serotonin and norepinephrine in the brain, which helps to improve mood and reduce symptoms of depression and anxiety. It is important to follow the prescribed dosage and consult with a healthcare professional for proper use and potential side effects.
Data Source:medlineplus.gov
Desvenlafaxine succinate extended-release (ER) is a medication used to treat depression. It belongs to a class of drugs called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). The extended-release formulation allows for once-daily dosing, providing a steady release of the medication throughout the day. Desvenlafaxine works by increasing the levels of serotonin and norepinephrine in the brain, which helps to improve mood and reduce depressive symptoms. It is typically prescribed by a healthcare professional and should be taken as directed.
Data Source:medlineplus.gov
Duloxetine HCL DR is a medication that is commonly prescribed to treat depression, anxiety, and certain types of chronic pain. It belongs to a class of drugs called selective serotonin and norepinephrine reuptake inhibitors (SNRIs), which work by increasing the levels of certain chemicals in the brain that help regulate mood and pain signals. This medication is typically taken orally and comes in a delayed-release form, meaning it is designed to release the medication slowly over time. It is important to follow the prescribed dosage and instructions provided by a healthcare professional when taking Duloxetine HCL DR.
Data Source:medlineplus.gov
Effexor XR is a prescription medication that belongs to a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs). It is primarily used to treat depression, anxiety, and panic disorders. Effexor XR works by increasing the levels of certain chemicals in the brain that help improve mood and reduce feelings of anxiety. This medication is available in extended-release capsules and should be taken as directed by a healthcare professional. It may take several weeks for Effexor XR to reach its full effectiveness, and it is important to continue taking it even if symptoms improve. Common side effects may include nausea, dizziness, headache, and insomnia.
Data Source:medlineplus.gov
FETZIMA ER is a medication that is used to treat major depressive disorder in adults. It belongs to a class of drugs called serotonin-norepinephrine reuptake inhibitors (SNRIs) and works by increasing the levels of certain chemicals in the brain that help improve mood. FETZIMA ER is an extended-release formulation, which means it is designed to release the medication slowly over time, providing a steady and continuous effect. It is typically taken once daily and should be used as directed by a healthcare professional.
Data Source:medlineplus.gov
PRISTIQ ER is a medication that belongs to a class of drugs called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It is primarily used to treat major depressive disorder and generalized anxiety disorder. PRISTIQ ER works by increasing the levels of serotonin and norepinephrine in the brain, which helps to improve mood and reduce anxiety. It is an extended-release formulation, meaning that it is designed to release the medication slowly over time, providing a steady and consistent effect. PRISTIQ ER is typically taken once daily, with or without food. It is important to follow the prescribed dosage and consult with a healthcare professional for any concerns or questions.
Data Source:medlineplus.gov
SAVELLA is a medication used to treat fibromyalgia, a chronic condition characterized by widespread pain and tenderness. It works by increasing certain chemicals in the brain that help reduce pain signals. SAVELLA can also improve sleep, mood, and overall quality of life for individuals with fibromyalgia. It is typically taken orally, and the dosage may vary depending on the individual's response and tolerance. Common side effects may include nausea, headache, dizziness, and sweating. It is important to follow the prescribed dosage and consult with a healthcare professional before starting or stopping SAVELLA.
Data Source:medlineplus.gov
Venlafaxine HCl is a medication that belongs to the class of drugs known as selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It is commonly prescribed to treat depression, anxiety disorders, and panic disorder. Venlafaxine HCl works by increasing the levels of serotonin and norepinephrine in the brain, which helps to improve mood and reduce feelings of anxiety. This medication is available in tablet form and is typically taken once or twice daily, with or without food. It is important to follow the prescribed dosage and consult with a healthcare professional for any concerns or potential side effects.
Data Source:medlineplus.gov
Venlafaxine HCl ER is a medication that belongs to the class of drugs known as selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It is commonly prescribed to treat depression, anxiety, and panic disorders. The extended-release formulation allows for a slow and steady release of the medication into the body, providing long-lasting effects. Venlafaxine HCl ER works by increasing the levels of serotonin and norepinephrine in the brain, which helps to improve mood and reduce symptoms of these conditions.
Data Source:medlineplus.gov
Data Source:medlineplus.gov
