Serotonin–norepinephrine reuptake inhibitors (SNRIs)

What they are?

Serotonin–norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant drugs used in psychiatric treatment. They are primarily used in the treatment of clinical depression, but also in the treatment of anxiety disorders, obsessive-compulsive disorder (OC), attention deficit hyperactivity disorder (ADHD), chronic neuropathic pain, fibromyalgia syndrome (FMS) and other mood disorders. Sometimes serotonin–norepinephrine reuptake inhibitors are even used to relieve menopausal symptoms.

How do they work?

Serotonin–norepinephrine reuptake inhibitors (SNRIs) are different from

other classes of antidepressants because they affect only neurotransmitters serotonin and norepinephrine. Research has shown that the neurotransmitters serotonin and norepinephrine play an important role in the regulation of mood and that mood disorder, such as medical depression or anxiety, can sometimes be explained by abnormal neurotransmitter activity. SNRIs correct imbalances of serotonin and norepinephrine levels.

SNRIs achieve this by blocking the reuptake of serotonin and norepinephrine, this allows more serotonin and norepinephrine to be available in the brain. That is believed to increase the effect of these neurotransmitters. As serotonin can elevate mood and cause a calming effect and norepinephrine can increase alertness, concentration and motivation, SNRIs are believed to relieve clinical depression and other mood disorders.

Do SNRIs have any side effects?

Yes. Side effects of serotonin-norepinephrine reuptake inhibitors (SNRIs) are similar to side effects of selective serotonin reuptake inhibitors (SSRIs) as they have a similar mechanism of action.

Side effects include: drowsiness, headache, nausea, changes in appetite, vivid dreams, sexual dysfunction, dry mouth, anorexia, sweating, insomnia, nervousness, tremor and hypertension.

Are SNRIs addictive?

No but like SSRIs, Serotonin–norepinephrine reuptake inhibitors can also have unpleasant withdrawal symptoms with the most serious symptoms relating to withdrawal syndrome.

Withdrawal symptoms include: dizziness, nausea, vomiting, headache, irritability, unpleasent sensations, such as tingling, burning and shocks, nightmares, tremors, lack of coordination, aggressiveness, suicidal thoughts and balance problems.

What types of Serotonin–norepinephrine reuptake inhibitors are currently availabe?

• Effexor ( Effexor or Efexor) - the first and most commonly used SNRI, works also on dopamine, but mostly effects serotonin and norepinephrine.
• Nefazodone (Serzone, Nefadar) - Serzone is without sexual side effects.
• Duloxetine (Cymbalta, Ariclaim, Xeristar, Yentreve, Duzela)
• Desipramine (Norpramin, Pertofane) - technically a tricyclic antidepressant, but works on both serotonin and norepinephrine, so it can aslo be categorized as an SNRI.
• Milnacipran (Ixel, Savella, Dalcipran, Toledomin)  - is not approved for the clinical treatment of clinical depression in the USA, but is available in Europe and Asia.