Selective-norepinephrine reuptake inhibitors (SNRIs) are commonly prescribed medications for depression. The name “selective-norepinephrine reuptake inhibitor” indicates how the medicine works in the brain by altering norepinephrine, one of the brains naturally occurring chemical messengers. SNRIs attach to cells in the brain in a way that interferes with the cell’s ability to vacuum back up the norepinephrine, which ends up causing more norepinephrine to remain in the spaces between brain cells. Changing this balance in norepinephrine levels modifies how different parts of the brain communicate with each other and can in turn improve depression symptoms.
What are the different types of SNRIs and what are their characteristics? The Federal Drug Administration has approved several types of SNRIs for use in treating depression. Each is listed in the table below along with important characteristics such as names, doses, and side effects.
Brand Name Generic Name Usual Dosage Range (adults) Side Effects
- Cymbalta Duloxetine 40-60 mg: Belly problems, sleep problems, dizziness, weakness, drowsiness, sedation, fatigue, headache
- Effexor XR Venlafaxine 75-225 mg: High blood pressure, weakness, severe headache, sweating, blurred vision, chest pain, ringing in ears
- Pristiq Desvenlafaxine 50-100 mg: Insomnia, dizziness, drowsiness, constipation, nausea, decreased appetite, vomiting, anxiety, tremor, blurred vision, abnormal dreams
Special Considerations
• SNRIs are commonly prescribed because they are safer and cause fewer side effects than MAOIs and Tricyclics . There is also good data to show that SNRIs are useful for the treatment of anxiety and the FDA has approved several SNRIs for use in anxiety.
• The different SRNIs are all slightly different from each other in terms of the structure of their molecules. This causes them to affect neurotransmitter levels in slightly different ways, which causes some people to have to experiment with several different types of SNRIs until the desired effects are found.
• It is important to take the medication consistently as prescribed because it takes several weeks for SNRIs to “build up” in the right places. This causes a delay from when people starting taking SNRIs until the medicine starts working. Sometimes, the side effects can start occurring before the therapeutic effects.
