Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

The first thing to know about serotonin-norepinephrine reuptake inhibitors is that they are a class of antidepressants. These drugs can be used to treat a variety of disorders, including: panic disorder, depression, GAD (generalized anxiety disorder), panic disorder, and social anxiety disorder.

The SNRI drugs are occasionally used for treating anxiety disorders, as well as ADHD, along with obsessive-compulsive disorder (OCD) and even for chronic pain. The drugs act on two certain neurotransmitters within the brain which are linked to mood; these are serotonin and norepinephrine. Because they work on two chemicals, they are different than selective serotonin reuptake inhibitors (SSRIs), as this type of drug affects only serotonin.

How SNRIs work

As a depressant, SNRIs will increase the quantity of norepinephrine and serotonin. It does this by restricting the re-absorption (reuptake) rate into brain cells. The exact way this work is not clear, but many believe higher levels of these chemicals can improve neurotransmission, which is the transmitting of messages between nerve cells. This, in turn, may help improve a person's mood.

It is believed by some, that antidepressants can help in a neuroprotective manner as well. They do this in order to reduce anxiety symptoms and depression. Some think antidepressants are able to increase the general effects related to brain receptors which assist nerve cells in keeping glutamate sensitivity in check. They do this by lowering glutamate sensitivity. This can help protect the brain from glutamate overwhelming the essential areas that are closely related to both depression and anxiety.

Types of SNRIs

SNRIs that are currently on the market include:

• Effexor (venlafaxine) - is a commonly used SNRI. This drug works on dopamine levels but is also effective on serotonin and norepinephrine.
• Serzone (nefazodone) - This drug is similar to the SSRIs, but it does not possess the same sexual side effects.
• Norpramine/Pertofraneis (desipramine) - This drug is technically a tricyclic type of antidepressant. It is usually classified as such and works on serotonin and norepinephrine. For this reason, it is also considered to be an SNRI.
• Cymbalta (duloxetine) - This drug is approved for treating depression as well as neuropathic pain.
• Desvenlafaxine (Pristiq) - This drug is used mostly for treating major depression.

Side Effects of SNRIs

Common SNRIs all work in the same basic way. This means they often have similar side effects. It should be remembered that individual SNRIs will also have certain pharmacological characteristics. What this means is every person may have a different reaction when taking the same SNRI medication. Also the side effects may differ with different SNRIs. In other words, one person may have side effects that are unpleasant, while on another drug, they have no side effects at all.

Common side effects found with SNRIs include:

• Vomiting
• Nausea
• Dizziness
• Insomnia
• Sweating
• Fatigue or Sleepiness
• Tremor
• Anxiety
• Vision Problems
• Headache
• Sexual impotency or dysfunction

Before you start taking antidepressants, consult with your doctor and tell him of any drugs you are taking, even nonprescription medications.

In some cases, Effexor XR and Cymbalta can lead to high blood pressure. Blood pressure issues must be under control before you start treatment. Monitor your blood pressure regularly.

Effexor is known to also increase heart rate when taken in higher doses. Effexor must be used with caution for those who have had heart failure, heart attack, or overactive thyroid gland.

In some cases, Effexor cause cholesterol levels to go up if taken for three months or more. Normally, this only occurs in those taking high doses of Effexor.

When taking SNRIs, you should not also be taking any monoamine oxidase inhibitor (MAOI).