Does Viibryd Increase Anxiety or Alleviate It?
Viibryd is a serotonergic antidepressant. How does treatment with Viibryd impact anxiety? Here's the quick-and-dirty answer:
- Viibryd (vilazodone) is approved in the United States as a treatment for depression, and also shows promise as an anti-anxiety agent.
- Viibryd increases serotonin (it's a serotonin re-uptake inhibitor) and binds serotonin receptors (5-HT1A partial agonist). These effects are relevant because serotonin regulates anxiety, among other things.
- Viibryd acutely (1-4 weeks) can increase anxiety but in the long-term tends to reduce anxiety.
- Put differently, excess serotonin can induce a state of agitation, inner tension, and anxiety. Since Viibryd boosts serotonin it can initially promote anxiety. But as your brain adapts, it tends to relieve anxiety.
- Unlike other SSRIs, Viibryd has insignificant sexual side effects, which gives it an edge over other options.
Repurposing Antidepressants as Anxiety Medications
Dr. Durgam tested the hypothesis that Viibryd might be an effective anti-anxiety medication.
He and his colleagues enrolled 400 patients with a diagnosis of generalized anxiety disorder (GAD). They randomized patients to either placebo or vilazodone 20-40 mg/d for 8 weeks of double-blind treatment. The authors reported that Viibryd had a statistically significant beneficial effect on anxiety symptoms. This result is in line with other studies that found SSRIs are effective anti-anxiety medications.
Anxiety Disorders Are Common
The most common psychiatric illnesses in the United States are anxiety disorders.
'Anxiety disorder' is a blanket term encompassing:
- generalized anxiety disorder (GAD)
- panic disorder (PD)
- social anxiety disorder (SAD)
- simple phobias (SP)
Pathological worry usually develop in the mid-twenties, and is twice as likely to affect women than men.
People with anxiety disorders experience a disproportionate and persistent worrying or obsession about the impact of an event, an inability to relax and difficulty concentrating.
Normal Worry vs Pathological Worry
What's the line between normal worry and an anxiety disorder? This is something that your physician can help you sort out. One author makes a good point about the difference:
Although worrying is a ubiquitous human experience, the worries that characterize generalized anxiety disorder (GAD) are so pervasive and excessive that they distort cognition and create a considerable burden of illness.
Anxiety that impinges on your quality of life is arguably disordered.
What Causes Anxiety Disorders?
There is no complete account of what causes anxiety disorders, but no explanation fails to mention neurotransmitters. Neurotransmitters are chemical signals between nerve cells (neurons).
Neurons release neurotransmitters which bind to receptors on other cells to influence their activity. The neurotransmitters serotonin, norepinephrine, dopamine, and GABA influence feelings of well-being and the capacity to relax.
Thus, pathways involving these chemical messengers are often targeted by anxiety medication. The most prescribed medications for anxiety disorders are anti-anxiety medications (also known as anxiolytics) and beta-blockers. Doctors also use antidepressants to manage reduce anxiety since there are several overlapping features between anxiety and depression. Depressed patients also tend to be anxious, indicating shared pathways.
Anxiety and depression are often treated with drugs that target serotonin or 5-hydroxytryptamine (5-HT) imbalances.
Serotonin modulates several behaviors including mood. Although it is not completely understood how serotonin contributes to anxiety, serotonin probably reduces anxiety by suppressing hyperactivity of the amygdala. The amygdala is a region of the brain responsible for emotional responses.
The phrase "chemical imbalance" has gotten a lot of flack in recent years because it's simplistic and technically inaccurate. However it can be a useful heuristic when first explaining how serotonergic drugs like Viibryd work.
For example, Dr. Kresser notes:
No one has explained why it takes a relatively long time before antidepressant drugs produce any elevation of mood. Antidepressants produce their maximum elevation of serotonin and norepinephrine in only a day or two, but it often takes several weeks before any improvement in mood occurs. Although some depressed patients have low levels of serotonin and norepinephrine, the majority do not. Estimates vary, but a reasonable average from several studies indicates that only about 25 percent of depressed patients actually have low levels of these metabolites.
Despite these objects, serotonin does modulate several behaviors including mood. Serotonin may reduce anxiety by suppressing hyperactivity of the amygdala. The amygdala is a region of the brain responsible for emotional responses.
Serotonin released from nerve cells modulate brain activity by binding to receptors on cells in brain regions responsible for different functions, including emotions. Unbound serotonin is taken back up by the releasing (presynaptic) cell using re-uptake transporters and disintegrated to help maintain a stable serotonin concentration in the brain.
Anxiety medications primarily function by regulating this process to increase serotonin concentration in the brain and increase serotonin signaling.
Common anxiolytics include selective serotonin re-uptake inhibitors (SSRIs)—which prevent the uptake of unbound serotonin and thus increasing serotonin concentrations. Another class of antidepressants, serotonin-norepinephrine re-uptake inhibitors (SNRIs) also target serotonin; they block the uptake of both serotonin and norepinephrine.
Depression and Anxiety are Bedfellows
The overlap between and anxiety and depression have been beneficial in developing treatments for these conditions. Many patients with major depression disorder (MDD) also have comorbid anxiety. Patients with anxiety (GAD) also have symptoms similar to depression (MDD).
So it comes as no surprise that these disorders often go hand-in-hand. Some common symptoms between MDD and GAD include difficulty completing everyday asks, low quality of life, and impairments in physical functioning, mental health, social functioning, vitality, general health and even bodily pain.
Viibryd A Viable Anxiety Treatment?
A novel antidepressant that has been investigated for its efficacy in treating anxiety in the last year is vilazodone.
Vilazodone HCl is a benzofurancarboxamide derivative produced by Forest Laboratories, Inc. Vilazodone was approved by the US Food and Drug Administration (FDA) in January 2011, to treat MDD in adults.
It is prepared as an orally administered tablet called Viibyrd.
Vilazodone inhibits re-uptake of serotonin by binding to the reuptake site on the serotonin transporter. It is also a partial activator of the serotonin receptor 5-HT1A.
Vilazodone peaks after 4-5 hours post-ingestion and has a long half-life of about 25 hours. Thus, a steady-state concentration can be achieved in approximately 3 days after the drug is started.
Titrating the Dose
As an antidepressant, vilazodone is not typically effective until 6-8 weeks following the initial treatment. Viibryd is administered at an initial dosage of 10 mg a day with food for 7 days. The dosage is then increased to 20 mg. If 20 mg is not effective, it may be increased up to 40 mg once a day after the patient has taken 20 mg doses for 7 days.
Since blocking serotonin receptors can result in light-headedness and nausea, it is no surprise that the most common side effects are nausea and headaches. Other reported symptoms include:
- dry mouth
- abdominal pain
- increased risk of bleeding
- suicidal thoughts
SSRI discontinuation can result in significant withdrawal symptoms, like nausea, sweating, mood swings, irritability, agitation, dizziness, “brain zaps” or electrical shock sensations, tremor anxiety, and headaches. The worst offender when it comes to SSRI discontinuation syndromes is Paxil.
Vilazodone for Anxiety?
You should recognize that vilazodone has only earned FDA approval for depression.
But although it's not approved to treat anxiety, there are several studies that have examined the effects of vilazodone on anxiety. vilazodone has also been increasingly prescribed off-label for anxiety.
Multiple recent studies of patients with GAD and other anxiety disorders that received 20 to 40 mg once a day for over several weeks was found to be effective at reducing anxiety symptoms.
No Sexual Side Effects
What makes Viibryd unique as an anti-anxiety agent is that has limited sexual side effects. If you're familiar with SSRIs, you'll know that the most common complaint patients have taking them is reduced libido and erectile dysfunction.
Viibyrd has recently been shown to be effective at treating anxiety with few severe side effects. It is unique from other antidepressants in that it also has little impact on sexual function. Further research on Viibyrd may provide a novel therapy to treat generalized anxiety disorder (GAD) and other anxiety-related disorders.