Well, another antidepressant is about to hit pharmacy shelves. That’s always exciting news. But what is it? Is it anything to write home about? Chipur strives to bring you the latest – objectively. So, let’s take a look…

The U.S. Food and Drug Administration (FDA) has approved vilazodone (Viibryd) for the treatment of adult major depressive disorder. And that means it’ll hit pharmacy shelves between now and May 31.

I’ve decided to maintain an ongoing journal of Chipur readers’ experiences with Viibryd. I think it’ll be helpful.

Viibryd is a selective serotonin reuptake inhibitor (SSRI) and a 5-HT1A receptor partial agonist. More on that in a short.

Viibryd is marketed by Clinical Data, Inc., Newton, MA. It was announced a week ago that Forest Laboratories, New York, will be acquiring Clinical Data.

An easy neurochemistry lesson

Viibryd: A New Antidepressant

Neural synapse

To the left, you’ll see a drawing of a neural synapse – the actual communication between two neurons. It’s facilitated by the transmission of a chemical/electrical signal. The arrows mark the flow.

Do you see the receptor site on the neighboring (receiving) neuron? Well, receptors are proteins that actually do the sending and receiving of signals.

A 5-HT receptor is activated exclusively by the neurotransmitter serotonin (chemically known as 5-hydroxytryptamine or 5-HT), and it can tweak and regulate the release of a variety of neurotransmitters and hormones – not just serotonin.

5-HT receptors are involved in functions and responses such as aggression, anxiety, learning, thinking, memory, mood, nausea, regulation of body temperature, and sleep.

Now, a 5-HT1A receptor is the most widespread of the 5-HT receptors. 5-HT1A receptors are prominent in high densities in all sorts of mood and anxiety relevant places, including the cerebral cortex, hippocampus, and amygdala.

Activation of 5-HT1A receptors decreases blood pressure, heart rate, and body temperature. Other activation effects include decreased aggression (or an increase in calm behavior), increased sociability, inhibition of addictive behavior, and the facilitation of sexual behavior and arousal.

On the other side of the coin, activation of 5-HT1A receptors generates increased impulsivity, inhibition of penile erection, and the impairment of cognition, learning, and memory.

Okay, one last morsel of biochemistry. An agonist is any chemical that binds to a receptor and triggers a response by that cell.

Lesson over. Let’s see how it applies to Viibryd…

What is Viibryd?

According to the folks at Clinical Data, Viibryd is a “new molecular entity.” What makes it “new” is it’s the first selective serotonin reputake inhibitor (SSRI)/5-HT1A receptor partial agonist.

Most of us are familiar with the SSRIs – fluoxetine (Prozac), citalopram (Celexa), paroxetine (Paxil), etc. Learn more about the SSRIs.

And now we know about the 5-HT1A receptor partial agonist piece. By the way, for our purposes, let’s not worry about the “partial” bit.

But to fully understand the action of Viibryd we have to dig just a bit deeper.

Ever hear of the atypical antipsychotic, aripiprazole (Abilify)? If you don’t have personal experience with it, you may have seen it in a TV or print ad.

In addition to treating symptoms of schizophrenia, mania, and mixed mood episodes; Abilify is touted as an add-on to antidepressants for treatment resistant depression.

Heavily involved here is overcoming a characteristic of serotonin-impacting antidepressants (like the SSRIs). It’s called therapeutic lag. Simply, it can take some time for them to work.

So, an antidepressant regimen that can somehow pick-up 5-HT1A partial agonistic properties brings faster relief and greater overall efficacy.

Oh, did I forget to mention that Abilify is a 5-HT1A receptor partial agonist – just like Viibryd? So, it appears as though Viibryd was designed to handle the work of two medications.

Risks and side effects

As with most any med for an emotional and mental health disorder, Clinical Data states, “The mechanism of the antidepressant effect of Viibryd is not fully understood.” Yep, certainty not surprising.

I’m not going to get into specific details regarding risks and side effects. Instead, have a look at Viibryd’s medication guide and prescribing information.

I will, however, make three comments…

  • Viibryd is touted as having fewer sexual side effects than other antidepressants.
  • I’m concerned about the following effects of activation of 5-HT1A receptors: increased impulsivity, inhibition of penile erection (I thought there were supposed to be fewer sexual side effects), and impairment of cognition, learning, and memory.
  • If Viibryd and Abilify are both 5-HT1A receptor partial agonists, do the risks and side effects of Abilify need to be considered?

The wrap up

So, there’s a look-see at the new antidepressant vilazodone (Viibryd). Interesting? Yes. Unique? Yes. Will it work for some? Yes. Will it aggravate others? Yes. Does it make me jump up and down in excitement? Um, I’ll hold my reaction until I receive input from users.

By the way, I’m simply offering information and opinion here, not making a recommendation. Using Viibryd is a personal decision.

But now you have enough information to perhaps have piqued your curiosity. And if it was, you can conduct additional research. And then it’s time to chat with your physician, psychiatrist, and therapist.

Plenty more mood and anxiety disorder related articles just waiting for you. Hit the Chipur titles.

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