Monday, July 18, 2011

New antidepressant - ViiBRYD - my 2¢

(Yeah, it's been a while. This was originally posted last week on the Axiom Message Boards)

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So there's a new antidepressant out, which is always kind of exciting. The antidepressant pipeline has been kind of dry for the last decade.

However, my initial impression after a bit of research is that, as is often the case, this new medicine will be an expensive way to get approximately the same effect that you can get with currently available generic medications.

The brand name of the new medication is ViiBRYD. Aren't the cutesy double lower case "i"s about enough to make you barf? The scientific/generic name is vilazodone, which at once made me think of trazodone (Desyrel) and nefazodone (Serzone), antidepessants from the 1980s. Indeed, vilazodone is a piperazine-class compound, just like trazodone, nefazodone, and a whole host of other medications.

The drug rep proposed that ViiBRYD works like a combination of Lexapro and Abilify, because it inhibits serotonin intake, like Lexapro and the other SSRIs (selective serotonin reuptake inhibitors) and is a partial agonist of the serotonin 1-A receptor (like Abilify). Thus, a patient can avoid the currently in vogue regimen of adding an atypical antipsychotic (Abilify, Seroquel) to his antidepressant, getting similar effects in one pill instead of two. Fewer copays, etc.

Wow! Sounds good! Those are some powerful meds you're emulating, alright! Sign me up and let me hand out these samples to all of my depressed patients!

Wait. What the drug rep didn't mention is that Abilify is actually much more than just a serotonin 1-A partial agonist. Its activity there doesn't even account for the majority of its therapeutic effect, which is from its effect on dopamine, where it is also a partial agonist. All in all, Abilify is active in almost a dozen ways - I call it my Swiss Army knife: good for almost anything.

A more accurate analogy would be to say that ViiBRYD is like a combination of Lexapro (or your SSRI of choice) and buspirone (BuSpar). Buspirone is a 1980s era molecule which had modest success treating generalized anxiety before going generic in 2001. About all it does chemically is through that serotonin 1-A receptor, so it was billed as having virtually no side effects. Of course, many patients also said it had virtually no good effects, either, but often they had seen the big guns of benzodiazepines (Xanax, Valium, Klonopin, etc) and, by that point, addressing their anxiety with buspirone was like addressing a bear with a slingshot. Now, for benzodiazepine-naive patients, buspirone was pretty decent. But I digress.

Anyway, on the $4 list at WalMart, Target, and several other pharmacies, one can find not only buspirone but several decent SSRIs such as fluoxetine (Prozac), paroxetine (Paxil), and citalopram (Celexa). I like citalopram due to its good overall tolerability. It was the precursor to Lexapro, anyway, with the same active ingredient; Forest Pharmaceuticals just played some isomer games to create Lexapro. So citalopram + buspirone = SSRI effect plus serotonin 1-A effect for $8. I don't have cost info for ViiBRYD, but most branded antidepressants are ~$200 a month. Even with insurance, you'll probably have a tier 3 copay, if it is even covered in the first place.

So I don't think I'll be writing a lot of ViiBRYD. But it was nice of them to remind me of some of the pharmacologic principles at work so that I could save my patients, and the health care system, some money.