Today, the U.S. Food and Drug Administration (FDA) approved Symbyax for the acute treatment of treatment-resistant depression (TRD). It is the first drug approved for this indication. Symbyax is a combination pill that combines olanzapine (Zyprexa) and fluoxetine HCl (a long-acting form of Prozac) in a single capsule. Symbyax is manufactured by Eli Lilly and Company.

According to the company’s press release:

  • The new Symbyax TRD indication is for acute treatment of adult patients with major depressive disorder who have not responded to two separate trials of different antidepressants of adequate dose and duration in their current episode.
  • Zyprexa, in combination with fluoxetine, is now approved for the acute treatment of TRD in adults.
  • Symbyax was the first drug approved by the FDA for acute treatment of bipolar depression in adults in 2003. Zyprexa, in combination with fluoxetine, is now approved for the same indication.

With these FDA approvals, clinicians in the United States have the choice to use the single pill option (Symbyax), or the two drugs (Zyprexa and fluoxetine) together, allowing physicians to tailor treatment to each patient’s needs. Neither Zyprexa nor fluoxetine are indicated as monotherapy for bipolar depression or treatment-resistant depression.

You might be asking, what is treatment-resistant depression? Treatment resistant depression is generally defined as an episode of depression that hasn’t responded to trying three or four different medications or courses of psychotherapy. It is not the same as chronic depression (otherwise known as Dysthymic Disorder) because in dysthymia, there is no treatment specifier and the depression must last a minimum of 2 years. (Treatment resistant depression, however, is not a formal diagnosis recognized in the DSM-IV.)

Because Symbyax contains Zyprexa, you can imagine the primary side effect of this medication — weight gain. Doctors and patients should weigh the risks and benefits of the medication with the patient’s own medical history as to whether this is an acceptable side effect or not.

I haven’t had the chance to dig into the studies that were used to approve this new indication for Symbyax, but trust that other bloggers will do so (and we’ll link back to them in the comments section). I will note that Lilly’s definition of treatment resistant depression (“did not respond to two antidepressants of adequate dose and duration in their current episode”) seems a bit lax, though. I don’t know of too many people who haven’t tried at least two antidepressant medications to treat their depression (as the STAR*D research trials also clearly demonstrated).

But for now, it’s nice that doctors have another option now for treatment resistant depression, as psychiatrists have been prescribing Symbyax off-label for this indication for some time now.