The market for drugs to treat unipolar depression continues to present significant opportunities, a new report tells drugmakers.

This is due to the high prevalence of depressive disorders in the world's major pharmaceuticals markets, and also to current low patient response rates, with more than one-third of patients with depression failing to respond to first-line antidepressants, according to the study, from Decision Resources. 

"Agents that offer faster and more sustained effect than currently-available agents or that demonstrate efficacy for treatment-resistant depression would be differentiated in the unipolar depression market," comments Alana Simorellis, an analyst at Decision Resources.

However, she also cautions that the growing number of generic products in this area will make it increasingly difficult for marketers to gain blockbuster status for branded emerging therapies. 

AstraZeneca's Seroquel XR, Seroquel XL and Seroquel Prolong (quetiapine extended release), plus generic versions of this product, and Bristol-Myers Squibb/Otsuka Pharmaceutical's Abilify (aripiprazole) are continuing to modestly increase their patient share as adjunctive treatments for major depressive disorder, and these two agents will contribute to the stability of the unipolar depression market in the near term, the report notes. 

It also forecasts that, to 2015, sales of the atypical antipsychotic drug class for the treatment of unipolar depression will reach more than $2.5 billion overall in the US, France, Germany, Italy, Spain, the UK and Japan, and that increasing generic competition within this class in the latter half of the forecast period will offset continued growth in patient share.

Emerging antidepressants will enter a crowded and highly-genericised market, the report goes on. In particular, this is because there is a lack of clinical differentiation among currently-marketed selective serotonin reuptake inhibitors (SSRIs) and selective serotonin and norepinephrine reuptake inhibitors (SNRIs) and, given the stronghold that these current classes hold in terms of price, generic options and physician comfort, emerging antidepressants will not likely be first-line agents.

Decision Resources expects marketers of emerging agents, such as Lundbeck/Takeda's vortioxetine (formerly Lu-AA21004) and Forest Laboratories/Pierre Fabre's levomilnacipran, to position their therapies as options for patients who have not responded to first-line antidepressants, or in those patients who have residual symptoms of depression, such as fatigue.