Is the antidepressant glass half-empty or half-full?

Generics have hit the antidepressant market hard. With patents on some key drugs either expired or near expiration, analysts figure the $12.3 billion field will lose more than $2 billion in value by 2021. Finding new drugs could turn the numbers around, but these days, fewer drugmakers are even looking.

Let's just count the casualties, beginning with the most timely. Lexapro, the Forest Laboratories ($FRX) antidepressant, lost exclusivity earlier this year, and the company's sales plummeted because of it. AstraZeneca's ($AZN) Seroquel, an add-on treatment for depression, is also off patent these days (though its extended-release version remains brand-only). Eli Lilly's ($LLY) Cymbalta, the company's biggest drug, loses its lock on the market in 2014. And think of all the previous patent cliffs among new-generation depression treatments. Prozac, Zoloft, Paxil, Celexa, Wellbutrin, Effexor ... the list goes on.

Among all that gloom for branded pharma, there's a bit of light. Add-on drugs for depression, including longer-acting Seroquel and Bristol-Myers Squibb's ($BMY) Abilify, also an atypical antipsychotic, are still growing. As Decision Resources reports, These drugs are "modestly" increasing their share of patients, and what stability there is in the antidepressant area depends partly on these meds.

And then there's the prospect of new products. If pharma companies could succeed at bringing new antidepressants to market--drugs that are truly different from existing therapies, Decision Resources points out--big sales would follow. Patients often don't respond to the first drug or two they try, and current antidepressants take time to kick in. But finding new treatments is a big task. AstraZeneca and Targacept had big hopes for their late-stage depression-fighter, for instance, but recently pulled the plug on that project. Some drugmakers have grown so frustrated with the effort that they've abandoned the research completely.

- see the PharmaTimes story