AstraZeneca antidepressant is dumped after trial failures

AstraZeneca's already thin drugs pipeline was battered again yesterday when the pharmaceuticals firm admitted that an experimental antidepressant, once hailed as a potential worldwide multibillion dollar-a-year blockbuster, had failed its latest clinical trials and would be dumped.

It is another blow for Britain's second-biggest pharmaceuticals company, which last year called off late-stage trials of a prostate cancer drug, before writing off $445m (£281m) as it abandoned a new respiratory medicine for children.

Meanwhile Astra is facing a "patent cliff" as current blockbusters begin to face generic competition.

The drug maker will take a $50m impairment charge for the failure of TC-5214, which it licensed from the biotech Targacept three years ago for up to $1.2bn, dependent on hitting targets.

Astra had hoped that the drug would be the first in a new class of mental health medicines that work by calming nicotine receptors in the brain and it paid $200m up front for the rights.

Strong results from a Phase II study gave it pole position in AstraZeneca's prospective drugs portfolio, but TC-5214 failed the first of two late-stage trials last year, prompting an initial $96.5m writedown.

Now Astra has entirely abandoned its application to get the drug licensed for use as anadd-on therapy for patientswith depression.

AstraZeneca has just one drug in development, fostamatinib for arthritis, that analysts believe could be a big hit.

This month, the patent will expire on Seroquel, the anti-psychotic drug which brought in revenues of $5.7bn last year. Its ulcer treatment Nexium, which contributed $4.4bn to 2011 sales, faces competition in America in 2014 and its $6.6bn-a-year cholesterol-buster Crestor goes off patent in 2016.