AstraZeneca's sales slumped 19% in the third quarter, underscoring the scale of the challenge confronting the drugmaker's new chief executive, Pascal Soriot.

Faced with patent expiries on once best-selling medicines and a thin pipeline of new drugs, the former Roche executive, who joined on Oct. 1, needs to re-focus operations and step up the hunt for acquisitions, analysts believe.

Sales in the quarter were $6.68 billion, generating "core" earnings, which exclude certain items, down 12% at $1.51 a share, AstraZeneca said on Thursday.

Industry analysts, on average, had forecast sales in the quarter of $6.75 billion and earnings of $1.44 a share, according to Thomson Reuters I/B/E/S.

AstraZeneca reiterated its forecast for a fall in full-year core earnings to between $6.00 and $6.30 a share, against $7.28 in 2011.