AstraZeneca's profit after tax dropped to $2.556 billion last year compared with $6.240 billion in 2012, it said in a statement.
"As expected, our financial performance for 2013 reflects the ongoing impact from the loss of exclusivity for several key brands," said chief executive Pascal Soriot
"In the near term these headwinds will remain challenging," he added.
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AstraZeneca announced also a net loss of $524 million in the fourth quarter compared with a profit of $1.507 billion in the final three months of 2012.