Earnings after taxation dived to $6.3 billion in 2012, compared with $10 billion in the previous year, AstraZeneca said in a results statement.
Revenues meanwhile tumbled 15 percent to $28 billion and were also expected to experience a "mid-to-high single digit percentage decline" in 2013.
"Our performance in 2012 reflects a period of significant patent expiry and tough market conditions globally," said CEO Pascal Soriot, who took over late last year.
"Despite the challenges we face, I am excited about AstraZeneca's fundamental strengths, which will be key in returning the company to growth.”
The London-listed company faces crucial patent expiries up until 2015 on drugs such as schizophrenia treatment Seroquel and heartburn and ulcer drug Nexium.
It will also suffer the loss of patent protection in the United States for its key anti-cholesterol drug Crestor in 2016.
Soriot was previously a senior executive at Swiss drugsmaker Roche and took up his role at the start of October after the resignation of David Brennan.
Brennan had already announced plans to cut 7,300 jobs by 2014 in a bid to improve profitability at the firm, which has come under heavy pressure in recent years from generic drugs competition.