Pre-tax profits declined by 5.5 percent to $2.143 billion in the three months ending March 31st, compared with the equivalent period of 2007.
That dashed market expectations of $2.23 billion.
Sales jumped by 10.2 percent to $7.677 billion, but the group’s major products enjoyed mixed fortunes.
Sales of the group’s leading drug, heartburn treatment Nexium, fell by nine percent to $1.238 billion, compared with 1.308 billion previously.
Nexium is a key focus for analysts as sales have been slowing in the United States and the market has been impacted by fierce competition from generic drugmakers.
Seroquel, AstraZeneca’s schizophrenia drug, fared better, with sales rising by 10 percent to $1.050 billion.
Cholesterol treatment Crestor saw its sales jump by 16 percent to $772 million.
Faced with soaring costs and competition from generic groups, AstraZeneca unveiled plans in 2006 to slash 7,600 jobs by 2010.
The group revealed on Thursday that it booked $117 million in restructuring costs during the first quarter of 2008.