"The initial market reaction probably reflects difficulty in understanding where consensus was and how these numbers fit in, rather than anything being too disappointing," said Tim Race, a pharmaceuticals analyst with ING.
"The underlying picture looks okay. Nexium sales are flattening, but we expected that," he added.
Few analysts had calculated earnings on the revised basis presented by AstraZeneca.
The London-based group has embarked on an aggressive programme of acquisitions to rebuild its pipeline, following a series of late-stage product setbacks, while at the same time restructuring manufacturing to save costs.
Brennan said he continued to look for opportunities but declined to comment on specific acquisitions, such as AstraZeneca's rumoured interest in Acadia Pharmaceuticals Inc.'s experimental schizophrenia drug, pimavanserin.
AstraZeneca's stock has been under pressure due to its weak pipeline and the poorly received deal with MedImmune in April.
But the shares have gained ground in the past month and now trade at 12.8 times forecast 2008 earnings, a 12% discount to the European sector average.
Investors have also been unsettled by the imminent departure of respected Chief Financial Officer Jon Symonds, who leaves at the end of this month to join Goldman Sachs. Brennan said a search for his replacement was underway, and the company's financial controller, Paul Kenyon, would act as interim finance head.