Mikael Dolsten, the U.S. pharma giant's head of research and development, said the deal would offer "much more value for patients and health care providers" in a video posted on the company's website Monday morning.
His remarks are an attempt to address concerns that Pfizer's main motivation for buying AstraZeneca is tax avoidance.
Meanwhile, their prey bolstered the case for remaining independent by announcing positive results for a new treatment for skin condition psoriasis. The U.K. based pharma company is also expected to announce clinical trial results for some of its most promising new medicines later in the week, ahead of key medical conferences later this month.
Ian Read, chief executive of the U.S. pharma giant, and Pascal Soriot, his opposite number at AstraZeneca, will both appear in front of U.K. members of parliament on Tuesday morning. Read will have to address mounting opposition to the deal from U.K. politicians.
Pfizer has two weeks from Monday to come back with a third bid for the smaller U.K. company, which would be big enough to bring management to the table and win over shareholders.
Prime Minister David Cameron told the BBC on Sunday the government had made "good progress" on securing commitments from Pfizer to keeping jobs in the U.K. - but added the government still wants "more."
One point Pfizer executives are likely to be pushed on is whether they could make a 10 year, rather than a 5 year, commitment to U.K. science jobs. A longer commitment before they do due diligence on AstraZeneca is unlikely, according to a source close to the company.
Read said the deal would be a "win-win" for shareholders and patients in a video posted on the Pfizer website Saturday morning.
The U.K. politicians he will appear in front of Tuesday will put him through his paces on what a completed deal might mean for the U.K. economy and science base. A meeting with Ed Miliband, the U.K. Labour Party leader who has led criticism of Pfizer's record, could be back on the cards. Miliband earlier turned down a meeting because of the European election campaign.