People with direct knowledge of the situation said Pfizer has been reviewing different takeover scenarios with a U.S. investment bank ahead of Nov. 26, when it is allowed to renew its pursuit of AstraZeneca under UK takeover rules. This includes a close analysis of the benefits of a tax-saving deal to buy Dublin-based generic drugmaker Actavis at more than a 20-30 percent probability," said Norbert Janisch, portfolio manager at Raiffeisen Capital Management in Vienna, which is a shareholder in AstraZeneca.