(Undated)  --  U.S. drugmaker Pfizer is angling to pull off one of the biggest pharmaceutical deals ever.  The American pharma giant is trying to buy British drugmaker AstraZeneca.  Pfizer made a bid for AstraZeneca earlier this year but the British firm turned down the cash and shares deal.  Pfizer contacted AstraZeneca again over the weekend but said the British company's officials don't want to talk about a merger.  Pfizer says it's now "considering its options."