(Reuters) – Shares in drugmakers AstraZeneca (AZN.L) and Shire (SHP.L) fell sharply on Tuesday after the U.S. Treasury took steps to curb “inversion” deals that allow companies to escape high U.S. taxes by reincorporating abroad. The move could jeopardize an agreed deal for AbbVie (ABBV.N) to buy Shire for $55 billion and deter Pfizer (PFE.N) […]