10/05/2014 03:52 BST | Updated 10/05/2014 03:59 BST

5 Reasons Why Pfizer's AstraZeneca Takeover Plans Should Worry You

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The Pfizer Inc. company logo, right, and the AstraZeneca Plc company logo, are seen on boxes of pharmaceutical products produced by the drug makers in this arranged photograph taken in London, U.K., on Friday, May 2, 2014. AstraZeneca Plc rejected Pfizer Inc.'s sweetened takeover proposal, saying the 63.1 billion-pound ($106.5 billion) offer fails to recognize the value of the promising experimental medicines under development by the U.K.'s second-biggest drugmaker. Photographer: Chris Ratcliffe

Pfizer's interest in taking over AstraZeneca has left politicians up in arms as they fret about what the US drugs giant could do once it has gobbled up its UK-based rival, in what would be the largest foreign takeover yet of a British company.

AstraZeneca has twice rebuffed offers from Pfizer so far, which has tried to offer in excess of £63 billion, arguing that it has been substantially undervalued. But the US drugs giant is still keen, even hinting at a hostile takeover bid.

Britain's politicians have clashed over the US drug giant, which brought Viagra to the world, and its takeover plans. Prime minister David Cameron and deputy Nick Clegg have demanded that Pfizer make "binding" pledges to keep investing in Britain and not to cut jobs and close factories, as critics warn that they have done before as part of previous takeovers.

Business secretary Vince Cable has indicated that he was open to scuppering the deal with a public interest test, while his shadow Chuka Umunna has warned that any promises by Pfizer are "not worth the paper they are written on".

Why the concern? HuffPostUK has rounded up five controversial Pfizer takeovers and decisions that show the risk of Pfizer gobbling up AstraZeneca.

5 reasons people are worried about Pfizer and AstraZeneca