JOHANNESBURG, CAMBRIDGESHIRE – MAY 15: Viagra drugs made by Pfizer and Nexiam (Generic name – Esomeprazole) made by the pharmaceutical firm AstraZeneca are displayed in a Pharmacy on May 15, 2014 in Johannesburg, South Africa. The proposed takeover by American pharmaceutical giant Pfizer of its British rival AstraZeneca has led to the UK Business Secretary Vince Cable addressing Parliament to affirm the government’s commitment to securing British science jobs. (Photo by Christopher Furlong/Getty Images)