GlaxoSmithKline will have to pay Pfizer a $900m break-fee if the UK drugmaker’s proposed multibillion-dollar joint venture with its US rival to create the world’s biggest provider of consumer medicines falls apart.

The new venture, which will be called GSK Consumer Healthcare, brings together household names including Anadin, Sensodyne and Nicorette under one roof with combined annual sales of £9.8bn.