In its biggest deal to date, Valeant Pharmaceuticals International has agreed to buy gastrointestinal specialist Salix Pharmaceuticals for an enterprise value of approximately US$14.5 B. The key driver of the acquisition is Salix’s potential blockbuster antibiotic Xifaxan®(rifaximin), with Valeant betting that the drug will win US regulatory approval in May 2015 for the additional indication of irritable bowel syndrome with diarrhoea. The deal comes only months after Valeant’s failed bid to acquire Allergan, which itself had been interested in buying Salix but was put off after identifying inventory irregularities.