 This is in contrast to Merck's Dificid (fidaxomicin) which was priced at $2,800 per course of therapy.Dificid did not sell well because it cost nearly four times as much as the generic vancomycin alternatives.According to H.C. Wainwright, ridinilazole is currently undervalued since ridinilazole allows the patients gut microflora to be preserved which helps prevents deadly recurrent infections and allows for the use of ridinilazole as a first line therapy, in contrast with antibiotics already on the market.