Title: Efficacy and safety of ridinilazole compared with vancomycin for the treatment of Clostridium difficile infection: a phase 2, randomised, double-blind, active-controlled, non-inferiority study

Neoptolemos, J.P. et al.


What You Need to Know:

Results of a phase 2 study found ridinilazole, an antimicrobial agent that acts specifically in the gastrointestinal tract, to be non-inferior to vancomycin in the treatment of Clostridium difficile infections.

Trial Design:

  • Double-blind, active-controlled, non-inferiority phase 2 study compared the safety and efficacy of ridinilazole to vancomycin in patients with “signs and symptoms of C. difficile infection and a positive diagnostic test result”
  • 100 patients were randomly assigned to receive 10 days of treatment with 200mg ridinilazole administered orally every 12 hours (n=50) or 125mg vancomycin administered orally every 6 hours (n=50)
  • Primary endpoint: “achievement of a sustained clinical response, defined as clinical cure at the end of treatment and no recurrence within 30 days, which was used to establish non-inferiority (15% margin) of ridinilazole versus vancomycin”
  • Efficacy analysis was conducted in a modified intention-to-treat population, which included all patients with a confirmed C difficile infection who received at least 1 dose of study drug)

Key Outcomes:

  • Primary efficacy analysis: included 36 patients in the ridinilazole group and 33 patients in the vancomycin group
  • 66.7% of ridinilazole patients (24/36) had a sustained clinical response vs 42.4% of vancomycin patients (14/33) (treatment difference: 21.1%; 90% CI: 3.1, 39.1; P=0.0004), which established “the non-inferiority of ridinilazole” and showed “statistical superiority at the 10% level”
  • 82% of ridinilazole patients (41/50) reported adverse events vs 80% of vancomycin patients (40/50)
  • No adverse events experienced by patients receiving ridinilazole led to treatment discontinuation