> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Guide on C-diff Infection Drug Development
- URL: https://www.fdaweb.com/guide-on-c-diff-infection-drug-development/
- Published: 2022-10-27T12:00:00.000Z
- Updated: 2026-09-14T18:04:29.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5153076

FDA has made available a draft guidance entitled “Clostridioides difficile Infection (CDI): Developing Drugs for Treatment, Reduction of Recurrence, and Prevention.” The document says clinical trials for drugs to treat CDI should be randomized, double-blinded, and controlled. “Sponsors should use an active control in trials for CDI treatment and treatment and reduction of recurrence” indications, and sponsors can use a placebo or active control in trials for preventing or reducing recurrence only, the guidance says.

FDA also recommends that a noninferiority (NI) or superiority finding of the investigational drug to standard-of-care is acceptable for a drug for treating CDI. “FDA prefers a showing of superiority for drugs developed for treatment and reduction of recurrence, and reduction of recurrence only, unless the sponsor can justify an NI margin for these trials,” it says. “As there are currently no suitable active comparators for CDI prevention trials, superiority trials are most appropriate for drugs developed for prevention of CDI.”

Regarding efficacy assessments, the guidance says two adequate and well-controlled trials are needed to support the investigational drug’s effectiveness. “One trial demonstrating evidence of efficacy for treatment alone and another trial for reduction of recurrence or for prevention of CDI alone may support two indications,” it says. “If treatment and reduction of recurrence are evaluated in the same trial, two adequate and well-controlled trials would be needed.”