DIFICID (fidaxomicin)
DIFICID is indicated for the treatment of Clostridioides difficile-Associated Diarrhea.
How DIFICID Works
Fidaxomicin is a bactericidal macrocyclic antibiotic that inhibits bacterial protein synthesis by targeting RNA polymerase. Specifically, it binds to the sigma subunit of RNA polymerase, thereby inhibiting the initiation of transcription. This mechanism is distinct from that of traditional macrolides. Due to minimal systemic absorption, the drug maintains high fecal concentrations, providing targeted action against *C. difficile* within the gastrointestinal tract.
Development Insights
Details
- Status
- Prescription
- First Approved
- 2011-05-27
- Patent Cliff
- 2034
- Routes
- ORAL
- Dosage Forms
- FOR SUSPENSION, TABLET
DIFICID Approval History
What DIFICID Treats
1 indicationsDIFICID is approved for 1 conditions since its original approval in 2011. These indications span multiple therapeutic areas including oncology, immunology, and more.
- Clostridioides difficile-Associated Diarrhea
DIFICID Competitive Set
ProThree rings of competition based on shared molecular targets and treated indications.
Indication competitors
Same indication, different mechanism — what else might this patient receive?
Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.
Drugs Similar to DIFICID
FDA-approved drugs for similar conditions. Compare mechanisms and indications to understand treatment alternatives.
Clinical Trial Registry
19 trials| Trial | Sponsor ID | Phase | Status | Title |
|---|---|---|---|---|
| NCT07328971 TAPER-V2 | 2026-12121 | Ph 3 | recruiting | Vancomycin Taper to Prevent Recurrent Clostridioides Difficile |
| NCT02667418 OpTION results posted | 596 #15-03, 1613088 | Ph 4 | terminated | Optimal Treatment for Recurrent Clostridium Difficile |
| NCT06794944 | 2025P000187 | Ph 4 | not yet recruiting | Use of Fidaxomicin Compared to Vancomycin for Decolonization of C. Difficile in Patients With Inflammatory Bowel Disease |
| NCT05201079 results posted | ICD-01 2020-004591-17 | Ph 3 | completed | Primary or Recurrent Clostridioides Difficile Infection Treatment With Capsules of Lyophilised Faecal Microbiota vs Fidaxomicin |
| NCT02437591 PROFILE | 2819-MA-1003 2014-003002-32 | Ph 4 | completed | Study to Evaluate the Pharmacokinetics of Fidaxomicin in Inflammatory Bowel Disease (IBD) Subjects With Clostridium Difficile Infection (CDI) |
| NCT02254967 EXTEND | 2819-MA-1002 2013-004619-31 | Ph 4 | completed | A Phase IIIB/IV Study to Compare the Efficacy of Vancomycin Therapy to Extended Duration of Fidaxomicin Therapy in the Clinical Cure of Clostridium Difficile Infection (CDI) in an Older Population |
| NCT02395848 results posted | CDI.FIDAXOMICIN.1 | Ph 3 | terminated | Efficacy of 30-day Duration of Fidaxomicin for Recurrent C. Difficile Infection |
| NCT02692651 results posted | Merck Fidaxo | Ph 4 | completed | A Comparison of Fidaxomicin and Vancomycin in Patients With CDI Receiving Antibiotics for Concurrent Infections |
| NCT01775397 FREEDOM | FID-EC-0001 2012-000531-88 | Ph 4 | terminated | A Post-marketing, Blinded Study to Investigate How Effective Fidaxomicin is Compared to Vancomycin in the Sustained Cure of Clostridium Difficile Infection in Adults That Are Receiving Therapy to Suppress the Immune System |
| NCT02743234 FACIT | FACIT | Ph 3 | completed | Fecal Microbiota Transplantation for Relapsing Clostridium Difficile Infection |
| NCT02057198 C-Diff results posted | Pro00043361 | Ph 4 | completed | Impact of Oral Antibiotic Treatment on C. Difficile |
| NCT01591863 results posted | 5119-010 OPT-80-206 | Ph 2 | completed | Safety, Tolerability, and Pharmacokinetics of Fidaxomicin in Pediatric Subjects With Clostridium Difficile-associated Diarrhea (CDAD) |
| NCT01691248 DEFLECT-1 results posted | 5119-001 OPT-80-302 | Ph 3 | completed | Safety and Efficacy of Fidaxomicin Versus Placebo for Prophylaxis Against Clostridium Difficile-Associated Diarrhea in Adults Undergoing Hematopoietic Stem Cell Transplantation (MK-5119-001) |
| NCT02464306 | 14-2257 | Ph 4 | withdrawn | Fidaxomicin Versus Standard of Care Therapy in Solid Organ Transplant Recipients With Clostridium Difficile Infection |
| NCT02784002 | SMT19969/C003 | Ph 2 | completed | A Study of Ridinilazole (SMT19969) Compared With Fidaxomicin for the Treatment of Clostridium Difficile Infection (CDI) |
| NCT01818141 results posted | NICO003785HE | Ph 4 | completed | Study to Assess Inhibition of Spore Production in Patients With C. Difficile Infections: Fidaxomicin Versus Vancomycin |
| NCT01552668 | 201109037 1U54CK000162 | Ph 4 | withdrawn | Fidaxomicin to Prevent Clostridium Difficile Colonization |
| NCT02083627 | 2819-CL-2003 2012-003924-20 | Ph 1 | completed | A Study to Assess the Effects of Multiple Doses of Fidaxomicin on a Single Dose of Rosuvastatin in Healthy Male Subjects |
| NCT01813448 | 2819-CL-3001 | Ph 1 | completed | A Study to Assess the Safety, Tolerability and Pharmacokinetics of Single and Multiple Ascending Doses of Fidaxomicin in Healthy Male Japanese and Caucasian Subjects |
Active Pipeline
Ongoing clinical trials by development phase
Key Completed Trials
Completed studies with published results, ranked by significance
Trial Timeline
Full development history with FDA approval milestones
Understanding FDA Approval Types
| Count | Type | What it means |
|---|---|---|
| - | ORIG | Original approval - drug first enters market |
| - | SUPPL - Efficacy | New indication (new disease/condition approved) |
| - | SUPPL - Labeling | Label text changes (warnings, dosing updates) |
| - | SUPPL - Manufacturing | Production changes (new facility) |
| - | SUPPL - Chemistry | Formulation changes (new dosage strength) |
Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.
DIFICID FDA Label Details
Indications & Usage
FDA Label (PDF)DIFICID is indicated for the treatment of Clostridioides difficile-Associated Diarrhea.
DIFICID Patents & Exclusivity
Patents (10 active)
Exclusivity
Pro Intelligence Preview
Deep insights for DIFICID
Revenue Insights
- • Quarterly revenue tracking
- • Historical trend analysis
Patent Timeline
- • Cliff: 2034
- • 20 active patents
Trial Analysis
- • 19 total trials
- • Stage: Mature
Competitive Landscape
- • 1 similar drugs
- • Same target/indication analysis
Full approval history • All patents • Revenue trends • Competitor analysis
Data Sources
Data sourced from official FDA and NIH databases. Click links to verify on original sources.
How We Calculate These Metrics
Trial Activity Stage
Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.
Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.
- Growth: High proportion of early-phase trials (Phase 1/2), active development
- Expansion: Significant Phase 3 activity, approaching or pursuing approvals
- Mature: Substantial Phase 4 post-marketing studies
- Stable: Mixed phase distribution, steady development
- Declining: Low active trial ratio, reduced R&D investment