Fidaxomicin

Fidaxomicin is an antibacterial drug [see Microbiology ( 12.4 )].

• Fidaxomicin tablets are a macrolide antibacterial indicated in adult patients for the treatment of C. difficile -associated diarrhea.

• Fidaxomicin tablets are contraindicated in patients who have known hypersensitivity to fidaxomicin or any other ingredient in fidaxomicin tablets [see Warnings and Precautions ( 5.1 )]. Fidaxomicin tablets are contraindicated in patients who have known hypersensitivity to fidaxomicin or any other ingredient in fidaxomicin tablets.contraindicated

Fidaxomicin tablets are administered orally with or without food. ( 2.1 ) Adults One 200 mg tablet orally twice daily for 10 days. ( 2.2 ) 2.1 Important Administration Instructions Fidaxomicin tablets are available for oral administration as 200 mg tablets. Fidaxomicin tablets are administered orally with or without food. 2.2 Adult Patients The recommended dosage for adults is one 200 mg fidaxomicin tablet orally twice daily for 10 days. Pediatric use information is approved for Cubist Pharmaceuticals LLC's DIFICID ® (fidaxomicin) tablets. However, due to Cubist Pharmaceuticals LLC's marketing exclusivity rights, this drug product is not labeled with that information.

Acute hypersensitivity reactions (angioedema, dyspnea, pruritus, and rash) have been reported. If a severe hypersensitivity reaction occurs, discontinue fidaxomicin tablets. ( 5.1 ) Fidaxomicin tablets is not expected to be effective for the treatment of other types of infections due to minimal systemic absorption of fidaxomicin. Fidaxomicin tablets should only be used for the treatment of C. difficile -associated diarrhea. ( 5.2 ) Development of drug-resistant bacteria: Only use fidaxomicin tablets for infection proven or strongly suspected to be caused by C. difficile. ( 5.3 ) 5.1 Hypersensitivity Reactions Acute hypersensitivity reactions, including dyspnea, rash, pruritus, and angioedema of the mouth, throat, and face have been reported with fidaxomicin tablets. If a severe hypersensitivity reaction occurs, fidaxomicin tablets should be discontinued and appropriate therapy should be instituted. Some patients with hypersensitivity reactions to fidaxomicin tablets also reported a history of allergy to other macrolides. Physicians prescribing fidaxomicin tablets to patients with a known macrolide allergy should be aware of the possibility of hypersensitivity reactions. 5.2 Not for Use in Infections Other than C. difficile -Associated Diarrhea Fidaxomicin tablets are not expected to be effective for the treatment of other types of infections due to minimal systemic absorption of fidaxomicin [see Clinical Pharmacology ( 12.3 )]. Fidaxomicin tablets have not been studied for the treatment of infections other than CDAD.

The most common adverse reactions in adults (incidence ≥2%) are nausea, vomiting, abdominal pain, gastrointestinal hemorrhage, anemia, and neutropenia. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Apotex Corp., at 1-800-706-5575 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adults The safety of fidaxomicin 200 mg tablets taken twice a day for 10 days was evaluated in 564 adult patients with CDAD in two active-controlled trials with 86.7% of patients receiving a full course of treatment. Thirty-three adult patients receiving fidaxomicin tablets (5.9%) withdrew from trials as a result of adverse reactions (AR). The types of AR resulting in withdrawal from the study varied considerably. Vomiting was the primary adverse reaction leading to discontinuation of dosing; this occurred at an incidence of 0.5% in both the fidaxomicin tablets and vancomycin patients in Phase 3 trials. The most common selected adverse reactions occurring in ≥2% of adult patients treated with fidaxomicin tablets are listed in Table 2.

Pediatrics: The safety and effectiveness of fidaxomicin tablets have not been established in pediatric patients younger than 6 months of age. ( 8.4 ) Pediatric use information is approved for Cubist Pharmaceuticals LLC's DIFICID ® (fidaxomicin) tablets. However, due to Cubist Pharmaceuticals LLC's marketing exclusivity rights, this drug product is not labeled with that information. 8.1 Pregnancy Risk Summary The limited available data on use of fidaxomicin tablets in pregnant women are insufficient to inform any drug-associated risk for major birth defects, miscarriage or adverse maternal or fetal outcomes. Embryo-fetal reproduction studies in rats and rabbits dosed intravenously during organogenesis revealed no evidence of harm to the fetus at fidaxomicin and OP-1118 (its main metabolite) exposures 65-fold or higher than the clinical exposure at the fidaxomicin tablets recommended dose [see Data]. The estimated background risk of major birth defects and miscarriage for the indicated populations is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

Metabolism

The pharmacokinetic parameters of fidaxomicin and its main metabolite OP-1118 following a single dose of 200 mg in healthy adult males (N=14) are summarized in Table 4. Table 4: Mean (± Standard Deviation) Pharmacokinetic Parameters of Fidaxomicin 200 mg in Healthy Adult Males Parameter Fidaxomicin OP- 1118 N Value N Value C max (ng/mL) 14 5.20 ± 2.81 14 12.0 ± 6.06 T max (h)* 14 2.00 (1.00-5.00) 14 1.02 (1.00-5.00) AUC 0-t (ng-h/mL) 14 48.3 ± 18.4 14 103 ± 39.4 AUC 0-∞ (ng-h/mL) 9 62.9 ± 19.5 10 118 ± 43.3 t 1/2 (h) 9 11.7 ± 4.80 10 11.2 ± 3.01 * T max , reported as median (range).

No cases of acute overdose have been reported in humans. No drug-related adverse effects were seen in dogs dosed with fidaxomicin tablets at 9,600 mg/day (over 100 times the human dose, scaled by weight) for 3 months.

• May 27, 2011NDANDA201699Cubist Pharms Llc
• Jan 24, 2020NDANDA213138Cubist Pharms Llc
• Jan 16, 2024ANDAANDA208443Actavis Labs Fl
• Jan 27, 2026ANDAANDA220374Torrent
• Feb 2, 2026ANDAANDA219559Apotex

1. 1Clostridium Difficile Infection47220%
2. 2Drug Ineffective40918%
3. 3Diarrhoea34315%
4. 4Disease Recurrence1787.6%
5. 5Clostridium Difficile Colitis1586.8%
6. 6Off Label Use1325.7%
7. 7Nausea1215.2%
8. 8Treatment Failure1195.1%
9. 9Abdominal Pain863.7%
10. 10No Adverse Event863.7%
11. 11Pyrexia763.3%
12. 12Death703.0%
13. 13Vomiting703.0%
14. 14Fatigue582.5%
15. 15Acute Kidney Injury522.2%

Recent PubMed references pinned to Fidaxomicin as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Comparative effectiveness of vancomycin and fidaxomicin in the treatment of Clostridioides difficile-associated diarrhea: A single-center experience in Taiwan.
  Medicine · 2026 · Tseng WC, Chen KC, Chung CS, et al.
  PMID 41995553DOI 10.1097/MD.0000000000048307
• Dichalcogenide Fidaxomicin Derivatives to Probe Thiol-Mediated Uptake into Bacteria.
  ACS infectious diseases · 2026 · Kraimps A, Griesser T, Wang R, et al.
  PMID 41510831DOI 10.1021/acsinfecdis.5c00833
• Effect of sub-minimum inhibitory concentrations of metronidazole, vancomycin, and fidaxomicin on growth rate and virulence of Clostridioides difficile.
  Diagnostic microbiology and infectious disease · 2026 · Azimirad M, Noori M, Looha MA, et al.
  PMID 41237659DOI 10.1016/j.diagmicrobio.2025.117184
• Consumption and expenditure on fidaxomicin and oral vancomycin for Clostridioides difficile infection: A 12-year longitudinal study of 43 countries and regions.
  International journal of antimicrobial agents · 2026 · Zhang Y, Li X, Wong AYS, et al.
  PMID 41202902DOI 10.1016/j.ijantimicag.2025.107664
• In vivo efficacy of fidaxomicin against rpoB mutant Clostridioides difficile infection.
  Anaerobe · 2025 · Hoai MT, Hitomi Y, Fujii T, et al.
  PMID 40912395DOI 10.1016/j.anaerobe.2025.102992
• Fidaxomicin Treatment of Clostridioides difficile Infections and Recurrences in Children and Adolescents: A Retrospective Multicenter Study.
  The Journal of pediatrics · 2025 · Conrad MA, Kaplan AL, Weinbrom S, et al.
  PMID 40482880DOI 10.1016/j.jpeds.2025.114681
• Extended-pulsed fidaxomicin therapy for recurrent Clostridioides difficile infection after standard vancomycin and fidaxomicin failure: A case report.
  Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy · 2025 · Hirai J
  PMID 40250802DOI 10.1016/j.jiac.2025.102709
• Fidaxomicin for Clostridioides difficile infection in patients with inflammatory bowel disease: a multicenter retrospective cohort study.
  Journal of Crohn's & colitis · 2025 · Noviello D, Chaparro M, Viganò C, et al.
  PMID 40168072DOI 10.1093/ecco-jcc/jjaf056

The 10 most recently updated of 39 ClinicalTrials.gov registrations naming Fidaxomicin as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Fecal Microbiota Transplantation in Clostridioides Difficile Infection First Episode and First Recurrence
  Recruiting · Phase 3 · Interventional · 100 enrolled · Benoit Guery
  NCT05266807updated 2026-06-02
• Vancomycin Taper to Prevent Recurrent Clostridioides Difficile
  Recruiting · Phase 3 · Interventional · 500 enrolled · McGill University Health Centre/Research Institute of the McGill University Health Centre
  NCT07328971updated 2026-04-30
• Prevention of Recurrence of Clostridioides Difficile Colitis With Ursodeoxycholic Acid (UCDA) as a Supplement to Standard Therapy
  Not yet recruiting · Early phase 1 · Interventional · 30 enrolled · Medical College of Wisconsin
  NCT06884748updated 2026-04-29
• Optimal Treatment for Recurrent Clostridium Difficile
  Terminated · Phase 4 · Interventional · 308 enrolled · VA Office of Research and Development
  NCT02667418updated 2025-12-15
• Use of Fidaxomicin Compared to Vancomycin for Decolonization of C. Difficile in Patients With Inflammatory Bowel Disease
  Not yet recruiting · Phase 4 · Interventional · 60 enrolled · Brigham and Women's Hospital
  NCT06794944updated 2025-11-03
• STOP-CDI: Efficacy of Fecal Microbiota Transplantation vs Fidaxomicin vs Vancomycin in Treating and Preventing Relapse of Clostridioides Difficile Infection
  Not yet recruiting · Interventional · 424 enrolled · Medical University of Warsaw
  NCT07120490updated 2025-08-13
• Primary or Recurrent Clostridioides Difficile Infection Treatment With Capsules of Lyophilised Faecal Microbiota vs Fidaxomicin
  Completed · Phase 3 · Interventional · 93 enrolled · Mikrobiomik Healthcare Company S.L.
  NCT05201079updated 2025-03-25
• A Study to Investigate the Safety and Efficacy of Fidaxomicin (Oral Suspension or Tablets) and Vancomycin (Oral Liquid or Capsules) in Pediatric Subjects With Clostridium Difficile-associated Diarrhea (CDAD)
  Completed · Phase 3 · Interventional · 148 enrolled · Astellas Pharma Europe B.V.
  NCT02218372updated 2024-11-26
• 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
  Completed · Phase 4 · Interventional · 364 enrolled · Astellas Pharma Europe Ltd.
  NCT02254967updated 2024-10-31
• A Study to Compare Safety and Efficacy of OPT-80(Fidaxomicin) With Vancomycin in Subjects With Clostridium Difficile-associated Diarrhea (CDAD)
  Completed · Phase 3 · Interventional · 210 enrolled · Astellas Pharma Inc
  NCT02179658updated 2024-10-31

Frequently asked questions

How does Fidaxomicin work?

Fidaxomicin is an antibacterial drug [see Microbiology ( 12.4 )].

What is Fidaxomicin used for?

According to FDA labeling, Fidaxomicin carries indications including: Fidaxomicin tablets are a macrolide antibacterial indicated in adult patients for the treatment of C. difficile -associated diarrhea.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fidaxomicin?

Fidaxomicin is classified as Antibiotics, Macrolide Antibacterial, Nucleic Acid Synthesis Inhibitors, Decreased RNA Replication.

What are the brand names for Fidaxomicin?

Fidaxomicin is marketed under brand names including Dificid.

What are the contraindications for Fidaxomicin?

Fidaxomicin labeling lists contraindications including: Fidaxomicin tablets are contraindicated in patients who have known hypersensitivity to fidaxomicin or any other ingredient in fidaxomicin tablets [see Warnings and Precautions ( 5.1 )]. Fidaxomicin tablets are contraindicated in patients who have known hypersensitivity to fidaxomicin or any other ingredient in fidaxomicin tablets.. Always consult the full prescribing information and a clinician.