From the Guidelines
Fidaxomicin is a preferred treatment option for Clostridioides difficile infection (CDI), particularly for patients at high risk of recurrence or those with multiple recurrences, due to its ability to preserve beneficial gut bacteria and reduce recurrence rates compared to vancomycin. Fidaxomicin belongs to the macrocyclic antibiotic class, specifically classified as a narrow-spectrum macrolide antibiotic, and works by inhibiting bacterial RNA polymerase, preventing bacterial RNA synthesis and ultimately leading to cell death 1. Unlike other antibiotics, fidaxomicin has minimal systemic absorption when taken orally, allowing it to remain concentrated in the gastrointestinal tract where it exerts its therapeutic effect. This localized action makes it particularly effective against CDI while sparing much of the normal gut microbiota.
Key Points
- Fidaxomicin is primarily used to treat C. difficile-associated diarrhea and has shown lower recurrence rates compared to vancomycin, likely due to its ability to preserve beneficial gut bacteria 1.
- The standard dosing for fidaxomicin is 200 mg taken orally twice daily for 10 days 1.
- Fidaxomicin has less impact on VRE acquisition than vancomycin, with patients who received fidaxomicin having a lower rate of VRE acquisition than patients who received vancomycin 1.
- Fidaxomicin demonstrated its treatment efficacy on CDI in two well-designed, large-scale RCTs and is recommended by the IDSA guidelines as one of the first-line treatment regimens 1.
Treatment Recommendations
- For initial CDI episode, fidaxomicin 200 mg given twice daily for 10 days is a preferred treatment option 1.
- For first CDI recurrence, fidaxomicin 200 mg given twice daily for 10 days, or twice daily for 5 days followed by once every other day for 20 days, is a preferred treatment option 1.
- For second or subsequent CDI recurrence, fidaxomicin 200 mg given twice daily for 10 days, or twice daily for 5 days followed by once every other day for 20 days, is a recommended treatment option 1.
From the FDA Drug Label
DIFICID (fidaxomicin) is a macrolide antibacterial drug for oral administration The class of Fidaxomicin is a macrolide antibacterial drug 2.
From the Research
Fidaxomicin Classification
- Fidaxomicin is a macrocyclic antibiotic 3, 4, 5, 6, 7
- It has a narrow spectrum of activity against gram-positive anaerobes, including Clostridium difficile 3, 4, 7
- Fidaxomicin is bactericidal against C. difficile and has minimal activity against Bacteroides species 3
- It lacks activity against gram-negative bacteria, which may help preserve normal gastrointestinal flora 3, 4
Mechanism of Action
- Fidaxomicin inhibits RNA polymerase at a site distinct from where rifamycins interact 5
- Its mechanism of action is related to the inhibition of RNA polymerase, which is essential for bacterial growth and survival 5
Clinical Use
- Fidaxomicin is approved for the treatment of Clostridium difficile infection (CDI) in adults 5, 6
- It is recommended for patients with mild-to-moderately severe CDI, particularly those who have not responded to treatment with metronidazole or vancomycin 3
- Fidaxomicin has been shown to be noninferior to vancomycin in the management of mild-to-moderately severe CDI 3, 5