Fidaxomicin is a narrow-spectrum macrolide antibacterial active pharmaceutical ingredient (API) used in pharmaceutical formulations for the treatment of Clostridioides difficile-associated diarrhea. It is an 18-membered macrocyclic lactone antibiotic with antibacterial activity against C. difficile. Current U.S. labeling identifies fidaxomicin as a macrolide antibacterial indicated for C. difficile-associated diarrhea.
Fidaxomicin has the molecular formula C₅₂H₇₄Cl₂O₁₈, molecular weight 1058.04 g/mol, and CAS Number 873857-62-6.
Fidaxomicin acts primarily within the gastrointestinal tract and inhibits bacterial RNA synthesis. Its narrow antibacterial spectrum makes it an important pharmaceutical ingredient for targeted treatment of C. difficile infection.
Fidaxomicin is a fermentation-derived macrolide antibacterial produced from the actinomycete Dactylosporangium aurantiacum. It is used as an active pharmaceutical ingredient in oral formulations designed to act locally in the gastrointestinal tract.
Fidaxomicin is characterized by a complex macrocyclic structure and multiple stereocenters, making appropriate analytical characterization important for pharmaceutical-quality material.
Fidaxomicin inhibits bacterial RNA synthesis by binding to bacterial RNA polymerase. It demonstrates bactericidal activity against Clostridioides difficile in vitro.
Fidaxomicin acts locally in the gastrointestinal tract against C. difficile, with limited systemic exposure after oral administration.
Fidaxomicin is used in pharmaceutical formulations for:
Current U.S. labeling indicates fidaxomicin for treatment of C. difficile-associated diarrhea and recommends use when infection is proven or strongly suspected to be caused by C. difficile.
| Parameter | Specification |
|---|---|
| Appearance | White to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Heavy Metals | NMT 20 ppm |
| pH (1% Solution) | 2.0 – 4.0 |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 1.0% |