DrugBank ID:

DB08874

Description:

Fidaxomicin is a novel macrolide antibiotic used in the treatment of diarrhea caused byClostridioides(formerlyClostridium)difficilein adult and pediatric patients over the age of 6 months.Fidaxomicin is a naturally-occurring 18-member macrocycle derived from fermentation.Because fidaxomicin contains an 18-membered lactone ring in its structure, it is referred to as a macrocyclic lactone antibiotic drug.The antibacterial activity of fidaxomicin is distinct from macrolides and rifamycins, as the bactericidal activity is time-dependent, and not concentration-dependent.Fidaxomicin was the first macrocyclic lactone antibiotic with activity againstC. difficile,and it displays a narrow spectrum of activity against gram-positive anaerobes.It mediates its potent bactericidal action on the bacteria by inhibiting the bacterial RNA synthase, thereby disrupting bacterial transcription.The minimum inhibitory concentration (MIC) for fidaxomicin is four times less than that ofvancomycin, which was the primary drug of choice forC. difficileinfection before the approval of fidaxomicin.Unlike vancomycin, however, fidaxomicin has a negligible effect on normal colonic microflora.The FDA initially approved fidaxomicin in May 2011 for the treatment ofC. difficile-associated diarrhea in adult patients over the age of 18.Later that year in December, the drug was also approved by the European Medicine Agency.In June 2012, fidaxomicin was also granted approval by Health Canada.The approved indication of fidaxomicin was expanded by the FDA in January 2020 to include pediatric patients over the age of 6 months in the treatment population. [DrugBank]

Targets:

RNA polymerase sigma factor (Clostridium difficile (strain 630)) [DrugBank]

Pharmacodynamics:

Fidaxomicin has a narrow-spectrum antibacterial profile, with potent bactericidal activity specifically against C. difficile.5 The minimum inhibitory concentration for 90% of organisms for fidaxomicin against C. difficile ranged from 0.0078 to 2 μg/mL in vitro.2 The bactericidal activity of fidaxomicin is time-dependent.6 Other than C. difficile, fidaxomicin has moderate inhibitory activity against Gram-positive bacteria (S. aureus and Enterococcus spp.) 5 and poor activity against normal colonic flora, including anaerobes and enteric Gram-negative bacilli.4 Isolates of C. difficile that are resistant to rifamycins or other antimicrobial classes (such as cephalosporins, fluoroquinolones, clindamycin) were not shown to be cross-resistant to fidaxomicin.4 [DrugBank]

SMILES:

CCc1c(Cl)c(O)c(Cl)c(O)c1C(=O)O[C@H]1[C@H](O)[C@H](OC)[C@H](OC/C2=C\C=C\C[C@H](O)/C(C)=C/[C@H](CC)[C@@H](O[C@@H]3OC(C)(C)[C@@H](OC(=O)C(C)C)[C@H](O)[C@@H]3O)/C(C)=C/C(C)=C/C[C@@H]([C@@H](C)O)OC2=O)O[C@@H]1C

2D structures:  

3D structures: