OP-1118

OP-1118 is the primary active metabolite of fidaxomicin, a macrolide antibiotic. OP-1118 is formed by hydrolysis of fidaxomicin in the gastrointestinal tract and is present in feces at concentrations higher than the parent compound after oral administration of fidaxomicin. While OP-1118 retains antibacterial activity against *Clostridioides difficile* (C. difficile), it has a higher minimum inhibitory concentration (MIC) compared to fidaxomicin, meaning it is less potent. The mechanism of action is similar to fidaxomicin: OP-1118 inhibits bacterial RNA polymerase, preventing transcription and thus bacterial replication and survival. OP-1118 exhibits a prolonged postantibiotic effect compared to standard treatments like vancomycin. OP-1118 is not marketed independently as a drug, but its pharmacological properties and activity are essential for the clinical effects of fidaxomicin therapy in treating C. difficile infection[1][2][3][5][7][9].

Other names

Fidaxomicin Metabolite OP-1118