Filibuvir (also known as PF-00868554, PF-868554) was a non-nucleoside orally available

NS5B Nonstructural protein 5B (NS5B) is a viral protein found in the hepatitis C virus (HCV). It is an RNA-dependent RNA polymerase, having the key function of replicating HCV's viral RNA by using the viral positive RNA strand as a template to catalyze ...

inhibitor developed by

Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation headquartered on 42nd Street in Manhattan, New York City. The company was established in 1849 in New York by two German entrepreneurs, Charles Pfizer ...

for the treatment of

hepatitis C Hepatitis C is an infectious disease caused by the hepatitis C virus (HCV) that primarily affects the liver; it is a type of viral hepatitis. During the initial infection people often have mild or no symptoms. Occasionally a fever, dark urine, a ...

. It binds to the non-catalytic Thumb II allosteric pocket of NS5B viral polymerase and causes a decrease in viral RNA synthesis. It is a potent and selective inhibitor, with a mean

IC50 The half maximal inhibitory concentration (IC50) is a measure of the potency of a substance in inhibiting a specific biological or biochemical function. IC50 is a quantitative measure that indicates how much of a particular inhibitory substance ...

of 0.019 μM against genotype 1 polymerases. Several filibuvir-resistant mutations have been identified, M423 being the most common that occurred after filibuvir monotherapy. It was intended to be taken twice-daily. Its investigation was discontinued in February 2013 due to strategic reasons.

References

Abandoned drugs NS5B (polymerase) inhibitors Lactones Triazoles Pyridines Pyrimidines Cyclopentanes {{Antiinfective-drug-stub