Uprifosbuvir

Uprifosbuvir (MK-3682) is an antiviral drug developed for the treatment of hepatitis C. It is a nucleotide analogue which acts as an NS5B RNA polymerase inhibitor. it was in Phase III human clinical trials.

In 2017 owner Merck wrote down the value of uprifosbuvir to US$240 million, for a write-down of $2.9 billion, reducing its earnings per share from 42¢ to a loss of 22¢ for the fourth quarter of 2016. This was attributed to the hepatitis C drug market rather than uprifosbuvir itself; the population of treatable patients diminished rapidly after the introduction in 2014 of sofosbuvir and the combination ledipasvir/sofosbuvir, drugs that cured hepatitis C, and whose market was also diminishing following their success in curing patients. Clinical testing of uprifosbuvir continued.