Celgosivir, in development by Migenix for the treatment of hepatitis C virus (HCV) infection, is an oral prodrug of the natural product castanospermine that inhibits alpha-glucosidase I, an enzyme that plays a critical role in viral maturation by initiating the processing of the N-linked oligosaccharides of viral envelope glycoproteins.

Celgosivir is well absorbed in vitro and in vivo, and is rapidly converted to castanospermine.

Celgosivir has a novel mechanism of action (preventing the glycosylation of viral proteins by the host), and demonstrates broad antiviral activity in vitro.

[1] Celgosivir is not efficient as a monotherapy for the treatment of HCV, but has demonstrated a synergistic effect in combination with pegylated interferon alfa-2b plus ribavirin, both in vitro and in phase II clinical trials that last up to 1 year in patients with chronic HCV infection.

Celgosivir may prove to be a valuable component for combination therapy and may help to prevent the apparition of drug resistance.