NTCP

Class

NTCP inhibitor (bile-acid transport modulator)

NTCP (sodium/taurocholate co-transporting polypeptide) is a transport protein located on the surface of hepatocytes, the main functional cells of the liver, where it normally imports bile acids from the bloodstream back into the liver as part of the enterohepatic circulation—the recycling loop that moves bile acids between liver, gut, and blood. NTCP also serves as the cellular entry receptor exploited by the hepatitis B and hepatitis D viruses: these viruses use a region of their envelope protein to latch onto NTCP and gain access into hepatocytes. Because of this dual role, molecules that block NTCP can prevent viral particles from entering uninfected liver cells, limiting the spread of infection within the liver even though they do not directly clear virus already inside infected cells. This mechanism is particularly relevant to chronic hepatitis B and hepatitis D infection, conditions in which ongoing infection of new hepatocytes drives disease progression toward liver fibrosis, cirrhosis, and liver cancer. NTCP inhibitors are typically administered as peptides designed to mimic the viral binding region, competitively occupying the receptor. Because NTCP also normally handles bile acid transport, its inhibition intersects with liver bile handling physiology, which is a consideration in how this class of therapy is used.