The Therapeutic Goods Administration (TGA) has advised that direct-acting antiviral (DAA) medications for the treatment of chronic hepatitis C are associated with reactivation of the hepatitis B virus (HBV). Unlike other medications linked with this adverse effect, DAAs are not known to be immunosuppressant.

Although the mechanism for HBV reactivation is unclear, studies suggest that co-infection with hepatitis B and hepatitis C inhibits the replication of each virus. DAAs produce a rapid reduction in the hepatitis C viral load which, coupled with their lack of activity against HBV, is thought to trigger HBV reactivation in some patients.

The high sustained virological response rates achieved with DAAs likely outweigh the risk of HBV reactivation. The TGA recommends that patients are screened for evidence of current or past HBV infection before a DAA is prescribed. Patients who test positive should be monitored for potential HBV reactivation and treated according to current guidelines. Hepatitis B vaccination may be considered for patients who are serologically negative.

DAA medications available in Australia include:

  • Asunaprevir (Sunvepra®)
  • Daclatasvir (Daklinza®)
  • Elbasvir / grazoprevir (Zepatier®)
  • Ledipasvir / sofosbuvir (Harvoni®)
  • Ombitasvir / paritaprevir / ritonavir and dasabuvir (Viekira Pak®) plus ribavirin (Viekira Pak-RBV®)
  • Sofosbuvir (Sovaldi®)

Despite only being listed on the Pharmaceutical Benefits Scheme (PBS) on 1st March 2016, ledipasvir / sofosbuvir represented the greatest cost to the PBS for a single item during the 2015-2016 financial year; sofosbuvir was the fourth highest. These figures illustrate that although these medications are expensive, there has been a high and rapid uptake of DAAs within the community.

References:

  1. Department of Health. Direct-acting antiviral medicines: safety advisory – risk of hepatitis B virus reactivation. Canberra: Therapeutic Goods Administration; 2016.
  2. Department of Health. Expenditure and prescriptions twelve months to 30 June 2016. Canberra: Pharmaceutical Benefits Scheme; 2016.
  3. Yu G, Wu R, Wang X, Gao X, Kong F, et al. Replication inhibition of hepatitis b virus and hepatitis c virus in co-infected patients in Chinese population. PLoS One. 2015; 10(9): e0139015.

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