It is estimated that over 230,000 Australians are living with chronic hepatitis C. Viekira Pak is indicated for the treatment of genotype 1 infection; the dominant genotype seen in Australia.

Viekira Pak contains a fixed dose combination of paritaprevir, ritonavir and ombitasvir; copackaged with dasabuvir tablets. The inclusion of ritonavir, a HIV protease inhibitor, is an interesting choice. Although ritonavir has no activity against the hepatitis C virus, it acts as a pharmacokinetic enhancer to increase plasma concentrations of paritaprevir. The other antivirals have direct activity against the hepatitis C virus, targeting different steps in the viral replication process. Viekira Pak-RBV is also available with the addition of ribavirin. Clinical trials examining both formulations have demonstrated a sustained virologic response is achieved in 97% of patients.

The introduction of Viekira Pak into Australia coincides with a health warning issued by the US Food and Drug Administration (FDA). Post-marketing surveillance has shown that Viekira Pak can cause serious liver injury, particularly in patients with underlying advanced liver disease. Patients should be closely monitored for signs and symptoms of worsening liver function. Caution should also be exercised in patients taking strong enzyme inducers or P-glycoprotein inhibitors as plasma concentrations are expected to be higher in these patients.

References:

  1. McGregor S, McManus H, Gray R, Costello J. HIV, viral hepatitis and sexually transmissible infections in Australia: Annual Surveillance Report 2015. Sydney: The Kirby Institute for infection and immunity in society. 2015.
  2. Viekira Pak (paritaprevir/ritonavir/ombitasvir/dasabuvir) Australian approved product information. Mascot: AbbVie Pty Ltd. Approved 20 July 2015.

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