Entecavir (Baraclude) is a nucleoside analogue that is used as a treatment for chronic hepatitis B virus infection. It is manufactured by Bristol-Myers Squibb and is available as tablets and a solution. During development, it was known as BMS-200475.

Entecavir works by inhibiting the hepatitis B virus’s enzyme DNA polymerase, preventing new viruses from being made. It is not active against HIV.

Entecavir was approved for marketing in the United States in March 2005 and in the European Union in June 2006. It can be used to treat patients infected with hepatitis B virus and for patients co-infected with hepatitis B and HIV, who have previously received 3TC (lamivudine, Epivir / Zeffix).

The approval for hepatitis B mono-infected patients was based on data from one year of treatment in nucleoside-treatment-naive and 3TC-resistant adult patients with hepatitis B e antigen-positive, or -negative chronic hepatitis B infection with compensated liver disease. Entecavir was more effective than 3TC in patients with no treatment experience, as well as those with 3TC resistance

The approval for HIV coinfected patients was based on more limited data from a randomised, double-blind, placebo-controlled study of entecavir versus placebo in 68 individuals co-infected with HIV and hepatitis B. All of the patients had experienced recurrence of hepatitis B viral load while receiving an antiretroviral therapy regimen containing 3TC. After 24 weeks, the mean hepatitis B viral load fell by 3.66 log₁₀ with entecavir but rose by 0.11 log₁₀ in the placebo group^[1].

Entecavir’s side-effects include headache, tiredness, dizziness, nausea and infections of the respiratory tract.

Entecavir use cannot lead to HIV resistance, nor does it not interact with any of the protease inhibitors or non-nucleoside reverse transcriptase inhibitors.

The recommended dose of entecavir for chronic hepatitis B virus infection in nucleoside analogue treatment-naive adults and adolescents 16 years of age and older is 0.5mg once a day. For patients with a history of detectable hepatitis B viral loads while receiving 3TC or known 3TC resistance mutations, the recommended dose is 1mg once a day. The higher dose must be taken at least two hours before or two hours after a meal.