Chronic hepatitis B affects 5-10% of HIV patients in Western countries. 
Lamivudine should no longer be used as a single anti-HBV agent in HIV-HBV 
co-infected patients, given its limited antiviral potency and high risk of 
selection of resistance, which further results in wide cross-resistance to all 
other nucleoside analogues. Recent reports of transmission of 
lamivudine-resistant HBV in HIV patients are of especial concern, and large 
surveillance studies suggest that it may occur in up to 10% of new HBV 
infections in Western countries. Another worrisome aspect of the selection of 
lamivudine-resistant HBV is the potential for selection of vaccine escape 
mutants. Currently, tenofovir must be viewed as the drug of choice in HIV-HBV 
co-infected patients in whom antiretroviral therapy is advised. Its 
co-formulation with emtricitabine (Truvada) is particularly convenient for 
treating both HIV and HBV in co-infected individuals. While pegIFN-alpha 
monotherapy for 1 year may be considered for HIV-HBV coinfected individuals with 
good spontaneous HIV control (elevated CD4 cell count, low plasma HIV-RNA), and 
certain HBV features (genotype A, HBeAg+, low serum HBV-DNA and elevated ALT), 
it is clear that very few coinfected patients fulfill these criteria. In 
HBeAg-negative HIV patients, adefovir may be an option but the relatively low 
antiviral potency of this drug discourages its wide use. Given its potential 
anti-HIV activity, both entecavir and telbivudine must only be prescribed with 
antiretroviral agents. Lack of information about potential pharmacodynamic 
interactions between entecavir and abacavir (both are guanosine analogues) or 
between telbivudine and zidovudine or stavudine (all are thymidine analogues) 
further discourages their concomitant use. At this time, most experts agree that 
early introduction of anti-HBV active HAART is the best strategy for the 
treatment of chronic hepatitis B in HIV patients, and Truvada must be part of 
the triple regimen.