Telbivudine: a new nucleoside analogue for the treatment of chronic hepatitis B.

Telbivudine, beta-L-2'-deoxythymidine (LdT), is a new beta-L-nucleoside analogue with potent inhibitory activity against the hepatitis B virus. In in vitro studies and animal models, telbivudine has demonstrated potent and specific antiviral activity against hepatitis B. Additionally, in preclinical animal toxicology studies, telbivudine showed no adverse side effects or adverse effects on mitochondrial function. The promising results of the early in vitro and animal telbivudine studies prompted the development and initiation of Phase I and II human clinical trials. The Phase I clinical study demonstrated that end-of-treatment virological response rates were better for telbivudine recipients at multiple dosing levels as compared with placebo patients. The subsequent Phase IIb human clinical study demonstrated superior antiviral efficacy of telbivudine, significantly better ALT normalisation and better hepatitis B e-antigen loss as compared with lamivudine. Telbivudine was well tolerated with no identified safety issues. Virological breakthrough with telbivudine was significantly lower than with lamivudine.