Great news from the 2013 AASLD Liver Meeting regarding a new, lower-dose formulation of Tenofovir for the treatment of hepatitis B
Published Thursday, 21 November 2013 00:00Written by Liz Highleyman
A new formulation of tenofovir that can be taken at lower doses demonstrated potent activity against hepatitis B virus (HBV) similar to that of the existing formulation in a 28-day study, but with less effect on kidney function, researchers reported at the 64thAASLD Liver Meeting this month in Washington, DC.
Gilead Science’s tenofovir disoproxil fumarate (TDF, brand name Viread) — the currently marketed formulation — is one of the most effective antiviral drugs for hepatitis B as well as one of the most widely used antiretrovirals for HIV. TDF is generally safe and well-tolerated, but it can cause kidney toxicity in susceptible individuals and is also associated with bone loss.
A new pro-drug formulation known as tenofovir alafenamide (TAF, formerly GS-7340) produces 5-fold higher concentrations of active tenofovir diphosphate in lymphoid cells that harbor HIV, but is more stable in plasma and results in lower blood drug levels and systemic exposures than those seen with TDF. This allows for reduced dosing with potentially less detrimental effect on the kidneys and bones.
Over the past year researchers have reported that a 10 mg dose of TAF is as effective against HIV as a 300 mg dose of TDF through 48 weeks in Phase 2 studies, but the former has less impact on markers of kidney function and bone mineral density.