Once in cells, pharmacologically active tenofovir diphosphate has favorable antiviral activity, selectivity and persistence.

Tenofovir in parent form lacks oral bioavailability and has poor cell membrane permeability.

Tenofovir disoproxil fumarate is generally well tolerated clinically but is associated with effects on the kidney and bone.

Tenofovir alafenamide more efficiently delivers tenofovir to target cells resulting in lower plasma and kidney exposures.

Clinical studies have shown tenofovir alafenamide has reduced impact on markers of renal function and bone mineralization.