Tenofovir disoproxil fumarate (TDF) is one of the most widely used antiretroviral drugs. It is highly effective in treating HIV,and for most people, generally safe and well-tolerated. However, in a small minority of cases it can cause kidney problems. And TDF has an impact on bones…for most people, this is small and not noticeable, but for some people, it may be more of a problem. TDF is included in the fixed-dose combination tablets Truvada, Atripla, Eviplera and Stribild.
There is now a newer version, tenofovir alafenamide (TAF). This is just as effective in treating HIV, but provides lower concentrations of the drug in the blood. This means it is much less likely to cause kidney and bone problems. TAF is included in the fixed-dose combination tablets Descovy, Genvoya and Odefsey.
Indeed, a three-year long study shows that the new version of tenofovir is better at maintaining an undetectable viral load and safer for the bones and kidneys than the older version of the drug. The three-year data come from a study in which people beginning HIV treatment for the first time, with normal kidney and bone health, were randomly allocated to either take a combination containing TDF or TAF.
In England, the newer version of tenofovir (TAF) is not routinely available to people beginning HIV treatment who do not have kidney or bone problems. The drug is however available to people who have been taking the older version, but have kidney or bone problems, or who have other medical reasons why they cannot take other HIV drugs.
A separate study of people with low bone mineral density (BMD) who switched from TDF to TAF is also of interest. After two years, bone mineral density in the spine and hip improved by 2.5% on average. A quarter of those who started the study with osteoporosis (weakened bones) no longer had this condition at the end of the study, although they still had osteopenia (lower bone mineral density than normal for their age).
The researchers say that – for people at risk of a fracture – switching from the older to newer version of tenofovir may be valuable.
More detail can be found here.