The Pill Box: tenofovir 2.0

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02 Mar 2015

Tenofovir 2.0

One of the most widely used antiretroviral drugs — tenofovir — has been re-formulated. So why the upgrade? Well, the original tenofovir (tenofovir disoproxil fumarate — or TDF) has been found, in some cases, to cause renal problems. The new compound, dubbed TAF (tenofovir alafenamide), better targets the immune cells, which allows for reduced dosing — meaning less toxicity. (TAFs dose is 10 percent of TDFs.)

TDF — available in its own right as Viread, or found in single-tablet combos AtriplaEviplera and Stribild — has also been associated with a small amount of bone loss (but this is usually within the first 12 months and not unique to TDF). So for people who have osteoporosis or who are already experiencing some renal dysfunction, TAF may be an alternative option. Your doctor will advise if a treatment change is required.

Ongoing research suggests people whose virus has built some resistance to TDF may have a better outcome with TAF instead — good news, considering tenofovir is the backbone drug for so many people living with HIV. As for side-effects, TAF has reported mild-to-moderate reactions including nausea, bloating, diarrhoea and headache.

In a nutshell: TAF offers equal effectiveness, but with less toxicity.

Truvada 2.0
Gilead has applied to the US Food and Drug Administration for approval of a new version of Truvada. The upgraded compound replaces tenofovir disoproxil fumarate (TDF) with tenofovir alafenamide (TAF). As already mentioned, TAF has a more favourable side-effect profile than TDF.

The application is backed by phase III clinical trials in which the improved formulation proved non-inferior in its ability to suppress HIV. However, Gilead has not filed for approval of the new Truvada as a preexposure prophylaxis as there have been no clinical trials of the tablet for that purpose. The drug — which will go under a new name — is only intended for use with other antiretrovirals to treat HIV in people age 12 or older.

Triumeq added to PBS 
The new single-tablet regimen (STR) Triumeq has been added to the Pharmaceutical Benefits Scheme. Developed by ViiV Healthcare, Triumeq has been found to be a highly effective, well-tolerated, easy-to-use antiretroviral drug. As the name suggests, Triumeq contains three medications: 600mg abacavir, 300mg lamivudine and 50mg of dolutegravir. It is the fourth STR available in Australia and is the only one not to contain tenofovir.