No significant differences in viral suppression between groups on daily dosing versus alternate-day dosing of combination fixed-dose tenofovir/emtricitabine/efavirenz (TDF/FTC/EFV, better known with the brand name of Atripla) were found in a randomised clinical trial published in AIDS by Dr Rita Bellagamba and colleagues at the Italian National Institute of Infectious Diseases.
While levels of efavirenz in plasma concentrations showed a significant decrease in the alternate-day dosing group, this did not significantly affect viral suppression.
Researchers are looking at the possibility of reduced doses of antiretrovirals with long half-lives, such as TDF/FTC/EFV. While efavirenz-based treatment is not as widely used in high-resource settings – due to concerns over neuropsychological symptoms and possible suicidal ideation/suicide – it is still widely used in developing countries, and with pregnant women.
Previous research included two randomised studies investigating treatment interruption using the FOTO strategy (five days on, two days off) in virally suppressed adults and young people on efavirenz-based treatment. When compared with standard schedules, there were no virological failures at 48 weeks. A proof of concept study looking at reduced dosing of TDF/FTC/EFV to three days a week showed no virological failure at 24 weeks. A recent double-blind, placebo-controlled randomised trial reported that a reduced dose of 400mg EFV was as successful at maintaining an undetectable viral load as the standard dose of 600mg at 48 and 96 weeks.