Importantly, the 24-week 'Five-on-Two-off' (FOTO) study results were presented in November 2008; these showed that when HIV-infected patients stable (viral load < 50 copies/mL) on Atripla® were randomised to continue treatment daily or to stop taking it at weekends, no difference in maintenance of undetectable viral load was observed. Eighty percent in the control arm and 83% in the 'weekend off' arm had a viral load < 50 copies/mL [4]. This suggests that either the drugs' effects, or the drugs themselves, persist for a significant time following drug intake cessation. However, the persistence time and the inter-individual variability of this parameter for the components of Atripla® have not been clearly defined.