Atazanavir launched in UK

On 10 March, atazanavir, the once-daily protease inhibitor from Bristol-Myers Squibb, was approved as a ritonavir-boosted treatment in Europe for patients who have already used one previous treatment. Approval was not granted for treatment naïve patients, although in practice many doctors will be interested in this option. Atazanavir was approved in the US in June 2003 for both first-line and salvage therapy.

When boosted, atazanavir should be used in a 300mg once-daily dose boosted with 100mg ritonavir. Trials with unboosted atazanavir use 400mg once-daily. Patients with >5-fold ULN increases in bilirubin during expanded access to atazanavir in the UK were often managed by switching to the 400mg unboosted dose, although this is not possible if tenofovir is included in the combination because of a significant negative drug interaction.

The US product label was recently amended to include new information about two drug interactions. Firstly, the two-way interaction with tenofovir requires that atazanavir has to be boosted by ritonavir when used in a tenofovir-containing regimen (see above), and that the patient will also require monitoring for tenofovir-associated side effects (as tenofovir levels are increased).

Secondly, information regarding PDE5 inhibitors (sildenafil [Viagra], tadalafil [Cialis] and vardenafil [Levitra]) was added to the warnings and precaution sections. The information included is consistent with the recently approved saquinavir (Invirase and Fortovase) label.