Taking it

In the European Union, boosted atazanavir (Reyataz) is taken once daily as one 300mg capsule with a 100mg dose of ritonavir. It can also be dosed with two 150mg capsules plus one 100mg ritonavir (Norvir) capsule once a day. Atazanavir is approved for use by treatment-naive and treatment-experienced patients in the United States and the European Union.

In the United States, the approved dosing for treatment-naive patients is 300mg ATV/100mg RTV once daily with food or atazanavir 400mg once daily with food. If taken in combination with efavirenz or tenofovir, both of those drugs are dosed normally, but the recommendation is to use boosted ATV (300mg/r 100mg once daily).

If using unboosted atazanavir, ARV-naive patients should avoid the combination of enteric-coated didanosine with tenofovir.^[1] 

Treatment-experienced patients should take 300mg ATV/100mg ritonavir daily with food. Unboosted atazanavir is not recommended.

Experimental doses of 300 or 400mg atazanavir plus 200mg ritonavir have been shown to improve atazanavir exposure in patients with suboptimal levels on the standard boosted dose.^[2]

A dosing study in uninfected volunteers found that taking 400mg atazanavir with food increased drug concentrations by 35 to 70%, so taking the drug without food could result in failing to meet the necessary pharmacokinetic targets for efficacy. Atazanavir should also not be taken with proton pump inhibitors or antacids as the AUC of atazanavir is decreased with co-administration.

Atazanavir should not be used in patients with severe liver damage. A dose reduction ot 300mg once daily should be made for someone with moderate liver damage (Child-Pugh Class B). In cases of mild liver damage, it should be used with caution.

Treatment-naive patients with end-stage renal disease managed with haemodialysis should receive 300 mg of atazanavir with 100 mg of ritonavir. Atazanavir should not be given to treatment-experienced patients with end-stage renal disease managed with haemodialysis.^[3]