March 28, 2012
Fact Sheet 475).
Protease inhibitors prevent the protease enzyme from working. HIV protease acts like a chemical scissor. It cuts the raw material for HIV into specific pieces needed to build a new virus. Protease inhibitors "gum up" these scissors.
There are no absolute rules about when to start ART. You and your health care provider should consider your CD4 cell count, your viral load, any symptoms you are having and your attitude about taking ART. Fact Sheet 404 has more information about guidelines for the use of ART.
If you take atazanavir with other ARVs, you can reduce your viral load to extremely low levels, and increase your CD4 cell counts. This should mean staying healthier longer. Although other protease inhibitors lead to increases in blood fats, atazanavir does not. If you have high cholesterol or triglycerides, or other risk factors for heart disease, your physician might want you to use atazanavir.
Fact Sheet 126 for more information on resistance.
Sometimes, if your virus develops resistance to one ARV, it will also have resistance to other ARVs. This is called "cross-resistance."
Atazanavir provides blood levels that are high enough to control HIV that has already developed some resistance to other protease inhibitors.
Resistance can develop quickly. It is very important to take ARVs according to instructions, on schedule, and not to skip or reduce doses.
Patients who cannot tolerate ritonavir should take 400 mg of atazanavir. However, this is not recommended for patients who have taken other HIV medications and experienced treatment failure.
Dosing for children at least 6 years old is based on their weight and prior treatment history. For more information see www.aidsinfo.nih.gov/DrugsNew/DrugDetailNT.aspx?int_id=314.
Atazanavir is available in capsules of 100 mg, 150 mg, 200 mg and 300 mg. Store atazanavir at room temperature, protected from moisture. Keep it in a tightly sealed container.
Bilirubin is produced by the liver when old red blood cells are broken down. High levels of bilirubin can cause yellow skin or eyes. This is called jaundice. About 10% of patients using atazanavir got jaundice.
High bilirubin levels can be a sign of liver damage. However, this is usually not the case for people taking atazanavir because the drug blocks normal removal of bilirubin.
Atazanavir does not seem to increase the levels of fat or sugar in the blood. That is, triglyceride, cholesterol and glucose levels stay close to normal, unlike with other protease inhibitors. This could be an advantage for people who want to reduce their long-term risk of heart disease. It is not clear if atazanavir is associated with lower rates of body shape changes (lipodystrophy).
Atazanavir may cause immune reconstitution disease (IRIS, see Fact Sheet 483.)
Drugs to watch out for include other ARVs (especially efavirenz or nevirapine), drugs to treat tuberculosis (see Fact Sheet 518), for erectile dysfunction (such as Viagra), for heart rhythm (antiarrhythmics), and for migraine headaches. Interactions are also possible with several antihistamines (allergy medications), sedatives, drugs to lower cholesterol, and anti-fungal drugs. Make sure that your health care provider knows about ALL drugs and supplements you are taking.