be less likely to cause lipodystrophy. There may be some cross-resistant with other protease inhibitors. When boosted with ritonavir it is equivalent in potency to lopinavir for use in salvage'' therapy in people with a degree of drug resistance, although boosting with ritonavir reduces the metabolic advantages of atazanavir. Pregnancy No evidence of harm has been found among pregnant women taking atazanavir. It is one of the preferred HIV medications to use in pregnant women who have not taken an HIV medication before. It was not associated with any birth defects among over 2,500 live births observed. Atazanavir resulted in a better cholesterol profile and confirmed that it is a safe option during pregnancy. Contraindications Atazanavir is contraindicated in those with previous hypersensitivity (e.g., Stevens-Johnson syndrome, erythema multiforme, or toxic skin eruptions). Additionally, atazanavir should not be given with alfuzosin, rifampin, irinotecan, lurasidone, pimozide, triazolam, orally administered midazolam, ergot derivatives, cisapride, St. John's wort, lovastatin, simvastatin, sildenafil, indinavir, or nevirapine. Adverse effects Common side effects include: nausea, jaundice, rash, headache, abdominal pain, vomiting, insomnia, peripheral neurologic symptoms, dizziness, muscle pain, diarrhea, depression and fever. Bilirubin levels in the blood are normally asymptomatically raised with atazanavir, but can sometimes lead to jaundice. Mechanism of action Atazanavir binds to the active site HIV protease and prevents it from cleaving the pro-form of viral proteins into the working machinery of the virus. If the HIV protease enzyme does not work, the virus is not infectious, and no mature virions are made. The azapeptide drug was designed as an analog of the peptide chain substrate that HIV protease would cleave normally into active viral proteins. More specifically, atazanavir is a structural analog of the transition state during which the bond between a phenylalanine and proline is broken. Humans do not have any enzymes that break bonds between phenylalanine and proline, so this drug will not target human enzymes. Formulations Atazanavir is available as a 150 mg capsule, 200 mg capsule, 300 mg capsule, and 50 mg oral powder packet. The 300 mg capsule should reduce pill burden, as one 300 mg capsule may replace two 150 mg capsules. Nanoformulation of atazanavir is being tested in primates together with PI-booster ritonavir and NtRTI tenofovir for a long-acting therapy. References External links Bristol Myers Squibb CYP3A4 inhibitors HIV protease inhibitors 2-Pyridyl compounds Wikipedia medicine articles ready to translate World Health Organization essential medicines