Atazanavir

Atazanavir, sold under the brand name Reyataz among others, is an antiretroviral medication used to treat HIV/AIDS.<ref name=AHFS2016/> It is generally recommended for use with other antiretrovirals.<ref name=AHFS2016/> It may be used for prevention after a needlestick injury or other potential exposure (postexposure prophylaxis (PEP)).<ref name=AHFS2016/> It is taken by mouth.<ref name=AHFS2016/>

Common side effects include headache, nausea, yellowish skin, abdominal pain, trouble sleeping, and fever.<ref name=AHFS2016/> Severe side effects include rashes such as erythema multiforme and high blood sugar.<ref name=AHFS2016/> Atazanavir appears to be safe to use during pregnancy.<ref name=AHFS2016/> It is of the protease inhibitor (PI) class and works by blocking HIV protease.<ref name=AHFS2016/>

Atazanavir was approved for medical use in the United States in 2003.<ref name=AHFS2016>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It is on the World Health Organization's List of Essential Medicines.<ref name="WHO23rd">Template:Cite book</ref> It is available as a generic medication.<ref>Template:Cite press release</ref>

Medical uses

File:Atazanavir (Reyataz)200mg.jpg

Two Reyataz 200 mg capsules

Atazanavir is used in the treatment of HIV. The efficacy of atazanavir has been assessed in a number of well-designed trials in ART-naive and ART-experienced adults.<ref name="atazanavir">Template:Cite journal</ref>

Atazanavir is distinguished from other protease inhibitors in that it has lesser effects on lipid profile and appears to be less likely to cause lipodystrophy. There may be some cross-resistant with other protease inhibitors.<ref name=AHFS2016/> 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.Template:Medical citation needed

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.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref name=":0" />

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.<ref name=":1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Atazanavir inhibits the enzyme UDP glucuronosyltransferase (UGT) 1A1, thereby impacting the hepatic glucuronidation and elimination of bilirubin.<ref name="Gammal et al., 2016">Template:Cite journal</ref> As such atazanavir may not be prescribed to patients with UGT1A1 deficiencies (e.g. those who suffer from Gilbert's syndrome or Crigler–Najjar syndrome) in order to avoid the possibility of jaundice.<ref name="Gammal et al., 2016" />

Adverse effects

Common side effects include: nausea, jaundice, rash, headache, abdominal pain, vomiting, insomnia, peripheral neurologic symptoms, dizziness, muscle pain, diarrhea, depression and fever.<ref name=":1" /> Bilirubin levels in the blood are normally asymptomatically raised with atazanavir, but can sometimes lead to jaundice.Template:Cn

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.<ref>Template:Cite journal</ref> If the HIV protease enzyme does not work, the virus is not infectious, and no mature virions are made.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Humans do not have any enzymes that break bonds between phenylalanine and proline, so this drug will not target human enzymes.Template:Cn