Atazanavir is an active medical substance. It is used to treat HIV infection.
What is atazanavir?
Atazanavir is a medical active ingredient. It is used for the therapy of HIV infections. The drug atazanavir is commercially available in Germany under the name Reyataz. It is taken orally and is used to treat HIV infections. The drug belongs to the group of HIV protease inhibitors. The U.S. Food and Drug Administration (FDA) approved the drug in June 2003, followed by the EU in March 2004. The U.S. pharmaceutical company Bristol-Myers Squibb serves as the license holder.
Pharmacologic effect
Atazanavir possesses antiviral properties. The effect of the substance is based on the inhibition of HIV protease. This is exceedingly important in the maturation of the HIV virus. The viral HIV protease is bound by atazanavir. By inhibiting the viral enzyme, it is possible to stop the virus from replicating. When the replication process is interrupted, the viral load in the body is reduced. Most of atazanavir binds to proteins (albumin) in the blood. The drug is broken down hepatically via the cytochrome system. If another HIV protease inhibitor is taken, this leads to a slower breakdown of atazanavir in the liver. In this way, the drug can achieve a longer effect. The half-life of the substance is approximately seven to twelve hours. It is possible to combine atazanavir with NRTIs (nucleoside reverse transcriptase inhibitors). These are triptase inhibitors. The efficacy of atazanavir has been evaluated in several studies. It was found to have comparable efficacy to other HIV protease inhibitors.
Medical Application and Use
As part of combination antiretroviral therapy, atazanavir is used to treat HIV infection (AIDS). The drug is approved for adult patients. In contrast to other preparations, it is sufficient to take atazanavir only once a day. This is due to the long half-life of the drug. It is administered in the form of tablets, which the patient takes after a meal. The dosage of the drug is 1 x 300 milligrams or 1 x 100 mg per tablet. When taken, there is also a combination between atazanavir and a pharmacokinetic booster such as cobicistat or ritonavir. These agents belong to the group of CYP inhibitors. They have the property of decreasing the metabolic degradation of atazanavir. In the USA, it is now possible to administer a dose of 1 x 400 mg to certain patients. In this case, ritonavir is omitted. The tolerability of atazanavir is considered good. However, the drug should not be used in cases of hepatic insufficiency or hypersensitivity to the active ingredient.
Risks and side effects
Despite the positive tolerability, various adverse side effects are possible from taking atazanavir. For example, patients may experience jaundice (icterus), nausea, vomiting, abdominal pain, diarrhea, headache, dizziness, or muscle pain. In some cases, fever, sleep problems, rashes on the skin, depression, and peripheral neurological symptoms are also possible. Rarely, elevated cholesterol levels or lipid metabolism disorders such as lipodystrophy or hyperlipidemia are seen after taking the drug. Occasionally, an increase in bilirubin levels within the blood leading to jaundice may require discontinuation of treatment with atazanavir. In general, however, this agent is less likely to cause troublesome side effects than those caused by the use of comparable substances. Interactions with certain other drugs can pose a further health problem. However, this is also possible with the other protease inhibitors. For example, when taking atazanavir or other protease inhibitors, preparations such as the neuroleptic pimozide, midazolam or ergotoxins must not be taken. The reason for this is the success of an interaction with the system cytochrome P 450, which changes the plasma level in the body. Simultaneous intake of atazanavir with didanosine, efavirenz, clarithromycin or stavudine may cause changes in blood plasma levels.Since the drug also degrades the enzyme UGT 1A1 (uridine glucorosyl transferase) and thus inhibits the degradation of indirect bilirubin, it is not advisable to administer it together with drugs whose degradation is effected by UGT. These include the integrase inhibitor raltegravir and the protease inhibitor indinavir.
