Atazanavir

At Atazanavir it is a medicinal substance. It is used to treat HIV infections.

What is atazanavir?

The drug atazanavir is commercially available in Germany under the name Reyataz®. It is taken orally and is used to treat HIV infection. The agent belongs to the group of HIV protease inhibitors.

The US Food and Drug Administration (FDA) approved the product in June 2003. The EU joined in March 2004. The American pharmaceutical company Bristol-Myers Squibb acts as the license holder.

Pharmacological effect

Atazanavir has antiviral properties. The effect of the substance is based on the inhibition of the HIV protease. This is extremely important in the maturation of the HIV virus. Atazanavir binds the HIV viral protease. By inhibiting the viral enzyme, it is possible to prevent the virus from multiplying. If the reproduction process is interrupted, the viral load in the body is reduced.

Most of atazanavir binds to proteins in the blood. The active ingredient is broken down hepatically via the cytochrome system. Taking another HIV protease inhibitor causes atazanavir to break down more slowly in the liver. This way the remedy can have a longer effect. The half-life of the substance is around seven to twelve hours.

It is possible to combine atazanavir with NRTIs (nucleoside reverse transcriptase inhibitors). These are transcriptase inhibitors.

The strength of atazanavir has been checked in several studies. A comparable effect with other HIV protease inhibitors was found.

Medical application & use

Atazanavir is used in combination antiretroviral therapy to treat HIV infection (AIDS). The product is approved for adult patients.

In contrast to other preparations, it is sufficient to take atazanavir only once a day. This fact is due to the long half-life of the drug. It is administered in the form of tablets that the patient takes after a meal. The dosage of the agent is 1 x 300 milligrams or 1 x 100 mg per tablet.

When taken, there is also a combination of atazanavir and a pharmacokinetic booster such as cobicistat or ritonavir. These drugs belong to the group of CYP inhibitors. They work by reducing the metabolic breakdown of atazanavir. In the USA it is now possible to give certain patients a dose of 1 x 400 mg. Ritonavir is not used.

Atazanavir is well tolerated. However, the agent may not be used in the event of liver insufficiency or hypersensitivity to the active ingredient.

Risks & side effects

Despite the positive tolerability, various undesirable side effects are possible when taking atazanavir. Jaundice (jaundice), nausea, vomiting, abdominal pain, diarrhea, headache, dizziness or muscle pain can occur in patients. In some cases, fever, problems sleeping, rashes on the skin, depression, and peripheral neurological symptoms are also possible.

Rarely do elevated cholesterol levels or fat metabolism disorders such as lipodystrophy or hyperlipidemia occur after taking the drug. Occasionally, increases in blood bilirubin that lead to jaundice may require treatment with atazanavir to be stopped. In principle, however, there are fewer annoying side effects with this agent than with the use of comparable substances.

Another health problem can be interactions with certain other drugs. However, this is also possible with the other protease inhibitors. Thus, 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 successful interaction with the system cytochrome P 450, which changes the plasma level in the body.

Concomitant use of atazanavir and didanosine, efavirenz, clarithromycin, or stavudine may cause changes in blood plasma levels.

Since the drug also breaks down the enzyme UGT 1A1 (uridine glucorosyl transferase) and thus inhibits the breakdown of indirect bilirubin, it does not make sense to give it together with drugs that are broken down by UGT. These include the integrase inhibitor raltegravir and the protease inhibitor indinavir.