April 29, 2009

Prezista Levels in the Brain High Enough to Control HIV

Levels of the protease inhibitor (PI) Prezista (darunavir) are high enough in cerebrospinal fluid (CSF) to control HIV reproduction in the brain, according to a study published in the April issue of AIDS Research and Human Retroviruses. Suppressing HIV in the brain may help prevent thinking and memory problems as people living with the virus age, though this has not been proved in clinical trials.

Studies presented this past winter at the 16th Conference on Retroviruses and Opportunistic Infections make clear that cognitive problems are a common and growing concern in people with HIV, especially as they get older.  Some experts studying HIV activity in the brain recommend people with cognitive problems—or who are at risk for them, such as people also dealing with diabetes or hepatitis C—include in their regimens antiretroviral (ARV) medications proved to penetrate the brain.

Because of a barrier between the blood stream and the brain, however, not all ARV drugs reach the central nervous system (CNS). PIs typically have the most difficult time getting into the CNS. But combined with Norvir (ritonavir)—low doses of Norvir increase concentrations of other PIs in the body—they achieve much better penetration.  

To determine brain penetration with Norvir-boosted Prezista—one of the newest PIs that haven’t been studied fully for CNS penetration potential—Aylin Yilmaz, PhD, from the University of Gothenburg in Sweden, and her colleagues compared blood and CSF levels of the drug in eight HIV-positive patients. In all, the authors compared 14 paired samples.

Yilmaz’s team found that Prezista was detectable in all CSF samples. What’s more, the researchers demonstrated, Prezista levels were within or exceeded the range necessary to control HIV reproduction in the majority of samples.

“[It is] probable that [Prezista], at least to some extent, contributes to the suppression of HIV replication in the central nervous system,” Yilmaz’s group concludes.

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