People with HIV who have severe hepatitis C virus (HCV)-related liver disease (cirrhosis) may be able to safely take Reyataz (atazanavir) without worsening their liver condition, according to a study published online March 17 in the journal AIDS.

Reyataz is one of the best tolerated protease inhibitors (PIs) available, and though it can cause significant elevations in a liver enzyme called bilirubin, it does not appear in clinical trials to negatively affect the liver in other ways—certainly no more so than other PIs.

While Reyataz is commonly used in people with milder forms of liver damage, some providers have expressed concerns about using it in people with cirrhosis. This is because advanced liver disease—just like Reyataz—can raise bilirubin levels. Adding Reyataz, therefore, might make it difficult to know whether a person’s increased bilirubin is being caused by Reyataz, and therefore harmless, or if the increased bilirubin is a sign of worsening disease.

To help shed light on this situation, Jose Rodriguez, MD, and his colleagues from the Hospital Ramón y Cajal in Madrid examined the medical records of 92 people coinfected with both HIV and hepatitis C virus (HCV) who had cirrhosis, 34 of whom were prescribed Reyataz at some point.

The majority were treatment experienced and had undetectable HIV levels when starting Reyataz. Roughly three quarters had a milder form of cirrhosis, and the other 26 percent had more severe cirrhosis. Most of the study participants (76 percent) used Reyataz in conjunction with low-dose Norvir (ritonavir). Only one person stopped taking Reyataz because of increases in other liver enzymes. The average length of time on Reyataz was about 15 months.

Though Reyataz did cause bilirubin elevations, the authors state that the elevations—surprisingly—were no greater than those seen in people without liver disease. Also, though people with more severe cirrhosis had higher bilirubin elevations than those with less severe cirrhosis, the difference was not large.

This finding had two practical implications. First, contrary to previous concerns, adding Reyataz did not make it difficult to determine if a person’s increased bilirubin levels were due to the drug or to worsening liver disease. Secondly, because the bilirubin increases were of a relatively small and predictable size, they did not significantly worsen a person’s model for end-stage liver disease (MELD) score, which is used to determine the urgency with which someone should receive a liver transplant.

Rodriguez and his colleagues concede that because their study did not randomly assign people to either Reyataz or another antiretroviral medication, it isn’t possible to say with certainty that it is always safe in this population, or to pinpoint those individuals who should not use it. They do state, however, that Reyataz can be safely used in at least some people with more severe liver disease.

“Atazanavir did not worsen hepatic function in more than 500 patient-months of follow-up. According to this data, [Norvir-] boosted and unboosted atazanavir could be considered a safe option in patients with cirrhosis in the clinical setting,” they conclude.