Tibotec has updated its prescribing information for the protease inhibitor Prezista (darunavir) to include a warning about possible liver toxicity, according to a letter being sent to health care providers by the company in cooperation with the U.S. Food and Drug Administration (FDA). The previously unrecognized risk of drug-induced hepatitis primarily was highest among HIV-positive people with other risk factors for liver damage.
The package insert for Prezista, approved for use in combination with low-dose Norvir (ritonavir) by treatment-experienced HIV-positive patients, has been revised to warn that drug-induced hepatitis has been reported. In various clinical trials of the Norvir-boosted Prezista, with a combined study population of 3,063 patients, liver damage was found in 0.5 percent of patients receiving Norvir-boosted Prezista in combination with other antiretroviral drugs. In these studies, patients with preexisting liver problems, notably those who chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections, had an increased risk of liver-related abnormalities, including severe liver damage.
Cases of liver injury, including some fatalities, have also been documented in patients who have been taking the drug since its June 2006 approval by the FDA. Patients at risk included those using multiple medications for HIV, AIDS and other illnesses; those coinfected with HBV or HCV; and those experiencing immune reconstitution syndrome, a potential concern among patients who experience rapid improvements in their CD4 count after having a severely suppressed immune system.
While most HIV-positive people on HIV treatment have their liver function tests (LFTs) monitored regularly, Tibotec reiterates that this is strongly recommended prior to starting therapy with Norvir-boosted Prezista and for as long as this regimen is used. If there is evidence of new or worsening liver problems—including significant elevations in LFTs or symptoms such as fatigue, anorexia, nausea or yellowing of the skin and eyes (jaundice)—Norvir-boosted Prezista may need to be discontinued.
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