The US Food and Drug Administration and Johnson & Johnson have issued a new warning about the danger of possible liver damage and deaths in patients on the firm’s HIV drug Prezista.

In a letter posted on the agency’s website, Johnson & Johnson's Tibotec Therapeutics unit said it had received reports of liver injury and some fatalities since Prezista (darunavir) was approved in June 2006. It also reported 15 cases of drug-induced hepatitis among 3,063 patients in clinical trials.

However the letter also noted that the liver-injury reports have generally occurred in patients with advanced HIV disease who were also on several other medications, as well as those who had chronic active hepatitis B or C, which puts people at higher risk for liver injury. Tibotec added that a causal relationship between the aforementioned injuries and Prezista has not been established when prescribed in combination with Abbott Laboratories' Norvir (ritonavir).

The letter said doctors need to test patients before starting treatment with Prezista and should continue monitoring liver enzymes.